will I need a controller?
- Thread starter wagoneer
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If you are willing to be the 'controller' it can work. You will need a digital volt meter.
Depending on the size of your battery, it might take several days to recharge if the battery is depleted.
If you plan on leaving it connected for hours or days without checking the voltage, OR if you only plan to use it to 'maintain' a battery, you will eventually, sooner or later, overcharge the battery and ruin it.
That is a 30 watt panel which is enough to ruin the battery without a controller. You CAN use a 5 or 10 watt solar panel to directly trickle charge a normal sized starter or deep cycle flooded battery, with little or no supervision of the charging process. (the panel should have a blocking diode to limit reverse current at night)
A decent and simple PWM controller will work in your case, and can be had for around $20.
Depending on the size of your battery, it might take several days to recharge if the battery is depleted.
If you plan on leaving it connected for hours or days without checking the voltage, OR if you only plan to use it to 'maintain' a battery, you will eventually, sooner or later, overcharge the battery and ruin it.
That is a 30 watt panel which is enough to ruin the battery without a controller. You CAN use a 5 or 10 watt solar panel to directly trickle charge a normal sized starter or deep cycle flooded battery, with little or no supervision of the charging process. (the panel should have a blocking diode to limit reverse current at night)
A decent and simple PWM controller will work in your case, and can be had for around $20.
wagoneer
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thanks man good advice.
highdesertranger
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x2 on what Texas said. I have a small 15 watt panel that would overcharge batteries once I put a cheap PWM controller on it, it works great. highdesertranger
Trebor English
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$7.89 with free shipping, Includes 2 USB ports.
https://www.amazon.com/Allrise-Cont...ge+controller&qid=1555619026&s=gateway&sr=8-3
It is just like mine. The translation to English causes a language issue. It has one programmable voltage. I set mine to 14.4 in summer, 14.8 in winter. It maintains that voltage until the sun goes down. They call that "float" but I use it like absorption voltage. If you set that to 13.6 the battery will only ever see 13.6 which may not be enough. The battery doesn't know that the instructions say that it is "float."
https://www.amazon.com/Allrise-Cont...ge+controller&qid=1555619026&s=gateway&sr=8-3
It is just like mine. The translation to English causes a language issue. It has one programmable voltage. I set mine to 14.4 in summer, 14.8 in winter. It maintains that voltage until the sun goes down. They call that "float" but I use it like absorption voltage. If you set that to 13.6 the battery will only ever see 13.6 which may not be enough. The battery doesn't know that the instructions say that it is "float."
Ticklebellly
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Was once in a situation where buying a controller was not in the budget. Two really old 36 Watt (nominal) panels and an 85 AH FLA battery to run a 40 Litre Engel kept me going for over a year. On many of those days, the ambient temp exceeded 40 degrees C. Would lift one cap of a cell to check when the electrolyte started boiling and depending on the time of day, disconnect the panels.
To the original question, if I could afford an AGM, then a $20 controller would be good use of the money.
To the original question, if I could afford an AGM, then a $20 controller would be good use of the money.
Seminole Wind
Well-known member
wagoneer said:
simple answer. DONT DO IT!
at least get a basic PWM controller for under $10
if the panel/battery ratio is sufficient to do any meaningful charge, left attached it will end up over charging the battery with way to high a voltage. AGM's do not last longwhen floated at 17 volts give or take
I had a bank of 4 7AH SLA alarm system batteries directly charging from 4 5 watt panels some years ago. I almost never overcharged them as I WAS the controller as some have said. I did RUIN a few smaller SLA batteries though so there was a learning curve. I pieced the whole thing together one piece at a time from bid sniping on Ebay. Can it be done? Yes. Should it be done? No. At the time about 80% of after tax income was going to repay a debt in collections so every nickel counted. If I had it to do over again I would have used a controller. Some of the 5 watt panels I got for $2 with free shipping from Hong Kong. Just a long wait for shipping.
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