Charging 18 volt tool batteries on solar power.

[bilmac]

I use a little cigaratte lighter inverter hooked up to the battery and plug the tool's 110v charger into that. Terrible inefficiency I know , the panels probably put out about 18+ volts DC, but the tool batteries are expensive and I don't want to smoke them doing something they can't tolerate. One advantage in going the inverter to charger is that I can let it run all night whereas I could only hook up direct to the panels when they are producing more than 18V,     I think. Also there is the possibility of the battery bleeding it's juice back into the panel at night,   I think.

[Rex in OTZ]

They do bleed back if your charger has a bad diode.

I useally pull em out reguardless, no question of bleed down that way.

[SHOOTALL]

bilmac we do this every day we use as many battry tools as possible . Some crews are all battry - circ saw , sawzall , drill, light , impact screw gun etc. The battries last as long ( life ) as they do charged from a wall outlet  . When we use a gas generator the battires have issues lasting ( life)  some times .

[efremtags]

Always use a dedicated charge regulator between the solar and the 12V solar battery. You can run a small AC inverter which will power a 18V tool charger. It doesn't take much solar (40W or so) for a setup like this. You need a 100AH battery or something close to it.

[WD45]

I'm curious as to why the batts do not last as long being charged from a generator ?

[efremtags]

battery life is based on the # of cycles at certain depth of discharge. A good battery should last several hundred cycles to full discharge (10.5V). The power source does not have any effect on battery life, so gensets, solar, whatever have no bearing on battery life (all else being equal). Power is power.

It is likely you are charging off the genset and over cycling the battery, so it is reaching it's end of usable life quickly. It only takes a yerar or so if the battery is used daily. To fix this, add more battery use a low voltage disconnect to break the load off below 11.8V.