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Charging NiMh batteries using a small motor - Help!! Answered

I want to build a battery charger that is capable of charging 12v (2x6v) of NI-Mh PCB type batteries (varta packs from farnell) . I think the batteries are button types bound together. The input will be from a small 1" diameter motor spun to give 12v out (I assume this is a dynamo). The output from the batteries needs to power : a 12v wireless reciever (6mA standby/66mA switching) a 12v - 24v dc/dc converter powering a solenoid at 25mA@24v. I have seen a 12v charge regulator in Maplins but it is designed for car batteries. If I send the 12v motor/dynamo output to the charge controller and then onto the batteries will they blow up? As I am a mechanical engineer this is new to me so can anyone help ?


batteries blow up if something vaporizes or thermally expands inside and makes pressure. so if you dont let them heat up i THINK youre safe from exploding batteries. unless the curret is really large (enough to blow them instantly) you can touch the batteries and see if they are heating or not if you overcharge them or charge at too high current (that is not high enough to blow the batteries but above the recommended charge current) you may shorten their life or at most make them die silently conclusion - charge thru a resistor large enough to limit the current to safe levels (so the batteries cannot blow up) and then tweak (PWM / larger resistor etc) to get the optimal charge

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