Lithium help please.

[cookie]

Got a Pvc and currently have 2 x 110 batteries and 200w solar , also have a 150w additional portable panel. do a lot of off grid and winter camping so thinking of changing to lithium battery's.

Thinking of 2 x 100 or 120a lithium so what else do I need to change, already have a decent solar controller.

Presume existing mains charger will need to go, but what about alternator charging?

Also my understanding is that lithium will charge quicker as no absorption phase needed, is this right ?

Also any recommends for battery suppliers, got a local one, county batteries but think they are a bit over priced, but have a 6 year warranty.

Cheers in advance for any help.

 

[Googlebot]

I have a thread in my signature about changing.

You can probably keep your existing mains charger but will need a B2B charger if you don’t already have one. Likewise your solar controllers will need a lithium profile.

You are right in that they don’t need an absorption phase, they take exactly what you put in with nothing wasted.

I got mine from Ecotree, a very good company to deal with.

 

[cmcardle75]

Better to go for a single battery, rather than the bother of having two. They're all multiple cells anyway and the BMS and chargers will do a better job if they're in control of the whole array. Also, if you get a single battery you can generally opt for a Bluetooth BMS which gives you some of the features that you would normally have to fit a battery monitor or smartshunt for. You can buy much larger LiFePO4 batteries than you can Lead Acid as they are lighter and more compact for the same effective energy. For example, my 300Ah which is on order is only marginally physically larger than my old 180Ah 629 battery. However, it weighs about 2/3rds what it replaces and has an usable capacity 3 times larger.

Whether you need to replace your mains charger or not depends on what it is. Most top end stuff has supported Lithium for a couple of years, provided you know how to find the menus. This charger must be lithium friendly, as not only is that required to reach full charge, it is likely to be continuously connected for long periods. A lead acid profile is likely to involve a float charge, which would be damaging to a LiFePO4, as it destroys the anodes). Once fully charged, the voltage must drop right down to a low "Power Supply" voltage significantly below a lead acid's preferred float voltage. If you are storing (or staying put on a site) for an extended period with EHU, it would be best to run the battery down to about 60% and then isolate it so there are no loads. This is very different to what lead acid prefers, which is a continuous low float whilst at full charge).

For alternator charging, you should really be thinking of fitting a B2B (aka 12V DC to DC charger). I personally wouldn't risk putting a lithium battery on a split charge relay. If you don't already have a B2B charger, you get to choose what you like, provided it has a lithium programme. I generally like Vitron stuff, but they only go to 30A ("Orion-Tr Smart 12|12 - 30"). Most people seem to fit the 60A Sterling charger (BB1260) if they do a lot of off-grid, as it will charge even a massive LiFePO4 array very quickly when driving. Votronic and CTEK are also well regarded. I'm not sure what their ranges are like, though.

 

[Rob Turner]

There’s a very good write up from Eddie in the latest magazine, all your questions will be answered there.

 

[Tombola]

What make of van is it\?
If its a UK van check the wiring thickness is up to the job. Fitting a higher rated MPPT for solar may do nothing if your wiring to carry the charge to the batteries is too thin.
I noticed a huge differnce when changing my weedy Autotrail cables

^{_{Subscribers  do not see these advertisements}}

 

[Pausim]

If your mains charger has a gel profile it will probably be fine with LiFePO4. It may slightly undercharge the battery but that does no harm (some say it even improves longevity) and when you are on mains you don’t need a full battery. A B2B and appropriate solar controller set up are more important.

 

[wolfie2]

cookie I have read that lithium should not be charged at low temperatures and if this is correct would it conflict with your winter camping? No doubt someone with real knowledge will be along to advise you

 

[Googlebot]

cookie I have read that lithium should not be charged at low temperatures and if this is correct would it conflict with your winter camping? No doubt someone with real knowledge will be along to advise you

You’re right.

They shouldn’t be charged below about 2 degrees.

If it’s a heated compartment then no problem.

 

[Pausim]

There is good news and bad news regarding LiFePO4 batteries in cold weather. The good news is that they do not exhibit anywhere near the loss of capacity due to cold as the other types. However, charging below freezing is best avoided (a trickle charge of one or two amps is probably ok). A fully winterised motorhome with heated battery compartment should avoid problems in use. If it is likely to be a problem there are low temperature versions with built in heating elements, the charge current is diverted to the heating elements until a safe charging temperature is reached.

 

[autorouter]

Also my understanding is that lithium will charge quicker as no absorption phase needed, is this right ?

It's true that no absorption phase is needed, and no float charge phase either. Lead-acid batteries are best charged at their Ah capacity divided by 5, ie C/5, and some would recommend even less, about C/10. Most Lithium batteries can be charged at C/2,and some are even quite happy at C. That's the main reason they charge quicker.

Using a simple split charge relay can cause problems. A deeply discharged lithium battery can present a very low resistance to the alternator. In some cases this can overload and overheat the alternator, especially if the engine speed is low - stuck in traffic, for example. A B2B controls the charging current, and avoids this problem.

^{_{Subscribers  do not see these advertisements}}