Wiring “Horn” and Digital Meter - Voltage Discrepancy

[srhoward]

Hi Guys,

Ok so I’ve done some questionable wiring on my 2002 36V EZGO TXT Sepex PDS. (Hoping that enough of a description of my cart in advance lol)

I’ve attached a diagram.

The main purpose was to introduce a digital voltmeter. I tapped into the +36V that is coming from the switch and sent it to the positive terminal of the digital voltmeter so that it would switch on and off with the key. I tapped into the -36V coming from the battery pack and sent it to the negative terminal on the digital voltmeter. Already I knew that this would introduce some error to the reading (vs. a direct run from the battery pack to the voltmeter). But I wanted it switchable on the existing switch (avoiding the introduction of another toggle).

Then I probably made the reading even more inaccurate by tapping into the + and - 36V from the pack, sending the positive to a push toggle to activate a “horn” (actually the horn is the reverse buzzer - since I keep it disconnected I thought I would use it to annoy people).

Here’s the result: battery pack measured at the source with a voltmeter is reading +38.13V. The mounted digital voltmeter that is tapped into existing wiring) is measuring +38.7.

For some reason the mounted meter is reading on the high side (probably because of all the shenanigans and the fact that the +36V is not even “pure” because it’s passing through the controller).

I expected the mounted reading to be on the low side, not the high side.

Any thoughts? I guess I’ll have to just set myself a new reference for what’s considered a full charge reading and what’s considered low.

Thanks!

yea ... lable all things in your diagram !!

but a couple members have had the same problem

i would ignore other readings and just watch the meter

also all readings need to be done with a fully charged battery pack
and after it has rested for 12 hours

[bronsonj]

I had inconsistencies when I wired my DVM in the dash. I tried it with three brands of handheld volt meters to see which was telling me the truth. All three hand helds read differently than the dash mount... The hand helds were a $7 junk meter, a $100 meter and a $140 meter. The $100 meter read the average of the other two and was the newest.

I spoke with an electrician buddy and he said that he'd trust the one that was the newest as they can go askew over time.

I don't know if he was correct, but he had far more experience in playing with electricity than I did so...

[srhoward]

Originally Posted by bronsonj

I had inconsistencies when I wired my DVM in the dash. I tried it with three brands of handheld volt meters to see which was telling me the truth. All three hand helds read differently than the dash mount... The hand helds were a $7 junk meter, a $100 meter and a $140 meter. The $100 meter read the average of the other two and was the newest.

I spoke with an electrician buddy and he said that he'd trust the one that was the newest as they can go askew over time.

I don't know if he was correct, but he had far more experience in playing with electricity than I did so...

Thanks bronsonj true could be the accuracy of my handheld...