I inherited a Ford F-150 with a 1500 watt inverter from a co-worker. I went to use it today and all it does is give me one long beep and then nothing.
I measured the voltage coming from the battery at more than 12 volts. When I press the on button on the inverter the voltage drops to 5 volts and then start slowly climbing once the inverter stops beeping. I did the voltage checks with the engine running.
As far as I can tell all the connections are good. The in line fuse at the battery is good.
Is the truck battery just going bad or is this something else? Like perhaps maybe one of the connections isn't good? Thanks for any help!

 

I paid more attention and the voltage goes from 12.55 to 4.05 on my multi meter after I press the power button on the inverter.

 

I would start by checking the wire bringing battery power to the inverter. Look for a loose connection. Also under full load that inverter will draw considerable power. The wire gauge to a 1500 watt inverter should be about AWG 4. Just as an example:

Cable Gauges When connecting the inverter to a battery bank use the thickest stranded insulated copper wire available in the shortest length practical. If the inverter & the battery are positioned within 4 FT of each other, a minimum of #4 gauge wire should be used to make the connections. When the distance between inverter & battery bank is 4-6 FT, a minimum of #2 gauge wire is required.

The above example taken from here for 1500 and 2000 watt inverters as an example. Anyway I would start with checking the cables which power the inverter.

Ron

 

Measure the voltage at the battery. If it drops to below 5 volts there, then you likely have a failing battery. If not, then there is something in the wiring between the battery and the inverter.

 

I would start by checking the wire bringing battery power to the inverter. Look for a loose connection. Also under full load that inverter will draw considerable power. The wire gauge to a 1500 watt inverter should be about AWG 4. Just as an example:


The above example taken from here for 1500 and 2000 watt inverters as an example. Anyway I would start with checking the cables which power the inverter.

Ron

The inverter was installed by the fleet garage our company uses so I assume the wire gauge is fine. It is certainly bigger than 8 gauge, the thickest wire I have on me that I know the guage of. The inverter worked fine the last time the other guy used it but that was more than a year ago.

I'll recheck the wire connections.

Thanks.

 

It's not at all normal for a perfectly good 12 volt battery to fold over to 5 volts under the load of an inverter with no real load on it. If the battery can start the truck it should be fine. Most inverters have protection on their power in so I would thing such a load would pop a fuse or breaker somewhere. I would be looking hard at the power cable(s) for the inverter for things like a loose terminal bolt. Yeah, I agree if it was installed by a fleet garage and worked previously it should work.

Ron

 

After checking the fuse a second time I saw it was blown. I'll blame the writing on the fuse for obscuring the black smudge. Yeah, that's it...

Teaches me to not look closely enough.

Thanks all for your help!

 

Glad it worked out for you.

Ron