StuartO Posted April 4, 2017 Share Posted April 4, 2017 We've had threads on this topic before but I came across an inexpensive but seemingly robust buck voltage converter on EBaywhich can step up 12 to up to 36v - would this supply power for charging electric bikes etc from MH 12v circuits? The output voltage is adjustable and converter can handle up to 8 amps. Would it make sense to install it with a small dc voltmeter/ammeter, to read the output? Link to comment Share on other sites More sharing options...
pagey Posted April 4, 2017 Share Posted April 4, 2017 watching with interest Link to comment Share on other sites More sharing options...
mgnbuk Posted April 4, 2017 Share Posted April 4, 2017 IIRC the lithium batteries used on electric bikes are charged on a constant current basis, not constant voltage. Given the propensity for lithium batteries to get "hot and bothered" very quickly if handled incorrectly, I would not want to try this ! Lead acid batteries may charge using a constant voltage supply - but may either not charge fully or overcharge depending on the voltage chosen. Modern lead acid battery chargers use a multi-stage regime - constant current until the voltage rises to a set point, then change to constant voltage with a reducing current until the battery is fully charged. Then a "float" stage maintains the battery. The setpoints vary with the type of battery - flooded, gel, AGM all charge with different regimes. You might be able to replicate this after a fashion by constantly monitoring the voltage & current and adjusting the regulator output voltage to suit, but is it worth it ? A "proper" charger to suit the battery in question, run through an inverter, would seem an easier way, even though maybe not as theoretically efficient. And you can always use the charger off the mains when available. Nigel B Link to comment Share on other sites More sharing options...
blaven Posted April 4, 2017 Share Posted April 4, 2017 With a replacement battery on my Kalkhoff electric bike coming in at over £700, I think I'll stick to the proprietory charger that came with it, thanks! Link to comment Share on other sites More sharing options...
Silicongyro Posted April 4, 2017 Share Posted April 4, 2017 StuartO I can see why you are keen - but this and other buck converters only convert to a lesser voltage not greater. The spec details are a little confusing with the votages mentioned. I think they mean the voltage operating ranges - albeit always with input higher than output. The module to increase voltage is known as a boost converter. Link to comment Share on other sites More sharing options...
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