Current too low charging LiFePO4 pack

[CCinBR200]

I'm new here and appreciate any help.

I have a 4s 280Ah LiFePO4 pack (currently wired as a parallel pack). I have it charged up to about 3.36V with a delta of 10mV. I have a small CV/CC charger which can supply about 65W. I have the charger set at 3.65V and 5.0A. When I turn it on, it shows that it's in CC mode, displays 3.37V and is suppying 0.001A. This doesn't seem right. Any ideas?

Thank you!

Carlo

 

[Bud Martin]

I'm new here and appreciate any help.

I have a 4s 280Ah LiFePO4 pack (currently wired as a parallel pack). I have it charged up to about 3.36V with a delta of 10mV. I have a small CV/CC charger which can supply about 65W. I have the charger set at 3.65V and 5.0A. When I turn it on, it shows that it's in CC mode, displays 3.37V and is suppying 0.001A. This doesn't seem right. Any ideas?

Thank you!

Carlo

Please show us the pictures of your setup that may help in troubleshooting.

 

[time2roll]

Would seem like a poor connection or poor connectors.

 

[CCinBR200]

I appreciate you looking at the setup. I know it's ugly. I'm finishing up the enclosure for it.

 

[MisterSandals]

You should connect the + and - leads to opposite ends of the parallel bank.

I have a small CV/CC charger which can supply

Is that the item labeled "Replacement AC Adaptor"?

 

[CCinBR200]

You should connect the + and - leads to opposite ends of the parallel bank.


Is that the item labeled "Replacement AC Adaptor"?

Yes, I'm using an old PC charger to supply the CC/CV charger. It should be 19V DC coming out of it. Is that ok?

When I put + and - on opposite sides of the pack, the only difference is that it is now alternating between 0.001A and 0.000A.

Thanks for your help!

 

[Bud Martin]

So is that the same power supply and that adjustable buck converter used when you charge the batteries in 4S?
Did you try using low Ohm resistor, I.E. 4R7 Ohms 5W, in place of the batteries to see if it will show any current draw?
And when the buck converter is not connected to the batteries, does the Volt meter on that buck converter show 3.65VDC?

 

[time2roll]

Have you independently verified the battery voltage and the charging source with a separate voltmeter?

 

[CCinBR200]

I have some ideas to try. I don't get a play day till Friday. I'll also have to get parts (e.g. 5W resistor). Will get back to you when I've tried out some of these ideas. Thank you again!

 

[Ampster]

When I put + and - on opposite sides of the pack, the only difference is that it is now alternating between 0.001A and 0.000A.

Perhaps your power supply is not current limited and going into hiccup mode. Or the buck converter is doing that,

 

[JeepDaddy]

It should be 19V DC coming out of it

Have you verified this with a meter?

 

[Bud Martin]

Have you verified this with a meter?

In his pictures, his buck converter Volt meter shows V IN of 20.01V.

 

[MisterSandals]

I recall a thread where someone figured out that with his charger, you NEED to set the output voltage BEFORE connecting to the destination battery (or started charging, or something like that). In other words you cannot adjust voltage on the fly.

Maybe the case here?

 

[Bud Martin]

I recall a thread where someone figured out that with his charger, you NEED to set the output voltage BEFORE connecting to the destination battery (or started charging, or something like that). In other words you cannot adjust voltage on the fly.

Maybe the case here?

Based on OP "I have a 4s 280Ah LiFePO4 pack (currently wired as a parallel pack). I have it charged up to about 3.36V with a delta of 10mV. I have a small CV/CC charger which can supply about 65W. I have the charger set at 3.65V and 5.0A. When I turn it on, it shows that it's in CC mode, displays 3.37V and is suppying 0.001A. This doesn't seem right. Any ideas?"
Based on that it looks like he did make the setting BEFORE connecting the buck converter to the batteries, but may be it is may not be the case.

 

[time2roll]

OK to crank up the charger for a few seconds to see what gives. Then detach and recalibrate.

 

[HRTKD]

What gauge are the wires? They look a little small in the pictures.

Wire Gauge Matters!

 

[CCinBR200]

Folks,

I absorbed all your ideas and I have a tentative (although not joyous) solution at the moment. I tested the CC/CV charger with 2 12V fans with known current limits (0.16A and 0.7A). The supply was unable to provide any current to either. It appears that I have damaged the CC/CV charger in one of my screw-ups experiments. Thankfully, it's inexpensive enough to replace. It was working before. I really appreciate the time each of you spent. You helped me up my troubleshooting so that I might find the issue easier before taking up all of your time.

Thank you!

Carlo