Lithium Batteries

laknox wrote:

mikewats wrote:
Need a new battery. I was thinking of a 12V Lithium battery. Not very familiar with them, will my AC/DC inverter 50amp with charging work or will I need a special charger for this type of battery? Any help would be greatly appericated

If you're up to building your own, the Chinese LFP modules are working out very well, according to my cousin who used a Nissan Leaf battery to power their bus conversion. They said that, if they were to do it again, they'd use these modules instead of the Leaf's. The ones their friends used for their off-grid homestead are 280Ah =each=, and they installed 32 modules, for 29 kwh. From what my cousin has told me, for an RV, with only a few modules, you probably wouldn't even need to add a BMS (battery monitor system); not that you =can't=, just not really necessary.

Lyle

This is incorrect unless you never have a hard freeze, LiFePO4 batteries will be permanently damaged by charging at low temp (usual 32F/0C but some go slightly colder) so you need a BMS with low temp charging cutoff.

StirCrazy wrote:

laknox wrote:
They said that, if they were to do it again, they'd use these modules instead of the Leaf's. The ones their friends used for their off-grid homestead are 280Ah =each=, and they installed 32 modules, for 29 kwh.

Lyle

not the best idea for your rv, the majarority of thermal runnaway issues have been using the chemistry that they are. there is a reason tesla is starting to switch over to LiFePo4. cheeper to manufactuer plus there not subject to thermal runnaway nearly as bad. I know if two RV's that have burnt down from using tesla packs, and you still need a BMS if you want to treat it as a install and forget battery.

Steve

Um, that's what the LFP modules are; lithium iron phosphate, LiFePO4.

Lyle

afidel wrote:

laknox wrote:

mikewats wrote:
Need a new battery. I was thinking of a 12V Lithium battery. Not very familiar with them, will my AC/DC inverter 50amp with charging work or will I need a special charger for this type of battery? Any help would be greatly appericated

If you're up to building your own, the Chinese LFP modules are working out very well, according to my cousin who used a Nissan Leaf battery to power their bus conversion. They said that, if they were to do it again, they'd use these modules instead of the Leaf's. The ones their friends used for their off-grid homestead are 280Ah =each=, and they installed 32 modules, for 29 kwh. From what my cousin has told me, for an RV, with only a few modules, you probably wouldn't even need to add a BMS (battery monitor system); not that you =can't=, just not really necessary.

Lyle

This is incorrect unless you never have a hard freeze, LiFePO4 batteries will be permanently damaged by charging at low temp (usual 32F/0C but some go slightly colder) so you need a BMS with low temp charging cutoff.

I'll check with my cousin on this. He never mentioned any =low= temp issues.

Lyle

mikewats wrote:
Need a new battery. I was thinking of a 12V Lithium battery. Not very familiar with them, will my AC/DC inverter 50amp with charging work or will I need a special charger for this type of battery? Any help would be greatly appericated

The battery seller will have the battery manufacturer's specs for best charging.

The manufacturer of your rv's power center/charger will tell you if it meets those specs.

Some equipment has a battery charging section that can be changed to a charger that meets the lithium battery specs, or may have settings you can change.

Low temps - LiFeo4 batteries can be damaged if the cells recieve charging voltage when they are below 28-32F. Probably most commercial "Group" type batteries include cold charge protection in their battery management system (BMS). Self heating batteries are available on the market that pre heat their cells when they are receiving charging current before turning on the charge to the cells.
The caution is for the temperature of the cells themselves inside the battery case, not the outside air temperature for 30 minutes at sunrise. Li batteries are sealed so you can have them inside your heated space if you want.

laknox wrote:

StirCrazy wrote:

laknox wrote:
They said that, if they were to do it again, they'd use these modules instead of the Leaf's. The ones their friends used for their off-grid homestead are 280Ah =each=, and they installed 32 modules, for 29 kwh.

Lyle

not the best idea for your rv, the majarority of thermal runnaway issues have been using the chemistry that they are. there is a reason tesla is starting to switch over to LiFePo4. cheeper to manufactuer plus there not subject to thermal runnaway nearly as bad. I know if two RV's that have burnt down from using tesla packs, and you still need a BMS if you want to treat it as a install and forget battery.

Steve

Um, that's what the LFP modules are; lithium iron phosphate, LiFePO4.

Lyle

tesla and Leaf uses Ni-Co-Mn lithium batteries. and tesla uses lithium-nickel-cobalt-aluminum curently. you used to see people takeing a couple moduals out of wrecked ev's and building systems, but they are highly suceptable to thermal runaway if damaged. LFP are not very likly to have a thermal runaway event. I may have misread as it looked like you said they would have used the Leaf's instead .. so may have been a bit of confusion on my part. but the above is why we want to use LFP over tesla or other car modules.

Steve

No, cousin currently =has= a Leaf battery (plus 1 module to make the voltage work out right), but would replace it with the LFP modules if he were building =now=. Check out their build; just Google Beginning From This Morning. Web site and YT, both. Lots of videos. Pretty cool!

Lyle

My question is what size or amp hour should I get? I now have 2 6 volt with 200 amp/hr.that need to be replaced. With lithium able to be discharged past the 50%. Thanks Lee.

lem55 wrote:
My question is what size or amp hour should I get? I now have 2 6 volt with 200 amp/hr.that need to be replaced. With lithium able to be discharged past the 50%. Thanks Lee.

Depends if you want to continue to eek by on the minimum. I would have 300 AH minimum.