Lithium Leisure Battery in Broadway 2019

Has anyone managed to fit a Lithium leisure battery in a 2018/2019 model? I’m trying to get my head around the battery harness & onboard wiring not being compatible with lithium as advised by our dealer who are saying that only Auto-Sleeper motorhomes built after 2021 are compatible? This is despite both the EC700 & PX300 Charger both being compatible with Lithium leisure batteries, with this in mind I’m struggling to understand why Auto-Sleeper would fit Lithium compatible power supply units & chargers yet not have a compatible wiring harnesses? Is anyone able to shed some light on this as I’ve not been very successful in getting clarification from both Auto-Sleepers or Sargent so far about this…

CC
Probably not the full answer you may be looking for but a couple of points for you to view consider/check
The PX300 charger is not a full lithium charger as such but close enough and yes used in current Auto-Sleepers set up. That’s prob a different paragraph just why it’s close enough due to its charging profile.
I suspect the main reason you may be on back foot as such with 18-19 set up will be it will most likely be a “split charge set up” for lead acid etc. via the EC700 at that year and in simplistic terms that and the wiring will be very smallish to give a lower current supply to a high resistance lead acid profile battery while engine running.
Normally you would not use this split charge set up for lithium as it has a much lower resistance and therefore can take a lot more current which can overload the split charge system via the Sargent system and would normally be done by a DC-DC charger with the split charge system disabled 
I say this as at time had a Swift with similar set up as described above on a 2018 Sargent system and on that the split charge was quite difficult(not impossible but needed a relay setting up) to disable as it was integrated into the Sargent EC600 which I suspect may be the same as the 700 you have.
That might be a good starting point just to confirm if the above is what you have.
The latest system has the function to disable the split charge mode and select lithium profile
Hope this helps to start
Cheers Sheppy

My understanding is the same as Sheppy’s. We have a 2020 Fiat with a smart alternator but AS and Sargent did not take into account the implication of such alternators for leisure battery charging until later, when they started fitting a Sargent B2B. I thought this change occurred in 2022 but I could be wrong.

We still have a lead acid leisure battery but even that wasn’t receiving much charge from the alternator via the split charge relay. Fitting a B2B has solved our underway charging problem and makes feasible a subsequent upgrade to a lithium battery.

This may only be part of the issue though. As well as fitting a B2B Sargent presumably have changed the solar regulator to one that has a lithium charging profile. The version fitted in our van was a cheap PWM regulator which I’ve bypassed using a Victron MPPT connected directly to the leisure battery.

Finally, there’s the question of cable ratings. Lithium batteries are capable of receiving much higher charging currents than for lead acid or AGM batteries, so it’s possible that Sargent have increased the cross sectional area of relevant cables to enable this. However I’d be surprised if they have, as their B2B charger is rated at only 20A.

Tim

Tim
You are definitely correct on the smart alternator issue, to be fair from what I’ve read it caught most UK converters out, some have been better than others in correcting this even for lead acid charging systems as you say.
The Sargent solar controller although now pretty much the norm for them being MPPT rather than the older PWM, they are “bog standard” output profile and not configurable for lithium like the Victron for example. Proberbly keeping it simple to cover the smart charging function to the Fiat battery also, but being able to harvest better.
Without hijacking CC’s query, can I ask how you are maintaining the fiat battery if you bypassed the Sargent with the victron directly to the leisure, as just setting my system up and could refit my victron the same with specific lithium settings but would then have those settings going to the fiat if didn’t bypass the Sargent unit, or fit a battery2battery to back feed the fiat if put all the solar to leisure
Cheers Sheppy

CC
Not sure if this will help, just dug out some old emails from Sargent
A guy called Adam Tanton in Sargent technical support team, he is very clued up on the systems and spent a lot of time with him on some of the above and proberbly your system similar, you can set up call backs with them by name to go into specific details, he was very good when I was going through similar to you on our Swift system, sometimes just getting the right person for specific queries/areas can help
Cheers Sheppy

What's the benefit of a lithium charging profile for a solar controller? I mean the 13.8V capped output of the Sargent MPPT is sufficient to charge a lithium battery, and even if a lithium profile means a higher voltage, that could only be at the expense of a lower current, because the input power is the same. So it wouldn't charge the battery any faster.

Thanks for the replies guys, probably should have made it clearer but I had a lithium battery along with a Victron 30amp DCtoDC charger fitted to our Broadway by Offgrid Power Solutions who did our last camper which worked absolutely brilliantly btw.

However some of you will recall my issues with the Sargent EC700 that I posted recently about going back to the dealers under warranty, who after investigating said the failure of the EC700 was down to the lithium install as the wiring is not adequate, as I’ve said earlier I find it astonishing that Auto Sleeper appears to have fitted a lithium compatible power supply & charger yet fit the motorhome with a non lithium compatible battery harness & wiring that’s not up to task.

Dealer disconnected the lithium battery & told us not to reconnect as it was unsafe, so have now reluctantly replaced it with a larger AGM, but wondering if that’s it or if the harness etc can be upgraded in order to go with lithium or wether I’m stuck with AGM.

As I said I’m still waiting for clarification from Auto Sleeper & Sargent, sadly the installer who I thought I had quite a good relationship with & which I have made aware of what’s happened has disappointingly gone quite on me, would have thought the wiring would have been checked to make sure it’s adequate before installing the lithium, bit annoyed at how much money I’ve spent only to have to revert it back.

Sheppy wrote:The PX300 charger is not a full lithium charger as such but close enough

Yes sheepy I was aware of the chargers limitations not really a problem as I’ve not put our Broadway on charge since getting it, just like our last camper the solar & B2B takes care of things, it’s very rare for us to stay in any one place for more than a night, & it’s quite rare for us to be on hook up, if I did need to charge the leisure battery I have a lithium specific charger which despite buying for use in our last camper it’s still in its box & I’m yet to use.

V8 - the charging profile is just really for top end/finishing charge when the lithium is full compared to LA batteries as such, but left at “close enough” as the Sargent controller would do,most people would use.

CC
Just my thoughts from your response above, if it was my system, I’d still be thinking it may have been an issue around the “split charge” on the 700 system. Mainly because of the 2018-19 dates also, the only 2 parts going through the 700 would be the solar - rated at 10amp with a onboard fuse on the ECU’s by Sargent, so that would never see any rating near the cable rating unless there was a massive upgrade in solar array, that check of wiring/setup should be easy to confirm with Sargent for any changes.
Defo the split charge could struggle via the ECU (this would come into detail around the “drop in”of lithium battery level of detail) and more importantly was this disabled on the lithium fitting, that could create issue back to the ECU if you’ve had a DC-DC fitted, that split charge area would defo be my line of thinking for any issue and possibly where the dealer is viewing.
Also although the 300 charger has been used for a while and capable of 20amp, again this would be a check to see if they have beefed up the wiring mainly on the assumption that it wouldn’t have been needed in a high resistance LA battery set up even with a low battery, unlikely but again worth the ask/check, this will at least narrow down the detail of what parts of the set up is/is not correctly rated on your setup
For reference, we have got the current lithium setup from AS and Sargent for their lithium and although bare minimum it is still 20amp max out of the 300 charger via hook up
20amp max via their 20amp DC-DC charger BUT on the current set up, the split charge is disabled via selection the control panel
Hope some of this helps in trying to get the answers or at least direction of queries to narrow down reasons for you
Cheers Sheppy

Sheppy wrote:Tim
You are definitely correct on the smart alternator issue, to be fair from what I’ve read it caught most UK converters out, some have been better than others in correcting this even for lead acid charging systems as you say.
The Sargent solar controller although now pretty much the norm for them being MPPT rather than the older PWM, they are “bog standard” output profile and not configurable for lithium like the Victron for example. Proberbly keeping it simple to cover the smart charging function to the Fiat battery also, but being able to harvest better.
Without hijacking CC’s query, can I ask how you are maintaining the fiat battery if you bypassed the Sargent with the victron directly to the leisure, as just setting my system up and could refit my victron the same with specific lithium settings but would then have those settings going to the fiat if didn’t bypass the Sargent unit, or fit a battery2battery to back feed the fiat if put all the solar to leisure
Cheers Sheppy

I fitted a Vanbitz Battery Master that keeps the vehicle battery topped up to within 0.5V of the leisure battery. It's a simple solution and I've been operating it for 12 months without a problem.

Tim

Tim
Thanks, thought that’s what you would have done, I’ve got the same on list depending on how the smart charging goes on this van, to be fair it did its job on last van during storage, even over winter period with batteries over 5 yr old and just leave the victron at “close enough” settings

Caraman
Noted, didn’t realise he had gone, to be fair most of the guys I used have been as good also
Cheers Sheppy

The Bargee
You should keep that paragraph for any “lithium drop in” queries 
Good food for thought for anyone.
Mind you, I’m not convinced the 300 charger in this new van,is going to have the same lifespan charging the lithiums as it did plodding on with LA batteries, in old van, it can be at full wack, as it’s specced for, but over how long time will tell, even for topping up a well drained 100amp as fitted, if those unsuspecting aren’t aware of how these things work.
Cheers Sheppy

The Bargee wrote:The simple answer may be that Sargent only rate the EC700 at 25 amps, and presumably the duty cycle has to be considered as well. Any excess current or a prolonged duty cycle may cause excess heat to develop in the CPU with resultant damage to pcb’s etc. and risk of fire. This might apply to any significant upgrade to battery capacity, whatever the battery chemistry. If more capacity is used, more amps consumed, then those amps have to be replaced, and the charging times, loads and hence the heat in the system will be greater. In short, the EC700 and its associated wiring harnesses may simply not be designed or rated for heavier duty use, hence the dealer’s concern.

But the manual clearly states it’s compatible with Lithium batteries. Like you say the dealer was concerned that the wiring harness was not adequate for the lithium installation hence why they disconnected it & deemed it unsafe. Surely the installer should have checked wiring somehow before doing the install as otherwise leaving themselves wide open in the event there was a catastrophic event like a fire

A couple of weeks ago I had the opportunity to have a close look at a relatively new Bourton Sargent installation with EC700 Sargent MPPT solar controller and Sargent B2B.  The cable harness wires were of the the same diameter as those used by Sargent for years.

In the extract posted by CC it is stated that the system is suitable for Lithium batteries with a built in battery management system (BMS), they should have added that the BMS should be set to limit maximum current flow to 20A.

The Sargent cabling system has always been rated to handle 20A.  In recent years Sargent and AS have increased the battery fuse rating to 25A as the 20A fuses were operating at the limit a lot of the time and failing regularly.  Again in the extract posted by CC it is stated that a single battery fuse could be up to 40A and two batteries at 20A each.  The implication is that Sargent are confident that a current of 40A would not overheat their cable loom but I expect they take into account the fact that the duty cycle of appliances would rarely if ever call for such a high current.  The exception would be if a 12v dc to 230v AC inverter was fitted but its reasonable to expect that the installer would include a suitable rated piggy backed 12v connection.

Peter Brown wrote:...
In the extract posted by CC it is stated that the system is suitable for Lithium batteries with a built in battery management system (BMS), they should have added that the BMS should be set to limit maximum current flow to 20A.
...

Which begs the question why use an LFP battery at all for this application?

My limited understanding of this, with having had NO experience of using Li-ion leisure batteries, is that one of the main benefits over lead-acid is significantly faster charging rates. Limiting the current flow to 20A when charging a, say, 100Ah LFP battery won't allow the battery to be re-charged any faster than a lead-acid one.

OK, there is a weight advantage and the battery can be used at higher depth of discharge (20% vs 50%) than lead-acid and it will last longer if properly maintained but is fitting one, given all that's been said, really worth the hassle.

Regarding the built-in battery BMS, and as I said before I'm just a novice here, are there any settings that the user can adjust and if not would one feel confident letting the Sargent controller handle it.

Having had Lithium previously in our last van it’s hard to not want it again, our current setup will always be a big compromise in comparison, lithium is way superior in speed of charging either with solar or via a B2B & with the accuracy of the info provided by the BMS. They can also sit for many weeks or months unused even without losing barely any charge.