Help with portable solar please
Many of you know my recent setup. Four Crown 6v CR235's. I know this question may be a bit vague but work with me on this. I would like to have a portable solar setup to help with the daily charging s...
Forum Discussion
You want to recharge for two hours every fourth day with a four-battery bank. Ok, so the recharge will be starting at 50% and to do a 50-90 on four 6s takes about 2.3 hours with a 100 amp charger like my PowerMax 100 or Mr Wiz's WFCO 100 amper or several brands of inverter/charger that can do at least 100 amps. If you insist on two hours max, you need a 150 amp charger and a big enough gen to run it.
So you want to be 235 AH down on the recharge day and 'some solar' every day will supplement your AH usage meanwhile to make sure you don't run out early.
I see "every fourth day" as meaning go three days and then recharge, then do another three days, etc. So your net usage would be 235/3 = 78AH.
In May at 49.3N with a 130w panel I tested and got daily haul of 56AH flat, 70AH tilted aimed South, and 90 AH 'tracking' (tilted and pointed at sun)
Let's pretend you can do that sort of thing with your say 120w portable kit whatever. So pretend you get say 70 AH with yours tilted up against a picnic table and you aim it once in a while.
So if your batteries decline 78AH/day and you were getting 70 in from solar, that means you were using a whopping 148AH a day. Let's get real and say you use more like 70 AH a day. So you might be recharging once a week.
The big thing is your poor 6s are not going to like sitting there for days on end "incompletely recharged" and they will sulfate and die an early death. That is why you must get them to 100% every so often.
Every two weeks at least in this situation. When you are off-grid that is hard to do, since you can't run your gen that long. They need to be 99% before you can even start your overcharge to get them to 100%.
But you can use your solar to do that just by taking the controller out of the loop and going battery- direct. Voltage will rise to the needed 15s/ low 16s to get that done. But how can you run the rig meanwhile? Split bank. Just run the rig on two 6s and do the overcharge on the other two disconnected, and then next chance when the sun is out all day, do the other two.
So you might be able to get by with 120w but I found here with four 6s from April to October with using about 70AH/day the 130w panel I had, even in its contraption, was not quite enough, and I had to use the gen more than I wanted to. It turned out that 200w was about right, so that is what we have now roughly. YMMV
(I don't even bother with solar here from October to March as we camp in the woods when camping then, and days are too short anyway.)
All of which is just meant to give you an idea how to approach the problem using some math to predict likely outcomes. Only you can fill in the correct scenario details.
So you want to be 235 AH down on the recharge day and 'some solar' every day will supplement your AH usage meanwhile to make sure you don't run out early.
I see "every fourth day" as meaning go three days and then recharge, then do another three days, etc. So your net usage would be 235/3 = 78AH.
In May at 49.3N with a 130w panel I tested and got daily haul of 56AH flat, 70AH tilted aimed South, and 90 AH 'tracking' (tilted and pointed at sun)
Let's pretend you can do that sort of thing with your say 120w portable kit whatever. So pretend you get say 70 AH with yours tilted up against a picnic table and you aim it once in a while.
So if your batteries decline 78AH/day and you were getting 70 in from solar, that means you were using a whopping 148AH a day. Let's get real and say you use more like 70 AH a day. So you might be recharging once a week.
The big thing is your poor 6s are not going to like sitting there for days on end "incompletely recharged" and they will sulfate and die an early death. That is why you must get them to 100% every so often.
Every two weeks at least in this situation. When you are off-grid that is hard to do, since you can't run your gen that long. They need to be 99% before you can even start your overcharge to get them to 100%.
But you can use your solar to do that just by taking the controller out of the loop and going battery- direct. Voltage will rise to the needed 15s/ low 16s to get that done. But how can you run the rig meanwhile? Split bank. Just run the rig on two 6s and do the overcharge on the other two disconnected, and then next chance when the sun is out all day, do the other two.
So you might be able to get by with 120w but I found here with four 6s from April to October with using about 70AH/day the 130w panel I had, even in its contraption, was not quite enough, and I had to use the gen more than I wanted to. It turned out that 200w was about right, so that is what we have now roughly. YMMV
(I don't even bother with solar here from October to March as we camp in the woods when camping then, and days are too short anyway.)
All of which is just meant to give you an idea how to approach the problem using some math to predict likely outcomes. Only you can fill in the correct scenario details.
