DIY Electric Car Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter #1 (Edited)
Looking for some help or info on this one.

The current state is the following.
I have 6 used 12v lead acid batteries installed and holding voltage at 74v.

If I jack the front end the wheels will move slightly then stop when on the throttle. I put a meter across the contactor and didn't see any voltage drop.
If I let it sit for a few seconds it will move a bit more, try again quickly and it will move very little.

The dash also has one red light on it which doesn't appear to be an error only part of the display. The stock green lighting is missing.

I'm trying to figure out next steps. The goal is to move to lithium but I want to make certain I have a working vehicle before I drop the $ for that.

I'm also unable to identify the controller.

Thanks for any info.
 

·
Registered
Joined
·
981 Posts
There should be a regular Curtis 1209b inside there

If the motor is actually getting amperage you have blown brushes or something is seized, should make a humming noise while it tries to move

A simple ammeter off the last battery will show how much current is flowing
My guess is very little

These cars commonly have bad connections by the steering column along with bad grounding points on the chassis.

If you disconnect, validate and repin the 12 volt stuff in the cab and it still won’t go I would take the controller out of the car lift the front wheels up, chock and secure the chassis and connect the controller straight to the motor without any contactors then attach to the batteries directly, simulate a throttle with a resistor and see if there is life,
If not hook a 12 volt battery straight to the motor to see if there is life.

My guess is that the signal from the throttle isn’t making it to the controller, if not that the interlock is stuck due to bad wiring last possibility is a bad fr contactor

Process of elimination

Good Luck
 

·
Registered
Joined
·
24 Posts
I have 6 used 12v lead acid batteries installed and holding voltage at 74v.

First, You might want to charge those batteris, they practically discharged at 12.3V each.
You should see 76.8-77.4V when they are charged.

Seems like its only low battery and the controller shuts down, then when the voltage bouncing back it's on again...
 

·
Registered
Joined
·
20 Posts
Discussion Starter #6
First, You might want to charge those batteris, they practically discharged at 12.3V each.
You should see 76.8-77.4V when they are charged.

Seems like its only low battery and the controller shuts down, then when the voltage bouncing back it's on again...
I will give it a try. Wish I knew what the LVC was.
If I push the pedal it will lurch forward a tiny bit so it seems that systems are working but it doesn't have the juice needed. It will do that in forward and reverse.

Still no dash lights but that could either be voltage or possibly grounds or a bad display.
 

·
Registered
Joined
·
981 Posts
If you don’t have an active voltmeter get one.

If you are cutting out you should see the voltage drop then pop up after the throttle kicks in and out.

The big black flooded agms in that car can have the center covers cut off you can then add a couple tablespoons of acid it each cell and trickle.

Do you have a 12 volt load battery tester and charger?

If you do you can see but you probably have a failed battery or two.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #8
I don’t have a load tester.
I have a good meter and a genius 7200 charger.

I will test the drop.
I did have it on one side of the contractor last night and the voltage didn’t change when hitting the pedal. Should I test voltage drop at the battery ?
 

·
Registered
Joined
·
981 Posts
If you don’t have dash lights you probably need to solve that first

Is the 12 volt side of the car working?
Aka when on small 12v battery should be 13.5 volts.
Also when you turn on the car the brake vacuum pump should sputter to life, Putting it into F then stepping on the gas should make a solid metallic click.

If the 12 volt is too low or the dashing wiring is bad the car sets the interlock which cuts power to the motor

As for voltage drop you need to see the whole pack voltage if it drops a lot after turning on the car and pressing the gas you have bad batteries.

72 volts of lead acid are basically flat when you reach 72volts resting voltage
I am uncertain where the LVA is on your car but on mine it’s pretty low but I have a 48 volt miles.
 

·
Registered
Joined
·
981 Posts
I don’t have a load tester.
I have a good meter and a genius 7200 charger.

I will test the drop.
I did have it on one side of the contractor last night and the voltage didn’t change when hitting the pedal. Should I test voltage drop at the battery ?
Based on the above it Sounds like no current is flowing
 

·
Registered
Joined
·
20 Posts
Discussion Starter #11
Based on the above it Sounds like no current is flowing
I'm going to start with the grounds under the dash and connect them to the - of the 12v accessory battery (this is working, i have headlights, signals, etc.).

Is there any advice on tracking down the grounds ? I think I saw a black w/white stripe that connected to quite a few switches. Guessing that's the ground but I have to look further to see what travels to the instrument cluster.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #12
I figured out the issue with no power to the wheels. Some animal lodged an acorn in the second contactor and it wouldn't close. Cleaned it all up and she's moving again.

The only issue that remains is that I have no gauge lights.
I have turn signal, head light indicator and the other general lights but the green fluorescent light isn't lighting (speedo, battery level, etc.). Any ideas ?

I went through some voltages on it and I see 12v on quite a few wires going into the cluster but still no go. I'm guessing I can't just replace this with something else easily.

Thanks
 
1 - 12 of 12 Posts
Top