Bad converter

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Paulaspack

Paulaspack

Member
Joined
May 9, 2017
Posts
15
Location
Beavercreek Oregon
I replaced my converter with the same make/model as the one that died. As soon as I plugged it in the fan started running and has been running continuously for several hours (just a thought, I assume it was the fan running...do they make noise when running?) I unplugged the RV and turned everything off so it doesn't run all night. The batteries are 1 year old, have water in them, never dried out. Battery check on panel says they are at 12.76.
I had the frig running to get ready for a trip, but that was all that was on.
 
What's the voltage of the batteries with the converter running? I don't know the backstory, if your converter was inop your batteries may be run down. "Dead" batteries can take several hours at converter full tilt to bring them back up.

Mark B.
Albuquerque, NM
 
Thanks Mark, the panel showed 12.76 with converter running, they had run way down as I was trying to figure out what was going on. I had a trickle charger on it for a day and a half waiting for the new part, so maybe I just need to plug it back in tomorrow and let it run. (it ran for at least 6 hrs today, I just worried about leaving it on all night)
 
12.76V is either very discharged and under charge, or sitting there doing nothing fully charged. Do you have a battery monitor that indicates current or watts? That would tell you if your converter is doing anything. A trickle charger does very little to bring up discharged batteries, it could take a week or more that way. With a good converter you could leave it plugged in indefinitely so once you know it's working OK, you should have no qualms about that.

Mark B.
Albuquerque, NM
 
If you measure 12.76 volts DC WITH CONVERTER RUNNING then you have a problem.. The converter will always indicate around 13.4 to 13.8 volts running..
 
Rene T said:
Would that apply even if the batteries were down to nothing?
Click to expand...
If the batteries are fully discharged often most converters will switch into boost or bulk mode charge rate which is around 14.2 to 14.6 volts.. The ONLY WAY to verify the converter is operating properly is remove the battery cables and with shore power applied measure the converter output at the batter cables -- if you have a shorted cell, etc trying to verify converter operation with batteries connected will result in erroneous readings
 
That’s what I was thinking. And they would only need to disconnect the negative cable then take a reading when plugged into shore power.
 
I leave my fifth wheel plugged in all the time when stored at the house.. running converter off 15 amp outside house outlet.. Have for the last nine years with the current RV we own.. The two GC2 six volt batteries are always fully maintained.. I do not remove the batteries for the long cold winter months here in Idaho. current batteries are now 7 years old and the specific gravity reading is still like new on all cells
 
Rene T said:
Would that apply even if the batteries were down to nothing?
Click to expand...
"Depends". If the batteries were really dead, were really good batteries (low impedance), the connection between the converter and batteries was low resistance, then upon plugging in the converter would be operating in current limit and the voltage could be 12V and change, until the state of charge came up and eventually hits the bulk limit of 14.4V. Conversely, if the batteries aren't dead, they're not in great shape, the connection between the converter and batteries uses thin cable then you'll see the voltage jump much more quickly, especially near the converter. 6 hours should be long enough to at least complete a bulk charge on the size of bank you'd typically see in a trailer, so I'd expect north of 14V at this point. I'm leaning to they're not getting charged (open fuse, breaker, miswired) but a battery monitor or manual amp measurement would be the final word.

Mark B.
Albuquerque, NM
 
Thank you everyone, it sounds like I need to leave it plugged in and expect it to run until the batteries (2 6v ) are fully recharged, I will do the tests suggested.
*update*
I tested at battery cables disconnected and shore power on, 13.69 which is what it was at the converter when I tested it as I installed it, so thats good.
batteries test at 12.3 with converter off. I am leaving everything on now.
I really appreciate the help here, it is so nice to have a place to come to for help. As a community we can do great things!
 
Last edited:
Paulaspack said:
Thank you everyone, it sounds like I need to leave it plugged in and expect it to run until the batteries (2 6v ) are fully recharged, I will do the tests suggested.
*update*
I tested at battery cables disconnected and shore power on, 13.69 which is what it was at the converter when I tested it as I installed it, so thats good.
batteries test at 12.3 with converter off. I am leaving everything on now.
I really appreciate the help here, it is so nice to have a place to come to for help. As a community we can do great things!
Click to expand...
I’m no expert but I’m wondering if 13.69 is a little low. Can you get to the converter and see what the label says as far as output?
 
13.8 is "trickle/float" and it would end up there after finishing bulk phase at 14.4V with most modern converters. If you look up the make/model of the converter you can find out it's exact charge profile if the question of where it's at and for how long ever comes up. 12.3V with the converter off is low - or did you mean 13.2?

Mark B.
Albuquerque, NM
 
Mark_K5LXP said:
13.8 is "trickle/float" and it would end up there after finishing bulk phase at 14.4V with most modern converters. If you look up the make/model of the converter you can find out it's exact charge profile if the question of where it's at and for how long ever comes up. 12.3V with the converter off is low - or did you mean 13.2?

Mark B.
Albuquerque, NM
Click to expand...
12.3 was what the batteries were at before I plugged the RV into shore power. The converter (fan) ran for about an hour more this morning. Batteries are fully charged at 13.5v and all is good.
I was just being over cautious, I never heard the old one run that long or loud, but then the battery was probably never that low.
Thanks for your help!
 
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