Chassis batteries are not charging

[RvFairyLady]

So we went up to Portland; 1st night was dry camping. Chassis batteries are brand new, we had been using lights and water pump, and the chassis batteries monitor showed the battery condition on the low side of "good". Ran the generator for 20 minutes and it was not changing at all so we shut it off. Spend the night running the heater and by morning they were down to "fair," almost "poor" on our meter. Made our way to our destination and plugged it in figuring it would charge them back up... but they next morning they were very low. We took them to auto parts store and they charged them for us. Next night they were down a bit below "good" again. We headed to our dry camp location figuring they'd last the night and we'd charge them up when we got home. The, on the last night we were dry camping again, we ran the generator again.., this time for over an hour... we saw no evidence that it was charging at all. We turned off everything but the heater and LP monitor so we'd have heat for the night... but batteries were dead around 2:30 a.m. and we were out of heat. Luckily we had lots of blankets.

Please advise... we like to try to do what we can ourselves.. obviously the chassis batteries are not receiving a charge. Where do we even start?

88 Ford Bounder. Old type converter. Thank you.

 

[Lou Schneider]

Hi Deanna -

The chassis battery is the one that starts the engine.  It also runs the "chassis" or automobile stuff like the headlights, windshield wipers, etc.

As a rule, anything you turn on from a switch on the dashboard draws from the chassis (starting) battery.  As does the radio and anything you plug into the dash cigarette lighter.  My motorhome has a pair of overhead bullet lights by the front window that are wired to the chassis system.  I can't use them when I'm parked or I'll draw down the starting battery.

Sounds like your house batteries (the ones that run the house stuff) are giving you problems.  They should be charged by the main engine when it's running and also from the converter.  The converter needs 120 volts to work.  Do your 120 volt outlets work when you start the generator?  If you don't have anything to plug in see if the microwave and/or air conditioner fan work when the generator is running.

If they do, it means the generator power is getting into the rig.  If it doesn't either your automatic transfer switch is bad or you don't have one.  Some older rigs don't have the automatic switch - instead you have to plug the shore power cord into a socket to get generator power into the rig.  Look inside the compartment where you store the shore power cord for that outlet.

 

[RvFairyLady]

ChassisHOUSE batteries. I knew what I was thinking but not what I was typing... 

Both the generator and the electric hook-up are getting power to the the rig. When plugged in to shore power, and/or when generator is on, the outlets, microwave, and TV's work.., so it is getting power from those sources. But neither source is charging the house batteries. Nor do they charge up when the main engine is running.

 

[boatbuilder]

When you say old style converter I assume(cringe) that you mean a basic one with the normal fuse panel attached.  If so check the fuses.  There are several that could blow and disable the charging.  There are two 30 amp fuses that protect against reverse polarity and one that protects the power lead to the batteries.

 

[Just Lou]

Just a couple of comments to try to focus your troubleshooting efforts.

There is most likely a common cause of the "non charging" from shore power and the generator.  Once past the transfer switch between the two power sources,  the path to the converter (charger) is common.  The converter/charger output is, of course, common to both power sources.  Problem could be: defective charger or blown fuses on the output.

With the coach plugged into shore power or the generator started and the batteries nearly dead (or very low), do the interior lights get brighter?  If yes, then the converter is okay, but the charging portion may not be working or, as Lou S. said, the output fuses are blown.  If no, then the converter is not working correctly.

How did you determine that the batteries were not charging from the engine alternator?  You could try the same test as above, but with the engine running instead of supplying shore or generator power.  The interior lights should brighten noticeably (under the low or dead battery scenario) when the engine is running.

The charging path is completely different from the engine (alternator), to the house batteries, than it is from shore or genset power.  There is a relay/solenoid involved that should provide this path.  The relay is the same relay that is used to provide the "Aux Start" function of bridging your chassis and house batteries when you activate the switch located on your dash.  If the "Aux Start" function does not work, then the charging from the engine alternator will not work either.

 

[Marsha/CA]

We took them to auto parts store and they charged them for us. Next night they were down a bit below "good" again.

88 Ford Bounder. Old type converter. Thank you.

By chance are you using regular car batteries instead of deep cell batteries?  If you are using regular car batteries to supply power to the "house" part of motor home then they will definitely run down much faster than marine type deep cell ones.

Also, just an FYI for future info after you figure out why your house batteries are not charging; when the house batteries get low, it takes a couple of hours of generator use to get them back up.  They won't fully charge with just brief generator time.

Marsha~

 

[carson]

  Too little info on the situation...

Problem could be: defective charger or blown fuses on the output.

  Pleas remember that many of the old-time converters have 2 circuits. 1. being the 12 Volt output for general house use..lamps etc.  The other 2. is the charging circuit for the batteries. Usually at a low amperage.

  The converter may work fine but the charging circuit may be dead. Happened on my old rig.

I guess the secret is to know if your batteries are functional (in good shape - fairly new) and then to see if the charging voltage reaches the batteries, when plugged in or on the generator. Should  read 13 to 14 Volts while charging.

If not, it ain't charging.

Carson FL

 

[RvFairyLady]

It's the weekend and we have to look at it, trying to see what we can do with it. We've tried/looked at what everyone here suggested.

I'm starting the topic on a new thread "need help with charging system" to see if I can't get some new replies.

Any of you that were helping, it would be great if you could check that out. I'm adding pictures so it may take a hour or so to get it up.

Thank you.

 

[Marsha/CA]

RVFairyLady,

One of the questions I asked you was whether you had deep cell batteries in your house batteries.  The reason I asked is that regular car batteries will run down very quickly when you use them to try to run the lights, fridge etc in your RV.  Deep cell batteries hold their charge for a much longer time.  So make sure you check to see if you do have "deep cell" batteries in your RV, not car batteries.

Marsha~

 

[RvFairyLady]

Thank you, yes, they are deep cycle marine batteries.

They are not losing a charge too quickly, but rather just never getting charged at all.

I've been trying to post but I can't seen to attach my picutures.

I'm working on it.

 

[Weewun]

1. I assume that you have measured the DC voltage across your House Batteries when plugged into Shore Power.  If you haven't then do it now,  it should read 13.6 volts or higher if the Converter is operating.

2. If the voltage across the House Batteries is 12.6 volts or lower then the Converter is not supplying charging voltage to the House Batteries. 

3.The next step would be go to the charging output terminals of the Converter and measure the voltage, if it is the same as measured at the Batteries, 12.6 volts or lower, then the Converteris not working. 

4. I would then check for input 120 volts AC.  If you have 120 volts AC at the input terminals I would then disconnect Shore Power and open the Converter to check for open internal fuses.

5.  IF you measure 12.6 volts or lower at the Batteries while connected to Shore Power and 13.6 volts or higher at the charging output terminals of the Converter then there is an open between the Converter and the batteries.  Could be a fuse, relay point or diode if you have an Isolator, broken wire, corroded connection, etc.

6.  If you read 13.6 volts DC across the terminals and you still exhibit the symptoms you described I would then suspect one or more defective House Batteries.  It is then time to use a Hygrometer, be sure to let the Batteries set (no charging) for 4 or more hours before testing the electrolyte.

Take the DC measurements and let us know what they are.

 

[RvFairyLady]

OK weewun... THANK YOU FOR RESPONSE... the charge of the batteries reads 12.9.. when unplugged and switched off as well as when plugged in and switched on. So, I believe it is not supplying charging voltage.. or it's wired wrong. I have another thread with a picuture link, I'll post it here at the bottom too.

3.The next step would be go to the charging output terminals of the Converter and measure the voltage, if it is the same as measured at the Batteries, 12.6 volts or lower, then the Converteris not working. 

OK... sounds good. Now where are those?

http://s44.photobucket.com/albums/f11/Seven11tech/RV%20wiring/

 

[OSSKOBRET]

check your (two) switches on your generator if one or both are not on this could be your problem, why do i think this ..........it happend to me once  ;D

 

[Weewun]

Did you turn the Perko switch to work on it.  On my MH that switch disconnects the Chassis Batteries from everything.

 

[RvFairyLady]

Thank you, we have some good leads.

We turned everything on to start working on it again before I go back to my 12 hour work days tomorrow...

We also had an appointment to bring it to a shop for a CA smog test... but today the starter went out.

We'll have to work on that before we can move forward.