Parallel connection of three 60V Li-Ion batteries

[mudpitrally]

Hello everyone - this is my first post, although I've been here a lot just reading since a while back. A lot of good information to be found here...

Anyway, the reason for my post is that I've purchased three lightly used 60V 30Ah Li-Ion batteries with the intent of making a second, seperate battery bank in my RV to be used with a 60V inverter to supply 220V.

So, I'd like to parallel connect the three batteries. I've read that its generally OK to parallel connect Li-Ion batteries as long as they have the same voltage (within some tolerances I can't remember).. On the batteries, however, it is written that it is "Strictly forbidden to use more than two battery packs in serial or parallel without permission", and that this will void any warranty. As I don't have any warranty anyway, this is not an issue.

What are your opinions on this? I would of course really like to connect all three, but it depends on what I am risking by doing so... Hope you can give me some advice!

These are the specs of the batteries from the manufacturer's website:

 

[snoobler]

Welcome to the forum.

All IMHO.

Sometimes, a component forces one to make crazy design choices to accommodate it. This is is one of those situations.

First, these have a VERY poor cycle life relative to LFP. This indicates they are the type of chemistry that results in fire if improperly handled, thus you have to be 100% confident in the battery's own BMS. On top of that, they are also fairly low current, again supporting the undesirable chemistry but also that they're using low C rate cells - think the 18650 cells that power a laptop instead of those in a Tesla - regardless of the manufacturer's claims.

In short, if I was paid to take these, and I knew they were brand new, I wouldn't use them.

Instead, I would spend $1000 on 8 280Ah LFP cells and a BMS and install a standard 24V system with readily available inexpensive components. This system would have 1.5X the capacity of your three batteries and 3-4X the cycle life.

 

[mudpitrally]

Okay, thanks for your reply. I'm too new to these kinds of batteries to recognize these things... Bad news, but better kill your darlings early. Thanks again..........