Acceptable voltage discrepancy, Voltage at dash vs. voltage at battery Options

[98101]

I started my car after sitting a few days and noticed the dash voltage meter went up over 15V. In Tech Tips 700 I read that overvoltage could lead to battery acid spills, so I quickly shut it off.

Prior to that, I'd noticed the dash gauge reads lower than I'd like when all the lights are on.

I checked the voltage at the battery under different circumstances and they weren't so extreme in either direction. So now I'm wondering what the acceptable differences would be before you'd start to expect a poor (ground?) connection somewhere?


https://www.youtube.com/watch?v=S6BcQC-cjXo

[Spoke]

Short bursts of 16V on the battery should cause no issues. Long exposure to 16V is not good as it would overheat the battery.

To fully understand what is going on the electrical system and layout must be known. That ammeter should be wired from alternator to cabin to battery as Mike mentioned. If not, it would only measure the draw of the accessories in the car.

Do you have a schematic of how the ammeter is connected?

Also, when you saw the 16V, was it stable or bouncing around?

[98101]

Do you have a schematic of how the ammeter is connected?

Also, when you saw the 16V, was it stable or bouncing around?

I don’t think I have that schematic, but there’s a lot of records I’m still sifting through. I wasn’t going to worry about the ammeter before because I’d assumed it would be like the test equipment I’ve seen that uses inductive couplers over the insulated wires without any direct electrical connection. If it’s not being done this way ... I’m not sure it’s worth even having an ammeter.

When I saw 16V, it was steady for the 10-20 seconds it took me to shut the engine off. I’m not experiencing any problem starting the car or turning on the headlights so maybe this is something I should leave alone?

Previous owner(s) may not have been electrical wizards, or it may not have been their highest priority. There’s no brake lights or reverse lights, and about half the gauges are illuminated. The steering wheel horn button doesn’t work, but there’s a working horn button under the dash. The back pad light doesn’t work, but there’s a new light added to the dash with its own switch. The parking brake / brake warning light doesn’t work. There’s a tiny black button on the dash; neither I nor the previous owner know what it’s for (windshield washer?). There’s a hidden switch for the fuel pump which I kind of like, not that any thief without a tow truck would figure out how to move it anyway.

Surely due to some sort of oversight, the headlights (H4), driving lights, running lights, and turn signals / hazard lights DO work. But the turn signal automatic cancel doesn’t. As a motorcyclist, I kind of prefer to cancel them myself though.

[porschetub]

Do you have a schematic of how the ammeter is connected?

Also, when you saw the 16V, was it stable or bouncing around?

Previous owner(s) may not have been electrical wizards, or it may not have been their highest priority. There’s no brake lights or reverse lights, and about half the gauges are illuminated. The steering wheel horn button doesn’t work, but there’s a working horn button under the dash. The back pad light doesn’t work, but there’s a new light added to the dash with its own switch. The parking brake / brake warning light doesn’t work. There’s a tiny black button on the dash; neither I nor the previous owner know what it’s for (windshield washer?). There’s a hidden switch for the fuel pump which I kind of like, not that any thief without a tow truck would figure out how to move it anyway.

Surely due to some sort of oversight, the headlights (H4), driving lights, running lights, and turn signals / hazard lights DO work. But the turn signal automatic cancel doesn’t. As a motorcyclist, I kind of prefer to cancel them myself though.

Sorry to hear your electrical issues,PO wasn't too forth right about stuff on my car,no wipers,tailights,and worst of all gauges disconnected...every wire (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif) .
Got there and you will ok (IMG:style_emoticons/default/beerchug.gif)