OK --- updates:
After the last posting --- when the battery appeared to be charged (following 30 minutes of idling van to recharge battery), I let it sit for a while and then checked the voltages twice over the next hour. (I left the house battery plugged in for this period of time, by the way.)
After 30 minutes, I read the following voltages:
- Electrician Voltmeter at terminals:
12.69v
- Plug-in wall socket voltmeter:
12.8v
After 1 hour, these were the readings:
- Electrician Voltmeter at terminals:
12.66v
- Plug-in wall socket voltmeter:
12.8v
Not much change.
Next (I know I'm jumping around a bit here, but bear with me) -- I plugged in the "Battery Load Tester" that I picked up at Harbor Freight and proceeded to do three separate 5-10 second long "load tests" on the battery.
It's ridiculously simple, just a high-load heat resistor (to create the battery "load" on demand) and a reasonably precise analog needle-gauge meter. Powers itself via the 12-volt battery itself.
Here's the voltage reading it displays prior to testing, appears to be around 12.7volts, pretty much on par with what the precision electrician's test meter indicated as well:
And then here's what the gauge shows *during the 5-10 second load test*.
Did not notice anything hugely out of whack by the needle measurements, although since this is indeed a 1000 CCA battery, I'm reading the needle as being *right on the edge* of the "weak" zone when under load. No idea if this is normal to be that close to the yellow zone.
I did note:
After three of these 5-10 second "load tests" (each spaced about 5 minutes apart), the overall battery voltage had dropped to around 12.45volts...but then over the ten minutes or so it rebounded to about 12.55volts.
Anyway --- I've absolutely absorbed what you guys have mentioned today to do....in order to properly test the battery out. (Especially
daveb!)
So....here's what's next:
Charged the battery back up fully using a 10amp bench charger.
And.....gonna let her sit (unplugged) for 24 hours.
Further load testing to commence then.
(As well as (firstly) the overdue "visual inspection" of the individual wet cells as you guys have insisted is necessary. I've also got a battery hydrometer on the way from Amazon...should be here by Tuesday.)
Thanks again tons guys --- hoping something becomes obvious that points to this indeed being a quirk with the battery (or, second best, the charging circuit), and not an endemic short or parasitic drain somewhere in the van itself.