Solar charge 18650

[francoisboivin]

Hi,

I have a 210W (24v) solar panel doing nothing so I decided to make a roof for my trike.

As I've understand, I can use a module like this: http://www.ebay.ca/itm/DC-DC-600W-10-60V-to-12-80V-Boost-Converter-Step-up-Module-car-Power-Supply-B9-/161917946480?hash=item25b30fca70:g:7JUAAOSwf-VWbsko
for charging the batterie (12S6P)

I am aiming for a charge voltage of 4.1V/cell. I have a BMS (non-balancing, 4.2V/cell).

Would I need anything else?

Thanks!

 

[ecobully]

Since your batteries need CC/CV, you might want to have a fully charged 2S 12V SLA 10A+ before the stepup. A PWM solar controller to maintain the SLAs @ 24V. As long as you don't try to use the full capacity of the SLA ~ 6A/hrs, but rather just use it as a charging buffer, it should last quite awhile.

I guess depending on much sunlight you normally get, you can even go with a smaller SLA for better weight savings. If you're in PHX, you might not even need an SLA as you can probably get CC/CV straight off of the panel.

 

[francoisboivin]

Yes thanks it is an interresting approach!

I would then need a relay to cut the alimentation from the SLA battery when there's no sun but that sould'nt be a problem as I will be using a arduino to control the CC/CV from the converter to the 18650 batteries

I'm also wondering, how the solar panel "sees" the dc-dc converter if directly connected to it. (fixed or variable impedance? depending on what factor?)

And i'm in Canada so right now there's not much sun (<8hrs/day) but it goes up in the summer (>15hrs/day) so there's potential.

 

[ecobully]

The PWM solar controller has the circuitry to handle the types SLA (Wet/AGM/Gel) to charge properly, but also has a "load" connection point so basically add your stepup. If there isn't enough current from solar, it draws the remainder from your connected SLA. Just make sure your PWM controller meets your current draw requirements as well as your solar panel capacities.

SOLAR PANEL (+)(-) BATTERY (+)(-) LOAD (+)(-)

Although I don't have any panels on my ebikes, I do carry them when I am camping and riding trails. (2) panels that are extremely light, high capacity, and roll up/super flexibile. I usually can manage to get direct sunlight (since I am not moving) at a campsite along with 12V and about 14A consistently (4-5 hours). I use an RC hobby charger (connected to LOAD of my PWM controller) to parallel charge my 4S battery packs. On a trike, this type of setup would be extremely beneficial as you gain a canopy and ELECTRONS!

 

[francoisboivin]

Hi again,

The panel I have is http://www.going-green.gr/products/panels/Solarworld_200-225_poly.pdf

I already have a PWM controller but the LOAD output only support 3A. I could use it to switch a mosfet.

The RC hobby charger I have is only 60W (imax) and it would be a waste to use this on a 210W solar panel when the sun is shinning. Plus it's only 6S so it is not possible on my 12s batt.

Earlier i was wondering ow the panel would see the dc-dc converter without a SLA and PWM charger because i'd be interested in plugging it directly on the panel...