Hey, hoping someone can help shed some light on a won't-hold-a-charge house battery issue in my 1995 RB30 (Fresno-built) SMB. This has me pretty stumped for the moment.
Quick description of my setup:
I've got a pretty-darn-simple Sportsmobile, as far as they go (electrically, anyway), with super-low electrical current needs.
* One 12V house battery (Group 27, basic deep-cycle RV/Marine)
* No solar.
* 2-way refrigerator (uses either 120V AC or Propane to operate)
* All light fixtures LED
* No sophisticated battery charge/monitoring system, only the simple "plug into the cigarette lighter" digital charge meter sold at most Camping World locations...
( This one: )
The Issue:
After getting two years out of the house battery (that I had installed fresh/new shortly after picking up the van in July of 2014)....it was starting to not recharge so well. Wouldn't return to a very high state of charge (only about 12.4 volts, sometimes 12.5 volts), and even while charging, the meter displayed a total voltage that was still in the low 13's.
After doing some reading, I realized that I had probably shortened the lifespan of the battery dramatically by (most likely) running the battery down **too low** before recharging it. I found this chart about two months ago, and it really shed some light (for me, anyway) on how "fussy" the house battery can be, in terms of how low you can safely discharge a "deep cycle" battery and not begin to ruin it.
(Up to this point, I had relied only on the three "GREEN/YELLOW/RED" state-of-charge lights on my cheap-o plug-in voltage meter...I didn't bother to recharge the house battery back-to-full until the meter was showing either yellow or red......hadn't paid attention to the actual voltage numbers as much. So I was quite often allowing the battery to drop as low as 11.9 or 12.0.)
So it became clear I had probably damaged the battery by letting it run down too low. Off I went to pick up an exact-replacement battery.
And so now....the real puzzler:
The new battery recharges wonderfully!
Tops off at a natural resting charge of between 12.7 and 12.8, most days. Displays well into the 14's while charging.
BUT:
Within literally 1 or 2 minutes after doing so much as turning on *ONE LED LIGHTBULB*, the displayed voltage abruptly drops from 12.7 to 12.5 volts. Or 12.4 volts. Or lower.
And it doesn't pop back up.
There's no way that one randomly-chosen LED fixture (among any of them in the van) can be suddenly draining that much juice from a brand-new house battery in 2 minutes. Or can it? (Perhaps by enabling some other parasitic "short" or something?)
I'm breaking out the electrician's test meter this afternoon, and verifying that indeed the displayed house voltage is correct (as shown on the cheapie voltage meter), but if it's indeed correct.....and the house battery voltage is indeed dropping that much, that fast......is a "bad battery" the most likely culprit here? Anything else that's obvious (not to me, anyway) that I should be checking?
Grateful for any advice or insight anyone can offer here.
Thirsty
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