Precedent Charging Issue

[lordj37]

Charging issue/question…..sorry for the lengthy question.

I just replaced the batteries on my 2010 Precedent with April 2022 stamped Interstates. I have a Modz charger (OBC still intact) that was working fine last fall and the couple times I used it over the winter with old batteries. During the first charge on the Interstates, the Modz charger started acting up early on in charge cycle. Fan would shut off, I would get random light colors/blinking and fan would kick back on. This would repeat every 20-30 seconds. Called Barry at Modz who initially thought charger was bad but had me check volts at charge receptacle. Pack voltage was 50.4 at the time but volts at receptacle was 43. While trying to diagnose the issue, I noticed anytime I unhooked and reconnected pack negative and pack positive, the volts at receptacle would reset and show the correct pack voltage (50.4) until I tried charging with the Modz at which point I would receive the same fan on/off and various blinking lights from charger. Unplug charger and volts at receptacle were back to mid 40’s. Did the unhooking and reconnecting of pack cables a couple times with same results. Moved to an OEM Power Drive charger and it ran fine however it charged for well over 16 hours and never shut off, eventually staying in the 3-4 amp range. I’ve read on here those chargers should shut off after 16 hours. Highest volts read before I unplugged charger (after about 20 hours of charging) was 66.4 volts, with each battery in the 10.9 to 11.0 range while charging. Any idea on what I have going on? OBC issues? Controller issues? I don’t want to cook these brand new batteries!!

Thanks!

[Fairtax4me]

You need to fully bypass the OBC. I don't know how the modz chargers manage to work when the OBC is still in the charging circuit, but somehow they do. However, They can NOT work if/when the OBC finally fails and it is still in the charging circuit.
The OBC is basically an SCR regulator, so it controls output voltage and current from the original Powerdrive charger. The reason you see lower voltage at the pins in the charge receptacle, is because you're checking voltage through the SCR circuit of the OBC, and not directly to pack positive and negative.
When the SCR circuit in the OBC fails, NO CHARGER will work properly, and the OBC must be fully bypassed and/or removed in order to properly charge the pack. It shouldn't even be connected at all if you're using a smart charger such as a Modz.
Bypass it and you should be good after that. If you continue to have problems, then replace the charger.

[lordj37]

Originally Posted by Fairtax4me

You need to fully bypass the OBC. I don't know how the modz chargers manage to work when the OBC is still in the charging circuit, but somehow they do. However, They can NOT work if/when the OBC finally fails and it is still in the charging circuit.
The OBC is basically an SCR regulator, so it controls output voltage and current from the original Powerdrive charger. The reason you see lower voltage at the pins in the charge receptacle, is because you're checking voltage through the SCR circuit of the OBC, and not directly to pack positive and negative.
When the SCR circuit in the OBC fails, NO CHARGER will work properly, and the OBC must be fully bypassed and/or removed in order to properly charge the pack. It shouldn't even be connected at all if you're using a smart charger such as a Modz.
Bypass it and you should be good after that. If you continue to have problems, then replace the charger.

Thanks for the quick reply Fairtax! That all makes sense I guess I was just being lazy by not bypassing the OBC when I initially started using the Modz charger. I’m assuming the bad SCR/OBC is the reason why the Power Drive charger ran well over 16 hours, failing to shut off as it should?

[lordj37]

Also…..any chance I damaged these new batteries when charger didn’t shut off after 16 hours?

[Volt_Ampere]

Overcharging like that does not damage FLA batteries. You may have to add water.

[lordj37]

Originally Posted by Volt_Ampere

Overcharging like that does not damage FLA batteries. You may have to add water.

Ok, thanks for the reply!