Any potential with spare 12v marine batteries and solar charging panels?

[GreeninNY]

Hello,

I have spare 12v marine batteries and solar charging panels...is there any potential for a small scale led grow set up using that as a foundation?

 

[wwwillie]

Whatcha got for charge controllers and inverters??

 

[wwwillie]

IMO, you would be better off using the sun to grow plants. Running grow lights off 12volt batteries will not work well unless you have a large solar array, many batteries, and of course an inverter to produce 120/240 volt power. For example, a pair of 6volt deep cycles connected in series would give you about 100 watt-hours that can be safely used between charges. Each of your 12 volters would likely have a fraction of that capacity. That is going to run the ~150 watt lights in a 2x2 for less than an hour. Not much help to the plants.

All true, but with out actual figures for amp hours, watt hours, etc. You cannot make those assumptions. I just built a 100ah 12v LifePo4 battery. So let's use that.
100AH X 12v = 1200 WH
That means that my 100 amp hour battery can sustain about 1200 watts from devices for an hour or 600 watts worth of devices for two hours and so on. So for a 60 watt Autocob we could get 10 hours from that battery (in an ideal world). I'm not going to attempt to size the array needed, but it would be a fair size.

 

[Olderfart]

All true, but with out actual figures for amp hours, watt hours, etc. You cannot make those assumptions. I just built a 100ah 12v LifePo4 battery. So let's use that.
100AH X 12v = 1200 WH
That means that my 100 amp hour battery can sustain about 1200 watts from devices for an hour or 600 watts worth of devices for two hours and so on. So for a 60 watt Autocob we could get 10 hours from that battery (in an ideal world). I'm not going to attempt to size the array needed, but it would be a fair size.

Oops, my bad. I said watt hours when I meant amp hours, and was too quick with the failed arithmetic for which I apologize. Maybe the second cup of coffee will help.

Let me try again. With your LiPo battery, as I recall, you can actually use maybe 70-80% of total capacity with each charge cycle, unlike other battery technologies which typically assume ~50%. So, that leaves about, say, 80 amp hours of useable capacity. If one assumes that your cob is 120 volts, you also have to account for inverter efficiency which I doubt would be much more than 90 or so percent, which would leave you with ~72 amp hours, or 72*12volts=864 watt hours. So, on a full charge your cob could be run for ~14 hours.

So, you are correct, it might be feasible to grow a plant on battery power, and it would certainly be feasible to reduce the power bill if you already had the solar panels, charge controller, batteries, and inverter sitting there anyway. A second LiPo battery might cover all the other stuff like fans and so on, and would give some extra capacity for poorer charging days. And of course, you would need backup options for cloudy weather when solar could not keep up.

Go for it mate, you would be the first here to do a battery supported grow! Sorry about the earlier brain fart. Early morning, grey hair and not enough coffee.

ps. my original post is deleted - it was dead wrong.

 

[wwwillie]

N

Oops, my bad. I said watt hours when I meant amp hours, and was too quick with the failed arithmetic for which I apologize. Maybe the second cup of coffee will help.

Let me try again. With your LiPo battery, as I recall, you can actually use maybe 70-80% of total capacity with each charge cycle, unlike other battery technologies which typically assume ~50%. So, that leaves about, say, 80 amp hours of useable capacity. If one assumes that your cob is 120 volts, you also have to account for inverter efficiency which I doubt would be much more than 90 or so percent, which would leave you with ~72 amp hours, or 72*12volts=864 watt hours. So, on a full charge your cob could be run for ~14 hours.

So, you are correct, it might be feasible to grow a plant on battery power, and it would certainly be feasible to reduce the power bill if you already had the solar panels, charge controller, batteries, and inverter sitting there anyway. A second LiPo battery might cover all the other stuff like fans and so on, and would give some extra capacity for poorer charging days. And of course, you would need backup options for cloudy weather when solar could not keep up.

Go for it mate, you would be the first here to do a battery supported grow! Sorry about the earlier brain fart. Early morning, grey hair and not enough coffee.

Nicely done! I obsess over accurate info when I try to explain something, especially when doling out advice.

I would recommend folks stay away from LiPo and use LifePo4 instead. For this kind of use anyways! The discharge curve is way better, full power till almost the end. Look at the amount of cycles these things can do!! The average of a good brand cell is 3,000 in actual use.
Time durability > 10 years
Cycle durability 2,000-12000 cycles
Nominal cell voltage 3.2 V

Discharge curve: