charge controller minimum voltage

[PlagueDoctor]

I made a small booboo in the name of cheapness, I got some solar cells, but I only have enough to make 12.5v MAXv (25 * 0.5v)

in order to charge a 12v battery I need a voltage difference higher than the battery. (obv)

but it seems like all the voltage controllers I see only start charging when the voltage is higher than that of the battery, meaning my panel will only charge in the most Ideal conditions.

anyone know of a charger that has a built in voltage booster that will allow it to charge at say 2v (there will of course be some loss, but some loss is better than no charging at all)

or will I need to build my own voltage booster and install it in front of the charge controller?

[Logan5]

If you have already assembled these cells into a panel. and can not add cells, use this set up for something else, like a 7.2 or 9 volt battery charger. depending on wattage this could work on an LED yard light or electric fence energizer. It could also work a small electric fan. I do not think a voltage booster will do it. How many watts are we talking here?

[PlagueDoctor]

I was afraid of that. I haven't built the panel yet. but it'll take a month or two before I'll have any more in. (and I was hoping to get a test panel built well before then)
I'll just use a lower voltage battery for now then like you suggested,

(it's 25 panels, 0.5v(Max) 8.6A (Max) 4.3W (Max) each, so 12.5v @ 8.6A 107.5W Max)

Thank you for the reply

[Logan5]

sounds like a good educational project, whatever way it goes.

[Wy_White_Wolf]

You could take 18 of those cells and cut them in half to achieve the 18VMP.

WWW

[inetdog]

There is one commercial line of MPPT CCs that includes a voltage boost, but it is designed for charging golf cart batteries from 12V panels and is way out of your size and price range.
If you do not need the MPPT function you can find hobbyist circuits that will do a voltage boost. But make sure you use one which will not drag the panel voltage down if it is not producing all of the power that the battery charging tries to take.