12v to charge 6v battery

When charging a battery you must have the same input as you have need for the battery. That is why many battery chargers have transformers in them to either step up or step down the voltage for the source. You will need a transformer to step down the voltage.

hello,

this tallies with my practicle experience. i once put a 12v battery on to charge from my nominal 24v solar panel, which actually measures 33v without a load and 28v with a load. it charged the battery just fine, did not damage it. i didn't leave it on long enough to damage the battery. the panel output was rated at 140 watts at 24 volts. i haven't repeated this. i only did this that time out of forgetfulness plus not thinking it thru completly. but, you would have to monitor the charge rate closly so as to not overcharge the battery. i do this with a volt meter. i disconnect one of the leads and measure across the terminal. discharged battery will read less than 12v for my batteries, less than 6v for yours. i do not let my readings get higher than 15 volts, meaning the battery is almost fully charged. for you, i am not sure what a fully charged 6v battery measures at, but i would guess at 7.5v. they also make 6v solar panels. i have one myself. then you would not have to worry about overcharging it. and yes the other postings about having a charge controller are correct are also correct. i personally no longer use one though. i have so many batteries in my battery bank, that the batteries never get to a fully charged state, just from normal usage. also, i have everything set up at 24v. that reminds me of one other way of doing this. that is to use two 6v batteries and wire it from 12v to 6v. meaning that one lead from the 12v+ going to one of the 6v+ terminals. the 12v- going to the other battery 6v- and then a wire connecting the other two terminals.

Need more info about your S-panel output current!

If your panel has a high current output it could cook your battery. To keep things simple you can just use a 47ohm .5W current limiting resistor in series to keep your charge rate at no greater than 100ma. Otherwise use a proper current limiter circuit.

If the S-panel is a Micki-mouse type (100-200ma) then leave it as it is with the blocking diode.

Dear Sir : I've made a cheap variable small charger; using a doorbell transformer(115vac IP/ 24VDC OP.) to recharge Cell Phones with different voltage batteries.

I had a piece of Plexy Glass to mount everything on, including 3 or 4 - 12vdc car tail light bulbs, wired in parrell/series combinations to drop volt & current to what specific volts & current I needed each time. You have a Volt/Ohm/Amp Meter to measure output, when plugged in with only the light bulbs hooked up. By checking the output, without the batteries hooked up, turn the lightbulbs in or out until your measured output is just a Volt ot two above the battery volts required, hook up the battery, the lights may dim a slight bit or maybe not, depending how much charge the batteries require. If your set up is to low output,(preferred for first test), you will do no damage to anything, increasing voltage by removing a bulb(with no batteries connected) you can easily arrive at the safe output. Good Luck, from a 70 yr old, Retired Diesel Electric Powersupply Technician. P.S. At least you likely won't have to do you tests in the Dark Like I have on a few occassions.

andy,

good answer. i agree that even though it is possible, it is not a good idea. i have used voltage dividing with good results though. splitting the voltage supplied between two batteries. as in 24v feeding a pair of 12v batteries. and yes i keep all of my batteries out in the open air.

With solar panels, it wouldn't be difficult to build a simple series regulator using a zener diode, a power transistor and a few resistors. Then, a more efficient design would be to charge a bank of energy storage caps with the panel and re-work your regulator to maintain 6v on your battery. The second arrangement would require some current limiting, as a large charging current drawn from a low resistance source could damage the 6v battery.

thats is way to much power to charge a battery

ive got a small little solar radio that uses a 6v battery but it uses seprate panels there are two 6 volt panels on the radio but it has more then one battery . it has a very good chargeing system on it has a light system green for charge red left side half charge then right full charge but it never takes over 98% charge in the battery

i find the 12volt pannel works fine but i only use it on over cast days on sunny days its manly the six volt pannel and on wet days i got back up from a dynamo generator so be very carful of what you use

your local nursery would sell 6 volt pannels for not very much

good answer