Possible answer for charging ebike batteries from solar?

I'm not sure I trust a Chinese website enough with my card info to order, I've had bad things happen before.

http://www.aliexpress.com/item/MPPT...708497647.html?spm=2114.10010108.0.203.SsGOEA

Inside 800W/20A boost converter ,input voltage auto hold at definite voltage when charge so that can increase charge current 30% more than PWM mode charger. Can charge all kinds battery by user set charge voltage (only use at battery's up limit charge voltage bigger than solar panal's open circuit voltage ) .

Solar Panal port input voltage: 10.5V-63V;

Battery charge upper limit voltage :11V-90V(User adjustable );

(12V lead acid battery---14.4V,24V battery---28.8V,48V battery---57.6V...72v battery---86.4V)

Charge current :20A(max);

MPPT voltage: Auto adjust;

Size:118mm*33mm*31MM.

Click to expand...

Hello Jonathan !

On the product, i don't think it has a CC-CV algorithm for Li ion charging. So it should not be used for charging li ion without this function, only a voltage limiter is not enough. It can be done but not recommended, and not sure your li ion protection circuit would like that.

Moreover, it seem like it s a boost converter, so it can only increase voltage to the battery side.
Therefore, you couldn t use a cheap home-type solar panel that has a higher voltage than the battery. And you have to make sure the max voltage from your panel (Voc) is under your minimum battery voltage.

On the power claims, when buying these kind of chinese products I found they tend to be overated by 300%. Most of the claimed 10-12A boost or buck converters I buy on ebay from china can usually only do 3-4A continuous, a little more if ventilation is added. Can't be sure about that one, but it seems quite small to handle power up to 20A.

If you are confident with your skills in electronic it is probably possible to manage to use this converter for ebike charging, with a decent efficiency and power. But it would require some testings and probably a few more components for dealing with CC/CV.

Hi titooon2014,

I just got one of these in the mail and I've been playing with it for a couple of days now.. I feel fairly confident this unit will charge seven serial lithium ion cells from two "12V" solar panels (in reality more like 17V each mpp) and it is an actual mpp controller but it only bucks voltage as far as I can tell, no success getting it to boost yet and I don't think it will. I was actually getting 80W into 3s18p 18650 cells this afternoon from a single 100W flexible solar panel. I'll either run 4x panels and 2x controllers to charge 2x 7s packs or switch one controller back and forth from one 7s pack to the other every so often through a DPDT relay while running off the entire 14s pack.

http://www.amazon.com/gp/product/B008KWPGS6?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

I've been playing around with one of the ebay "600W boost converter" that goes up to 80V or so. I'm modifying it to use an MPPT algorithm to charge my lawnmower in the shed so I don't have to run utility power out there or put the mower in the garage. Fairly easy to modify, just replacing the so called shunt on the board with a real current sense resistor and the current adjust pot with a digital pot and Arduino to track panel voltage/current and calculate MPP. Once I'm done I'll post it here.

As long as you don't exceed the charge current or voltage rating of your battery, you don't need a well defined CC/CV profile. A solar panel will work just fine if you step up the voltage and limit the current out of the panel to avoid shorting it out. Exactly what I'm going to do with my mower, which has a 20Ah 8S LiFePO4 pack in it.