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I have a back of 16 Thundersky 100Ah cells on my first Elithion BMS Job. The BMS is functioning but I am having a difficult time getting the pack to balance. My Max voltave per cell is set to 3.7v and my cells are at (3.41, 3.55, 3.41, 3.41, 3.45, 3.45, 3.7, 3.45, 3.52, 3.45, 3.62, 3.65, 3.41, 3.65, 3.60, 3.43)

The charger comes on for a few moments (it had not CCL, just a relay on/off control from HLIM) and then cycles off when the top cell hits 3.7 (as it should). The number of loads 7, which makes sense, but I'm just not sure how long it would take to balance this pack. I get frequent messages "Cell boards too hot to balance", or "resting for 4 minutes" so the balance load time is pretty small. Should I just leave this thing plugged in for a very long time to balance? I did not know if this was a normal condition.

In retrpspect, I wish I had tied these cells in parallel to balance them all before the inital intstall,but no sense looking back!

 

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It will balance, but its going to take a while because you installed unbalanced cells in a pack.

ALWAYS equalize before you install.

What I would do?
Get a single cell charger and individually charge them.


oh, and BTW, thats normal. The boards heat up, they reach HLim and the BMS cuts the charger off, rests, then when the cell settles below its HLim, it will start charging again.
 

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I made the same mistake with my pack of 24 TS 160AH batteries this week.:eek:

So, can I charge individual cells while they're in series or do I have to take the pack apart? I will order a couple of these chargers if they will work. http://www.batteryspace.com/smartch...k1cellstandardfemaletamiyaplug38vcut-off.aspx

Or this one? http://www.batteryspace.com/Smart-C...cells-LiFePO4-Battery-Pack-100-240VAC-CE.aspx

There's about three days of labor spent assembling the pack and BMS. As much time as I have spent reading here, I can't believe I missed this! There no substitute for hands-on experience I guess.

It will balance, but its going to take a while because you installed unbalanced cells in a pack.

ALWAYS equalize before you install.

What I would do?
Get a single cell charger and individually charge them.


oh, and BTW, thats normal. The boards heat up, they reach HLim and the BMS cuts the charger off, rests, then when the cell settles below its HLim, it will start charging again.
 

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just disconnect the pack from the main charger (the series charger) and you can individually charge each cell without taking anything apart. If you're using two chargers, just make sure they're isolated (switching) chargers (both of those apear to be).

Get the 6A version, it'l speed things up a bit if you ever have to use them again.
 

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just disconnect the pack from the main charger (the series charger) and you can individually charge each cell without taking anything apart. If you're using two chargers, just make sure they're isolated (switching) chargers (both of those apear to be).

Get the 6A version, it'l speed things up a bit if you ever have to use them again.
Thanks Travis,

I've seen two LA packs with chargers for each cell, but wanted to ask just to be sure.
 

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It should be fine unless the chargers aren't isolated. Most are, so you should be fine. Better to ask now.
 

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It should be fine unless the chargers aren't isolated. Most are, so you should be fine. Better to ask now.
I contacted their tech support and the chargers I linked to above are NOT isolated.

nogas,

I'm sorry for hijacking your thread. I hope you're finding answers to your questions.

T
 

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Why not just parallell them for a while? Voltage should be equal on all cells then. Notice that you MUST disconnect the series connection first!
Well for one its a PITA since he's already installed the pack.....

its much easier to put a single cell charger on each one for a little while and do it that way.



As far as isolated chargers, you really only need one if you're using multiple chargers at the same time.
 

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Well for one its a PITA since he's already installed the pack.....

its much easier to put a single cell charger on each one for a little while and do it that way.



As far as isolated chargers, you really only need one if you're using multiple chargers at the same time.
Ok, that is true (but still for free).

Could someone explain why switching chargers are necessary? :confused:
 

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because switching chargers are isolated by their design.

There is no connection between AC and DC, its all isolated by transformers. The problem with non-isolated supplies, is when you connect two to the AC side, and then try to connect them to two different batteries in a series string, it causes a short because they share a negative connection.

If you're only using one charger its just fine.
 
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