Solar Battery Charger

Q: If you have a solar battery charger hooked up can you start the engine and leave it hooked up. Will anything get damaged?

A: Extremes are possible. If it is incredibly cheap and there is no diode in the line to prevent discharging when the battery is higher than the output of the panel like at night and your voltage regular is bad and over charging you might also fry your solar panel. You might fry the diode anyway if its that bad. There is no point in keeping it plugged in though unless your charging system is bad. Its been a long time since an automotive alternator was put on a new car that put out less than 60 amps, and most are 80 or 100. A dashboard trickle charger MIGHT put out 1.5 amps. Not even enough to realistically charge the battery. Barely enough to maintain the battery against the draw of the onboard computer, clock, radio light, etc. If your charging system is toast it isn't really providing you any benefit either. The vehicle takes a lot more than 1.5 amps to run. Probably more like 15 or 20 with all the lights off, AC off, and radio off. And of course the initial current draw to spin the starter to start it up is really high. In general, no I do not see how. If it's a laptop, just look at the current rating of the power supply. If you use that as a guideline it will tell you. It probably has at least 1/3 safety margin built in. Also, does the computer go into sleep or power saver mode or is it left in always on mode. You might also be able to tweak your power saver mode. If a desktop, the fans and drives do use some power, but the biggest power sucker is the monitor. Turn the monitor off. 80 watts will charge most 12V batteries fully in a single clear summer day. On a cloudy day with a drain or during the winter maybe not. Your 80 watt panel will give you 5-6 amps of charging current during most daylight hours. Figure 30 AMP Hours for the average full size lead acid battery. Maybe a lot more depending on the group size, and battery type. You would definitely want a deep cycle or better yet an AGM deep cycle for this application. My sons laptop power supply is labeled 3.5 amps at 18 volts. Figure a 1/3 safety margin, and the fact that even then it will not be pulling max at all times... monitor sleep... drive sleep etc... So average of 2 amps at 18 volts or about 3 amps at 12 volts. Add in the loss and parasitic drain of the inverter. It could kill a single group 24 battery in 10 hours. If it's a good AGM deep cycle the solar panel would charge it back up fully in a clear sunny summer day. Go to a group 30 or group 31 battery it would probably be ok, but marginal some days. Put two of them in parallel and you should have no issues. This is all just wild guesswork based on my own presumptions. To know you really need to look at your own equipment and do your own math. If you use { amps X volts = watts } and then de-rate your available power by 33% you should be fine for 99% of applications.

Discuss It!

Most Popular Articles

More