Hello everyone, I have a small problem. I have such a bank of energy from a Chinese company, I am worried about some of his performance quality. Energy Bank has parameters 51.2V and 66Ah, rated discharge current 70A. This is LiFePO4 cells.
I added a couple of photos from inside, it worried me that all the connections are so exposed and small diameter of the wires. The system has the ability to check the cells temperature there is 16 and they are connected in series are they balanced? There are some wires connected but it is hard to say whether it is from temperature measurements or from balancing. What do you think about all this?Are those cells that are loaded at about 1C in general need balancing? Are there any big mistakes?
Post a circuit diagram if you want to know it's safe.
Nobody can give you any reassurance without that.
Educated guess is that you shouldn't worry about the thin wires.
They seem for cell ballancing and/or voltage measurements of the cells, and don't carry any significant current.
The actual battery current flow through those big metal interconnection strips.
The white ceramic blocks on the bars could be the temp sensors.
Leo..
All lithium rechargable chemistries require a balancing charger. The small wires are for balancing, the main
current path are the aluminium busbars strapped between the cells, and the multiple black and red wires
from that to the controller (seem to be 5 of the black and a fat red wire at the other end).
I presume the controller handles all the balancing.
Exposed wiring for low voltage is quite normal inside a case.
Nothing about those pictures raises any red flags for me.
Patryk20:
I added a couple of photos from inside, it worried me that all the connections are so exposed and small diameter of the wires.
Is this the first time you've opened up any kind of 'energy bank'? If you've opened up other ones before, then show photos of those ones as well to compare with the one that you just opened.
Also, if any doubts about exposed wires.....could add some AquaSeal TM at connections.
Thanks for the answers. I've never unplugged such a device before, so I'm asking you on the forum. The manufacturer states that for LiFePO4 cells the number of cycles is 2000. They are loaded and discharged by 1C. I think the real number of cycles is about 800, right? I think I could charge batteries to full charge and discharge with measurements to see if they have declared capacity?
Number of cycles will depend a lot on how well you treat the pack - over rapid charge and discharge
will reduce lifetime, as will operating at temperatures very different from the optimum. The nominal
figure will usually be the under optimal conditions, so derating that figure makes sense. The depth of
discharge is a crucial factor too - try not to use the full capacity of a pack, most rapid degradation happens
at low states of charge (never over discharge, never store at a low state of charge).
Batteries are very imperfect devices.