A 5 watt solar panel isn't that much. The laptop current draw on the battery plus the draw of the inverter is likely to be high. I don't think the solar panel would be able to recharge the 12V battery enough. I am assuming the inverter is a DC to AC inverter and you use your laptop AC charger for you laptop. The best way to figure this out would be to try it out first. I would recommend getting rid of the DC to AC inverter. They aren't that efficient. I got a 12VDC to 20VDC inverter for my laptop. This is more power efficient. I use a Deep Cycle Marine battery and trickle charge it off my 18 watt solar panel during the day. Jim -----Original Message----- From: az-observing-bounce@xxxxxxxxxxxxx [mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of Stan Gorodenski Sent: Sunday, March 15, 2015 11:52 AM To: Az-Observing Subject: [AZ-Observing] Recharging A few years ago I had asked a question of how long a 12V battery would last to power a laptop on a night of observing. I have a related question. The reason I ask it is because I know nothing about electronics or electricity. I need to be away from power for days at a time. I have a 5 watt solar panel I bought years ago. If I run a laptop for about 3-4 hours a night with an inverter, would this 5 watt solar panel be enough to charge a car battery (not a battery in my pickup but a separate battery) with the amount that was used by the laptop? I doubt it and probably need a larger panel for this to work, but maybe it would have to be too large to be practical. Alternatively, I would be driving about 80 miles per day. Can one charge a separate car battery plugged into a cigarette lighter? Stan -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list. -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.