[DIYDAN]

Hi Everyone,

I'm really excited to be able to join a forum with people willing to convert a car to electric. I decided to ease my way into an EV conversion by buying a used Ford Ranger that was converted by a professional garage. I realized just how complex a conversion can be after buying the conversion and looking it over the past few weeks.

The issue with the truck is that it is running very slow, the max amp draw reads about 45A and the max allowable is 500A (without any discharge limits).
When I first bought the truck, one battery was at 3.26V and all the others were at 3.32V. When I plugged it in, it would charge for 30 seconds and then stop. I charged the low battery by itself with a power supply to bring it up to 3.32V because I thought it wasn't charging due to the low battery voltage. After that I bought the Orion Candapter and was able to communicate with the BMS. The batteries showed 94% state of charge and there were no errors reported. The Curtis controller is also not reporting any errors on the leds (flashes yellow). Is there a way to test the remaining life in the batteries?

About the Truck:
2008 Ford Ranger
Converted in 2009 for the city of Littleton and claimed to have about 10k miles on it post conversion
AC-50 motor, Curtis 1238 controller
34 cell LifePo4 batteries, 160AH, 110V
Orion BMS
Elcon PFC 2500 Charger
Lenco - IEDrives 2 speed Transmission

One image came in upside down, I tried to Save it upside down and re-upload it but it's still upside down

 

[brian_]

I don't have any useful suggestions at this point, but I'll just note that this is a pretty nice used conversion compared to buying a typical used DIY conversion:

• LiFePO4 instead of lead-acid
• AC motor
• 2-speed EV-specific transmission

 

[DIYDAN]

I don't have any useful suggestions at this point, but I'll just note that this is a pretty nice used conversion compared to buying a typical used DIY conversion:

• LiFePO4 instead of lead-acid
• AC motor
• 2-speed EV-specific transmission

Thanks. I got it at a good deal so I figured even if I have to replace something major it's still worth it considering how nice of a conversion it is.

 

[DIYDAN]

Log into the BMS and pay attention to the discharge current limit (DCL) and maybe try driving with BMS logged in and have someone Else watching the screen. I assume since they’re using an Orion with Curtis 1238 controller, they’re using the built in can bus to allow those two to communicate.

I personally think one or two things could be happening:

1. The Curtis is having an issue internally and throttling back current for whatever reason.
2. The Orion is having an issue, or thinks the batteries are having an issue, and therefor reducing the discharge limit and not letting Curtis discharge what you want it to.

That’s my first thought as to why, and in regard to charging, same issue. The wind can blow the wrong direction and throw error codes on the Orion so pay attention to DTCs. Chances are it thinks there’s a loose connection or dead cell, and isn’t allowing the pack charge or discharge.

Hope that helps

First off, thank you for your reply. I missed the reply notification and I just saw it today.

I got my hands on a Curtis Programmer and determined that the throttle wiper voltage range it was looking for was 0.5-4.5V and it was only getting 2V at full throttle, so I adjusted this and it was much faster after this. The next set of problems I ran into was 1) a severe undervoltage cutoff causing the truck to shut down and 2) a low discharge current limit. WRT the undervoltage, pack voltage starts at about 111V and it shuts down at about 99V when I’m pulling around 100A current. I see cells get down to about 2.84V. Pack SOC was 78%. Not sure if this is a normal voltage drop, or a sign of worn batteries. I attached a couple pics and a video of the live parameters while driving. Apologies for the shakiness, there's still snow on the roads.

WRT the discharge limit, I drove the truck with the Orion utility running as you suggested and I'm seeing a discharge current limit lower than expected, and then dropping down as I drive. In the video it starts at 83A (keyswitch off after pulling over from undervoltage shutdown), jumps up to 444A for a split second as keyswitch was turned, then with keyswitch on it settled to 161A. Is it combining discharge limits from the controller and BMS to sum to the discharge limit it shows? In the video, as I drive you can see the discharge limit go down as low as 77A. Do you know what parameter is making the limit drop while driving?




Video of live parameters while driving

 

[kennybobby]

... Do you know what parameter is making the limit drop while driving?

i would guess temperature. Or the low cell is pulling down the overall SOC such that the reduction for SOC is kicking in.

A cell below 3.0 volts has no energy left to contribute, might want to investigate the health of your cells and pack, and not let any cells go so low.

 

[DIYDAN]

Thanks kennybobby.

For the video I modified the derating for temperature to be 10A per degree C below 15C, and the low battery temp was 4C so that should account for 110A of reduction. As far as the cell voltage, the average drops down to 2.91V around when the truck shuts off, so a large number of cells go below 3V. Is there usefulness in further testing the health of the cells or is this a clear sign they should be replaced, and how should I further test if so? Any recommendations on a new/used battery pack? These are 34 Winston LifePo4 160Ah, 17.4Kwh total

 

[DIYDAN]

One thing I am surprised about is that I don't get a fault code from the controller or the BMS when the car shuts off. I'm assuming that I should see a fault code in this instance, so it is making it difficult To figure out the reason for shutting off