Promble with truck

[kenfrank]

I have a promble with my electric truck. When I turn on my open controller my gages shows 126 dc volts when I step on my gas petal to go it drops to 0 volts and I can go. What is wrong? How do I fit it? Thanks

[Frank Lee]

That ain't the only promble here.

[user removed]

Check for bad connections with a volt meter? If I understand your problem?

regards
mech

[Astro]

Ken,
There are a few more words misspelled that just one. Normally people can work out what you mean but sometimes a misspelled word changes the entire meaning of the sentence making it difficult to easily understand the issue.

Originally Posted by kenfrank

...when I step on my gas petal to go it drops to 0 volts and I can go.

I am assuming you meant "i can't go."

If so then Old Mechanic has given you the most likely cause.
A voltage that reads correct under no load and then drops to near zero when a significant load is placed on it is usually a bad connection (high resistance).
The bad connection may be one of the battery connections (most likely) but could also be an internal connection in the controller or a failing contactor etc.

Use a volt meter to measure each connection.
Look for a connection with a raised temperature.
Check the torque on each of your battery connections (with an insulated tool for safety).

[kenfrank]

I checked all of the batteries, had 2 loose connections. Fixed that. still does not run. On the batteries pack the last battery the neg- post gets hot and smokes. What could be causing this? The wire coming off of the dc-dc convertor +V1 one end goes to the 250 amp breaker to the + postive side of battery pack has a fuse in it that keeps blowing out. The other wire coming off of the +V1 went to -neg side of the big 300amp fuse. Now nothing works. What am I doing wrong? Any sugestions?

[thingstodo]

Originally Posted by kenfrank

I checked all of the batteries, had 2 loose connections. Fixed that.

Good start.

On the batteries pack the last battery the neg- post gets hot and smokes. What could be causing this?

If the connection is tight, my first guess would be some corrosion. If you remove the cable and use an emery cloth sanding block to shine up the battery post and the battery cable lug (the side that touches the battery post is the only side that needs to be shiny), then put the cable back on the battery post and tighten it up - it should not heat up any more.

The other end of the cable may also be the problem. If that connection is corroded, it will heat up the whole cable and the battery post as well. The smoke may be the plastic on the cable, or the varnish on the copper wires. Either way, it's too hot!

If the hot cable is connected to the fuse, the fuse holder will be hot as well. The way a fuse triggers is based on heat (current * current * number of seconds) so heating up the fuse may cause it to trip when there is not really too much current flowing through it. And DC fuses are usually expensive.

The wire coming off of the dc-dc convertor +V1 one end goes to the 250 amp breaker to the + postive side of battery pack has a fuse in it that keeps blowing out.

The fuse for the DC-DC converter blows, right?

The other wire coming off of the +V1 went to -neg side of the big 300amp fuse.

The other wire comes of the -V, right? I've heard of DC-DC converter fuses failing when you accelerate hard. Putting a diode (rated for at least twice the current you expect the converter to use) between the +V1 and the breaker should fix that (allowing current into the converter, but not back out). If you are still burning fuses, some people have had success adding an inductor. The size depends on how big the capacitors are in your converter and how much your battery voltage sags. There is still some debate how much the inductor helps, if at all.

But if V1 is connected to both the positive and negative of your pack, it obviously won't work.

Now nothing works. What am I doing wrong? Any sugestions?

If 'nothing works' means the contactors do not close, then your DC-DC converter may have failed. It is a common problem in EVs. You can test that by wiring a 12V battery to your 12V system and see if some things work again.

Some EV conversions have a small lithium 12V battery pack that they use instead of a DC-DC converter. It avoids some problems, but requires another charger and a separate battery.

[kenfrank]

I disconneted the dc-dc- converter for now. Try to run it not a thing. when I turn on my 250amp breaker my light for the controller come on and stays on. When I turn the the controller sparks fly and blows my 250amp breaker, Now whats wrong?

[thingstodo]

Originally Posted by kenfrank

I disconneted the dc-dc- converter for now.

OK

Try to run it not a thing.

What do you mean when you say 'run it'?

when I turn on my 250amp breaker my light for the controller come on and stays on.

Is this both lights, Green and Yellow? That sounds like everything is OK at this point. Or is this another light, like on your dash?

When I turn the the controller sparks fly and blows my 250amp breaker, Now whats wrong?

Does this mean when you press the accelerator?

If you really mean that sparks fly - that would be bad! If that's what you mean, where do the sparks come from? The fuse, the contactor, the motor, the controller? Nothing should spark unless there is a bad connection.

It is difficult to figure out what is happening, even when you are there to see the problem. The fewer details you give, and the more we have to guess, the less useful our comments and guesses will be.

A description like this would be more helpful:
- I turned on the 12V to the controller. The Green and Yellow LEDs come on and stay on.
- I turned on 250 amp breaker on. The Green and Yellow LEDs stay on
- I pressed the accelerator a bit. Nothing changes. The motor does not run.
- I pressed the accelerator to about half. There are sparks from the motor and the breaker trips. The Green and Yellow LEDs are still on.