Airstream Forums

Airstream Forums (
-   Electrical - Systems, Generators, Batteries & Solar (
-   -   Batteries not charging via shore power??? (

crazylev 07-14-2016 12:46 PM

Batteries not charging via shore power???
Hi all.

I'm wondering if I have an issue with my batteries and charging while connected to shore power. Two brand new Interstate group 24's in the Bambi.

While connected to shore power and with the trailer battery disconnect swith set to "use" I went to take a reading of the voltage with multimeter on battery terminal and my reading was only 11.8 volts!

The fridge fan was running, and I had the two ceiling fans off, but they were running all night. I know I've heard that there should be no load on batteries for several hours to get a proper reading, but what confuses me is if I am hooked up to shore power, and that is going through the converter, shouldn't that voltage be 12 something, not 12.8?

Shore power (AC) works because I was running the air conbitioner all day yesterday.

5 years ago I replaced the original Paralax converter that exploded with a replacement that I can't remember the name of but this forum reccomended it.

Amy ideas?


Al and Missy 07-14-2016 02:23 PM

1. Since you have a multimeter, measure the voltage at the output terminals of the converter. If it is 11.8 (or whatever you are reading at your batteries) either the converter has failed, an output fuse has blown, or the converter has no power. If it 12-13 volts you have a bad connection, a bad STORE/USE switch, or a blown fuse or bad auto-resetting DC circuit breaker on your DC distribution panel. My Safari 25 had fuses, my Classic 30 has circuit breakers.

2. On my 25, the converter was plugged into an outlet and the outlet failed. Make sure you have power to the converter.

3. Wherever the converter gets its power from, that circuit is on a breaker. Go to your AC panel and throw all breakers off and back on. Sometimes it is not obvious they are tripped.

4. Follow the wiring from the converter to the distribution panel, at least checking at both ends to ensure that no wire has vibrated out of its terminal. Be careful here - a loose wire may be energized with significant current behind it.

5. My converter has fuses in its output. Check to be sure none are blown.

6. My trailer has a auto-resetting circuit breaker in the circuit to the battery. Make sure yours is not failed.

Hopefully it will be a simple fix and not a bad converter.


rocco52 07-14-2016 02:27 PM

I am no electrical genius but I always start with checking breakers and fuses and then I would check the output of the converter with a multi-meter. When you switch to "Use" do you hear the solenoid 'clunk"? You can also check the voltage at the Battery Disconnect itself. Mine is under the bed. I had to remove 4 screws and a wooden cover to get to it. I would also check the voltage of the batteries themselves with the Multi-meter.

crazylev 07-14-2016 03:58 PM

Thanks Al, Missy and Rocco.

I just checked the voltage at the output terminals at converter. Not good with electrical stuff to much. There are two giant red wires. One gors into a metal block called "conu. Pos" and the other goes to another block not labeled. There are two white cables too. Reading placing black lead from multimeter to white and red lead from multimeter to each red converter cable was 11.6 volts

All breakers reset. Checked little 22v fuses and they look good.

Here is what I've tried:

Unplugged AS from shore power. Turned Use/Store swich to store. It definately makes that relay "click" sound doing that.

I then switched to "Use" and again the click as well as a fan in the converter that runs for a second or two, leading me to think that the converter is getting power.

Thanks guys. Anything else I should look at?

DKB_SATX 07-14-2016 04:28 PM

Try isolating the converter. Carefully remove one of the battery cables and wrap it in something non-conductive to prevent arcing, then re-measure the voltage at the converter on shore power. If it's 0 volts your converter may be dead or it may not be receiving AC power. If it's 11.x volts, your converter is toast. If the converter's output voltage is over 13V without the batteries in the circuit but pulled down to 11.x with the battery in-circuit, you should have your batteries tested. Nothing prevents a brand-new battery from being bad.

Al and Missy 07-14-2016 04:31 PM


Originally Posted by crazylev (Post 1820786)
Thanks Al, Missy and Rocco.

I just checked the voltage at the output terminals at converter. Not good with electrical stuff to much. There are two giant red wires. One gors into a metal block called "conu. Pos" and the other goes to another block not labeled. There are two white cables too. Reading placing black lead from multimeter to white and red lead from multimeter to each red converter cable was 11.6 volts


This shows you have a good connection to the batteries. The fan running and the relay click says you have power to the converter. I you had a bad cell in one of the batteries, the converter would probably be running full bore and the fan would be on all the time. My take is you have a bad converter.

Isolating the converter could confirm that, but may not. Disconnect the white wire or both of the red wires. No need to tape the white one, it is connected the ground. If you still read 11.8 volts or lower (0?) the converter is bad. IF you read 12-13 it may be good, but you need to try another charger on the batteries to confirm that the batteries are good. Connect another charger to the batteries. If they charge up, the converter is bad. If they don't one or both of them is bad.


crazylev 07-14-2016 05:02 PM

Thanks again guys!!!!

I got my converter replacement from Bestconverter. I spoke with them briefly and as you fellows have mentioned, I need to run one more test:

Disconnect shore power. Disconnect terminals from batterys ( all pre cautions taken) re-connect shore power and measure voltage at converter output terminals. As mentioned, if it is zero, then I was actually reading battery voltage, not what is output from converter. Right?

And if this is the case, then yes another new converter replacement is imminant.

It was reccomended that between a 45w and 55w, the 55w was the best way to go because it charges the batteries faster. Something I need to consider whether it is worth the added cost.

When I asked Bestconverter why this may have happened, the reply was most lkely a power surge. I do use a Honda 2000 generator frequently to dry camp. What I think might be the problem is that I start the gen woth the cord attached. The honda on start up has an initial high rpm for a moment

Bottom line is after this, I will start generator and then plug trailer cord in.


crazylev 07-14-2016 05:06 PM

Oh, amd not to mention the two new batteries I may have ruined:angry:

DKB_SATX 07-14-2016 05:11 PM

I know the brief sound of a fan when you connect shore power is suggestive of power to the converter, but if I were troubleshooting my own trailer I'd want to be sure. I'm assuming the meter you used to measure the DC voltage is a multimeter that will also measure AC voltage, no? Does your converter plug into an electrical outlet, or is it hard-wired in? If you find 0V output by the converter when you're on shore power with no batteries in the circuit, make certain you have 120V AC to the converter before you order a new one. Just to cover all the bases, y'know?

crazylev 07-14-2016 05:32 PM


Thanks. I remember installing the converter I have now. There was an actual plug that I wrapped in electrians tape.

I have a feeling I was less than careful on how i handled generator to trailer hygene.

I will report more when my better half joins me tommorow to run that last test. Right now I need alcohol:blink:

crazylev 07-14-2016 07:17 PM

Ok. So before booze, one last test:

After all precautions, disconnected battery terminals, plug in to shore power, volts read at converter dc out red and white wires is now 13.6 volts. So again that's without the 2 new Interstates connected at all.

Ideas???? You have all been helpful, thanks again.


dougandlori 07-14-2016 07:24 PM

When I bought my 28 I immediately changed the converter to a 4 stage boondocker from best converter. It failed a few months later and was covered under warranty. The replacement is still working. Sometime things just happen.

crazylev 07-14-2016 08:57 PM

I almost forgot I also checked voltage at battery terminal end that voltage was 0.2volts!!!! WTF???

So 13.6v at converter out and 0.1v at battery term.

Don't have a clue about this? A short? Where to begin.


Al and Missy 07-14-2016 09:11 PM

That's weird. So you had 0.2 volts from the red wire to the white wire? If you had a short it probably wouldn't read the same at the batteries and the converter with shore power connected and all the wires in place.

What kind of STORE/USE switch do you have, a mechanical rotary switch or an electronic pushbutton? I don't know how an electronic switch will respond to the batteries being disconnected. You may have to physically follow the wires.


All times are GMT -6. The time now is 04:35 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.