I would like to charge my Li-ion battery from Dyson V6 vacuum cleaner with my solar system/controller (12V output voltage) with a step up converter 26.1V/3A. I already charge my apple computers and ipad pros, and all the other electronic stuff, which are all tolerant to current, as they handle current control themselves. However this one is trickier:

The original dyson poweradapter states 26,1V and 780mA. To step up to 26,1V can be easily achieved, but what about the current? My current step up module limits current to 3A. Do I need to limit the current somehow?

I appreciate any feedback. Would it be safe if I step up to 26,1V e.g. with a maximum of 1A only? Or do I need to fit the exact data stated by the original poweradapter?

Kind regards, Alex

  • \$\begingroup\$ I just checked. The Li-ion pack comes equipped with a circuit control inside. But I do not know what it does. May I be wrong, that charging with 1A won`t do any harm? \$\endgroup\$ – afitterling May 5 '18 at 11:44
  • \$\begingroup\$ if your source can provide 3A, and you only need 0.78A, what's the problem? Amps need to be higher on the source than the load, whereas voltages must match closely. \$\endgroup\$ – dandavis May 5 '18 at 13:10
  • \$\begingroup\$ You do not know if the li-ion pack has a charging logic and limits current. Dyson answered today, their powersuply will smart handle this, not the li-ion electronic build in \$\endgroup\$ – afitterling May 14 '18 at 18:45

Please note that any voltage source, including your step-up converter, only tries to supply the output voltage, it is up to the circuit it's connected to (your Li-ion pack in this example) to determine what current will flow. E.g., if it's an open circuit, the current drawn will be 0; if it is a resistor, then you can apply Ohm's law. The current rating (3A in your example) only determines the maximum amount that the voltage source can supply (if the circuit "requests" it), above that it may fail to work, overheat, etc.

In your case, the best way to see if everything looks normal is to apply those 26.1V from the step-up, and check what the current is with a multimeter:


simulate this circuit – Schematic created using CircuitLab

If you're measuring 780 mA or less, then it's all good.


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