Minimum needed to convert to lithium?

[GeoffL]

I currently have 2 x 110Ah wet lead/acid leisure batteries that are recharged from a built-in mains charger when on EHU, by the alternator via a split-charge relay when driving, and by a 200W solar system (Victron SmartSolar 75/15 controller) during daylight. The batteries are now 7 years old and starting to discharge sooner than they used to -- so soon be time to change. I'd like to swap the 2 I currently have for one 150Ah LFP. I know the Victron solar controller has a lithium profile, but I'm unsure of the mains charger and alternator. I'm hoping that those will charge the battery to some extent and the solar can then finish the job but I'm unsure. FWIW, the van is a 2001 Autotrail and both the mains charger and alternator are original equipment. Can I just swap to LFP and reprogram the Victron unit or will I need to do more (and, if so, what)? Thanks for looking.

 

[trevskoda]

I think you on board charger will be old hat type power supply type unit, you may have to swap out for a smart charger with lithium settings,
David is the chap to get help from as regards charging & toys required.

 

[Nabsim]

Ideally you want everything you will use to charge to have a setting for Lifepo4 but you don't have to have it all at once depending what is there now.

I ran my mains charger on the Gel setting for quite a while before I got a proper replacement. What you don't want though is the mains charger staying on float so once battery gets near full flick the switch/breaker off to stop mains charger.

The split charge system in my van never showed more than high 13V with engine running so there wasn't a problem with potential overcharging. You don't want much more than 14.4V, (tops 14.6V on one) when its charging. I had seen a lot online saying the battery would never get fully charged at 13.8(ish)V but mine did. You see a lot online that may not be correct though.

If you are staying under the charge recommendations on your battery you should be fine. My batteries are still as good as the day I bought them in 2019

 

[wildebus]

I currently have 2 x 110Ah wet lead/acid leisure batteries that are recharged from a built-in mains charger when on EHU, by the alternator via a split-charge relay when driving, and by a 200W solar system (Victron SmartSolar 75/15 controller) during daylight. The batteries are now 7 years old and starting to discharge sooner than they used to -- so soon be time to change. I'd like to swap the 2 I currently have for one 150Ah LFP. I know the Victron solar controller has a lithium profile, but I'm unsure of the mains charger and alternator. I'm hoping that those will charge the battery to some extent and the solar can then finish the job but I'm unsure. FWIW, the van is a 2001 Autotrail and both the mains charger and alternator are original equipment. Can I just swap to LFP and reprogram the Victron unit or will I need to do more (and, if so, what)? Thanks for looking.

Your Solar will charge a Lithium Battery to its full potential (assuming you are harvesting enough power of course).

Your original OEM charger for mains will NOT charge a lithium battery fully. (It would never have charged the lead battery fully either for that matter). The risk (IMO) of using a pretty low-spec charger/power supply as would be installed in your van is it will end up running at full power for far longer than was expected when originally specificed and it could overheat and fail - potentially taking other items in the distribution box out with it.
You original split-charge system on a 2001 van *may* charge the Lithium better than a newer van oddly enough as it is probably just a straight relay. But with that you run the risk of exceeding its current capability as the old Lead Batteries mainly and the cabling to a degree used will essentially have been the charge bottleneck. Once you swap lead for Lithium, it will take all it can get, so you may find you are overloading the cable and blowing the fuse repeatedly, or overstressing the vehicle alternator.
One of the key functions of a B2B (Battery to Battery) Charger is to limit the current demanded from the alternator. On a 2001 van, the chances are the alternator is past its first bloom of youth and treating it with a little caution may be wise to avoid having to replace?

Personally I would not recommend using either the original split-charge system (or its cabling) with Lithium. Similarly, I would not use the original Mains Charger with Lithium.
For those who say a Lithium Battery is a "drop in replacement", I would say fine, go for it. But how lucky do you feel today?

 

[GeoffL]

Thanks David, I was hoping you'd jump in! I understand that the mains charger won't fully charge a LiFePO4 battery and suspected that neither would the existing alternator/split-charge relay and intended to rely on the solar for that with the other charging systems perhaps taking the leisure battery to 75%-ish. @Nabsim mentioned the need to not leave the battery on float, which was something that I didn't think of, but I can get around that by switching the mains charger manually when on EHU. From about May to September, the solar can generally replace everything I take from the system and we need EHU mainly for the fridge, water heating and 240v lights.
Thus I can possibly deal with shortcomings of the mains charger but I'm not too sure about the alternator. I suspect a series resistance won't do the trick but wonder whether there is another way to limit current without spending hundreds of pounds on a B2B system or whether the cheapest I've found (Victron Orion 18A @£155) would be enough? If there's no easy way, my other option is to wait until absolutely necessary and then replace what I have like-for-like, although I'd welcome the slightly higher voltage and flatter discharge curve of a LFP battery!
Thanks again...

 

[Outdoors Dad]

I fitted a fogstar lithium 300amp last year. I bought a Renogy 30a b2b and installed another 100w solar panel that now gives us a total of 250w solar. The setup works great. If I'm honest a good 150w mobile/ folding solar panel would be perfect as you can adjust it to harvest the max energy from sun. I can still do this as the Renogy b2b has an input for solar also. I have since installed a Renogy inverter just a 1000 w which I use with a small oil filled radiator and electric grill.

 

[wildebus]

Thanks David, I was hoping you'd jump in! I understand that the mains charger won't fully charge a LiFePO4 battery and suspected that neither would the existing alternator/split-charge relay and intended to rely on the solar for that with the other charging systems perhaps taking the leisure battery to 75%-ish. @Nabsim mentioned the need to not leave the battery on float, which was something that I didn't think of, but I can get around that by switching the mains charger manually when on EHU. From about May to September, the solar can generally replace everything I take from the system and we need EHU mainly for the fridge, water heating and 240v lights.
Thus I can possibly deal with shortcomings of the mains charger but I'm not too sure about the alternator. I suspect a series resistance won't do the trick but wonder whether there is another way to limit current without spending hundreds of pounds on a B2B system or whether the cheapest I've found (Victron Orion 18A @£155) would be enough? If there's no easy way, my other option is to wait until absolutely necessary and then replace what I have like-for-like, although I'd welcome the slightly higher voltage and flatter discharge curve of a LFP battery!
Thanks again...

If the change to a B2B is something you would like to do but need to delay due to budget constraints, it might be worth running new cables that are suitable for the new charger in preparation? not a massive expense and not money wasted as needed eventually, but will provide a useful benefit if combined with a basic 200A relay that is turned on by the D+ signal that is available by the Sargent system you have in place.
What would be worth checking is seeing what kind of voltage you are getting at the starter battery when the engine is running. If it is in the region of 14.2-14.4V, you should be ok (at least in terms of charge voltage).
It is is under 14V, hmmm.
If over 14.4V you could see overvoltage errors on the Lithium as it reaches full charge. You would need to be able to disable the relay in this situation (easy enough to do)
overall, delaying the 'right' chargers can be certainly done but it involves more monitoring and checking for the owner rather than creating a "fit and forget" setup.

Some folk do current limiting by deliberatly using undersized cabling to create increased resistance. Each to their own but I really dislike that approach and question its safety and wiseness.

 

[Robmac]

If the change to a B2B is something you would like to do but need to delay due to budget constraints, it might be worth running new cables that are suitable for the new charger in preparation? not a massive expense and not money wasted as needed eventually, but will provide a useful benefit if combined with a basic 200A relay that is turned on by the D+ signal that is available by the Sargent system you have in place.
What would be worth checking is seeing what kind of voltage you are getting at the starter battery when the engine is running. If it is in the region of 14.2-14.4V, you should be ok (at least in terms of charge voltage).
It is is under 14V, hmmm.
If over 14.4V you could see overvoltage errors on the Lithium as it reaches full charge. You would need to be able to disable the relay in this situation (easy enough to do)
overall, delaying the 'right' chargers can be certainly done but it involves more monitoring and checking for the owner rather than creating a "fit and forget" setup.

Some folk do current limiting by deliberatly using undersized cabling to create increased resistance. Each to their own but I really dislike that approach and question its safety and wiseness.

That was a great post until the very last word David!

 

[Robmac]

That was a great post until the very last word David!

...although I now see there IS such a word. My bad as they say!

 

[wildebus]

...although I now see there IS such a word. My bad as they say!

I could have tapped my inner Norman, I guess? (but 'wiseness' is a little more descriptive )

 

[GeoffL]

...although I now see there IS such a word. My bad as they say!

TBH, I too wondered about "wiseness" and would probably have used "wisdom". However, a quick check revealed that "wiseness" is more related to prudence while "wisdom" to insight and so "wiseness" is probably the more appropriate in this case. Two lessons learned from David!

 

[Robmac]

TBH, I too wondered about "wiseness" and would probably have used "wisdom". However, a quick check revealed that "wiseness" is more related to prudence while "wisdom" to insight and so "wiseness" is probably the more appropriate in this case. Two lessons learned from David!

Yes, and maybe I should have said "My badness".

Back to another point, I am thinking of putting a smart charger in my system (2 x 6v Trojans) I'm wondering if I can leave it on trickle charge for that setup, along with my Ring MPPT and 100w solar?

 

[wildebus]

I was listening to an audiobook of one of my favourite novels this morning .... 1984.
Maybe with that in mind I could have said something like "over unbig a cable is a double-plus ungood idea"?

Back to another point, I am thinking of putting a smart charger in my system (2 x 6v Trojans) I'm wondering if I can leave it on trickle charge for that setup, along with my Ring MPPT and 100w solar?

seems ok, but of course as you would have active charging, albeit at a low level, could this have an impact of the battery water level on those Trojans and you would need to check them more frequently? (never used these but I understand they like periodic top-ups?)

 

[Robmac]

I was listening to an audiobook of one of my favourite novels this morning .... 1984.
Maybe with that in mind I could have said something like "over unbig a cable is a double-plus ungood idea"?

seems ok, but of course as you would have active charging, albeit at a low level, could this have an impact of the battery water level on those Trojans and you would need to check them more frequently? (never used these but I understand they like periodic top-ups?)

They do like a drink! Like Geoff's mine are also about 7 years old and I am thinking of replacing them with 12v versions which of course would mean parallel instead of series so while I'm at it I would like to add a smart charger instead of the rather useless power supply unit.

I may just switch it off once the batteries are up to speed to avoid any droughts.

 

[trevskoda]

To save to much trouble and expence maybe loach lead carbon with 13/1500 cycles and a smart charger my be the way to go.

 

[barryd]

Watching with interest as if we get a new(er) van I might want to go this route. I was aware you would need a solar controller with a lithium setting and probably the same with a mains charger but I never realised there maybe a requirement to upgrade the vehicles charging system / Alternator.

 

[wildebus]

So what do you really need to charge a Lithium Battery?
Well, I have this ready at the moment .....

Chargers! by David, on Flickr

 

[barryd]

So what do you really need to charge a Lithium Battery?
Well, I have this ready at the moment .....

Chargers! by David, on Flickr

Does that cover all three sources of charge then? Engine, 240v EHU and solar charging?

 

[wildebus]

Does that cover all three sources of charge then? Engine, 240v EHU and solar charging?

It would - Orion-XS is engine, Multiplus is EHU and MPPTs are Solar.

 

[barryd]

It would - Orion-XS is engine, MPPTs are Solar and Muliplus is EHU.

Whats the total cost of that lot then fitted.