Lithium battery charging

[quadrider]

I have a 400 amp hour lithium battery with a progressive PD9160ALV 12V Lithium 60 amp charger. The charger is right next to the battery with 12 inch cable run and 2 Gauge wiring. When I unhook the ground wire from the charger, it shows 14.6 V but as soon as I connect the wire, it shows 13.6 V at the charger. The lithium battery is not charging I’ve taken it from 100% down to 75% down to 50% and still the charger is not charging back up. The BMS module it’s inside the battery case and the case does not come apart. I’m thinking that the BMS module may be bad and not allowing a charge to go to the battery. Any other ideas On what could be the problem.

 

[Isaac-1]

This sounds like something wrong with the charger, the ground wire should just be a safety ground to the frame and should not alter the output voltage.

 

[Contributor]

How are you determining that the battery is not charging? Are you measuring the current flowing into the battery?

 

[quadrider]

Progressive trouble shooting says to disconnect the negative wire at the terminal and measure voltage output. It says it should be around 14.6 give or take .3 and it shows 14.6. When i connect the wire it shows 13.6 volts at the terminals. My 400 amp battery guage shows 340 amps available. I put the charger on for one hour and the gauge stayed the same at 340 amps and 13.6 volts.

 

[Isaac-1]

Try leaving it for long enough for the batteries to fully charge, about 7 hours, and then retest the output voltage.

 

[Contributor]

what is your battery gauge? Is it a shunt?

 

[quadrider]

Yes its a Renogy 500A Battery Monitor with Shunt. The voltage on the battery meter was the same as on the multimeter. I’ll put the battery on charge tomorrow for 5 to 6 hours and then retest with a multimeter. since the battery meter and the multimeter were showing the same voltages during testing I don’t think I checked the voltage on the battery with a multimeter After I ran the charger for an hour. Maybe the gauge is defective. also I forgot about the shunt. The shunt is hidden down by the battery and I didn't check the connections there so i will check those tomorrow.

 

[John From Detroit]

I have a Crafstman 82360 Clamp On AC/DC ammeter.. From a quick google search no longer sold but there are others (But at a much higher price) you can find.

Unlike the harbor Freight clamp on ammeters this one measures both DC and AC amps with the clamp on (400 amp top current)
Use a clamp on multi-meter to measure current in one of the wires (either positive or negative) coming off the converter.
That converter will take several hours to make a noticeable difference in 400 amp hours of LI battery.

 

[Isaac-1]

Remember LiFePo4 batteries have much much lower internal resistance than Lead Acid batteries so you will not see the big spike in voltage while charging that you typically see with lead acid.

 

[quadrider]

Thank you for the help. I checked the shunt and realized the ground cable from the charger should be hooked up to the shunt and i had it on the battery. The other thing is the renogy 500 amp gauge is more software than a meter. i thought it used the battery voltage to determine the battery is full or not but it looks at the amp going out and in to determine the battery level.

 

[Lou Schneider]

Thank you for the help. I checked the shunt and realized the ground cable from the charger should be hooked up to the shunt and i had it on the battery. The other thing is the renogy 500 amp gauge is more software than a meter. i thought it used the battery voltage to determine the battery is full or not but it looks at the amp going out and in to determine the battery level.

The cumulative amp-hours going in and out of the battery is a much more accurate indication of the battery's state of charge than just looking at the voltage.