Community Forums

knightinme · 06-08-2009, 07:43 AM

The only two 30 amp fuses in my inverter instantly blow when the battery is attached. With shore power everything works fine (obviously except the charging mechanisim for the battery since the fuses keep blowing).
Initially it was fine; there was no heavy load and suddenly pop -pop both fuses blew.
Is there a quick or easy way to verify anything related to this? I am comfortable around a multi-meter and any help is really appreciated.

Paul R. Haller · 06-08-2009, 10:25 AM

Disconnect the converter out of the charge circuit by removing one of the +wires from the battery to the converter at the converter and measure the output voltage of the converter plugged into shore power. It should read 13.5 volts or higher and the polarity should be correct at the converter. + side of converter should be connected to the + side of the battery and - side should either go to - battery post or to the frame. Check that the batteries are installed correctly and wired up right. If you have 2 12 volt batteries, they should be wired in parallel with each other. If 2 6 volt golf cart batteries, in series with each other. No matter the configuration, the total out put from batteries is, as measured at the fuse panel, should be about 12.5-12.65 fully charged and not connected to shore power.
Modern converters will both charge the batteries and power up the 12 volt side of the circuit at about 13-14 volts when plugged into shore power if all is working properly. If this is a new problem in an otherwise used trailer I would suspect a bad converter. If however you are buying this trailer and do not know its history or if the trailer just had new batteries installed ,look carefuly at how they are wired.
-Paul R. Haller-

knightinme · 06-09-2009, 08:39 PM

Thanks for the info Paul; I will post my results.

wa8yxm · 06-10-2009, 08:43 AM

I see two possible issues

1: Those are called REVERSE POLARITY Fuses.. Are you sure you are connecting the batteries properly of if using a disconnect switch that they were installed properly? I have heard horror story after horror story about "OPPS, I put 'em in backwards"

2: IF you have "Upgraded" batteries and they are dead, and I mean DEAD dead, and your coverter is big enough.. It could be they need a pre-charge. Normally if they are that dead they also need a funeral (Recycling)

WindRVer · 06-14-2009, 03:22 PM

Quote:

Originally Posted by wa8yxm

I see two possible issues

1: Those are called REVERSE POLARITY Fuses.. Are you sure you are connecting the batteries properly of if using a disconnect switch that they were installed properly? I have heard horror story after horror story about "OPPS, I put 'em in backwards"

2: IF you have "Upgraded" batteries and they are dead, and I mean DEAD dead, and your coverter is big enough.. It could be they need a pre-charge. Normally if they are that dead they also need a funeral (Recycling)

I'm seconding this. My only 30 Amp fuses in my converter are Reverse polarity fuses, meant to protect against hooking the battery up improperly.

Good luck!

knightinme · 06-15-2009, 02:45 PM

Thanks guys for all of your help. I put my nose to the grindstone on this one. I actually bypassed the possitive cable by running a seperate 8 guage cable to the power converter in an effort to bypass any hidden ground shorts; no luck, still blew the fuse. I even took the unit out placed it on my bench and guess what... they blew, + to + and - to -

Reluctantly I drove the rig back to where I purchased it from and the technician said "oh yea, we get a bad batch of those from time to time". Changed it out under warranty repair and all works good now. The only reason I didn't go that route in the first place was that it is over three hours away. So I figured I would waste three days trying to save one

Anyway, thanks guys. You have enlightend me on other aspects of these devices as well.

But truth be told. Those fuses will blow for reasons other than what the manufacturer claims.

rvten · 03-30-2013, 12:58 PM

What make and model converter?
I just replaced my batteries. Dum A$$ me I did reverse polarity.
Blew the 2 30 amp fuses. corrected my mistake.
Put new fuses in. They blew again.
This is with a Parallax 7345 converter.

I am charging the new batts with a car charger right now.