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Topic: Are My (now two) Coach Batteries Toast? (Read 840 times) previous topic - next topic

Are My (now two) Coach Batteries Toast?

Still trying to go to Florida................but problems keep arising.

I took the FT over to Cummins for a second time to have the fuel leak addressed, which hopefully has been fixed now by
replacing one injector line and sealing the remaining five.

It was at Cummins for ten days, and when I went to pick it up the coach batteries were dead, there was no display at the inverter panel and the CO detector was chirping from lack of 12VDC power.

I started the engine and everything returned to normal, and I ran the generator on the way home (about 45 minutes).  When I got home I shut the engine down and checked the VDC at the inverter panel and found it to be 13VDC.

I realize there was a drain on the batteries from such things as the auxiliary compressor, electronics, detectors, etc. but shouldn't
two good, fully charged MK 8G8D batteries last longer than ten days when only powering the above mentioned items?

The other question I have is whether they are deeply charged now (been plugged in to shore power since last night) if they're not toast from being completely drained.?

Re: Are My (now two) Coach Batteries Toast?

Reply #1 –
Maybe, maybe not, how old are the batteries?  If new they may provide some useful service.  Completely discharging a battery shortens it's life.  Someone probably left something on when at the shop.  As batteries age they loose capacity, essentially becoming a smaller battery that cannot power whatever is in use for very long.  For maximum life try not to discharge below 50% and 75% is even better, but not practical. New batteries will take a long time to fully charge, old batteries charge up rather quickly.

Re: Are My (now two) Coach Batteries Toast?

Reply #2 –
It is certainly not good to completely drain batteries but they probably aren't "toast." They will likely work just fine. That sort of thing has happened to many batteries that then want on to have a good lifetime.

Re: Are My (now two) Coach Batteries Toast?

Reply #3 –
Forgot to mention that if the alternator is working properly, it will provide more voltage  than the inverter/charger. Thus running the generator does not add a faster charge when the engine is running.  However if the alternator conks out by all means run the generator when driving and turn on the boost switch to keep the engine batteries charged.  Also to evaluate battery voltage you must wait a few hours after charging to get a true reading of it's state of charge. 

Re: Are My (now two) Coach Batteries Toast?

Reply #4 –
Thanks guys.

The batteries are 2012 vintage.  One of the three was toast a month ago, that's why I'm down to two now.

If I set the generator on auto start at what VDC does it come on to keep the batteries charged and not allow them to
get toasted?

Re: Are My (now two) Coach Batteries Toast?

Reply #5 –
The autostart voltage is actually adjustable IIRC.  But mine is set to around 12.01-12.02 volts.  If you leave the autostart on  your batteries should be fine.

Also our gel batteries sat *completely* and *totally* flat, not enough to run a light bulb on the dealer lot for months.  They charged up and still work but of course were probably damaged from that event.  One of them now has an internal short so we're down to 2 from 3.  I do wish I could find a source for used Gel batteries.  I might have to start trolling local stores for cores on a regular basis.

Re: Are My (now two) Coach Batteries Toast?

Reply #6 –
Quote from: Mark D –
I do wish I could find a source for used Gel batteries.  I might have to start trolling local stores for cores on a regular basis.


Where are you based out of?
I have one core now and will have two more later in 2016 when I replace the remaining two with AGMs.

Re: Are My (now two) Coach Batteries Toast?

Reply #7 –
Bradenton, FL.  I do travel regularly up the coast on I95 though.  I would be after exactly your situation - the other two batteries that still function are what I'd want.  Not sure if I can install 4 batteries but if I can, why not?  At least until I do a similar setup with Trojan 6V's which is what I've decided on + an auto watering system.

Anyway, regarding your original issue, your coach is much newer than ours but we found several drains:
1) Open half the bay doors and look through to ensure all of the lights on the other side are off.  We had bad switches, non-contact, etc.  The flourescent lights ours come with are reasonably high wattage and will happily drain those batteries over many days.
2) Our porch light turns on whenever it rains.  And it just stays on.  I mostly fixed that issue but it can still be a bit finicky sometimes.
3) Our coach doesn't have the slide but if you have any serious leaks that aux compressor could run quite a bit and is high wattage, especially if you leave the HWH system armed and levelled.
4) This may or may not be obvious but if you leave the inverter on, it will drain around 60 watts just idling.  They are not efficient at all at light loads.  We use a small inverter that draws only 0.2amps at idle for our smaller loads.