Help!!! Smoke during top balancing

moonlitsouls

Solar Enthusiast
Bought a 5amp power supply on Amazon to top balance my 280ah cells

wired in parallel but only had 4 bus bars so after discussing on forum, I created two additional bus wires using 6awg , stripped the ends and crimped , attached in staggered form as recommended pls see photos

I set my charger to 3.6 volts and the amps to 5 ,

then after all my research and preparation, I was still so stupid as to attached the positive red wire to the wrong side of the batter

yes , I repeat I mixed up the red and black alligator clips and attached them on opposite sides

After 30 seconds the charger started smoking and the wires got really hot , I realized what I did, let it cool and started again, seems to be ok now

I feel so upset right now

is it possible I did any damage to my batteries?

pls take a look at the images and let me know if I’m ok. Also, how do I know the charger is actually charging ?

79266C87-8A2A-4A2A-BA95-A8D9E78CB354.jpeg89AA833D-EBB8-4689-A63A-1CE1485BFD11.jpeg
 

Bud Martin

Photon Sorcerer
I you plan to charge at 5A I would suggest to get 10A charger to have head room, these cheap chargers cannot really run at full load current. Run at 80% of rating is what I would run.
 

Hedges

I See Electromagnetic Fields!
Electronics protects wires?

Maybe put red tape by the positive battery terminal.

Considering the supply only cost as much as one cell, don't feel too bad.

Check open circuit voltage of supply on its display and with a meter, try adjusting.
Check short circuit current, try adjusting.

I'm not sure what in a supply would smoke without failure, but you can let us know after inspecting as suggested and possibly repairing.

Assuming all is good, the next thing you'll complain about is supply is at the CV you set and current is tapering off.
Skinny wires and alligator clips have too much resistance (which was beneficial this time.)
Fat wires and connecting to opposite ends of busbars will be better.

Bud's "Don't Push it!" advice sounds good.

Got a BMS? If so, and if it as ability to disconnect as soon as a single cell hits target voltage, you can charge 4x as fast with the cells wired in series for 14V 4A as compared to parallel 3.5V 4A. Once near full, revert to parallel to finish top balancing.
 

moonlitsouls

Solar Enthusiast
The batteries are 100% fine. The charger may have been damaged. I would verify its output voltage. Even then, I wouldn't trust it without taking it apart and inspecting it.
Ok I attached my multimeter to the power supply where the alligator lines plug into and there is no volts , is that the correct way to verify output ?
 

moonlitsouls

Solar Enthusiast
Electronics protects wires?

Maybe put red tape by the positive battery terminal.

Considering the supply only cost as much as one cell, don't feel too bad.

Check open circuit voltage of supply on its display and with a meter, try adjusting.
Check short circuit current, try adjusting.

I'm not sure what in a supply would smoke without failure, but you can let us know after inspecting as suggested and possibly repairing.

Assuming all is good, the next thing you'll complain about is supply is at the CV you set and current is tapering off.
Skinny wires and alligator clips have too much resistance (which was beneficial this time.)
Fat wires and connecting to opposite ends of busbars will be better.

Bud's "Don't Push it!" advice sounds good.

Got a BMS? If so, and if it as ability to disconnect as soon as a single cell hits target voltage, you can charge 4x as fast with the cells wired in series for 14V 4A as compared to parallel 3.5V 4A. Once near full, revert to parallel to finish top balancing.
I do have a BMS that I planned on installing when I assembled the battery pack. I want to keep this process as simple as possible. Ok I attached my multimeter to the power supply where the alligator lines plug into and there is no volts , is that the correct way to verify output ?
 

Bud Martin

Photon Sorcerer
I do have a BMS that I planned on installing when I assembled the battery pack. I want to keep this process as simple as possible. Ok I attached my multimeter to the power supply where the alligator lines plug into and there is no volts , is that the correct way to verify output ?
No DC output at all? Sounds like the power supply is damaged by the back feeding from the battery into the power supply when the wrong connection was made.
 

Hedges

I See Electromagnetic Fields!
I do have a BMS that I planned on installing when I assembled the battery pack. I want to keep this process as simple as possible. Ok I attached my multimeter to the power supply where the alligator lines plug into and there is no volts , is that the correct way to verify output ?

Simple is good. It just takes four times as long.
What Ah capacity are your cells?
Do you know how long it will take to charge in parallel?
 

moonlitsouls

Solar Enthusiast
Simple is good. It just takes four times as long.
What Ah capacity are your cells?
Do you know how long it will take to charge in parallel?

280ah and I tested them all at 3.29 volts , I have no idea how long it will take, how do I calculate that? Thanks a lot for your help
 

Hedges

I See Electromagnetic Fields!
280ah and I tested them all at 3.29 volts , I have no idea how long it will take, how do I calculate that? Thanks a lot for your help

280 Ah x 4 in parallel = 1120 Ah.
You could try to look up what 3.29V at rest is as far as SoC. I'm lazy. Assuming 50% ...
560 Ah to go / 8A (assuming 80% of max on your replacement supply) = 70 hours or 3 days.

Not so bad to keep it simple.
Maybe it's a bit longer as current tails off. But you're only doing a 12V pack not 48V, so it isn't 2 weeks.
 

moonlitsouls

Solar Enthusiast
280 Ah x 4 in parallel = 1120 Ah.
You could try to look up what 3.29V at rest is as far as SoC. I'm lazy. Assuming 50% ...
560 Ah to go / 8A (assuming 80% of max on your replacement supply) = 70 hours or 3 days.

Not so bad to keep it simple.
Maybe it's a bit longer as current tails off. But you're only doing a 12V pack not 48V, so it isn't 2 weeks.
Oh hellllll no 3 days ?!!!! Lol
 

Hedges

I See Electromagnetic Fields!
Oh hellllll no 3 days ?!!!! Lol

Simple math. And it will be more or less depending on actual state of charge. If 30% SoC, need to put in 70% not just 50%
Did you wait 3 months for the cells to arrive? Or buy locally?
One forum member waited 90 days to hear the ship lost 700 containers at sea, and unloading what's left will take longer than normal.

With BMS having FET or relay to disconnect your charger, you can wire as a 12V pack and charge until the first cell hits 3.65V. Detailed instructions are available somewhere on this forum.

I changed front differential oil on my truck, squeezing quart bottle to push 80W 90 through a 15" tube. That was really a drag, putting in 3 quarts. In my day job I'm paid much more than a grease monkey.
 
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