solar power for storage unit

[wncranger]

Hello all,

I have spent a number of hours on the web researching this project and am not sure I have thought everything out. I welcome comments, suggestions, criticisms, etc.

Situation: 4 motorcycles in a storage unit with no access to AC power. MC batteries are 12V, 9AH. Owner has given permission for a solar panel on a pole mount. Length of run from pole to unit will be under 20 feet.

Proposed solution: 30W panel => regulator/switch => 2 marine batts => 150W inverter => 4 battery tenders (drawing 0.4A each at 120Vac).

I live in a stale air area so a windmill is out of the question. That only leaves solar as a solution. My only concern is that the area is sometimes cloudy for days. Will my solution work?

Thank you all.

wncranger

[Volvo farmer]

Uhhhh, with those numbers you need some serious rethinking.

My first question would be.. How hard is it to remove four motorcycle batteries and float them someplace that is grid-connected?

My second question would be.. How hard is it to hook each motorcycle battery to it's own 5 watt panel? This would surely keep them up. Maybe even a one or two watt panel each would work.

Get rid of the 120V stuff, it adds lots of inefficiency. Charge 12V batteries with 12V panels. Also get rid of any battery bank that does not start motorcycles. You can probably do this with 30W of panels. If I take your numbers seriously, I'd need over 4KW/day to float motorcycle batteries. Something ain't right here.

[Phssthpok]

Forego the marine batteries, inverter, and battery tenders. They all add up to loss of power (inefficiency).

Paralell your 4 MC batteries and run the solar panel through the charge controller directly to the 'bank' of MC batteries. A single 30w panel should easily keep four 9AH MC batts. topped off even in overcast conditions. If your batteries die due to even a full two weeks of overcast conditions, then you have other issues to address. Just make sure whichever charge controller you buy has a blocking diode so you don't wind up having your batteries 'push' their charge back through the panel.

[vawtsup]

Take the batteries home. total cost $0

Ron M

[maker of toys]

I'd be tempted to put an isolation diode on each battery, so if one decides to go kerplowie, the rest don't get dragged down. In that scenario, a separate blocking diode isn't needed.

[ghurd]

What Volvo farmer said.  Your numbers don't work, and it would cost $1000.

Not sure how large the batteries are or if there is a drain (clock, etc), but it could be done a lot easier and cheaper.  They don't need charged much, they only need to keep from going dead or below 12.3V.

Maybe 4 of the 1.5W $10 red Harbor Freight panels?  Maybe 8? Those need a bit of silicone for outdoor use.

Maybe 4 of their 5W $40 panels if they are GoldWings or something?

G-

[DanG]

start playing with that much connected 'unattended' wiring you really risk loosing the bikes to fire - rodents of both two and four legged variety messing with the wiring would be an excellent opportunity for damaged insulation and thats just for starts.

Replacing the wet lead-acid batteries with a gel or AGM type would extend their storage life 3-6 times, then simply disconnect the ground wire and walk away. If it is a nominally heated storage unit you can have three or more months before battery will not turn over the motor; it's up to you to have drained carb, fuel ines and tanks & add fresh gas on your return to best help the motor start on a low battery...

[asheets]

My solution would be those 1.5W Harbor Freight auto battery maintainers, connected directly to each battery.  You can find them on eBay for $3.99 and shipping.

[craig110]

+1.

If the motorcycles are going to be in the storage shed so long that draining the batteries are a concern, I'd take the batteries home and put them on a trickle charger there.  Disconnecting and reconnecting the batteries has to be easier and cheaper than messing around with trying to keep them charged in the storage unit.

[wncranger]

Thank you, everyone. Alan, Volvo farmer, ghurd, I like your idea. Again, thank you all for your input.