maintenance panel

[zingaro]

Watt would be a good size of panel (lookin for the maximum output) to use on a lead acid battery to keep topped off without having a charge controller. What is the effect of a panel, in the sun, and  in addition then redirecting the sun via a mirror to the panel? Possibilly creating a "hot spot" depending on the focus of the mirrow.

And while on the subject of mirrows, years ago at one of many jobs i had the opportunity to install some mirrows that were plexiglass, i think. Anyway they were flexible and could be bent into a concave position. Does this have any "intensity" factor

[wpowokal]

What size panel very much depends on the amp hour of your battery/s. However as a max full charge should not exceed 10% of full a/h IMHO. For a trickle charge I would use 1-2% of full a/h.

What happens to panels in the sun is they can/do heat up and output decreases with rising temperature. IMHO using mirrors is not advisable, althought it is done, I am sure with diminished life.

regards allan

[ghurd]

Don't use mirrors, that will cook the panel.

Any panel small enough to not overcharge the battery, is to small to do much good.

64w is a decent size panel for some applications, costs about $350. Ad $50 minimum for wire, mounts, clamps, bolts, fuses, etc. Ad $50-100 for a battery.

A controller for it would only be about $30.  Saves that much on the first battery it doesn't ruin. Not that big of an expense in the big picture.

G-

[juiced]

How long would it take to 'ruin' a battery with a 50-60w panel? Are fuses really needed? How can you build  'reverse-current protecter diode' (just a big LED?)?

[ghurd]

I've seen 'newer' 100ah batteries about shot in a week on a 50w PV. Can't say how good they were to begin with.

Same, 32w PV, about a month.

No loads, just charging.

Its just a diode. 6a will do a 50w PV.

Dude! Get a controller!

G-