Quote:
Originally Posted by Surly73
As long as you don't have a malfunction in the car, any will do. Full sleep draw will be low (just guessing 20mA - some quick googling suggests that 80mA is defined as a max acceptable upper limit). If you think about it, this current draw is always present and a 90-100Ah battery needs to be able to restart a car that's been parked for weeks. It can't be very high when things are working properly.
I'd say 2A will work, but one of the ~4A models would allow it to more quickly recover a battery which is low and get to the "floating" stage. I like my CTEK MXS 5.0 I've had about 1.5 years. I had a de-sulphating battery minder for about 15 years before that which worked OK too. I plug in overnight regularly (from every 1-2 weeks in the summer, sometimes every night in the dead of winter).
Now if you're using solar panels to direct connect and charge (I've thought about this too so that the car charges while parked in the commuter lot  ) you'd just need to be careful of the output controllers - can they handle being connect across a battery and not just a load like a cellphone charger? What is the target output voltage? If they make sufficient power to charge, when would they cut off? (AGM batteries have a hard upper limit of 14.8VDC before damage) and that kind of thing.
Sounds like a fun project  Some times I think that I'd like to put solar panel on the top side of the moon roof sliding shade. |
I'm using the battery tender solar controller, so it handles most things you mentioned and is AGM safe. Also prevents discharging the battery when the solar panel is "off". I'm probably abandoning this idea, as even with a 100W panel I'm only getting like 5mA lmao. So to actually get enough current to charge my battery I'd have to spend like 400 bucks in solar panels. Not worth!