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1986 Grand Villa electric problems

We recently purchased a 1986 GV (same person as Uncle Pa, using our DBA computer).  I am pretty sure the current battery system is not original.  When we bought it, it had 4 size 31 Super Start batteries under the entry steps--2 for the engine and 2 for the coach.  As best I can tell (ABICT), these are not deep cycle batteries.  The only battery charger is a Stanley 25 amp automotive type charger.  It is directly connected to the *engine* batteries.  Again, ABICT, the only way to charge the coach batteries is with the boost switch on while connected to shore power or running the 6.5kw Onan generator.  My guess is that the previous owners intended to always be connected to shore power because it takes all day to charge the coach batteries the way it is currently set up.  One of the coach batteries turned out to be bad and I replaced it with a Super Start AGM marine deep cycle battery.

We are using the motor home off-grid while we build our home.  We only run AC things (Nutone blender, coffee grinder, vacuum cleaner, laptops, etc.) when the generator is running.  The refrigerator and water heater are both propane.  ABICT, the only DC loads are whatever circuitry is needed to keep the 'fridge and water heater running, lighting (which we rarely use), and the water pump, but the coach batteries seem to go down quickly, and it seems to be almost impossible to ever get the coach batteries fully charged using the generator and the Stanley charger.  When I start the generator, the charger shows full 25 amp charging.  After 2-3 hours, it has dropped to about 14 amps and that is when I turn it off.  I'm currently doing this once or twice a day.  I realize this is bad for the AGM battery but I don't know what else to do.  If we connect to shore power at a friend's house nearby, it takes 10 hours before the Stanley fully charges the batteries and they need charging the next day.  It has taken me a couple of months to figure this out which probably shows how ignorant I am of these things.  Anyway, I'm looking for suggestions on how to improve this.  We will be going solar in the future, but it seems to me we should be able to run the generator occasionally to charge the batteries and not for hours every day.

I'm probably missing something obvious.  I will try to get pictures and more details if that will help.

Also, I remember seeing some posts about a battery monitor system by a small company that doesn't always have them in stock.  I can't seem to find those posts now.  Some kind of monitoring system might help me find what is draining the batteries so quickly.
1986 3600 Grand Villa ORED SBI

Re: 1986 Grand Villa electric problems

Reply #1 –
Wow CC, you are picking the most difficult way into using your RV.  Everything is an unknown to you.  To start, the batteries you have are very low end batteries with only 100 amp hours each(only get to use 50 AH until you get to damage area of that kind of battery).  If you have not load tested each battery, that is where I would start.  Add the Victron BMV 712 battery monitor to better assess how the batteries are discharging( this will check the house side and if boost is on it will show all draws).  Pretty cheap and easy to install.  Clean all your grounds.  Your battery charger is not robust enough.  You have parasitic 12v loads(always on 12v use) somewhere on you coach and it will take some time to track down where the energy is going both on the chasis side and the house side(you may not be able to change this).

Add your coach info into your signature.  There are a lot of GV owners here to help you sort thru the issues you will find.

Jerre
Jerre and Kathy Griffin
2003 U320 4220 Special
Build # 6207
2022 RAM Laramie 4X4 EcoDiesel
2002 Country Coach Magna 37 Tag- Forever Coach-Died in fire 7/23
1997 Country Coach 32 Intrigue-No slides-Wonderful

Re: 1986 Grand Villa electric problems

Reply #2 –
The original factory specs for your coach show it was equipped with a 75A converter/charger.

Media [ForeForums Foretravel Motorcoach Wiki]

A converter/charger serves two purposes.  The primary purpose (especially in your situation) is keeping the batteries charged.  The secondary purpose is the "conversion" of shore or generator supplied AC power to 12V DC, thus providing power to the 12 volt circuits in your coach.  Modern converter/chargers include a "smart" 3 or 4 stage battery charger function that will properly charge your batteries.  They are usually very simple to install, only requiring a nearby 110V outlet to accept the power plug, and two cables connected to your coach batteries.  Once the converter/charger is in operation, you can use it to charge all 4 batteries by employing the boost switch.

There are a number of high quality converter/chargers on the market from reputable manufacturers.  You can either do the prepurchase research yourself, or follow the recommendation of other ForeForum members, or call an expert such as Randy at BestConverter.com.  Randy is a good guy who will answer your questions truthfully, and won't sell you junk.  I derive no personal or financial benefit from recommending his company.

Up to you, but you definitely need to upgrade your battery charging equipment.

BestConverter - Converters, Inverters, Electrical Supplies, Electronics

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 1986 Grand Villa electric problems

Reply #3 –
No question, you need a battery charger/converter with a lot more capacity to minimize generator run time.

Check with the batteries you have or will get for their max recommended charge rate and get a device that will provide that number of amps and the recommended voltage.

Your 15 amp automotive charger is completely inadequate.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 1986 Grand Villa electric problems

Reply #4 –
You might try to isolate each battery and check its voltage sitting .  That will give you a vague  clue as to batt life or almost death.
If both coach batts test the same or very close.  Start looking for draw.  Pull the12 volt fuses ,etc
The sound systems can draw a bit . Even off.  Any amplifier should be wired to the antenna lead of the radio to turn off.
 Overall it sounds like you need at least a good charger  and probably batteries. 
Autozone has deep cycle for a fair price.
I had good results from RuralKing 8d start batts  . (For coach batts.  ).
They are not ideal but the price overcame the technical issues for me.  I shopped around and picked up a 400ah of li iron hospital standby batts to dovetail with my 2000 watts of solar.
I seldom plug in.

Re: 1986 Grand Villa electric problems

Reply #5 –
Thanks very much, everyone!
So, something like this:
Boondocker Converter/charger?

I have a pretty good battery tester which is how I found the one battery had gone bad.  I've been checking them every 2-3 weeks and they are still fine.
1986 3600 Grand Villa ORED SBI