Community Forums

travelingbard · 08-13-2015, 06:51 PM

Hi all! I'm changing out my house batteries tomorrow (they died quickly on the trip we're on - old and not proper deep cycles anyway). My question is this...

I can pull the batteries out in the morning and carry them with me to pick up a new pair of T105's, but I won't be able to get back to the RV until late in the afternoon. Provided I have the house battery cables isolated where they don't touch, could I reconnect shore power while I'm out during the day to keep the AC running? The cats would certainly appreciate it, but I don't want to risk causing another problem since there would be a completely open circuit at that point (converter/charger not hitting anything, etc).

Any quick advice would be hugely appreciated!!

Thanks!
Chris

**CLIFFTALL** · 08-13-2015, 06:55 PM

Your AC will not work without the batteries connected.

Mr_D · 08-13-2015, 06:58 PM

Some of the rigs that use a cheap converter use the batteries to even out the power. There could be a problem with the refer controls and thermostat for the air cons though as they use 12 volts.

Typing too slow, Cliff beat me to it!

Skip426 · 08-13-2015, 07:02 PM

The coach batteries act as a buffer between the converter/inverter/charger, and the rest of the 12 volt system in your coach. With no batteries in the circuit there could be a 12v power surge that could damage some very expensive parts. Safest would be to leave the batteries in the coach , get the new batteries and shut down everything while you install the new ones , run the cores in to the battery shop the next day.

EDIT: not as slow as me .LOL

Re-edit; but to be fair we both posted more info than Cliff did.

travelingbard · 08-13-2015, 07:03 PM

Ah, that makes since, assuming the converter doesn't feed the 12V system directly (only through the batteries). Is that normally the case?

travelingbard · 08-13-2015, 07:06 PM

On a related note, could these original house batteries (they were a pair of cheaper Marine 12V) cause the AC unit to sometimes Shed randomly? Like the control panel was getting shoddy voltage?

travelingbard · 08-13-2015, 07:09 PM

(BTW - I didn't expect replies until the middle of the night, so ALL of you guys are fast! Thanks!)

Skip426 · 08-13-2015, 07:11 PM

Quote:

Originally Posted by travelingbard

Ah, that makes since, assuming the converter doesn't feed the 12V system directly (only through the batteries). Is that normally the case?

The convertor/charger may feed 12v power through the coach BUT , it may think that it's being asked to charge completely dead batteries and run it's output voltage to high for the coach systems to tolerate.

Skip426 · 08-13-2015, 07:13 PM

Quote:

Originally Posted by travelingbard

(BTW - I didn't expect replies until the middle of the night, so ALL of you guys are fast! Thanks!)

Just hanging around waiting on supper .

YES DEAR! Be right there.

elkski · 08-13-2015, 07:16 PM

I don't agree. I think AC circuits & Air con system would work. converter may not.

tbbg II · 08-13-2015, 07:23 PM

Quote:

Originally Posted by Skip426

The coach batteries act as a buffer between the converter/inverter/charger, and the rest of the 12 volt system in your coach. With no batteries in the circuit there could be a 12v power surge that could damage some very expensive parts. Safest would be to leave the batteries in the coach , get the new batteries and shut down everything while you install the new ones , run the cores in to the battery shop the next day.

EDIT: not as slow as me .LOL

Re-edit; but to be fair we both posted more info than Cliff did.

This what I would do. I remember (barely) trying to power something directly from the charger and I had fits. I don't know for sure, but it seems the batteies act as some sort of buffer for the charger. I don't think chargers make good a 12VDC power supply. I think it may cycle on and off with no resistance from a battery bank.

twinboat · 08-13-2015, 07:33 PM

You should check the specs of your converter but most power converters are just that. They convert 120 volts to a regulated, 12 volts ( actually 13.5 ) to run the low voltage components in the RV. Many are single stage chargers but newer ones have 3 stage capabilities.

Unless someone has removed it and replaced it with a cheap battery charger, like the ones seen in Walmart, you will be fine.

TQ60 · 08-13-2015, 07:34 PM

The batteries are the filter for the converter.

So options...

Pay core charge and return batteries to get core back.

Or locate any working 12 volt battery like one from another car or lawn mower and install it in place of removed batteries.

Turn off all unneeded devices.

Skip426 · 08-13-2015, 07:40 PM

Quote:

Originally Posted by elkski

I don't agree. I think AC circuits & Air con system would work. converter may not.

Wall t'stat works on 12v and controls relays for the 120v in the A/C units themselves.
However, on older RV's with A/C controls at the roof unit would operate without 12v.