Leisure Battery

Thanks David - that’s really helpful - we’ll look into those batteries.  Did you need to get a new tray/case?

Doonhamer5 wrote:Hi Peter, what Ah were these batteries?  Is it OK to add more than one battery when AS suggest 75-120 Ah in the manual?   Although the manual says that some installations can have 2 batteries in parallel, it only refers to the fuses and not to the overall capacity.  How do you know whether your installation is OK for 2 batteries (assuming that the Malvern is OK from this thread - but you found problems)?  Are there any other wiring considerations?   Is a set-up like this something you’d recommend, or is it more trouble than it’s worth?

Just been reading the online version of the PX-300 charger unit instructions (for other reasons) which confirm it will cope with two batteries up to 220ah total. Just look up PX-300 battery charger and it is avaiable on Sergent website.

David

Good to know the charger definitely copes.

The reason we’re thinking about is is because we want to be able to go for more than 2 days off hook-up.  The battery we removed was 110Ah, so perhaps was not the original, but it didn’t cope well with usage in low temperatures. 

The replacement we got in France is a 100Ah AGM (selected by the shop on our behalf, we only had 5 mins before it shut).  I read that there are concerns with AGM, although the Autosleeper manual suggests that the charger can cope with them OK.  We had no further issues once it was in place, and I was even able to use the heating overnight.   

If we had had more time to think about it, we might have bought 2 at the time.  I like the idea of no maintenance / no venting worries, though it does seem that people tend to avoid AGM.

No both batteries fitted side by side beneath the (Merc) passenger seat, strapped down and packed at sides. The fitter has also used plastic capped terminal blocks for extra protection.
 
The Varta LFD90 - although a form of lead acid - is also maintenance free.

David

Doonhamer5 wrote:Good to know the charger definitely copes.

The reason we’re thinking about is is because we want to be able to go for more than 2 days off hook-up.  The battery we removed was 110Ah, so perhaps was not the original, but it didn’t cope well with usage in low temperatures. 

The replacement we got in France is a 100Ah AGM (selected by the shop on our behalf, we only had 5 mins before it shut).  I read that there are concerns with AGM, although the Autosleeper manual suggests that the charger can cope with them OK.  We had no further issues once it was in place, and I was even able to use the heating overnight.   

If we had had more time to think about it, we might have bought 2 at the time.  I like the idea of no maintenance / no venting worries, though it does seem that people tend to avoid AGM.

Doonhamer5, Since Swift have started installing AGM batteries the number of failed Sargent PX 300's has increased.

An AGM battery not only requires 14.7v for optimum life but can also draw a lot more current.
Sargent quote that the Sargent PX300 was designed to charge wet acid batteries. It has been around quite a long time, since before most AGM's were considered an option in motorhomes and it hasn't changed fundamentally in that time.
 
Obviously a charger designed to support wet acid batteries isn't going to have double the current charge capability that an AGM will try and suck out of the charger. 
The golden rule for most wet Acid mains chargers is that they support 10 times the charger output converted to Ah, so while the 25amp PX300 will, in theory support 210Ah, it's not as robust as most. 
But double the current a 200Ah AGM battery bank tries to draw, an equivalent 400Ah, and you can see it's a very different picture.

One 2018 model Swift owner went through 3 Sargent PX300 chargers since new. Swift/Dealer had replaced them under warranty without quibble, but found no reason for the failures. The owner went to A and N Caravan Services and we put the vehicle through it's paces with it's twin AGM batteries.
We were shocked at how much the PX300 struggled. When the owner additionally told us that the Dealer had told him "with AGM you can discharge them to 80%, no problem", we were surprised the third PX300 was still operating as that is a greater load again.


Despite what Sargent say, the PX300 is not an AGM suitable charger, let alone AGM optimised.

The AGM's were already well down on capacity, through not having been charged properly (the higher AGM load had also increased voltage drop when charging on Alternator so it was only charging at 13.5v, not the 14.4v we should have seen), so we advised a move to Yuasa L36-EFB's.

EFB (Enhanced Flooded Batteries) are the latest technology ousting AGM batteries in Cars, yet they don't require specialist chargers.
Like the best of the latest batteries, they are maintenance free.

We were contacted by Banner last Autumn and told the old Banner Energy Bull range, that drinks like a Fish, was about to be replaced with a EFB zero maintenance battery, but not heard anything since then.

There are lots of reasons to not fit AGM's.  Audi can probably give you millions, literally, well their battery recycling depot can.

As stated above Varta LFD90/Bosch L5's are as tough as old boots.

Thanks AllaFEvans.  Actually this is quite worrying.  We have spent way over the odds on the AGM battery because of our situation on holiday, and now we not only have a battery that might fail but it also might knacker the PX300?  We had been minded to use it as the vehicle battery while getting two new leisure batteries (our vehicle battery was drained flat twice by the tracker before we realised what was happening).  Are we now faced with the need for three new batteries?  Is it too dangerous to keep the AGM in place?  How much is a new PX300?  We are not under warranty.

Doonhamer5 wrote:Thanks AllaFEvans.  Actually this is quite worrying.  We have spent way over the odds on the AGM battery because of our situation on holiday, and now we not only have a battery that might fail but it also might knacker the PX300?  We had been minded to use it as the vehicle battery while getting two new leisure batteries (our vehicle battery was drained flat twice by the tracker before we realised what was happening).  Are we now faced with the need for three new batteries?  Is it too dangerous to keep the AGM in place?  How much is a new PX300?  We are not under warranty.

If you read our page on AGM batteries, http://www.aandncaravanservices.co.uk/agm-batteries.php  you will see it is a technology being 'abandoned' by those in the know. Audi, VW, BMW, Mercedes, Seat, etc. have either moved over to the better, cheaper, more robust EFB technology or are in the process of doing so. Even Land Rover are looking to replace AGM batteries with alternatives. The short experiment with AGM doesn't seem to have been an automotive industry success story, with reports of battery lifetime well short of the manufacturers claims.

While your existing AGM is unlikely to have more than 80% of it's rated capacity after 3 years, it is unlikely to fail suddenly, so I would go on using it. While AGM batteries are more prone to explosion/fire from thermal runaway the battery should tell you long before it breaks up that is past it's best.


The PX300 can be bought for about £115 on ebay or Amazon. You will find lots of suppliers, that might indicate a big demand for it, which there does seem to be, but it is also used to replace lesser model chargers. 
Although it doesn't have any intelligence (not at all smart) being a basic 3 stage unit, it is a huge improvement over many of the others out there which are little more than single stage Power Supplies.

Moving the Leisure AGM to the Starter Battery position might not be a bad idea, because if the existing Starter battery has run flat twice, it will have suffered damage.
It won't get the 14.7v it needs for ideal life, but the Alternator voltage at the Starter battery terminals should be higher than in it's current location so should be better off there and might give you 4+ years life?


Why was the Tracker wired off the Starter battery? Most modern Charger/controllers have for a long time had 'take off' points specifically for Alarms and Trackers, like the EC700 for example?
Most Habitation area battery banks will power a Tracker for twice as long and if it does take the batteries down low, it doesn't disable the vehicle.
I guess he was a car Alarm based guy who didn't understand motorhome electrics?


If I was in your position, I would move the AGM to the Starter battery slot, fit two new Yuasa's and get the Alarm wired from where motorhome manufacturers are providing wiring points for them. 
Even on the old Controller/chargers there are takeoff points that are permanently 'Live', even when the control panel is 'turned off'.

Just out of interest; if the PX300 is not the dumbest charger out there, is there a better alternative that’s suited to the larger bank of batteries and relatively easy to exchange with the PX300?
I’ve garnered some useful info from these posts and I’ve realised that my knowledge of battery care is no where near as good as I’d thought...


Ray

Struggling with quote functionality on the iPad...

“Why was the Tracker wired off the Starter battery? Most modern Charger/controllers have for a long time had 'take off' points specifically for Alarms and Trackers, like the EC700 for example?
Most Habitation area battery banks will power a Tracker for twice as long and if it does take the batteries down low, it doesn't disable the vehicle.
I guess he was a car Alarm based guy who didn't understand motorhome electrics?”

The Tracker was already fitted when we bought the van, and I think it was fitted by BC Motorhomes in Ayr, who had delivered the vehicle when it was new, as they are a Tracker dealer.  When we re-registered it, Tracker told us that the tracker battery was flat (it’s supposed to have it’s own one?) and came to service it, which was followed by our flat vehicle battery issues.  We’ve had it on EHU at home ever since, but hoping a solar upgrade might mitigate.  Not holding my breath given that Solway winters aren’t really very dry and sunny!

Libraryman2 wrote:Just out of interest; if the PX300 is not the dumbest charger out there, is there a better alternative that’s suited to the larger bank of batteries and relatively easy to exchange with the PX300?
I’ve garnered some useful info from these posts and I’ve realised that my knowledge of battery care is no where near as good as I’d thought...


Ray

Note that this reply excludes car battery chargers, like CTEK, which are not designed for motorhomes. To understand why we suggest you read our web page, "how a charger works" : http://www.aandncaravanservices.co.uk/how-does-a-charger-work.php

The Sargent PX300 isn't bad, but we would suggest it is about the lowest spec most motorhome owners should look to buy. Even though it is multi stage, it is single technology meaning it doesn't have separate charge profiles for Gel, AGM or Lithium batteries. 
The relatively recently introduced Sargent  201 and it's smaller sibling the 151 are just 13.5v fixed voltage power supplies of 10amp and 16amp. 
They won't properly charge any battery, which as you know likes a 'boost' of 14.4v. 
The 201 and 151 are used in the EC155 and  EC160 type units.
 

The BCA Powerpart chargers are similar to the Sargent 201, but late versions may also be multi stage. They are not intelligent/smart, even the 3 stage versions are dumb. Single battery technology profile, wet acid only. They generally don't have 'mains connected' signal output.


Nordelettronica NE287 21amp charger with Sargent compatible signal output at about £120. The latest version of the old NE143 charger is well built, sophisticated and limited multi battery technology. Although it is quite clever, it isn't really smart. Supports Gel and Wet, but not AGM.


 
Very few Motorhome/Caravan chargers are 'Smart' the Waeco PerfectCharge and the Victron range are pretty much the only main stream motorhome 'Smart' chargers around. A multi stage charger is rarely smart in our industry.
The issue is that many of these motorhome after market chargers don't have the 'Signal' output that often tells the LCD Controller unit that 'Mains' is connected. 
On most motorhomes/Caravans the 'mains connected' Icon is usually powered from the Charger 12v output, which obviously only lights when mains gets through to the charger.


Waeco Perfect charge - It is over £200 for the 25amp version, yet not that impressive. Despite it's 'Dometic' heritage it is more designed for boats than motorhomes. No signal output. 
Although it has twin battery output, the format is not compatible with the Sargent units.


The Victron charger range is Smart and very sophisticated, as well as having multistage fast charge functionality they have separate selectable profiles for Wet Acid, Gel, AGM, Lithium, etc. But it doesn't have a signal output to show 'mains connected", if you have that feature. But it's not hard to rig up.

They include a special long term 'Storage' charging function specifically designed to maintain batteries while on EHU in long term storage. 
These chargers work out the battery might be at risk of overcharge on long term EHU at 13.8v, so drops the rate down to 13.2v, which is the constant charge voltage used by Data Centre, Banks, Police, Hospitals for long term charging their standby batteries.
By dropping to a lower 13.2v rate, it reduces the risk of Antimony poisoning, over charge, rapid fluid loss, etc. 
How do Victron know this is a good idea? Because Victron Energy started as manufacturers of Standby system kit for Datacentres, etc. 

I went around the South Stacks Lighthouse on Anglesey and was surprised to see that all the backup power kit for the light, radio, etc was supplied by Victron. 

Every 22 days (or some similar time) the Victron charger 'wakes' up and boost charges the battery for an hour or two to reduce stratification of the battery acid. After an hour or so they drop back to 13.8v Float and then down into 13.2v 'Storage' mode.

 The Victron Blue Smart IP22 is just one of several ranges They tend to be about £169'ish for the 25amp version which should cope with 10 times it's output (the usual rule when sizing wet acid chargers) converted to AH. We wish all chargers had the storage mode feature.



The CBE CB516/520 20amp charger is the only charger which actually shuts down totally when the battery is charged, all others charge the battery 'fully' then drop to a short term Float/maintenance rate of about 13.6v - 13.8v.
The CBxxx charges at a Float of 13.8v and then powers off the charge totally. It then waits for the voltage to drop before switching back on.
Despite the 'shutdown' initially seeming a good idea, it has flawed implementation, relating to it's restart and other logic.
 
   

To fit the new charger :

To fit a Victron charger, or any other, to replace a failed PX300, just connect up the new charger following the old wiring layout. 
If the charger is a Sargent 151/201 inside the ECxxx housing then open the housing remove the power supply and fit the new charger following the existing cabling. 
Wiring it this way will will ensure the ECxxx passes the new chargers output to both Starter and Habitation battery.


You can just wire the new charger straight to the habitation battery if you wish, but you then lose the capability for it to charge the Starter battery.

 
For AGM batteries, the Victron Energy Blue Smart  IP22 30amp charger would be my suggestion as this is one of the few chargers that will give it the 14.7v an AGM needs.

I guess you already realise that the same Solar solution in Cornwall will harvest 30% less energy if you move it to North Scotland? 
You will be lucky to harvest 4Ah a day from a 100watt panel in mid December?

A Tracker can drop a Starter battery into the 'Sulphation' zone within 2 weeks so you will need a really efficient and quite powerful solution to provide enough power in mid Winter. 
Even a 300watt set-up typically harvests only 12Ah a day at that time of year.

Hi

AllaFEvans wrote:The PX300 can be bought for about £115 on ebay or Amazon. You will find lots of suppliers, that might indicate a big demand for it, which there does seem to be, but it is also used to replace lesser model chargers.
Although it doesn't have any intelligence (not at all smart) being a basic 3 stage unit, it is a huge improvement over many of the others out there which are little more than single stage Power Supplies.

The PX 300 is an intelligent charger by any industry standard,  “intelligent” meaning that it has built in electronic monitoring and control either by a microprocessor or dedicated battery charger chip.
A smart charger may, but does not have to have built in network communications and in any case how many motorhome owners would use that if it did?. We tend to use the term intelligent rather than smart nowadays to differentiate from chargers for “smart batteries”.

AllaFEvans wrote:Since Swift have started installing AGM batteries the number of failed Sargent PX 300's has increased.

If you are suggesting that that is proof that the PX300 cannot charge AGM batteries it isn't. There are a whole host of possible reasons for a failure. You need to provide hard data,what was the failure rate before, what was the failure rate afterwards and fundamentally what was the fault (was it the same in all cases)?

If Swift fitted the chargers I suggest that the only people that could provide this are Swift themselves but if there is a generic problem with the PX300 it should be reported to Sargent for investigation.

AllaFEvans wrote:Obviously a charger designed to support wet acid batteries isn't going to have double the current charge capability that an AGM will try and suck out of the charger.

Not obvious at all.

Like all IUoU chargers the PX300,s main charge phase is constant current (manufacturers diagram above) It doesn’t matter what size or type of battery you charge, a charger in constant current mode will output exactly the same current. You cannot “suck” current out of or overload a charger in constant current mode. If the Sargent unit does not meet its specification again the matter should be reported to Sargent, along with measurement data to support the claim.

AllaFEvans wrote:One 2018 model Swift owner went through 3 Sargent PX300 chargers since new. Swift/Dealer had replaced them under warranty without quibble, but found no reason for the failures. The owner went to A and N Caravan Services and we put the vehicle through it's paces with it's twin AGM batteries. We were shocked at how much the PX300 struggled.

I’m afraid “Struggled” doesn’t tell us anything, in what way did it “struggle”?. What did you test and how did you test it? What results did you get and how did you interpret them. Perhaps most importantly what did Sargent Technical have to say?

For anyone interested, here is a document I created a couple of years ago showing how smart chargers work. It demonstrates constant current charging  by looking at some test and measurement data taken during a complete discharge / charge cycle. I think it is very relevant to the current discussion.

https://drive.google.com/file/d/1LjtQ_yszoSuP4cqtw_Csz4lLPiZYuxZ-/view?usp=sharing

The raw data is available here for anyone that wants to check it:

Parallel Pair
https://drive.google.com/file/d/1tWo5C_IDnNtDCV8-65lCZvs_wAJsEGZv/view?usp=sharing
Yuasa Alone
https://drive.google.com/file/d/1SlY0lyB_QFkXtOfYwfkmCGYKjo6zR906/view?usp=sharing
Fiamm Alone
https://drive.google.com/file/d/15A9HUhpEx3-vARuq0Xb786vAcVSLKlht/view?usp=sharing
Parallel Pair
https://drive.google.com/file/d/1tWo5C_IDnNtDCV8-65lCZvs_wAJsEGZv/view?usp=sharing

Brod

Brodco, an intelligent charger is one that makes 'decisions' based upon the circumstances found at the time. For example to initiate a desulphation phase if it detects sulphation may be an issue or to switch the normal phasing of stages like jumping back to an early stage if voltage drop is detected.
Almost zero motorhome chargers have intelligence, including the Sargent PX300. It has fixed criteria that will dictate when the next phase is initiated. It is unable to make decisions based on changing circumstances, just 3 fixed, steps.
 I think you are confusing multi stage fixed steps with intelligent decision making?



You then write, "Like all IUoU chargers the PX300's main charge phase is constant current ".

Sorry but that isn't true, if it were then throwing 25amps into a battery over 4 hours would shorten the life of even the best 100Ah battery. 

The first stage is not the main charging stage on a Leisure battery charger.
The purpose of the Stage 1 is to start the charge on what might be a fully discharged battery, yet motorhome batteries are seldom fully discharged. 
Stage 1 is an initial charge, it charges at max current and rising voltage, until the charger voltage (not the battery voltage which could still be a real 11.9v) reaches 14.3v.

There is a lot of confusion of this as some think that when the voltage at the battery reaches 14.3v, it is fully charged when it isn't.
So to explain further/show the difference between the battery voltage and voltage at the battery, try running your Starter battery down to 12.3v. Then start the engine and the Alternators 14.4v will be applied to the Starter battery. The voltage at the battery will leap to 14.4v almost immediately, yet the batteries true voltage is still only 12.3v. You will see a similar effect by turning on a good mains charger.
No matter what you do with the volt meter, you will not be able to 'see' the Starter batteries true voltage, which will be revealed if you shut off the engine straight away and wait a few hours. Then the batteries State Of Charge (SOC) voltage will slowly drop back to 12.3v within an hour or two.


Once the PX300 charger reaches 14.3v (once again I stress this is not the true battery voltage but the chargers voltage) it switches to Stage 2, which is the main charge phase for most Leisure batteries that will usually 'start' with significant capacity still in the battery, for example 50% DOD. 
The Stage 2 charge phase is not determined by any artificial intelligence or decision making but purely by a 'trigger', just dumb electronics.
Intelligence at this point would describe where one of several options can be selected by the charger based on various scenarios. 
The Sargent can't do that, only trigger a single, set action. 


Stage 2 
During the main charge, stage 2, the battery will charge at a constant voltage (14.3v) with the current reducing as the battery charges up
Once the battery is fully charged, it will drop to a Float/trickle voltage of around 13.6v - 13.8v.

Once again that change of stages is controlled by another trigger that is either timer based or uses a set current point. 
For example, most Car battery chargers drop down to 13.8v Float once the current being drawn by the battery reduces to below 1 or 2 amps. 
There is no decision making or intelligence at this point. Not several options that can be selected by the charger based on various scenarios. 
Just a trigger to put a single set action in motion. 
Sorry but by any definition that is not a Smart charger, a term misunderstood by many.


The best Leisure battery chargers drop down into the Float phase after a timer has expired, say 4 hours.
They operate like this to ensure a battery that has an issue and continues to draw 5 amps never charges indefinitely till it catches fire or explodes.

Car battery chargers are 'on charge' for just hours. Leisure battery chargers can be in operation for months, you obviously don't want to 'Boost' charge a duff battery at 14.4v for days, let alone weeks, hence the best Leisure battery chargers dropping to a safer voltage after a set time.
Not surprisingly, the absence of any safety timers on car chargers is one of the reasons it says not to leave them unattended. Even the newer underwelming CTEK's now have safety timers on most of it's stages.


AGM's
All the PX300 chargers we were sent were from AGM habitation battery vehicles. Every one. All overloaded and stressed.

When the Sargent PX300 is used to charge 2 x AGM batteries from 50% DOD, the first stage will expire very quickly, usually within minutes when the charger reaches 14.3v.
  
It is at this Stage 2 that the two AGM's try and draw double the current from the charger.
The charger runs with more current and for far longer than it does with conventional wet acid battery pair. 
It gets really, really hot. If you don't believe me, then try it. In our test it was not able to deliver the current being requested, even though it was flat out, but did try valiantly.

While the PX300 has current limiting and temperature sensing it is being driven way beyond design and will eventually succumb. As will all things run beyond their limits.
One charger we know of, has the 'shutdown' temperature sensor on the same heat sink as the 'power' electronics, but if the AGM's are discharged too low, the current draw is so high the components overheat and burn out before the heat has reached the temperature sensor to start limiting the power draw.


Sorry you don't like my term 'struggled', but the term reflects what we saw and analysed based on the 8 years we have been repairing chargers from Sargent, BCA, Toptron, Schaudt, Nordelettronica, Calira, Arsilicii, etc. and working on motorhome electronics.



As for your work with Smart chargers, is it relevant when there are so few in any in mainstream motorhomes, as already stated?

Then again, perhaps I am wrong and you can tell me what Smart/Intelligent chargers are installed in mainstream motorhomes and explain the intelligent decisions they make at each stage?

.

Wiki describes DIN 41773 as multi stage charging, it makes no reference anywhere to it being Smart or Intelligent charging


I am guessing you and Brod are both confusing IUoU multi stage charging with intelligence/Smart, when they are not?
Smart chargers may use multi stage charging, but not all multi stage chargers are Smart/intelligent, the Sargent PX300 definitely doesn't have any O' levels.

See this explanation from Wiki :
IUoU is a DIN-designation^[1] (DIN 41773) for a lead-acid battery charging procedure that is also known as 3-stage charging, 3-phase charging, or 3-step charging. It consists of three phases (or stages), to be executed by a battery charger. The three phases are: I-phase (constant electric current), Uo-phase (constant over-voltage), and U-phase (constant voltage). The purpose is to fully charge the battery in a relatively short time without reducing its life span and to indefinitely keep the battery charged as long as the charger is connected.


I think if you look at the definition of Smart charging on Wiki, it also doesn't mention DIN 41773 or multi stage charging at all. 
Wiki seems to think they are completely separate things.

I know who I think is wrong.


Peter, as you seem to be claiming to be so knowledgeable about DIN 41773 and Smart chargers, maybe you can list all the Smart/Intelligent chargers used in mainstream motorhomes and the intelligence they use to make the decisions they come to under those varying scenarios?

.

Peter wrote:

Yuasa make chargers that they describe as Intelligent (SMART) that have at their heart the 3 stages defined in DIN 417733.  Other 'stages' described do not actually participate in the charging process.

Wiki has already established that DIN 417733 and Smart charging are not the same.

I also thought we had already established that Smart chargers may have multi stage charging but that multi stage chargers are not all Smart or intelligent?

I am not sure that showing an image of a Car battery charger spec, which may or may not be correctly described as the term is often misused, tells us anything at all?
Especially so as the 'Marketing' teams like to inflate the spec of their chargers.

Peter Brown wrote:https://en.wikipedia.org/w/index.php?title=IUoU_battery_charging&action=history

I can go and edit that wiki entry, as can anyone else.  Information gleaned from wiki needs to be treated with caution as it is not a matter of fact, just someone's opinion.

What a great counter argument.

And there was me thinking Wiki was a World Wide Fountain of excellent knowledge. I notice you don't offer an alternative definition, just put down the one I present?

The CTEK 10 amp charger phases image above shows an example of a true Smart/Intelligent charger. You will see that step 6 does an analyse phase where it tests the battery and makes a decision based upon the results. 
Smart chargers almost always deviate from the straight DIN standard of just 3 stages

How about answering the question on what Smart/Intelligent chargers are used in main stream motorhomes and their intelligence decision branches. It was you who wanted to keep it technical?

Hi  

AllaFEvans wrote: I think you are confusing multi stage fixed steps with intelligent decision making?

Not at all,

It's all about terminology and what would be generally understood to be a smart charger. Any microprocessor

controlled charger running a program that adjusts its output to suit the battery state can be described as a

smart charger, to distinguish it from other types of charger or power supplies. That’s not to say that they

don't frequently have enhanced functionality.

From battery stuff .com

https://www.batterystuff.com/blog/3-stages-of-smart-chargers.html

“the three stages of smart chargers”


From MDS batteries:

“they are also programmed to provide a planned and varied output to charge and maintain your battery in the

best condition”

https://www.mdsbattery.co.uk/blog/advantages-of-a-smart-battery-charger.html

Also:

https://www.adendorff.co.za/types-of-battery-chargers-applications/


So, Sargent are quite entitled to call the PX300 an intelligent charger.

AllaFEvans” wrote: You then write, "Like all IUoU chargers the PX300's main charge phase is constant current

"
Sorry but that isn't true, if it were then throwing 25amps into a battery over 4 hours would shorten the life

of even the best 100Ah battery. ?

Yes it is!

Any charger not in current mode for the bulk charge stage is not following the IUoU curve.

https://en.wikipedia.org/wiki/IUoU_battery_charging

but;

The IUoU standard requires the main charge stage to be constant current (the I bit). What that current

is up to the charger designer. Any charger claiming to use this curve must be in current mode hence back to the

original point you cannot “suck” current out of it and you cannot overload it. Incidentally for any company to

claim to meet a standard that they do not is an offence and could render that company to a fine.

Where did the 25A for four hours come from? None of the chargers we’ve looked at in this thread charge at

anywhere near 25A. You wouldn’t charge a 100Ah battery at 25A for four hours anyway because the charger would

come out of constant current mode well before that.

https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

AllaFEvans wrote:The first stage is not the main charging stage on a Leisure battery charger.

I can’t see why it matters which stage it is but I didn’t say first stage I said main (i.e. bulk charge) stage.

That’s not to say there may not be other stages for various reasons. That said Look at the diagram from Sargent

and from Schaudt (taken from your own website). They both give the fist stage as the main stage.

AllaFEvans wrote:Sorry you don't like my term 'struggled', but the term reflects what we saw and analysed

based on the 8 years we have been repairing chargers from Sargent, BCA, Toptron, Schaudt, Nordelettronica,

Calira, Arsilicii, etc. and working on motorhome electronics.

If it “struggled” what aspect of its specification did it not live up to? Surely that’s a reasonable question. You're telling us that the PX300 is not up to the job but you're not telling us why.

Add to that if you tell us what you tested and what the results were somebody may be able to repeat the test and see if they agree with you.

Brod.

Yes keep it Technical, this is a good debate...luv it
Some clever sods out there:rolleyes:

Ray

Sorry but that is all 'marketing' not a definition. 
Clearly the Sargent has no intelligent decision making capability, but I once again ask you to name all the smart chargers and their decision making branches because you said in another thread that were lots in our industry?


You write :-

"I can’t see why it matters which stage it is but I didn’t say first stage I said main (i.e. bulk charge) stage"
. 

Sorry but you did stipulate the first phase as noted by your comment that it was the constant current phase which is the first one, you wrote -


"Like all IUoU chargers the PX300,s main charge phase is constant current" 


But it isn't. For typical Motorhome multi stage chargers and batteries the main charge is done at stage 2, with stage one being entered and exited very quickly. 
Only if a motorhome battery is over discharged will it linger longer in Stage 1.
 

So it does matter because your argument suggests that  during the Constant current 1st phase the batteries can't suck the life out of the charger. 
I pointed out that our test took place with 50% DOD batteries and the charger left the 1st Constant current phase very quickly, because it reached 14.3v very quickly. 
Just as powerful multi stage Leisure battery chargers do with Leisure batteries.


That might not be how small Car batteries and small chargers behave but the more powerful motorhome chargers only stay in the first stage until they reach 14.3v, then switch to the main charge (for a typical 50% DOD Leisure battery) very quickly, in minutes. Even faster for a 30% DOD.

Because the main charge is done at stage 2 which is varying current, but constant voltage, the batteries can suck the life out of the charger.

I think you have a misinformed view of how motorhome chargers and batteries work based on theory and automotive usage.
Most charts show the 1st stage for Starter batteries and Car chargers where the starter battery is flat. Under these circumstances nearly 50% of the battery has got to be charged to get it up to a level where the constant current draw doesn't 'hold down' the voltage. 

On a motorhome charger with motorhome batteries, that are advised to never discharge below 50% DOD for the ideal between life and usability, that phase is mostly redundent. So stage 1 is entered by the charger, which reaches 14.3v in minutes, jumping on to stage 2, the primary charge stage for Motorhomes.

That is based on real world experience of working on thousands of chargers and many motorhomes. It isn't a test based on a 1.5 amp Car charger and a 7Ah battery that you carried out. Very different. 


Again you write -

"Where did the 25A for four hours come from? None of the chargers we’ve looked at in this thread charge at anywhere near 25A". 

I think you will find that the Sargent PX300 is a 300watt charger and at the 'held down lower voltage' of the constant current phase (where the voltage is still rising above 12v) a max 25 amp is achievable. 
If it really did 'all the charging' in the first stage as you suggest at max constant current, then that would equate to 25amps at 4 hours, hence my example of just how silly your suggestion was. 

And before you argue and say that you didn't say that, you said you believed the PX 300 was a constant current charger.
You wrote -
"Like all IUoU chargers the PX300,s main charge phase is constant current"

I disagree, Leisure battery chargers on motorhome batteries have a main charge phase (2nd Stage) that is constant voltage and variable current, your 'main' constant current phase lasts minutes. 


You write again -
If it “struggled” what aspect of its specification did it not live up to? Surely that’s a reasonable question. You're telling us that the PX300 is not up to the job but you're not telling us why".

Isn't that obvious when 3 x PX300 charger units on the same van had already failed and the fourth one struggled to supply the current being drawn. We didn't see the three that failed, swapped under warranty by the Dealer, but I do write above all the failed ones from other AGM equipped vans were overloaded. 
Quite clearly the PX300 has an issue with durablity under extreme current draw?? 


To test it yourself run 2 x good 100Ah AGM's at around 11 months of age down to 50%, connect EHU and get the marshmallows ready.
Watch both the current draw and the voltage and if the charger starts to glow red like a turbo on a Formula One car, you are on the right track.
If the batteries haven't already lost capacity from undercharging from an inadequate mains charger and Alternator voltage of the usual 13.7v, you should see what we did.



One final thought -

We were sent an email from someone on here that said something like, "there can't be a real issue because Gel batteries have been taken to deep discharge levels without issue for years, so why can't we deep discharge AGM's?".

It's a good question but the writer was not aware that Gel batteries, like the old Exide G80, typically draw half the current of a conventional battery, which compensates for the extra charger load from the longer recharge time.

That isn't quite the same situation as a battery that tries to charge twice as fast by drawing twice the current and doubles the charge time from deep discharging.
Regardless of what we say, surely logic suggests that will end in tears if you don't modify the charger to suit?

*Warning* Please keep personal insults out of conversations or risk thread being locked. Offending posts have been edited.

I have received a couple of emails querying my remarks above about AGM battery chargers and  Gel's being slower charging.
So rather than me answer the questions, I will let Concorde take over. 
Concorde had been making Gel batteries since the 1970's. They are now the biggest supplier of AGM's to the military and commercial airlines. They have been making quality AGM batteries in quantity longer than almost anyone else They also build batteries for the RV market.

Clearly they know what they are talking about.
Their documents are published below and the relevant text highlighted.

Below the voltage temperature table can be found the following text :-

"For repetitive deep cycling, (AGM) chargers should have an output current of at least 20amps per 100Ah battery (40amps for 2 x 100Ah AGM's) or the cycle life of the battery may be negatively affected".



I would suggest that they expect two AGM batteries to try and draw at least that amount, 40 amps, possibly more.

That says to me that a Sargent PX300 AGM charger of only 25 amp peak, is either going to 'struggle' on 2 x 100Ah AGM's that want to pull 40amps or the batteries are going to be prematurely terminated. 
Or even both prematurely terminated?

While the Sargent PX300 might cope ok with one AGM, adding a second AGM is going to bring a load that it isn't ready for. 


Brodco, you said in an earlier thread that chargers don't have limits, I think this proves they do and blows out of the water the old 'Conventional battery' Rule of Thumb that a charger can safely support a battery bank 10 times its output converted to AH. 
The above suggests that where AGM batteries are involved the charger can only safely support a battery bank 5 times it's output, i.e. 20amp x 5 = 100Ah. 

So not only does the voltage of an AGM charger need to be higher but so does the current by, at the very least, double.


That supports what Varta say, that their AGM batteries charge twice as quickly. Exide claim twice the charging time with their AGM's, etc.
That can't be because they all use magic water, only that they draw twice as much current during the same time interval. 
That all mirrors what we have seen and published.




 

The second paragraph on the same page , back up to near the top, on charging AGM batteries, gives a description about 3 stage charging.
Although the first stage is mentioned, it is glossed over. Whereas the second stage (the one we say is the main charge phase) gets lots of extra description including voltages, temperatures and fully charged state, etc. 
Clearly they also see this as the key charging phase.


Wiki, in it's description of DIN 41773 states :- 
"Stage 1 is called the I-phase, constant-current stage, or bulk charge stage. This phase occurs when an IUoU charger is connected to a deeply discharged battery".   

Most other documents talk about stage one being relevant with a fully flat battery.


On a Motorhome battery that still has 50% charge, Stage 1 won't hardly come into effect. Just run for a few minutes then onto Stage 2 for the primary charge.



You will note the other highlighted section that Concorde also think that AGM's (as do Victron Energy) that a Float of 13.3v is the ideal, not the 13.6v of a PX300 or the 14.4v of an Alternator. 


As regards Gel being slower charging, see the last highlighted section on the document below;

"...tests have shown that when discharged to 50%, gel batteries took twice as long to charge".


If you look at the Schaudt Elektroblock charger document published by Brodco above you will see that while AGM batteries only get a 4 hour timer window at Stage 2 14.4v "Boost" charge, Gels get 16 hours. 
They are given 4 times longer at the 14.4v "boost" phase because they take less current.