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AMP-HOUR+ amp hours number not changing

April 09, 2022, 06:30:02 pm

I'm trying to figure out my amp-hour+ meter by cruising equipment in our 94 U300. The volts and amps seem to be displaying the appropriate information however the amp hours reading stays at -0 no matter how much we've been using the battery or charging back up. Anyone have advice on what the problem might be or some troubleshooting steps I should take? Thanks!

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Re: AMP-HOUR+ amp hours number not changing

Reply #1 – April 09, 2022, 06:54:02 pm

Most likely, if you are plugged in to shore power, the battery charger is taking care of your 12 vdc loads and no Amp Hours are being removed from your batteries.  So "-0" indicates the batteries are being floated at full charge.

When I sit on my batteries over night, my display will read about -127 amp hours removed from the batteries to power all my 12 vdc loads.

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Re: AMP-HOUR+ amp hours number not changing

Reply #2 – April 09, 2022, 09:06:37 pm

I've been pulling ~20amps for over an hour with no change of the amp hours display, still at -0 with no shore power or generator.

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Re: AMP-HOUR+ amp hours number not changing

Reply #3 – April 09, 2022, 09:12:42 pm

I believe amp hours are measured by a shunt that is mounted on a wire near the batteries.  Perhaps there is connection problem with the shunt.

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Re: AMP-HOUR+ amp hours number not changing

Reply #4 – April 10, 2022, 07:57:06 am

If it were a wiring issue wouldn't the volts and amps not display correctly?

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Re: AMP-HOUR+ amp hours number not changing

Reply #5 – April 10, 2022, 08:04:36 am

Oops, my error here.  The shunt measures the current flow, amps.  Since that value is being shown, the shunt and wiring is okay.

Amp hours is a calculation of the current flow over time - number of amps times number of hours.  So, after getting my senior brain into a better gear, I think you have a problem with the component that calulates the amp hours.  I bet it is not repairable, only replace able.  Do not know where this item is located and what would replace it.

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