No announcement yet.

12v NiMH battery charging with solar (stick vacuum cleaner charging)

  • Filter
  • Time
  • Show
Clear All
new posts

  • 12v NiMH battery charging with solar (stick vacuum cleaner charging)


    I bought a rechargeable stick vacuum cleaner, and I'd like to use it my summer cottage. Cottage has a smallish solar panel system.
    This thing has a 12v NiMH battery, and the charger that came with it has
    output 15v, 200mA. Charging time 24h.

    I've got a laptop charger that takes 12v in, output is 15v 4A.
    Can I use this? Does it need somekind of current regulator?
    Can a NiMH battery be charged with more current than that?

    If not, what would you suggest? Using an inverter here in between just seems somehow silly..

  • #2
    What you've listed is indicative of a standard "slow charge" that has no current regulation, other than being about C/20 for 16 to 24 hours. I'll bet your stick battery has about 2ah capacity.

    You can charge them with more current, but for nimh you'll need a more advanced charging setup - typically one that can detect delta-v, temperature, time, and overvoltage measures.

    Unless the manufacturer offers that, I'd stick to the setup you have now, as inefficient as that may be. If you want to get with modifications and so forth, be sure to visit the Candlepowerforums site for a vast amount of info on small-scale nimh charging. Even though small, you still have to do it safely.


    • #3
      Safety is most important here.. so I ordered the smallest car-inverter I could find. That one has output of 500mA@230VAC. Quite cheap
      So this is the plan to charge that NiMH battery:
      Solar 12v (from lead-acid battery) -> car inverter 500mA@230VAC -> vacuum cleaners own charger, 200mA@12v.

      Is this ok? I have a bigger inverter, but I don't want to run that noisy inverter 24h. I do not need fast charging.


      • #4
        At this point, perhaps all you need is just a current limiting resistor in series with the battery since all we're talking about is 200ma. Some of the online current limiting resistor calculators for leds might get you there.