charging batteries from a solar panel

Google "DIY solar charger"

thank, will do.

Commercial panels (called modules in the industry) typically come in 12 and 24 volt configurations. You will need multiple modules to do the job. There are small wattage modules available to not exceed the power you plan to use. Best check with the battery manufacturer to see their recommendations for charging then work back to the modules and charge controller you will need. Voltage and watts are fine to know but what is the size (amp hour rating of your batteries)? That is the first step you need to take.

thanks . I hardly know anything about this stuff. appreciate it.

thanks

thanks for the good info

thanks- the batteries are 3 separate 12 volt batteries that power a 36 volts electric motor scooter ( they are sealed)- the easiest would be to charge them from my solar pane setup using and inverter ( they are normally charged this way (110), since I know I loose something from using inverter I was hoping to charge them directly

you are very kind. thanks for info

John

Andy gave us some theoretical explanation from the Battery terminals view.

In his simple diagram 3 * 12V there are missing controllers.

If you have 120Vac / 36 Vdc charger that you want to exchange by solar units, try somehow to do measurements of charging current (in A dc) as a function of time. This is important for two reasons: the way of charging and ability of energy production by PV ( night is not good time to do this job!) so it could be the set of parameters that could send you to catalog for already manufactured PV + controller sets.

thanks for good info

1.Battery charging requires that the correct charging voltage be applieded to the battery
Unless your batteries are exact electrical duplcates, (improbable), you can't just tie them together.

2. The output voltage of solar panels varies with the light. The rating you see on the panel is for peak sulight.

You are going to need some type of charge controller and solar panels rated in excess of the nominal voltage required..

thank. i think i'll just use and inverter and use the 110 charger that comes with the scooter. will save a lot of hassle

You are right.

The 110 -120 Vac you may use also for other applications! At least lower the cost of electricity received from the grid/service.

thanks , good advice

I agree that DC to DC is the most efficient. Getting a controller that can match the voltage (plus one volt per set of 12 volts... I.e., 3 series wired 12 volt battery's equals 36 VDC means the controller must charge with 39 - 40 volts to get a reverse flow into the battery pack.). Some folks don't know that DC controllers USED to be called Pulse DC controllers, I.E., they output a pulsing square 'sine" wave such that the collapsing DC input in a heavy induction coil can be regulated to any voltage output value one selects within certain max variables. The senior variable in the equation is that solar cells can't always output their rated voltage, so the controller ups the voltage but the amps will drop to lower values, i.e., basic amps, volts, ohms algebra equation. Clouds, debris, dirty solar cells just output less than their max clean condition, clear day amps, but the Voltage the controller is set to output to the load (batteries in parallel with the load, if any) will remain steady; open the load and all the amps from the array route straight through the battery.).

When one powers up an inverter - there is a significant reduction in capacity for a given solar array. One has to pay a great deal of cash for a high efficiency inverter, last I looked. Worse, due to their losses one has to buy several square feet more solar array to make up for the efficiency losses incurred by inverters.

thanks

hi,

there is a new thread that has a link to a product that seems to be exactly what you asked for. below is the link. i am sorry for not making a clickable link. don't know how.

www.pulsetech.com

the part number is 735X200. it is a solar powered 2-36V battery maintainer. actually designed to keep the batteries charged and desulfated.

My interest in this thread is selfish. While I don't have an answer, you do have my support and I've joined this thread to see if anyone has some data an this topic. I have a growing fleet of 36 VDC powered adult trikes that I'd like to charge from solar cells directly - but there are no easy to understand means to convert off the shelf Photo Voltaic (sport) systems to direct current equivalent means - which appear to be the only cost effective way to do this upgrade to the use the sun's "free' energy to charge one's DC battery powered toys.

Good luck and I'll send you some data if I find it.

thanks, will eventually get most economical system by trial and error