Solar charge a li-on battery it's achievable nowadays. Genasun has some cool little gadgets for custom voltages that allows u to have mppt solar safely hooked to li-on or lifepo4.
The main problem is its price, about 300$, that alone, could be more expensive than the solar panel and battery combined ( yes...cheap panels and cheap battery
. I've been trying to work around this issue, and i came with a couple of cheaper ideas.
- No charging, means that you don't charge your battery on the move, and your battery becomes just a backup of the solar power, That means, that the battery woud kick in, just in those cases of shades, heavy clouds and so. This is the system i've been using so far. A bit primitive, but fairly comfortable, solar would power you most of the time, and i would usually use the battery between the 5 or 15% of the riding time, charging the battery (36v9ah) every 300 kms or so( 2 weeks using it every day...). The system was manually triggered, that means, that i´ve got a switch between battery and solar, when i see i dont have solar juice, i click it, use the battery, and unclick it once i'm done with the shade, tunnel, etc...
It's a bit problematic if have an area with zones of sun and shade, like tree areas, and so, usually u end up going battery through it, but those are not too common, and many times, i don't even use the battery and i just pedal.
But after some time with the manual system, i want to go full automatic (still no "on the move" charging...).
There are some types of solar ups or dc back up systems, but they mostly work on 24v and 48v and there's almost nothing on 36v. Also, i've looking for dual input dc redundant systems, but they're either industrial type, pretty expensive (>500$), or they're mostly focused in AC/DC, when i need DC/DC.
So, where i need help on, it's on finding some type of hybrid ups, or hybrid redundant system working on 36v, DC/DC power balancer, OR diodes, any info on this devices would be greatly appreciated.
Back to the idea of charging the battery, you can't do it, if your drawing power from it, so, in order to charge your battery with solar, you would have to power, both the motor and the battery with solar (power balancing of some sort...), and that, with a pitiful 250w/24v/6A, it's not doable, you barely can ride with it on hills, the only thing you could do, it's charge the battery with a good 4-6 amps meanwhile you pedal or you take a break (in the sun...yes...signed by Cpt.Obvious
.
And for those who think that a microinverter+charger could cut it, sorry to disagree, but that would be a waste of energy, and on solar mobility, you respect every bit of amps you can get, and having multiple devices on the system, just leads to loss of amps, and also, it's bulky, heavy and expensive, it's a no-no.
Sorry for the wall of text
