LiFePO4 Battery Charger

[Sergio]

Perhaps PingEye3 has seen that model, I have not.

You can always try each trim-pot.

Place your voltmeter on the charger output and leave it there.

Use a small screw driver to turn VR2 slowly clockwise half-turn at the time up to two turns.

If the voltage goes UP, then turn it counter-clock-wise.

If the voltage does not change, put it back in the original position and try the the same procedure on VR3 then VR1.

[flyons78]

Originally Posted by Sergio

Perhaps PingEye3 has seen that model, I have not.

You can always try each trim-pot.

Place your voltmeter on the charger output and leave it there.

Use a small screw driver to turn VR2 slowly clockwise half-turn at the time up to two turns.

If the voltage goes UP, then turn it counter-clock-wise.

If the voltage does not change, put it back in the original position and try the the same procedure on VR3 then VR1.

No problem. What voltage am I aiming for? 53v?

[Sergio]

How many LiFePO4 cells do You have?

There is very little capacity above 3.6v (really 3.4v) so You don't need to charge to the limit.

If You have 14 cells, set the charger voltage to 50.4v or 49v for more conservative level (approximately 1% less capacity).

That VR2 should be the correct trim-pot if that charger follows the conventional functionality terminology found in other Lithium chargers.

[flyons78]

Originally Posted by Sergio

How many LiFePO4 cells do You have?

There is very little capacity above 3.6v (really 3.4v) so You don't need to charge to the limit.

If You have 14 cells, set the charger voltage to 50.4v or 49v for more conservative level (approximately 1% less capacity).

That VR2 should be the correct trim-pot if that charger follows the conventional functionality terminology found in other Lithium chargers.

I have 16 cells with a rated voltage of 3.2V and a charging limit voltage of 3.65V. So does 56V seem too safe?

[Sergio]

I would use: 56v (3.5vpc x 16 cells), that will give You 99% of the cells capacity.

[flyons78]

Originally Posted by Sergio

I would use: 56v (3.5vpc x 16 cells), that will give You 99% of the cells capacity.

Ok, so the middle trimpot seemed to do the trick. With about 20 full turns, I was able to get it up to 55.7V. That's as high as it would go with the middle trimpot.

Any clue what the left and right trimpots do? Should I tinker with them to see if I can get the 56V we discussed?

[Sergio]

I would not mess with the other two trim-pots unless your charger is exceeding 11 amps.

The VR1 typically controls the output current and it should only be adjusted (current reduced) when you increase the output voltage in order to keep the power output below the charger's maximum rating.

The VR3 trim-pot typically controls the current threshold levels and it should be properly calibrated from factory.

[flyons78]

Originally Posted by Sergio

I would not mess with the other two trim-pots unless your charger is exceeding 11 amps.

The VR1 typically controls the output current and it should only be adjusted (current reduced) when you increase the output voltage in order to keep the power output below the charger's maximum rating.

The VR3 trim-pot typically controls the current threshold levels and it should be properly calibrated from factory.

Any advice on how to test the amp output if my multimeter is only labeled at 10A?

[Sergio]

If You don't have a BMS that can display current or access to a DC clamp meter than the best way would be an external amp meter.

There are several options for dash meters from $25 to $$$ on Amazon.

I added a cheap hall effect sensor model like this one instead of using a shunt model that requires additional cable connections.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You need to put it in an enclosure as it is not water proof.

You also don't have to worry much about it unless you think your charger is getting unusually hot during charge.

[flyons78]

Originally Posted by Sergio

If You don't have a BMS that can display current or access to a DC clamp meter than the best way would be an external amp meter.

There are several options for dash meters from $25 to $$$ on Amazon.

I added a cheap hall effect sensor model like this one instead of using a shunt model that requires additional cable connections.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You need to put it in an enclosure as it is not water proof.

You also don't have to worry much about it unless you think your charger is getting unusually hot during charge.

You're always so helpful and it's very much appreciated! Yeah, in this case my BMS should give me what I need. I'm in the process of wiring up my BMS now. It's my first time wiring one up and connecting cells to make my pack. Couldn't do it without you guys answering my dumb questions.