Help 12V battery

[Mark/Phyllis]

On board battery will not charge. Onboard generator will not charge battery either. Any suggestions

[chuckster57]

Without knowing anything about your RV, it’s just guessing

1) battery disconnect not switched to allow current flow.
2) battery hooked up backwards and “reverse polarity” fuses blown
3) converter shot

[Mark/Phyllis]

Converter shot I don't want to hear, but maybe possible. Battery hooked up properly. Double checked. Switch working properly because I can charge battery and it will work until runs out of juice. Can run auxiliary power unit until voltage gets too low to sustain spark. Then power unit shuts off. Will check fuses on converter tomorrow.

[flybouy]

Battery may have a shorted cell. Take the battery out and have it tested.

[Mark/Phyllis]

New battery. Less than 3 weeks.

[Javi]

New battery. Less than 3 weeks.

Very possible that the battery was hooked up backwards which in turn will blow the 40 amp fuses on the charger... wouldn't be the first or even the 9,000,000 th... :D

[flybouy]

Battery may have a shorted cell. Take the battery out and have it tested.

New battery. Less than 3 weeks.

The battery could still be defective it happens. When you changed the battery was the unit plugged in? If the positive lead touches the frame of other ground you can still blow out the fuses. Any other pertinent information you can recall?

[SC Dreamer]

If it was charging before you changed battery, then Javi is likely correct. Touching the wrong cable just briefly to the wrong post on battery will blow the fuses on converter!

[Mark/Phyllis]

That is the thing about it, we are 2nd owners and I don’t ‘think’ it was working properly when we bought it, but I am not 100% sure. Just know all fuses in panel are ok, but no charge.

[JRTJH]

1. Disconnect the battery from the RV wiring
2. Connect a voltmeter to the RV battery cables.
3. Plug in shore power and check the voltage produced by the converter and sent to the battery cables. It should be 13.6 VDC.

If the voltage is correct, the converter is probably OK. (troubleshoot your batteries) If the voltage is not correct, then you'll need to troubleshoot the system to determine if it is the RV wiring or the converter circuitry.

Those two "reverse polarity fuses" (40 amp red ones) are a safety feature for the converter and will blow "instantaneously" if you touch the positive battery cable to the negative battery terminal. Note I said "touch" not "connect and realize it's connected wrong".... It only takes a microsecond to blow the fuses.... BTDT.....

[GHen]

Good info above! My daughter has had problems with her new trailer batteries (2) since it was new. It appeared not to charge the batteries. Ended up one battery had a bad cell. This has been going on for a couple months.
To solve issue, disconnect batteries and check each on its own. In our case one was 12.9 volts, one was 10.8. System always goes with the lowest, so it looked like both were not charged. Checked voltage from the converter, 13.6, so converter was fine. Disconnected the 10.8 battery and all of a sudden everything in the trailer worked great again.
On my rv, my batteries were not charging, took me awhile to notice my battery disconnect needed to be switched. All works now.
Lesson, all your batteries need to be similar and equal. Check batteries separately to eliminate battery issue, 12.8 or so. Check output from converter, 13.6. Flip battery disconnect and check again. Check all 12v fuses, check all 120volt breakers. Then...call the dealer or electrician.

[Mark/Phyllis]

Well...........appears that converter has shot craps. Did not disconnect batteries, but converter output voltage followed battery voltage, with shore power and apu running. Guess it is time to shell out $275.00 and bite the bullet! Thanks for all your comments and suggestions. Gave me a lot to check before just throwing parts at it.

[Tom N OH]

Hopefully you checked the 2 40 amp fuses on the end of the converter.

[Mark/Phyllis]

Yes. Have 3 of them as a matter of fact. Checked continuity with my brand new multi-meter!!!

[ChuckS]

Did not see hat brand of converter but I’d replace with progressive. Dynamics.

[JRTJH]

Well...........appears that converter has shot craps. Did not disconnect batteries, but converter output voltage followed battery voltage, with shore power and apu running. Guess it is time to shell out $275.00 and bite the bullet! Thanks for all your comments and suggestions. Gave me a lot to check before just throwing parts at it.

I would urge you to disconnect the batteries from the converter and recheck the voltage at the battery cables (from the converter). There is a monitor circuit in the converter and it will shut the converter down if there is a defective battery attached to the system. The way you checked, with the batteries connected, if you have a bad cell in a battery, the converter is programmed to not provide the appropriate charging voltage to the defective battery. You may find that you have a good converter/charger and a bad battery.

[Frederick]

I had this problem found out rv teck had touch the hot bolt on my hyd. pump blew 2 40 amp fuses in converter fuses were a dollar labor 156