Lithium battery default setup on models

Hi all
Another pre-purchase query if you don’t mind  
Quite a detailed post but hopefully may help get specific answers and details from any one who has the specific knowledge and/or similar setup and requirements I’m currently using and trying to get same in the new XL

background what I have now.

Currently a Swift with Sargent system 120w solar and I’ve swapped to a Victron MPPT just to harvest the bit extra from the Sargent controller - works fine and I’ve always used the smart function for storage and direct to leisure when needed
2x 110ah LA batteries now just coming to 6yr old, I’ve fitted a 2000w inverter and used this perfectly for our needs, coffee machine, her hairdryer and tong things and e-bike chargers, just to be clear mainly summer usage and never have problems, I understand the limitations and manage this perfect for us and did all the cost benefit exercise to lithium change and in that system wasn’t worth it. My reasoning for last 4yrs was just kick the LA batteries and replace if needed rather than full gold standard upgrade and not get value out of it, I think a lot of the people reading the above who I hope will answer the below will understand the query below and understand why I’ve wrote this bit.
So I can see Autosleepers didn’t do the transition to fitting the default lithium batteries very well including the Sargent inclusion, but can see these have been addressed as such to date.
The set we are looking at is new 2024 so I’ve already checked and it should have the Sargent updates done i.e. split charge disable ready on control system - tick
The 2 batteries I’ve seen fitted are either the TN brand or Topband make, I’m again guessing but looks like they may be coming away from TN to this other make - tick. I say this as looks like the Topband brand has Bluetooth monitor and heater built in so better spec and easy to get matched pair( I know matched pair   Give me time I’m coming to that)
Also checked and it’s got the 20amp DC-DC charger fitted
So this leads me to the real tech query and I’ve done my homework on the Sargent charger and got the specs etc.
I’ll put this as an example so anyone answering will understand why I think (am I missing something)

Ok so far I can see AS are pretty much saying at present 100ah lithium battery maximum due to limitions on system 

Well I can see it has a 20amp DC-DC charger fitted, which has limitation's through wiring size, output, temp protection and the obvious fuse to protect…. Totally get that and understand that, and I know the chemistry difference I simply think of it as LA has pretty quick resistance so very quick to no high current input due to natural nature of system, whereas the lithium will open its mouth and just suck in what you can give(to the limitions of BMS and spec) and in this example to the 20amp the Sargent will give, ok no problems there
The actual AC charger not too concerned even if still the 300 type as again it has 25amp max output and that’s actually split to DC usage and any charging requirements while on hookup - don’t need to really dwell on the deficiencies of the voltage, main,float etc. I know all that and that’s just again gold standard top end charging etc. I can work with.
Expecting their new solar will have spec but if not I’ve got the victron I can fit so no problem there - tick

So the one I can’t get my head around is: ok I’ve got the 1 fitted 100ah lithium fitted that is ok to have and is at limit of all their system.
So example in my head is someone has dropped their battery down to +/- 20amp, engine gets switched on Sargent DC charger goes flat out and gives the battery 20amp and it drinks it for as long as it needs till back to +/- 100%, yeah the charger will now be getting hot, the wiring resistance will build a bit with heat, the Sargent charger might even get hot and tired enough for its internal protection to shut down and cool down and give it a rest and start again but it will work and is specced to work… great I get that and my head happy with that, and yeah for this query essentially the same if coming via the Sargent AC charger 

So my example I put 2x 100amp lithium batteries into the same system, I take out the same 80amps across the 2 batteries as I would on the LA system above and the same as you all will with a bigger system.
So I’ve got 80amp to replace except across the 2 batteries so give or take 40 to each… as expected and normal
So engine starts again and the same Sargent system does exactly the same work the same output the same load on the wiring, the charger etc. even if I used the example of dropping both batteries to say they needed 160amps to refill, the only difference is time I.e. will need longer because of the same 20amp limit

Does this make sense to someone, what am I missing here, time is the only changing factor if more amounts needed and I can at moment only think the limitation they have set is more about the longevity of the equipment lasting as it could be working flat out quite often if not managed well with battery AH usage rather than any additional loading that would/could give a overload scenario, but this could easily be seen on bad management of the 100ah alone anyway.

Enlighten me guys….. what I am I  missing from the basic examples of above and 1 or 2 batteries wanting to be fed from same limited system

Thanks in advance for even getting to here, but I know the people who could answer this would also expect the detail to understand 
Cheers Sheppy

Hi Snowwolf
Yeah just the nature of the LA resistance gives minimal charge rate, rightly so for them.
As mentioned above they put the right system in for lithium via the DC-DC charger and it has max 20amp output so protecting their system to design but the query is really trying to understand the 100amp single battery limit, when the protection of this is essentially from the 20 amp charger.
Similar if someone fitted a bespoke system with say 2x 250amp batteries, the likelihood they would pair it with say a 60amp DC-DC charger and correctly sized cabling for that and well away from normal alternator capacity, but would still increase only time factor of charging to 2 hungry empty-ish 250ah batteries but wouldn’t overload the rated system for that, or at least that’s how it’s always made sense to me 
Cheers Sheppy

Alan
Thanks for the reply. Can I ask is it just a simple add on, parallel connection with another fuse on the positive as such.
Is it same size and from Autosleeper’s or just from common suppliers
Cheers Craig

Alan WH, thanks for the reply, I knew what you meant BTW, i asked mainly to see if you had seen any issues if you have stayed with-in the limitations of the system and just increased the AH capacity, also I’ve while I’m waiting for new van only had my head under the bench seats a couple of times and the Swift currently have Sargent used 2 fuses, whereas I would normally wire for correct balance and fuse on output.

Bendog, you haven’t gave much info but that doesn’t mean the query is wrong. Someone else may also be able to give further help to response.
To date as Peter Brown alluded to, the Sargent DC-DC 20amp charger is at the limit of the whole Sargent system,I’ve had a good chat with them for my requirements for the new van,contact them, they are very good to confirm anything you are not sure off, even down to cable sizing etc. Also the 300 series AC charger fitted is a 20amp max. charger.
Again as Peter alluded to, and it may suit some people to do a full refit, but this can also be a “Rolls Royce when a mini will do” if you don’t need it all.
If you look at my example on initial query, I will be adding extra battery, but will leave system and only “time to re-charge fully will increase” I will try that 1st, although again if it helps I knew my requirements roughly in AH/hr but these got skewed abut when I realised it was a compressor fridge. Which ironically is better when it’s hot and sunny to get temps down for the cold beers, but you get more solar to compensate for the juice it uses…
Cheers Sheppy

v8oholic, yes, sorry I should have been clearer, the limit of the DC-DC system, as I mentioned the 300system separately.
Your example pretty close to my requirements, I’m currently on 120w solar but swapped the Sargent PWM to MPPT and can get 5-6amps on a nice summer day and on 2x 100amp LA batteries and have a 2KW inverter, but only really for the old coffee machine, her hairdryer, tongs and our E bike charger and has worked well for 5years and the LA batteries still happy.
So we not huge users but my addition was to ensure the biggest draw of the coffee machine could possibly be at max of the 100ah lithium’s even for short duration, so easiest to add a bit more to pot and split draw over 2, or like you, may even go for a 200ah and would be well within the max draw capability.
Everyone different, but in the Swift the whole system was so convoluted I just fitted a separate socket for the inverter usage, more just because of how the elec circuits were set up and to ensure myself and the good lady didn’t forget to ensure the fridge/heating etc. didn’t get put on elec and kill the batteries. Not, not doable as you’ll probably know but seemed a lot of other work just to have all the sockets usable. In the XL same again, it seems the logical place for us to fit a separate socket would be just on left side of kitchen at end of lounge seat for what we would need socket usage for on the inverter.
Just as a side note, again I’m sure you aware but I would expect if you were fitting a 230ah lithium it would have a >100amp discharge rate even if not needed. That’s my other option for the same as above, but I do like a bit of redundancy I.e. 2 batteries.
Also if you or anyone else don’t mind, what brands are you looking at, I’m currently looking at Frogster drift models just with their specs and price points, but have noticed Sargent are showing some of their own, and will get some details from them.
Cheers Sheppy

v8oholic wrote:As it is separate, when driving, the DC-DC charger's output is supplemented by up to 5A from the standard solar panel.

Although this might appear at first glance to be true, the problem with this is that the primary factor determining how much a charge controller will try to put into a battery is the voltage of the battery. In this situation (i.e. driving, with both DC-DC and solar operating), each charge controller is seeing a battery whose voltage is being altered by the other charge controller (which of course it has no way to compensate for).

In this case it's likely that the DC-DC charger will employ a higher voltage charging profile (because it is designed to be a "fast charger") which is likely to completely inhibit the solar charge controller. In effect, the solar charge controller will "think" that the battery is already at a high state of charge and will stop trying to charge it.

Roopert,
Again, great reply for anyone interested in this level of detail, and the reason for joining this type of forum, to be able to get some responses from people.
Similarly on that point, it’s another question on my list to Sargent, in that I know how their SMART charging sequence works in, in simple terms, 4hr switch and looking at greater than/less than figures etc. I remember when I looked at changing current van to lithium and the natural resting voltage figure, they agreed the smart sequence would effectively just keep going back to vehicle in simple terms.
My 2 main checks with them is to ensure the 970 unit still has an advanced setting to allow vehicle/leisure/smart selection (would be very surprised if it doesn’t) that’s how I ensure full solar to leisure while offgrid as such.
I’d be very surprised if the newer MPPT solar controller they use has any configuration settings for lithium, mainly my assumption on that as they still fit to LA systems with that newer controller.
Again for my starting point, I’m pulling the victron MPPT solar controller I put into this van and will probably swap for there’s 
My 2nd check would be if they have modified their SMART sequence to ensure it will give to the leisure now its standard fitting of lithium (which again, would expect they have caught that up aswel) if not I’ll put the 1amp constant trickle off the victron unit or a battery master and just have the solar set to leisure and use it’s bigger pot while in storage.
Again this is me just thinking aloud to what I might need to do/check for new van, and hopefully get some of the answers from others out there that have already got the T shirt, while the wife is just deciding on kettle and Duvalay colours Haha
Thanks again gents for the input, really appreciated 
Cheers Sheppy

v8oholic,
Thanks again for the above.
Couple of things, 1st off, I’m sure you aware, Frogster have a 5% discount avail for 1st orders, there is also a 10% route which isn’t to be sniffed at depending on which size your buying and the specs they are doing, I’ll drop you a PM when I’m done.
2nd, had a great chat with Sargent, they did confirm both, that they have modified the SMART solar sequence basically taking out the top voltage to account for lithium when you need it as such, and yes as you say, their MPPT does not have a specific lithium setting but no big deal.
As for their batteries at 1st sounded great although not to the frogster drift spec, but as it has the CAN-BUS link to the 970 controller it gives full detail of the batteries as would a Bluetooth app and it can do 2 batteries same detail, rather than sometimes flaky apps to get info. Or in my case I was going to use the Victron BMV 712 that would give details, although this only does “the pot” if more than 1 battery via the shunt, and the 2nd battery link is voltage only(not much good with lithium as it’ll only change when virtually empty) great I thought, then the sting, not really the cost as expected that to be a bit higher but they only got either 30 or 70amps until possibly next year not any 100amp ones. For my plans even 2 70amp may be borderline to give enough headroom to do things differently in this van when I add in the fridge.But again may help/suit others
Cheers Sheppy

Alan WH,
Thanks for the reply and detail, yes I’ll watch for your results just gives some more info great.
Yes agree winter another angle, balancing battery pot size, solar cost for gain or quicker charging on move
Cheers Sheppy

Bendog wrote:As mentioned earlier I am looking at fitting a 1000/2000w inverter to my updated Symbol, what size fuse should I be looking at or I be better off using a cuicuit breaker kind regards.

IMO, the best thing to do is to buy a good well-known make and follow the installation instructions that come with the inverter. This should specify the minimum size of cabling (often for a given distance from the battery) and the exact fuse requirements.

This is critically important because the input current can be very large - a 2kW inverter can take well over 100 Amps at full load, so it needs to be done exactly as the manufacturer recommends.

If it's a good make of inverter, I doubt there's a strong case to fit a circuit breaker rather than a conventional fuse. Modern inverters are quite "smart", and you'll probably find that any internal protection will trip faster than a fuse will.

Bendog
As Roopert has said above, I’m sure you may already have some level of knowledge and a certain make in mind.
I’ve used a company called Sunshine solar, they have a lot of products, they do a picking list as such that will match the inverter depending on size etc. as Roopert has mentioned, very good on phone also for any queries for set up and requirements, again including cabling etc as Roopert mentioned
Also sure you are aware but most (not all) items you may want to use the inverter for will need a Pure sine wave not a more basic modified sine wave type, just with most items now having electronic internals that would not like basic modified sine type, even bike chargers, laptop chargers, coffee machines Etc.Etc.
Cheers Craig