openinverter forum

Hello again. As an update on my situation, I am getting the car ready to be towed to the shop for the battery swap out using the recently acquired 14 modules. In prepping the car, I removed the passenger seat to expose one of the batteries. Since I can easily access this one, I used my old BatteryGO to connect to this module and here are the readings. Once again, maybe this was the one good battery, but all of the reading are above 2.9v. None of these readings are anywhere close to any of the ones in my ORION Screenshot from 8/14. I remain baffled. Batteries should not be increasing in voltage.
I am not sure if I should pull out the other car seat and test that battery and if those readings are all in the 2.98 range, should I put this swap out on hold or go ahead an pull out all of the batteries and test them each???

Has anyone ever experienced batteries giving off incorrect readings through the BMS like I was seeing or are the shitty voltage batteries buried in the boxes and I will find out when we finally remove all of them and I test each one. At that point, I am swapping out the batteries regardless, I assume.

I pulled out the driver's seat and took the BatteryGO reading on that one and this is what is says:
Once again, these are much higher than what the BMS was telling me and they do no match up with any of the numbers showing on the ORION readouts. I wonder if all of my other battery modules are in this range since I kept them balanced and if the BMS wiring is messed up or the ORION itself. I cannot take any other readings unless I pull the battery boxes from the car (PITA and costly) but I do not know what else to do to confirm or rebut the BatteryGO readings.

I would say use a multi meter.

The fact these readings do not line up with your Orion 2 or the Cell tap tester means there are issues with your wiring. Potentially Cell taps and the HV interconnections between packs.

Hi Tom. Thanks for the reply. When you say test it with the multi-meter, I want to understand where I am testing it at. The BatteryGO was connected right at the battery mpdule without using any of my wire taps. I previously tested at each of the latge boxes at the HV +- inlets to each box with the multi-meter and I also tested the multi-meter at the HV box where it powers the AC and DC/DC. Are those what you are talking about or somewhere else? Again, I cannot get to the box battery modules without taking out the boxes, which is the plan tomorrow. No wire issues since putting the car into service until the day I ran the power down to 10%.

I also tried to connect up the old ORION 1 to the car but it it is not connecting for some reason.

I agree with Tom 100%. If something seems wrong with BMS readouts, check by hand with a multimeter. In fact, if I'm really skeptical about something, I will check with two different multimeters.

Test directly at the battery, and at the BMS end of the harness. If they're the same, move the harness around a bit, and test again. If its still the same, then the wiring is probably not the problem.

Determine which specific cells in the battery correspond to which specific cell readouts in the Orion. Compare those values.

I pulled out the cell taps from the ORION 2 and inserted them one at a time to take readings. Here is what I got. Unfortunately, I started popping fuses like popcorn when I got to the last one so I shut it all down and emailed Andrew Ewert again. Oh well . . .

All sorts of cell tap issues on most of those. No idea how its meant to be wired. why would cell 35 be missing in the first picture.

I agree Tom. Its a mess! I am getting a new ORION 2 from Chris Hazel, since he will be in Nashville next week and we can meet up. While the car is open and all of the battery boxes are removed, I will run the new harnesses to the battery boxes and start over on all of this. Once all of the batteries are out of the car, I will take readings on each of the 14 modules and if the readings are all above 2.5V, I will keep those batteries as spares or for a solar box or something in the future.

Find the problem with your devices or wiring, because you definitely have a problem there. Taking the car apart and replacing 400 kg of batteries, which are probably perfectly fine, won't solve it!

Based on these measurements, which match your measurements of the front box exactly, I would assume that your car batteries and wiring are fine. The 32 individual values or second 32 values displayed in the Orion, depending on how it is wired, must add up to the box voltage you measured, which they do not.

jsimonkeller wrote: ↑Wed Aug 13, 2025 9:40 pm ORION Cell Tap Validation tool

Do you have HV fuses or other disconnect devices between your battery boxes? Orion writes on this topic:

" if a safety disconnect or fuse is incorrectly wired to the Orion BMS such that it is in the middle of a cell group (12 cells),
if the fuse blows or the safety disconnect is removed, current can flow through the Orion BMS,
bypassing the safety disconnect or fuse leading to dangerous conditions."

Thanks for the additional posts.

Do you have HV fuses or other disconnect devices between your battery boxes?

Yes, but nothing in the middle of any cell groups. I have one box of 6 batteries (36 cells) which passes through a FUSE on its way to the next box with 6 batteries (36 cells) which then routes to the 2 batteries under the seats (12 cells). I think there is one more fuse after or before the 2batteries under the seats.

find the problem with your devices or wiring, because you definitely have a problem there.

Chris Hazel is bringing me a new ORION 2 BMS from the UK on his travels through Nashville later this week. Do you think I should wait to disconnect everything until I try the existing battery set up through the new BMS or go ahead and swap out these batteries with the new ones and work from there?

Hello everyone. Just as way of an update, the new batteries are installed and I finally was able to charge them up for the first time over the weekend after updating the replacement ORION 2 BMS parameters for my now 83 cell setup. Here is a screenshot following the initial charge.


Now onto the rest of my wiring. Thanks to all for your assistance along the way.