Genasun GVB-8-Li-41.7V-WP, 8A (Input) Waterproof Voltage Boosting MPPT Solar Charge Controller for 36 V Nominal 10S Lithium Batteries (eBikes)

I used this to build my own solar charger for Bosch e-bike batteries. An additional converter for the 5V signal line is needed, I used the DROK waterproof DC Buck converter. The connector for Bosch batteries is hard to get, I was able to get a matching cable (ONgineer cable for Lion smart charger, Bosch compatible) from Bike24.net (shipping from Germany).Back to the Genasun converter - I'm running it a bit outside the spec with a Renogy 175 W flexible panel, so far without problems. It also survived an accidental short circuit while I measured the voltage. The temperature, even when charging with 125 Watts, remains very moderate. Both thumbs up.

To be somewhat fair, there is ALMOST no comparison to this product. If you need / want a HIGHLY effecient, lightweight, waterproof MPPT charger for special purposes, this is pretty much the ONLY option. it works well and matches all specifications, so no complaints there.My only wishes are the following:1) It would be nice to have a higher AMP input rating. 9A max is a bit low for many situations. Yes, I know I can just buy another one, but that is 2X the wiring, 2X the size, 2X the cost.2) The fact that there is a different model for EACH output seems a bit excessive. Would be nice to have ability to select what output voltage is generated, or at least small range of options.But again, my nits above are rather minor.For those that care. I used this to create a solar powered e-bike charger for my Bosch motor / battery combo on my Cannondale Tesoro e-bike. As others have indicated, this requires an additional 5v input line to the Bosch, which I created by using a separate Uxcel DC buck converter to take the 40v output, and create a 5v source. The combination of +41.6v, ground and +5v along with the correct cable enable you to charge a Bosch ebike battery.

These Boost controllers are extremely well made (in USA). They are waterproof which makes them great for outdoor applications. The are relatively small, fast-acting and efficient MPPT controllers. There have two down sides. First they are expensive. Second, they can not be configured. You have to order exactly what you need. I'm using the 36V Lithium one to charge my Bosch eBike battery. I used it with a 100W Richsolar Flexible panel ( https://amzn.to/3efAe8I ) which I have mounted on a Burley COHO cargo trailer ( https://amzn.to/3cd3gDc ).