Prolong Charger Volt Readout Issue?

Hey guys, been lurking on here for a while. I have a somewhat strange issue with my Prolong Charger.

The first charge cycles it seemed to work fine. Got up to about 247V and just stayed there. After discharging to 101V and then 84V, the charger seems to be off on reading the voltage by about 12V.

When charging after the 101V discharge, it read 253V and then I freaked out and turned it off bc it was still climbing. I called HA and they said that's not possible bc it only outputs 250V.

So then I discharged to 84V and started charging again. It got up to 245V in about 5hrs or so so I turned it off worried that it would get over 250 again in the middle of the night. I also noticed that the amp cycling didn't stop until 212V where the first time it stopped at 202V.

This morning, I turned it on again and it got to 237V. Turned it off and connected the discharger but left it in idle just to get another reading and it showed 225V. So I figured the volt reading is off on the charger.

I connected the charger again and now it's running. The amps are stable at 344mA. Voltage is already at 248. I figured the system is working but something happened to the voltmeter. So it should be fine to let it run until it stops climbing, which I guess would be somewhere around 260?

Wondering if anyone else has experience this issue?

TLDR; volt meter seems off on the charger by 12V but amp meter is stable. Should it be OK to run even though volt meter will likely stabilize at 260?

 

As an update in case anyone else runs into this issue, it turns out that the multimeter in the charger is likely bad.

I ran some tests at the direction of Hybrid Automotive (thanks George!) And we determined that the charger was putting out 250V but the reading was inaccurate. So they have shipped out a display/meter module that I can fix myself.

For now, I've been letting it run and it seems to have stabilized around 255/256V on the display, which is likely 243/244V.

If you're wondering how to test the charger output voltage, disconnect the harness cable, turn the charger on, and then check the reading on the display. It should show 250V but mine was showing 272V. Then connect a multimeter carefully to the top and bottom pins on the charger output port that goes to the harness. Red on top and black on bottom. In my case it read 250V. This indicated the charger was safely outputting 250V but the display was wrong.

Like I said in the original post, another telltale sign was that the amp cycling didn't stop until the display read 211V instead of at 202V.

 

That would be cool though. Even a charger / discharger combo unit that would operate automatically would be great. So you'd still need to install the harness one time but then after that just plug in the device, power it up and let it run for the weekend without having to switch back and forth.

No more having to worry about the discharge finishing in the middle of the night that way as it could just start charging right away.

Allow smartphone monitoring/alerts/control and you got a pretty nifty device.

 

Yeah it all seems to have gone well. It stabilized yesterday reading around 258V. That was my final balance so will put it all back together later and see the results.

The balance after the 101V discharge was likely cut short though since I turned it off when the reading was so high but I figure I got at least two good cycles in so not going to bang on the pack anymore for now.