Now that I have a garage (and a DC power supply), it's much easier for me to monitor every stage of charging, from the initial constant current stage to the constant voltage stage to completion. Even doing this the battery is usually at only 80% or so charged, because of my wife's driving routine.
When I lived in a condo, I had to perform you OP's number 1. every few weeks to a month. Our assigned parking spot was luckily right in front of our front porch, but I still had to run an extension cord through the cracked-open storm door, which was annoying, especially when it was really hot or cold outside. To be honest, I would usually perform my charging routine earlier or later, based on temperature. If we had two weeks of intermittent 10F or below, I'd wait an extra week or so, maybe up to two months between charges. MORE often, I'd find a decent day before it started and short-cycle my routine (e.g., 8 days, 15 days, etc. after the last charge cycle).
This seemed to work really well for us. The Forester in our signature is still going strong after 5+ years on the same battery (it didn't sit long at the dealer, so I'll only assume a little over 5 total years on the battery), with my wife being the main driver. She likes it toasty (e.g., running the heater and seat warmers as soon as she hops in) and routinely drives locally, so not so good for the battery.
Originally Posted by eljefino
Originally Posted by Quattro Pete
Down to what temp is it still OK to charge a lead acid battery? I've read somewhere -4F is the low limit.
You don't want to charge a frozen battery but they get frozen by being discharged! I know of no lower limit and a little current can only be good for it!
The solar panel chargers have diodes so they only do good. The rear tint's an issue but I guess you could use it on the windshield, then put it on the passenger floorboard when driving.
I would worry about one of those diodes failing or even bleeding through when light isn't strong enough, resulting in the circuitry draining the battery instead of charging it. The only way to be sure would be to perform a diode check every once in a while (I would do it weekly, just because), to ensure the charging circuit is doing its thing.
I guess what I'm asking is, are these things really any good at a reasonable price? My biggest concern would be cooking the circuitry over many hot days, if it's built into the panel itself. i.e., I can't imagine these things lasting more than a season, if they're your basic chinese special.
I'd rather just run an extension cord and charge the battery weekly than have to worry about it, which I would most certainly do, even if I checked up on the circuit using a DMM every so often. Then, you'd be out the money for the panel and, potentially, for the cost of a new battery!
