Agm batteries v wet batteries. Charging options

[Masman]

I have a 2004 rapido. With wet battery. Looking to replace. My set up consists of charger that can charge gel or wet batteries. And when driving charges both hab and leisure battery. Will my charger be able to charge a AGM battery without damaging it.Or do I stick with wet battery.

 

[Just smiffy]

With your set up I would definitely go with gel batteries, agm do not make good leisure batteries….

Lithium is in some ways cheeper then other batteries now and will give you more amps per pound, even a fairly cheep lithium battery being charged on the gel setting (not ideal) will be better value, although it won’t fully charge it will still be better value..

Getting a lithium set up is the optimal best but it depends on how you use your motorhome….

 

[AdrianChen]

I have a 2004 rapido. With wet battery. Looking to replace. My set up consists of charger that can charge gel or wet batteries. And when driving charges both hab and leisure battery. Will my charger be able to charge a AGM battery without damaging it.Or do I stick with wet battery.

If your charger has settings only for flooded or gel, then an AGM would not be the best choice - AGM's normally require a higher charge voltage to fully charge than either flooded or gel, so you would very likely be undercharging the AGM which may then succumb to sulphation/capacity loss.

Gel batteries tend to be better for hab batteries, and if you have a suitable charger should last very well, but they are quite expensive compared to bog standard "leisure" batteries.

If you do decide to fit Lithium, which may not look too costly compared to a quality Gel battery, the gel setting of your charger will work and fully charge the battery, but often chargers Gel settings give up to 8 hours of absorption charge, which is quite a long time for a lithium vs the ideal, although it seems many folk do it and seem happy with the results. The wet/flooded setting may not get a lithium to the voltage point where some batteries balance their cells, which may not give an immediate issue, but contribute to them loosing capacity over time, unless they are occasionally given a full charge on a compatible charger, so if you had a lithium compatible Solar regulator for example.

So all things considered, if you have been happy with the previous battery's performance why not just do a like for like change?

 

[Jimbohorlicks]

Your gel set up will charge a lithium battery which will also give you twice the energy available and half the weight. Lithium are now about the same price as an agm or gel so a no brainer. The gel setting will charge the lithium but not to a 100% but that's still provides more power for longer than lead or gel or agm

 

[AdrianChen]

Your gel set up will charge a lithium battery which will also give you twice the energy available and half the weight. Lithium are now about the same price as an agm or gel so a no brainer. The gel setting will charge the lithium but not to a 100% but that's still provides more power for longer than lead or gel or agm

Why will a gel setting not charge a Lithium battery fully? My Lithiums have an absorption setting of 14.25v for a full charge - many Gel settings are around 14.4v. I get with a flooded/wet setting the absorption voltage will be around 14.1v, but even that is "full" just not perhaps enough for some BMS systems to complete cell balancing. My batteries go from 13.8v to 14.25 in a few minutes, with the charge current dropping very rapidly, so I doubt I'm getting as much as 1AH into the battery during that time...

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[Masman]

Your gel set up will charge a lithium battery which will also give you twice the energy available and half the weight. Lithium are now about the same price as an agm or gel so a no brainer. The gel setting will charge the lithium but not to a 100% but that's still provides more power for longer than lead or gel or agm

Jimbohorlicks My motorhome charges both batteries. Engine and leisure. Will fitting a lithium battery be suitable. Looking at other post re lithium I didn't think my motorhome was suitable for this.Unless I changed other parts on van. ie smart alternater.

 

[AdrianChen]

Jimbohorlicks My motorhome charges both batteries. Engine and leisure. Will fitting a lithium battery be suitable. Looking at other post re lithium I didn't think my motorhome was suitable for this.Unless I changed other parts on van. ie smart alternater.

Not who you asked, but I will offer an opinion.

The charging of both batteries by your engine given a 2004 vehicle will probably be accomplished by a split charge rely, which simply connects the leisure battery to the cab battery using a cable thought suitably big enough by the vans builder to connect two lead acid (similar) batteries, that system will likely give around 20-30amps max, unless the hab battery is pretty empty in which case more might go through for a time. When you put in a lithium hab battery it can accept a much higher charge current than the original LA battery. In some cases the split charge relay and cables will simply limit the current by virtue of the cables resistance, without it getting hot enough to cause any issues. In others it may be that the cable and relay are sufficient to allow a significant current that might be enough to cause the vans alternator to get too hot especialy if the new lithium is a large capacity jobby. So it depends on what is fitted to the van currently, and again there are folk who report no problems with just dropping in a lithium replacement. (Not a huge 500AH bank, but single 100AH for eg which will still give double the usable power of a standard wet leisure battery).

Worth having a chat with somebody like Offgrid Power Solutions (Funster Discount Available), or even a battery supplier like Fogstar. It may well be viable financialy vs a quality Gel battery, even if a small b2b is fitted.

I was guessing your van was 2004, but perhaps not! A smart alternator isn't something you could fit, and if you don't have one that's better in many ways! So if the van isnt start/stop with smart alternator, then the above treatise is fine, if its post 2016ish and does have a smart alt, then it may well have a B2B charger instead of a split charge, which would likely make adding lithium an easier proposition, since many b2b's have a lithium setting.

 

[Masman]

Not who you asked, but I will offer an opinion.

The charging of both batteries by your engine given a 2004 vehicle will probably be accomplished by a split charge rely, which simply connects the leisure battery to the cab battery using a cable thought suitably big enough by the vans builder to connect two lead acid (similar) batteries, that system will likely give around 20-30amps max, unless the hab battery is pretty empty in which case more might go through for a time. When you put in a lithium hab battery it can accept a much higher charge current than the original LA battery. In some cases the split charge relay and cables will simply limit the current by virtue of the cables resistance, without it getting hot enough to cause any issues. In others it may be that the cable and relay are sufficient to allow a significant current that might be enough to cause the vans alternator to get too hot especialy if the new lithium is a large capacity jobby. So it depends on what is fitted to the van currently, and again there are folk who report no problems with just dropping in a lithium replacement. (Not a huge 500AH bank, but single 100AH for eg which will still give double the usable power of a standard wet leisure battery).

Worth having a chat with somebody like Offgrid Power Solutions (Funster Discount Available), or even a battery supplier like Fogstar. It may well be viable financialy vs a quality Gel battery, even if a small b2b is fitted.

I was guessing your van was 2004, but perhaps not! A smart alternator isn't something you could fit, and if you don't have one that's better in many ways! So if the van isnt start/stop with smart alternator, then the above treatise is fine, if its post 2016ish and does have a smart alt, then it may well have a B2B charger instead of a split charge, which would likely make adding lithium an easier proposition, since many b2b's have a lithium

 

[PeterCarole29]

With your set up I would definitely go with gel batteries, agm do not make good leisure batteries….

Lithium is in some ways cheeper then other batteries now and will give you more amps per pound, even a fairly cheep lithium battery being charged on the gel setting (not ideal) will be better value, although it won’t fully charge it will still be better value..

Getting a lithium set up is the optimal best but it depends on how you use your motorhome….

You could add that if you have solar and get a solar charger that can charge lithium correctly then I think that elevates the problem of not having the correct 240v charger
Or a b2b

 

[Masman]

AdrianChen .Thanks for reply.Yes motorhome is 2004.Will get in touch with Offgrid solutions and see what can be done.

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[Just smiffy]

You could add that if you have solar and get a solar charger that can charge lithium correctly then I think that elevates the problem of not having the correct 240v charger
Or a b2b

Indeed it will be better if he has any other charging systems fitted, I got the impression that cost and ease of fitting is paramount….

As Masman is going to seek advice from off grid solutions then that would definitely be his best option, he may find that having a good system fitted will expand his horizons of more comfort and more off grid capabilities when touring and indeed save a few bob on paying for EHU….