I think 2 dead batteries, can't bring them up

[redbeard]

Hey All,

I am busy on many fronts in my 86 Sunradar. Put in a WFCO 8955 Converter/Charger, but I have not been running the Sunradar this winter and both batteries are suspect so I put both on a charge. The charge seemed to take and I thought I was in business. We were able to to check all the connections in the panel to get it set up, the lights worked off just the battery for the first time since I have owned her (since Sept.). I wrote earlier about the isolator, didn't end up getting it but did get a new circut breaker (right next to the isolator on the inner fender), that seemed to get the power moving thru the isolator and onto the coach battery....success. So the new power generator is in and we are having great thoughts, well we woke up the next day and both batteries we dead again. Now I don't know if the converter has a short and is draing both batteries or if they are both suspect and I should just get new batteries and go from there. I have had the voltmeter on both and when they were charged I got 12.4 but then both have gone under, I charged them again, the truchk battery came back to 12 but the coach battery is toast and won't come back from the dead.

I will take some pictures soon of the interior, I am five shades of blue, all the windows have been taken out and re-sealed, new louvered shades (blue), new fabric covered the cornices (valences), new privacy curtains bed over the cab, all the doors taken off in the coach and masked and repainted blue glossy, the project is coming along!!! I just about have it pretty enough, that the wife will get in it!!!

I know I rambled sorry, should I just get two new batteries and start from there??

Thanks, Redbeard

[5Toyota]

have them checked by an honest party first

[Vanman]

My charge chart says 12.4 VDC is only 70% charged, varies some with the temperature.

If charger is good and they won't come all the way up or they go down fast they are damaged.

[zero]

. I have had the voltmeter on both and when they were charged I got 12.4 but then both have gone under, I charged them again, the truchk battery came back to 12 but the coach battery is toast and won't come back from the dead.

Thanks, Redbeard

How long after charging did you check the battery voltage? If you unhooked the charged and checked right away, the voltage should of been over 13 volts. If you waiting an hour or so and then checked it should of been around 12.7-12.9 volts at 70 degrees F (depends on battery make).

#1 you ought to check while the charger is on and make sure they are well over 13 volts. Should be 13.8 to 14.2 volts while charging unless very dead. If the charger is automatic it ought to shut itself off at 13.8 volts - 14.2 volts.

#2 once fully charged - unhook the batteries. Let sit for a an hour or so and then check voltage on each one. Unhook from the system and from each other. Two 12 volt batteries hooked in parallel will equalize until each has the same voltage. If one is bad and one is good- the good one will be discharged by the bad one.

#3 if the batteries are around 12.7-12.9 volts an our after charging but 12.4 volts the next day (while hooked to nothing) they are bad. All batteries self-discharge but only at a rate around 5%-10% per month. Not that much in one day.

#4 if the battery voltage is OK when unhooked then I assume you've got a drain from the electrical system.l A cheap $5 VOM from Harbor Freight will have a 10 amp range to check for a drain. Put it in-line with one of the battery cables when hooked into the system and see if it shows any amp-flow. Anything over 50 milliamps when all is "off" shows a problem.

If you choose to have the battery load-chec ked - find someone with a real load-tested and not some "simulated load" electronic checker like many autoparts stores have. A real load-tested has a carbon-pile and can put a 500 amp load on a battery while checking voltage. A good 12 volt battery must be able to maintain 9 volt with a 150-300 amp load on it (depending on its size). Any such test is worthless unless the battery is fully charged when tested.

By the way - you should never have batteries sitting in an RV for half a year or more without being hooked to some sort of low-amp charger. A cheap $20 maintainer or a solar panel. Even if unhooked they will go dead and once dead and sitting for awhile - we be damaged. If hooked to the system - then can go dead even faster.

[Maineah]

Even plugged in your truck battery will not charge. It needs it's own charger long term or a jumper. If a battery is discharged in the winter it can freeze (of course depending where you live) if it does it's pretty much toast freezing will wreck the plates.

[zero]

Even plugged in your truck battery will not charge. It needs it's own charger long term or a jumper. If a battery is discharged in the winter it can freeze (of course depending where you live) if it does it's pretty much toast freezing will wreck the plates.

I use a Guest marine dual battery maintainer. Model 2611A. It has two outputs. One goes to the vehicle's cranking battery and the other to the vehicle's "house" battery (or batteries). It works automatically, keeps them all isolated and charged. Two of my RVs have two cranking batteries and two house batteries and the Guest 10 amp model has worked great.

http://www.hodgesmarine.com/GUEST-2611A-10-AMP-BATTERY-CHARGER-p/gue2611a.htm

[5Toyota]

as i have to remote park my rv not at home i remove the camper battery in the fall bench charge it at least every two weeks . and make shure i start my r v once a week all winter.its good to pump the brakes and go back and fortha few times. also i dump in a bunch of gas stabill never had a problem. hope this helps those not able to park at home long term.

[waiter]

Both batteries going dead sitting over night is not good. However, if they are bad to start with, It is possible that both batteries are bad and die while just sitting the (internal shorting )

It sounds like you need to bite the bullet and bu two batteries. Get a normal "starting" battery for the truck, but get a "deep cycle" or "Marine" battery for the coach.

Before getting into troubleshooting you need to start with a known good point, as both batteries going bad overnight shouldn't happen.

The isolators job is to isolate the coach and truck batteries and electrical systems. this will prevent the coach from discharging the truck battery while your camping.

Look at the diagram, its generic, but should be close to what you have.

Normally, the isolator ties the two batteries together when the truck is running, That way, the trucks alternator can charge the truck battery AND the coach battery.. Then when the truck isn't running, the batteries are isolated from each other so if you run the coach battery dead, you don't kill the truck battery.

When you plug into shore power, your converter also acts as a battery charger, it will charge the battery, and also supply the 12 volt power.

The old original converters do a poor job of charging the battery, Depending on how they are adjusted, they either undercharge the battery, or overcharge and cook the battery. The newer style "multi stage" converter power supplies automatically adjust to battery conditions and do a great job of charging the battery without cooking it.

i.e. If you have the old style converter, its OK for a few days, If your plugged into shore power all the time, I would recommend disconnecting the coach battery so as not to cook the battery.

You can see how I upgraded my converter to a new style "Multi-Stage" converter. READ HERE. I now leave my Toyhouse plugged in all winter without worrying about cooking the coach battery.

John Mc

88 Dolphin 4 Auto

[zero]

Another option for keeping both the cranking and house batteries maintained when parked is a "Smart" bi-directional battery isolator from Cole Hersee. Model # 48530 is rated for 85 amps and model 48530 is rated for 200 amps.

It gets hooked to all the batteries. When the house batteries are used - with the engine off - the cranking batteries are disconnected and cannot be drained. When you start the engine - the cranking batteries get charged first and then the house batteries. If you wire in the RV's converter-charger into the system - it will also maintain all the batteries. Cranking battery(s) gets priority and then the RV battery(s).

[DanAatTheCape]

I would take the batteries out. charge them up & then take them & get them tested. Most chain auto parts will do it for free.

If they are old you probably need new ones anyway.

I would also review your charging system.

After all that when batteries are re-installed I would look for draw on the batteries after shutdown. Easy way to do that is just to take one side off the battery. BTW, if there is a spark that is because something is drawing juice.

Typically radios have a very small draw - for the stations saved. Propane alarms draw on the house battery - should not kill it overnight by any means.

Both batteries going at once is odd. If both batteries are bad (old) or (sulfated) then so it is. Note that in my camper (& I think this is common) the engine start battery is connected to the house battery via a relay that is only supposed to be be closed (allows juice to flow) when a solenoid closes. This was easy to find on camper as it was on the firewall behind the start battery & I could follow the hotwire from that battery to the solenoid.

Another test for batteries is after charging just let them sit a few days & see if they take a lot of charge.