House battery gremlin(s)?

boybach

boybach

Well-known member
Dec 9, 2020
1,033
195
63
I picked up my new-to-me 1977 palm beach coach over the weekend and drove it about 500kms home to Vancouver Island.

When we tested the house circuits before we left, the monitor panel showed a voltage of a couple of volts or so and testing one of the house lights
resulted in a barely visible glow. The engine battery was good and strong but we assumed the house battery needed a good charge. The coach had been
stored outside over winter.

After driving about 400km we parked up and tried the house systems again, but the house battery hadn't come up at all, may have even been worse.
Next morning we pulled it out from behind the Onan and checked the cells. Cells were very low so topped her off with distilled water and ran the
engine for about 5 mins. Next, I flipped the battery boost switch and tried to get the generator running using the starter by the coach door. The
genset fired right up and the 110 stuff all seemed to work fine.
After we shut down the Onan, (which ran for about 5 mins total) the panel monitor showed the battery voltage up above 12v and indeed we could crank
over and start the generator and use the house lights too. I thought it was weird that the battery would come up so quickly but other than that,
everything seemed fine.

So we continued driving for about 100km and checked the system again. Nothing worked again and even the previously dim house lights couldn't light up.
In that state of affairs we couldn't crank the genny and the monitor panel gauge hardly moved, couldn't even register 1/2 volt.

Not sure where to start, plan ATM is to take the house battery in and have it checked.

Any suggestions on what/how to check appreciated

all the best

Larry
--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
Well, the important part is you got it home. Congrats.

Anyhow, it seems like the alternator is not charging the house/rear batteries. With the engine running check to see if it's getting charging voltage
at the back (I assume you can operate a multimeter). If not,
first place to look would be the battery separation diodes at the front (battery isolator), if that diode to the rear is open or bad connections, it's
not going to be charging the rear batteries from the alternator. (unless the boost/auxillary battery switch is on)

I'm finding that mine is wired nothing like stock, so I'm going off online prints. Who knows, yours might have custom wiring too.

--
Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, don't know the model
 
> Well, the important part is you got it home. Congrats.

Thanks!

blur911
> Anyhow, it seems like the alternator is not charging the house/rear batteries. With the engine running check to see if it's getting charging
> voltage at the back (I assume you can operate a multimeter).

Yes I can run a meter - barely! Should I disconnect the battery and clip on to the cables or can I just meter across the terminals with the battery in
place?

blur911
> If not, first place to look would be the battery separation diodes at the front (battery isolator), if that diode to the rear is open or bad
> connections, it's not going to be charging the rear batteries from the alternator. (unless the boost/auxillary battery switch is on)

Is the battery isolator the finned unit mounted on the upper left of the firewall?

Thanks

Larry

--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
With the engine running, go to the Isolator located outside on passenger
side, Blue finned device 3" x 3" with 3 wires.
Take a reading on all 3 .
They should measure 13-15 volts.
If you're not getting about the same as the center, it indicates defective
isolator.
Let me know.

> > Well, the important part is you got it home. Congrats.
>
> Thanks!
>
> blur911
> > Anyhow, it seems like the alternator is not charging the house/rear
> batteries. With the engine running check to see if it's getting charging
> > voltage at the back (I assume you can operate a multimeter).
>
> Yes I can run a meter - barely! Should I disconnect the battery and clip
> on to the cables or can I just meter across the terminals with the battery
> in
> place?
>
> blur911
> > If not, first place to look would be the battery separation diodes at
> the front (battery isolator), if that diode to the rear is open or bad
> > connections, it's not going to be charging the rear batteries from the
> alternator. (unless the boost/auxillary battery switch is on)
>
> Is the battery isolator the finned unit mounted on the upper left of the
> firewall?
>
> Thanks
>
> Larry
>
>
> --
> Larry - Victoria BC -
>
> 1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
> > Well, the important part is you got it home. Congrats.
>
> Thanks!
>
> blur911
> > Anyhow, it seems like the alternator is not charging the house/rear batteries. With the engine running check to see if it's getting charging
> > voltage at the back (I assume you can operate a multimeter).
>
> Yes I can run a meter - barely! Should I disconnect the battery and clip on to the cables or can I just meter across the terminals with the
> battery in place?
>
> blur911
> > If not, first place to look would be the battery separation diodes at the front (battery isolator), if that diode to the rear is open or bad
> > connections, it's not going to be charging the rear batteries from the alternator. (unless the boost/auxillary battery switch is on)
>
> Is the battery isolator the finned unit mounted on the upper left of the firewall?

Upon thinking about it and looking at the diagram, I think your problem is in the front around the diodes. Since your interior lights worked the
connections at the rear are good. According to the diagram https://www.gmcmi.com/wp-content/uploads/2014/05/77-78-chassis-electrolevel-I.pdf if you
close the Auxiliary Battery SW (boost switch) and you start getting charge voltage to the rear, then the problem is in it's usual charging circuit on
the left side of the diagram coming out of the isolator.
You could check that at the rear, leave the battery connected, put your meter on DC volts, one lead on negative post and other on positive, check
battery voltage at rear with engine running, toggle boost switch and see if it comes up to charging voltage.
Here's where I run out of knowledge, I can read a print, but I don't even know where the isolator is under the hood yet.
--
Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, don't know the model
 
As for were to start, there are many places to start. One approach is not necessarily the only way to do it.

Jimk is almost correct if you want to start there. Except the center terminal should read about .6 volts higher than the two out side ones WITH THE
ENGINE RUNNING.

Also keep in mind that there are two parts to every 12 volts circuit. The one you are talking about is the +12 volt engine circuit {the alternator}
but the return is the -12 volt house circuit. There are two separate 12 volt ground circuits. One for the house system and one for the engine
system. You are using the 12 volt engine attached the alternator to charge the house system batteries and the engine system battery. So were you
attach it minus lead of the meter could make a difference. The two grounds should be connected together through two jumpers. One is located on the
back of the transmission to the steel frame and the other is located from the steel frame to the aluminum body. More on that later if we need to go
there.

Since it started once and now will not, the the isolator screws should not enter into the equation at this point. The Onan cranking has nothing to do
with the alternator. The alternator is the supply of battery charging current to both batterys and also running the engine accessories only when the
main engine is running.

SO go ahead and check voltages at the isolator with the engine running. Then go check the voltages directly across the house battery(s) with the
engine running. Then report back and we will tell you where to go from there.

This is a guess and a poor substitute for proper diagnosing before determining the repair action needed, BUT I am GUESSING that you have a poor
connection of the battery cables somewhere and all we need to do now is diagnose where that is.

So go do Jim suggestion of readings at the isolator and then also read the batteries.

The fact that you were able to start the Onan which is on the house 12 volt house system says you probably have a reasonable 12 volt source, Probably
the battery(s} on the house system.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
thanks lads, will do some checks and report back.

Larry
--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
Well I drove out to the coach storage to do the checks and when I tried to start the engine, the engine battery was dead too. Oh Joy!

Fortunately, Rob was there with me and we figured out why she'd flattened the main battery ...apparently GMC ignition key switches have an auxiliary
setting one position past "off" and I guess in a new switch you can't remove the key but ...you can remove the key on mine (wear?) so when I parked
her up on Saturday I switched the key all the way to what I THOUGHT was "off" but of course this was actually the auxiliary position, so I think the
heater fan or some other system must have been running.

Good thing that Rob was there because I would have NEVER figured that out.

So instead of dealing with the house battery I removed the other one (no handle on it so had to bring it out from under the coach, lying on my back)
and it's on charge as I write.

I'll try again tomorrow :roll:

Larry
--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
We never remove the keys around here so we do not have to go look for them later. MY wife occasionally does the same thing as you did, leave it in
accessory position. So I had to teach her to remove the keys and throw then on the dash. That worked well until my adult daughter moved my wife's car
and left the keys in the ignition on accessory. I found it 2 days later with a dead battery.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Lesson learned on the keys Ken!

Once bitten etc.

Well coach battery fired up the engine after a charge and we got to test the isolator. Tested good.

Removed that POS old house battery and stuck it on the charger. Even though the charger was supposed to be smart, it couldn't figure out it had a
battery attached to it, just kept cycling zeros. So we ditched the battery, no doubt the dry cells and the -20c temps had done it in - not to mention
it was manufactured in 2010.

Thought about buying 2 6v golf cart batteries but the cost was just a bit much so went with a single 12v 120AH deep cycle acid battery instead.

The battery compartment floor was fairly disgusting, the plywood was sodden, delaminating and crumbly so we whipped it out and replaced it with 1/4"
aluminum plate screwed to a pair of snap-together strips of plastic flooring. TIDY!!

House systems working again, touch wood. (or maybe that should be touch aluminum/plastic? :) )

Larry
--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
Larry, I did the same thing to the floor under the house battery(s). Diamond plate aluminum. After a couple years it corroded badly from the fumes
and maybe liquid comming off of the battery(s). So I pulled that plate, bead blasted it to clean it up again. Then I painted it with POR15. I have
also used POR15 on rusted battery boxes in cars. That stuff dries rock solid and does a great job on battery boxes and that aluminum floor plate
which has stayed perfect for at least 10 years.

If you do decide to do this, get the smallest container of POR15 available. Be aware that it dries from exposure to moist air. So never leave the
can open any longer that necessary to pour out any amount that you will need into a second container and reseal the can immediately. When resealing
the can use a double piece of saran wrap between the can and the lid. If you do not do this, the POR15 will set up on that seam and you will never
get the can open again. Store the opened, now resealed can upside down.

Last, If you choose to use this stuff on something that is exposed to direct sun light, put a protective coat of paint over the dried POR15. I have
never done this because I have always used this stuff on pieces that are under the hood.

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> Lesson learned on the keys Ken!
> Once bitten etc.
>
> Thought about buying 2 6v golf cart batteries but the cost was just a bit much so went with a single 12v 120AH deep cycle acid battery instead.
>
> House systems working again, touch wood. (or maybe that should be touch aluminum/plastic? :) )
>
> Larry

Larry,

Keep thinking about GC2s for a house bank. The Grp 31 that you got is good for 60AHrs. If you draw it down more than that (12.1 is 50%), and do not
recover it immediately, it will loose capacity. A pair of GC2s is good for about 105AHrs and if you don't recover it immediately, it won't care a
lot.

If you do go for GC2s, look up the sliding tray that someone makes for out coaches.

Matt
--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
 
> Larry,
>
> Keep thinking about GC2s for a house bank. The Grp 31 that you got is good for 60AHrs. If you draw it down more than that (12.1 is 50%), and do
> not recover it immediately, it will loose capacity. A pair of GC2s is good for about 105AHrs and if you don't recover it immediately, it won't care
> a lot.
>
> If you do go for GC2s, look up the sliding tray that someone makes for out coaches.
>
> Matt

Hi Matt, I'm a total newbie to the world of house batteries and maybe I will end up with the GC2s but not knowing if the house systems were working or
not (they work) I just went for something to replace the dead weight thing I had back there. The one I picked was the largest I could find, a
31DC-205. At the moment I'm trying to figure out exactly how many systems rely on the house supply, so far I know it's the interior lights, water
pump, genny starter. Hope that's all and I haven't missed anything.

I intend to pick up and replace all the light bulbs with led's as soon as I find out what bulbs to get.

Ken, thanks for the tip on the POR15, I'll put it on the list.

Larry



--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
> Hi Matt, I'm a total newbie to the world of house batteries and maybe I will end up with the GC2s but not knowing if the house systems were
> working or not (they work) I just went for something to replace the dead weight thing I had back there. The one I picked was the largest I could
> find, a 31DC-205. At the moment I'm trying to figure out exactly how many systems rely on the house supply, so far I know it's the interior lights,
> water pump, genny starter. Hope that's all and I haven't missed anything.
>
> I intend to pick up and replace all the light bulbs with led's as soon as I find out what bulbs to get.
>
> Ken, thanks for the tip on the POR15, I'll put it on the list.
>
> Larry

Larry,

That will answer your questions, but I already know you missed the coach heater (big draw all night) and any interior fans. Are you running a Laptop
(5A charging - 2A running) or other things that might be entertainment.

I do a lot of house electric upgrades (like one right now) where a retired racing sloop is getting made into a performance cruiser. I am thoroughly
convinced that the house bank should be all the weight you can carry. Fortunately, a sailboat that is no longer trying to beat its rating isn't that
weight sensitive. LiFePo4 sure are nice for that, but they still have cost and compatibility issues.

Matt


--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
 
I turned the thermostat down as low as it could go, is that the only way to shut off the heater? Fans aren't running. Seemed ok today when I went out
there.

Larry
--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
Mine has a rocker switch on the right side, kind of inside of the hot air outlets. It wants some contortion to get to, but turns the furnace totally
off.
You can do the same by removing its fuse at the 12V panel

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Larry,
I installed the following LED and it didn't break the bank.

First lights I used for under the counter in the kitchen, above the table
and above the coach in a 26' Palm beach
Amazon.com: Leisure LED 2 Pack RV LED Ceiling Double Dome Light Fixture
with ON/Off Switch Interior Lighting for Car RV Trailer Camper Boat DC 12V
Natural White 4000-4500K 48X2835SMD (2-Pack): Automotive
https://www.amazon.com/gp/product/B07S656NQW/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1

Second set of lights I installed in the bathroom, overhead light in
hallway, generator compartment and propane tank compartment.
Amazon.com: Cargo LED 20 Pcs Extremely Super Bright 1156 1141 1003 1073
BA15S 7506 50 SMD 3014 LED Replacement Light Bulbs for RV Indoor Lights
6000K Xenon White(12V DC): Automotive
https://www.amazon.com/gp/product/B071V2DBWP/ref=ppx_yo_dt_b_asin_image_o01_s00?ie=UTF8&psc=1

They give off an extreme amount of light so you might not want to put all
the bulbs in the bathroom light fixtures.

On Mon, Mar 29, 2021 at 3:55 PM John R. Lebetski
wrote:

> The stock Suburban house thermostat has an on /off slide switch for true
> OFF.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
 
First of all thanks lads for the tips on switching off the furnace, will have a fumble around for the rocker switch tomorrow. :)

As far as the LED's go, I picked up a great unit on Amazon, (well 4 of them actually). They start out at 6000k white but if you switch off and switch
on again immediately they switch down to warm white. Really impressed so I changed all the fixtures out except the bathroom, I just went for LED
"bulbs" in there. I hear ya though on the brightness ..6 LED's screaming at me while I brush my teeth may be a bit much before I've had my coffee.
May have to re-think that one!

I changed out the bulbs for festoon LED's up in the front speaker panel lights too. Of course I forgot the under-hood, entry, floor, propane and genny
lights, but hey there's always tomorrow

The bits I got were:

fixtures:
https://www.amazon.ca/gp/product/B072Z9VW7D

bathroom bulbs:
https://www.amazon.ca/gp/product/B08S7428XT

speaker panel
https://www.amazon.ca/gp/product/B07Y392JP5

Larry

--
Larry - Victoria BC -

1977 Palm Beach VIN TZE167V101295 - 39,000 miles, new wiper blades!
 
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