12V circuit only works on shore power or generator

[heyobie]

I have two 12V circuits that intermittently do not work. When I run the generator or connect to shore power the circuits work fine.

I am not sure what the electrical gods are telling me. Any advice is appreciated. It just rained and the problems resurfaced. Not sure if there is a connection.

Thanks in advance
1988 TravelMaster Ford E350

[tenbear]

I replaced the single stage converter with a modern 3 stage converter in my old RV, not as old as yours, and I also replaced the #8 wire from the converter to the battery with #4. If that wire in your RV is long it is probably worth the effort since the voltage drop in the old smaller wire may be fairly high and may produce too much heat when charging at a high rate.

[whemme]

Hey, if your 12 vdc appliances are working when you are plugged into shoreline power or when running the generator then you charger/converter is working just fine. It is not the problem. Are you sure your house battery master ON/OFF switch is in the ON position.

[heyobie]

I received and installed the upgraded converter/power supply that was a swap-out for my orignal BM Manufacturing 6345 with a 6345RU

The unit I bought came with a new DC distribution panel as well as the converter power supply. I know there are better options but it took me about 45 minutes to pull and replace.

It works beautifully and my problems appear to be resolved. As someone mentioned, they thought that the charging portion was not working. I believe this to be the case because the battery reads about 1 volt higher than it did with the old unit. So instead of 12.7 it was reading about 13.65 when I turned of the generator.

Thank you for your help. I'm a happy camper.

https://www.amazon.com/gp/product/B01DQBSTIO/ref=od_aui_detailpages00?ie=UTF8&psc=1

[Dakzuki]

Matt speaks truth. If you intend to keep the RV you will be much better off with a modern power converter. You will charge faster, batteries will last longer, and you quite possibly will solve your problem.


I was just troubleshooting my brother's 12 volt woes this weekend. His old converter is dead on the "filtered" 12 volt side which is also the battery charging circuit so it will be getting a PD replacement unit.

[heyobie]

So I took the advice to have the battery checked out. Battery is good. Talked to a couple vendors about my current system produced by B-M Manufacturing. They led me to Parallax Power who makes a replacement for the bottom end of the 6345. They say the problem is in the bottom of the unit which handles the charging and converting. So for $220 bucks, I'll give it a shot.

I'll report back when I get it installed.

[heyobie]

Thanks guys.i like swapping it out. I like my old rig that I have been restoring for two years and plan on crossing the country. Only 30000 on it. I got everything working with a couple bugs. In it about 6 grand at this point. Not fancy like the new rigs but it is historic and a good starting point.

[ksg5000]

Another possibility. Your rig likely has an auto reset circuit breaker near your coach batteries. When the circuit breaker goes toes up it disconnects your batteries from the rig. On most rigs the converter will operate without the batteries which would allow your 12 volt to work fine when hooked up to shore power. You can test whether the auto reset breaker works with a simple continuity test - they are available at any auto parts house.

[Matt_Colie]

Heyobie,

Check out/maybe replace your current converter/charger.

Your coach was built before the current versions of really good converter chargers were available. Because the controls were both expensive and bad, many had an internal 12V transfer (not to be confused with a generator transfer switch) so part of it made ~14.2 to recharge the house bank and another part made 12.5 to run the internal 12V service.

My bet is that the battery charge and the transfer are both dead. This is not altogether bad. After you have checked it all out and if I am right (that unit will have a pair of leads that go to the house bank and another pair to the DC panel), rip that thing out of there. Get a new three (or four) stage unit. I will suggest that you look at Progressive Dynamics 93XX numbers or Iota and I don't know the series and get one and put it in.

When you put it in, just make the connections from the panel, the house bank and the new converter all together and you should be good to go.

Unless you have a much more massive house bank than I would expect, just get a new version that is rated at about 40 amps and you will be happy. With the Iota and PD converters, that trickle charger will be a waste of time as they will do it better and be kinder to the bank also.

Matt

[naturist]

Several years ago I had a battery that charged up and would deliver 12.5 volts but deliver current for only a couple minutes to my trailer lights before things went black. I pulled it off the trailer when it was supposedly fully charged and took it to an Auto Zone where their tester showed it was toast. A new battery solved the problem. Charge your battery fully and then take it in to be tested. My guess is you have the same issue I did.

[Roadpilot]

Your measurements of 13.45 and 12.8 were probably done with either a trickle charger or shore power on. Measure the battery when you have the problem. It does sound like a battery issue.

[77rollalong]

Would check the relay that does the transfer for the 12V, as with our rv i have 1 circuit that is a direct battery connection for the radio ( separate fuse) , the rest go through the transfer relay, ours also has a battery disconnect switch which will kill all 12Vs from the battery to the 12v panel as well too but still work fine off the generator or shore power but will not charge the RV batter when off.

[heyobie]

The RV battery is only 2 years old and I take good care of trickle charging. I took a meter to the panel to check the voltages. On battery power, the main wires to the 12v panel were 13.45 and the same was found at each fuse

What surprised me was that when I measured with shore power the voltages dropped to 12.8. I thought since the problem was happening on battery power, that the voltage would be lower on battery not higher.

[2oldman]

battery