I have 2 12V SLA batteries for recreation use in my camper. One very old (+10 years), another a bit less (unknown, maybe 5 years?).
I noticed both of them were working fine in the beginning, but now the first one is completely used up and ready to recycle (5V after 5H charge!). But the second one is also more or less broken. For example it quickly discharge to 9V after half of the charging time on 60W only!
Now, unless the first one was its due time and because I left it too long connected parallel to the second one (can that be?), I suspect that this DC-DC converter I use for my laptop is at cause. The DC-DC converter 95W and converts from 12V to 19.9V, but it pulls amps in a very alternate way. E.g. alternating between minimum 4A and maximum 9A.
So, I'm wondering if this alternating current can quickly wear out an SLA or other negative effects?
But my more general question remains priority:
Can a (certain designed) DC-DC converter destroy or very quickly wear out an SLA?
With very quickly I mean, in months or so, compared to the years left in it. (Since I'm going to buy a AGM battery as replacement and don't want to kill it.)
Thank you, more experienced battery users!