The mystery of the slowly dying batteries

[daveb]

And don't discount more than one thing going on... sometimes things cascade through multiple problems and one issue might lead to a different failure at a later date. One thing in your favor is having a well made house battery.

[mtbjonny]

Update: Just checked the voltage on all 3 batteries. The van has been sitting in the driveway with the House disconnected from the Van/Aux battery.

House: 12.98V
Aux: 12.67V
Van: 9.34V.

Me thinks I have a load somewhere that I need to hunt down in the van system. Could be either something along the lines of stereo (multiple 'professionals' have touched that) or something wrong with one of the van systems.

I'll start some parasitic draw testing soon (pulling fuses).

[daveb]

Maybe. I'd pull the lead on the starting battery, charge it up an see if the amperage tapers off as it charges. If it does then yeah you might have a phantom draw. I'd also be watching the charge to make sure it (the battery) doesn't get hot. After it's fully charged leave it unhooked, note the voltage and then let it sit overnight. If the battery stays in or around 12.8 great, there's no issue with it. If it starts to drop in voltage let it sit for another day and see how low the voltage goes.

[ShuttlePilot]

I second what Daveb is suggesting as the next step. If you follow his procedure you will confirm if the van battery is ok or if it's developed a short internally (bad). My house battery at the end of it's life behaved exactly as he described. The charge amps would go down and then rise again with the battery getting warm on one cell. Once its confirmed that the battery is ok THEN dive into finding the phantom load.

I'll also second the idea that there could be two things going on. A) that there is a phantom load drawing from the van battery and B) that the van battery has developed a short due to being cycled so low, 9 volts and back up a few times is pretty harsh. So confirming the van battery is ok would narrow it down to maybe just the power draw somewhere.

[mtbjonny]

Update:

Got the battery charged & load tested. I wasn't there to watch the charging (so I can't speak to a dip in amperage during the charging. But I watched the guy do a load test. the results were 'marginal' - the battery was on the green side of the red (replace) & green (good) scale, but only just.

They think the battery is ~ 4-5 years old (Nothing on the battery indicates a manufactured date, as far as I or the mechanics) can tell.

Currently the voltage is ~ 13.1V. I'll check tomorrow to see where the voltage is. If it's below 12.8V - should I assume the battery is toast & (hopefully) the root cause of the problem?

[mtbjonny]

Update #2. disconnected the house, aux batteries & connected the van (with my newly charged ‘marginal’ battery). Here’s what I saw.. (checking between the negative leads of the van battery).
(@7:30PM) drawing 0.5A
(@7:57PM) drawing 0.048A
(@7:59PM) Turned on the alarm - went up to 0.24A
(@8:50PM) back down to 0.05A again.. ← So that’s good..

Seems like I have something that stays on for 20 min or so (not unexpected, as I understand). At this point I can’t see any parasitic draw that should be draining the batteries. I can only believe that I’ve got a bad starting battery that has been bringing down the house battery, as boywonder and others have speculated). Cycling this way must be killing the house battery over the course of a year (or so).

So I’m going to head down to batteries plus tomorrow to pick up 2 X2Power Battery (SLI65AGMDP) for the start & aux batteries based on recommendations here to use AGM Deka/East Pen batteries (I believe the X2Power batteries are the house brand for batteries plus).

I’m also going to get my lifeline battery load tested to confirm that it is OK. Assuming it’s OK, all 3 batteries will be AGM & known good. Fresh re-start to see if that ‘fixes’ the issue. Hopefully everybody won’t hear from me in a year with a repeat of this issue..