2 LiTime 100ah Bluetooth LiFePO4 in parallel

[Jon R]

Thank you Jon. I’m not using the LiTime. I am going to order different batteries but not sure I really trust the BMS of any of them. So probably maybe just get a Blue Sea fuse block and an 80A fuse for the 4awg wires that I have.

Amazon.com

However the positive wires to each terminal will be longer than the negative wires. Not sure if that really matters though.

The relative wire length probably doesn’t matter, but I’m not sure I understand exactly what wire lengths you are saying would be different.

If your new batteries are matched and behave like every battery I’ve read about other than your LiTimes, you should not need to fuse the inter-battery connections to protect against large currents from charge state imbalance. Most people have direct unfused wires or bars between adjacent parallel batteries in a battery bank. Just make sure those wires are short and installed to prevent physical damage. The positive wire coming from the battery bank to your positive bus bar should have a fuse or circuit breaker as close to the bank as practical. My wire from the battery positive terminal to the fuse is about 12 inches long.

 

[crashmaster]

After seeing that LiTime BMS, I don’t trust any of the Chinese battery BMS’s so I figure it’s cheap insurance to fuse between the 2 batteries in parallel.

With the wire I have I would wind up with 16” wire between the negative terminals and about 20” of wire and fuse block between the positive terminals.

That whole LiTime experience has me thinking of going back to AGM’s.

 

[Jon R]

After seeing that LiTime BMS, I don’t trust any of the Chinese battery BMS’s so I figure it’s cheap insurance to fuse between the 2 batteries in parallel.

With the wire I have I would wind up with 16” wire between the negative terminals and about 20” of wire and fuse block between the positive terminals.

That whole LiTime experience has me thinking of going back to AGM’s.

Try not to get frustrated. I think once you have a well-thought-out LiFePO battery system installed you will be very happy with it. I really like that I don’t even have to think about electrical power when I camp. I occasionally check my battery level out of curiosity (hmm, it’s noon, am I back at 100% yet?), but never because I’m worried I might be low. Even more importantly, you don’t have to worry about always charging to full to maintain battery characteristics. Partial charging is fine, so you just drive and camp and don’t think about it.

I doubt you will run into another company that has a BMS that behaves the way you have described for LiTime. I would suggest, though, that you stick to one of the brands that has a lot of review and forum information that confirms the workability of a parallel battery bank. Alternatively just buy a 200 ah battery assembly.

There is nothing wrong or even that expensive about fusing the interconnect as we’ve discussed, though, so go ahead and add that safety feature if you want that conservatism. I like overkill in fire safety and electrical reliability.

 

[crashmaster]

Thanks for your help Jon.

Its probably overkill for battery safety. But in those close quarters I’ll sleep better, so it’s worth it. Besides that, it’s cheap and easy to do.

I was happy with my 220 ah 6V AGM’s. Was never lacking for power and I never had to keep checking it. Was typically fully charged in float mode by noon or so each day in the lower 48 in winter from a 160W panel.

I just figured the LiFePO4’s longevity would be better. Although the more I experience the Chinese stuff and read, the less sure I am of that.

I might just go to a single Battleborn 100ah LiFePO4 and just run it low and not worry about it. One thing I am sure of is it will not be a LiTime.

 

[Vic Harder]

+1 on your decision to ditch the LiTime batteries. You can't go wrong with a Battleborn battery.