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Question of the Day: Are you watching the Commonwealth Games?
LIFEPO4 Battery discussion thread
- Thread starter cavedog
- Start date
But the pacebms has a passive balancer, right? That means its passive balancing a group of 6 cells as one. Is that not the problem?
wingnut771
Honorary Master
No, parallel is like one cell. Like your 3 x 5kWh batteries is 1 x 15kWh battery.
I'm guessing they 17Ah cells, 17x6=102Ah.
There's no difference in capacity between 100Ah prismatic cell and 6 cylindrical cells in parallel totalling 100Ah.
It just made it more difficult for me to balance it because its in a plastic case and I need to remove the pack so I can attach the lead at the top and bottom. Sigh
wingnut771
Honorary Master
I wonder if this pack was ever balanced properly, I doubt it. I can't believe now seeing there are 6 cells in parallel that all 6 are faulty.
I double checked the balance cables they are spot welded so I could not see anything loose or an issues. I don't see any swelling. Don't smell any odors so so far visually I could not really see any issues.
Maybe 1 of the 6 in a bundle is faulty causing it to have less capacity as a cell?
wingnut771
Honorary Master
Could be or could be they never top balanced from factory. Most (if not all) batteries are not top balanced from factory. Not a problem with active balancers but with puny passive ones...
Lets hope not:
How do you even find which one is a problem?
If that is the case and this battery becomes useless I will just install prismatic cells.
wingnut771
Honorary Master
I dont think you can without stripping the 6pack and testing each one.
I can always install a 16s 5a active balancer. There is plenty of space in the case the issue is just removing that battery pack then soldering the balancer wires to the same point where the pacebms balancing wires are.
Pho3nix
The Legend
When did you upgrade and get a 5kW system?
wingnut771
Honorary Master
Dont think its neccessary once you have top balanced. Also, you dont want a balancer that is running all the time.
wingnut771
Honorary Master
He bought the 5kW, 5kWh all in one with sundries bundle special from builders for R10k. Sold out now but they still have:
wingnut771
Honorary Master
Its harder installing an active balancer than it is to top balance with dc-dc converter.
Pho3nix
The Legend
This isn't bad. Actually have 4kW of solar on the roof and this is cheaper than getting a 10kWh battery alone and a 8kw battery lol.
wingnut771
Honorary Master
Exactly. Was basically a free inverter and free sundries, so cheap in fact that if it wasn't for builders selling it you would think it was a scam:
wingnut771
Honorary Master
So the UVP disconnect means that it leaves the pack with roughly 20% capacity left in the other 15 cell packs.
I'm just going to use it like this and see if it ever improves but I have my doubts.
If I'm really keen to fix it I will get 6 of those cells and see if I can chisel the busbar off and then just drill small holes in it and replace them with cells that have studs on them for example. That would probably be the cheapest way to repair if it doesn't get fixed. Replacing the whole pack with prismatic will probably only be worth it if I buy cheap 2nd hand cells or if the entire pack fails.
I'm just going to use it like this and see if it ever improves but I have my doubts.
If I'm really keen to fix it I will get 6 of those cells and see if I can chisel the busbar off and then just drill small holes in it and replace them with cells that have studs on them for example. That would probably be the cheapest way to repair if it doesn't get fixed. Replacing the whole pack with prismatic will probably only be worth it if I buy cheap 2nd hand cells or if the entire pack fails.