Bad Batteries and Air Conditioner?

poopskooper · 05-16-2011, 10:01 PM

Hi, I'm not only new to this forum but relatively new to RVing.

I don't have a real good understanding of RV electrical systems so I hope this won't sound too stupid.

First, I know my house batteries are shot. I haven't been in a hurry to replace them since I'm sitting stationary at the current time. I just assumed since I'm hooked up to 50 amps that I really don't need good batteries.

However, now that we now have days where we are needing the air conditioning, I am noticing a phenomenon that I hope somebody can confirm my suspicions.

The a/c will run for awhile and then shut off. It will then start back up in a few minutes and then go for another stretch of time (maybe five minutes) and then shut off again for a minute or two and it will continue to do this or until the desired temperature is reached.

I thought it was an a/c problem at first but then after I had shut the a/c down, I heard the muffled sound of the inverter going on and off for about an hour or so until the batteries indicated they were back on “float” mode. For that hour or so, the inverter would go on for about 30-seconds then off for about a minute or two then back on for 30-seconds, etc., etc.

Is this problem of the a/c not able to sustain itself until the desired temperature is reached related to the bad batteries? The batteries themselves no longer can hold a charge on their own.

This is on a 2007 Journey.

Thanks.

--skoop

The General · 05-16-2011, 11:12 PM

Skoop,

Replace the batteries before they destroy your converter which turns A/C into D/C.
Your air conditioner works with thermostatic sensors and may be working as designed.
Others will chime in on these subjects.

Welcome to the forum and hope all of your questions will be answered by our members.

Steve

Petro · 05-17-2011, 07:07 AM

Skoop;

I agree with Steve that you need to replace your batteries as a start to your problem. I assume you have an Inverter/charger. When plugged into 110V A/C your charger should be activated. It is trying to charge your batteries which supply 12V DC to your coach. Failure to replace your batteries I believe could damage your charger. I do not know what thermostat you have but mine requires 12V DC to operate correctly.

Don

poopskooper · 05-17-2011, 08:51 AM

Thank you, Steve and Don.

I know my batteries must be bad because if I unplug from 50 amp, I can't hold proper voltage for more than 15-minutes or so. Everything works normally otherwise when plugged in except when I try to use the A/C in a normal manner.

Last summer when I first acquired the coach and the batteries were seemingly normal, when it was 95 inside the coach and I set the thermostat to say 80, it would run continuously until it reached the desired temperature.

This year, the A/C will shut on and off before reaching the set temperature and then, as I mentioned, I can hear the inverter going on and off afterward for about an hour or so until the inverter display shows it is back in "float" mode.

My question is if the A/C problem is associated with the bad batteries?

Perry White · 05-17-2011, 09:01 AM

The thermostates work off of your low voltage. When your 12 volts goes low it tries to lock out ac. Your overloading the Inverter trying to keep all the low voltage appliances and lights going and trying to charge dead batteries.

RJay · 05-17-2011, 09:06 AM

Welcome to the forum!

Your batteries have very little to do with your A/C units. However there is 12 volts that feed into your thermostat. I think your A/C problem may be due to the coils freezing and thawing. When is the last time you changed your filters? What is the voltage on your batteries? Did they ever run out of water to the point of exposing the plates?

The only dumb question is the one that's NOT asked.

poopskooper · 05-17-2011, 09:07 AM

Thanks, Perry.

So running the A/C would cause the 12 volts going low? Everything seems normal when not running the A/C.

poopskooper · 05-17-2011, 09:10 AM

Thanks, RJay.

Yes, the plates on the batteries were exposed last year. I then refilled them but overfilled them, evidently, because there was all kinds of corrosion. This year, they're low again but I haven't yet refilled them. I know the batteries are shot so I have to replace them.

I just wondered if the A/C problem was related to the batteries or is it a separate problem. From what you're saying, it may be two separate problems.

AFChap · 05-17-2011, 09:20 AM

Quote:

From what you're saying, it may be two separate problems.

The a/c issue could be caused by the low 12v power. Fix the known/obvious problem with the batteries first, then worry about other issues IF they still exist.

The General · 05-17-2011, 10:02 AM

Quote:

Originally Posted by poopskooper

Thanks, RJay.

Yes, the plates on the batteries were exposed last year. I then refilled them but overfilled them, evidently, because there was all kinds of corrosion. This year, they're low again but I haven't yet refilled them. I know the batteries are shot so I have to replace them.

I just wondered if the A/C problem was related to the batteries or is it a separate problem. From what you're saying, it may be two separate problems.

Skoop,

As you can see by all the comments, if the plates have been exposed to air, the batteries are usually toast. Always keep the fluid level at bottom of the battery filler case hole, well above the plates and check monthly or more.
Without a properly operating a/c, d/c system your Air and other systems may not operate correctly and as many have stated, "the batteries must go before you will know."
Get my drift?

Steve

wa8yxm · 05-17-2011, 10:04 AM

You said "Inverter" which is a device that makes 120vac out of 12vdc, I think you meant "Converter" which converts 120vac to 12vdc.

Step 1: Take a can of RED spray pint (The Testor's brand from the tow (models) section at K-Mart or other super store is good here) or if you like a bottle of RED nail polish and paint all the wires on the most POSITIVE terminal on the battery (This is the one with more than one wire hooked to it normally., wires that run "off to somewhere" other than another battery.

Use black on the negative end.

Now disconnect, (Negative first) Unplug before you pull the positive wire, Put the positive wires in a plastic cup or tape them iside a tissue roller or other means of insuring they do not accidently touch anything metal and plug back in

If you do not have a Magnetek converter you should be good. (if yo uhave a magnatek converter (it will say so on the breaker box door) do not plug in,

now go visit the battery store. and get new batteries

When you hook back up,, Remember RED is positive

TXiceman · 05-17-2011, 05:55 PM

Lots of varied info her. If the pales are uncovered in the batteries, they are probably toast. The converter powers the 12 volt portion of the trailer.

As for the A/C short cycling, there is another problem. The compressor is protected with a Klixon (thermal overload). If the compressor is getting hot, the Klixon wil cycle it off and when it cools down enough, it will restart. Several things can cause the compressor to run hot.

First thing to check is the voltage inside the coach with the A/C running. You need no lower than 108 volts with the A/c running. Lower than 108 volts, will make the A/C draw more amps and the compressor run hot.

It could also be freezing the coil and cycling on the freezestat if the unit has one. If it is freezing you should get a smell of frost. Freezing generally caused by low or restricted air flow. Check the unit for dirty filter, dirty evaporator coil and internal air bypassing (inlet to outlet air).

Low refrigerant is what most inexperienced folks will tell you, but 90% of the problems with RV units are low air flow related.

If the units have an electronic control, operated from the 12 volt source, a bad battery can bother the A/C control, but it does not sound like this is the root cause of the A/C problem.

Let us know what you find.

K

Hikerdogs · 05-18-2011, 09:17 AM

The thermostat is not the only thing using 12 volts while you are plugged in. The lighting is running off the batteries, the furnace/AC blower, the control panel for the refrigerator, the propane detector and the monitors on the 1 place conrtol panel and anything plugged into the 12 volt power points all use battery voltage.

While each individual device places a relatively small load on the batteries the combined load is enough to keep the battery charger cycling more often than necessary. At some point it's going to overheat and shut itself down. When that happens the fridge, AC, and furnace will no longer run.

Perry White · 05-18-2011, 09:25 AM

No it's inverter. It takes 12 volts and changes it to 120vac AND charges the battery when pluged into AC. If the batteries are dead or bad it can overload the INVERTER and drops out the 12 volts to the charger. At least that's what mine does. If the batteries are too low it over amps the charger part and drops out. just sits and recycles till the batteries are up enough to lower the charge.

Perry White · 05-18-2011, 09:29 AM

Here ya go

http://rvbasics.com/techtips/rv-inverter-basics.html

The General · 05-18-2011, 10:13 AM

Quote:

Originally Posted by poopskooper

Hi, I'm not only new to this forum but relatively new to RVing.

I don't have a real good understanding of RV electrical systems so I hope this won't sound too stupid.

First, I know my house batteries are shot. I haven't been in a hurry to replace them since I'm sitting stationary at the current time. I just assumed since I'm hooked up to 50 amps that I really don't need good batteries.

However, now that we now have days where we are needing the air conditioning, I am noticing a phenomenon that I hope somebody can confirm my suspicions.

The a/c will run for awhile and then shut off. It will then start back up in a few minutes and then go for another stretch of time (maybe five minutes) and then shut off again for a minute or two and it will continue to do this or until the desired temperature is reached.

I thought it was an a/c problem at first but then after I had shut the a/c down, I heard the muffled sound of the inverter going on and off for about an hour or so until the batteries indicated they were back on “float” mode. For that hour or so, the inverter would go on for about 30-seconds then off for about a minute or two then back on for 30-seconds, etc., etc.

Is this problem of the a/c not able to sustain itself until the desired temperature is reached related to the bad batteries? The batteries themselves no longer can hold a charge on their own.

This is on a 2007 Journey.

Thanks.

--skoop

Hey Skoop,
Here are all of your specs including electrical:
2007 Winnebago Journey Specifications

Steve

wa8yxm · 05-18-2011, 02:50 PM

Two possible relationships (Well 3) between Air Conditionaing (A/C) Alternating current (AC) and Direct Current (DC or your house batteries)

1: T-Stat: May use the battery power to close a relay on the air conditioner board.. considering a few things... I think I'd do it that way myself. I mean you got it (12vdc) and DC relays cost less than AC relays so why not.

2: Carrier V's like I have have a computer operated control system, it's built into the Air Conditioner itself and it runs on... 12 volts DC provided by the house 12 volt system.

3: Energy management systems are computer controlled devices, now there is no reason they can not make thier own operaitng power (Generally 5vdc) from the mains, but.... you have all this lovely DC floating about so why not use it. A DC-DC down verter is way cheaper than an AC to DC conveter.

TXiceman · 05-18-2011, 07:28 PM

Perry, I don't follow you reasoning. An inverter converts 12 vdc back to 120 vac. There is a converter to change 120 vac to 12 vdc.

ken

targaboat · 05-18-2011, 08:33 PM

A converter IS the battery charger! It also supplies 12v to the coach. There is no charger AND converter together, they are the same thing. Functionally the ones in an RV are the same as the ones you buy and plug into the wall to charge the battery in your car at home. The RV units have more features to protect the battery from over charging and are usually much larger in their capability to product amps at 12 volts. One should not be giving advice until this is understood.

wa8yxm · 05-19-2011, 08:25 AM

TX and Tar.. You and I know a converter from an inverter...

1: Not everybody does

2: One of my converters (I have 2 on board) is also an Inverter (Prosine 2.0) The box says "INVERTER" on it,, but as a technician (electrnoics) I know it's both.

Actually I have a few more converters on board including one I designed and a couple I built myself, but those are for other things and are basically "Spares"