DIY Electric Car Forums banner
1 - 2 of 2 Posts

·
Registered
Joined
·
72 Posts
Discussion Starter · #1 ·
Ok, so as it stands now, I am regularly charging my 2011 Th!nk EV with a gas powered generator: Booooo!!

This situation has arisen because we live off-grid up in the mountains, and our batterey-inverter situation just isn't cutting it for charging with 110-120VAC. Our Honda eu2000i will charge it just fine but... Gasoline! *Planetary belch!

So I just bought two 100W, 18V panels, thin flexible ones that together weigh less than 10 lbs. This little Th!nk has a roof rack on it, and I am planning to devise some system for being able to clip these panels onto the roof rack with an easy adjustment for side to side movement (for aiming at the sun). It will give the flexi panels a bow, so they will be arodynamic-ish, if I want to drive around with them, but I could also pop them off and use the roof rack for gathering supplies.

I don't care that it's going to take a ridiculously long time to charge the car (24kwh/200w=120hrs of full sun, or 15 days). I only need to charge it up an extra 10-20% to make it over the hump and get back to town (I have only been charging with the Genny for a few hours here and there.) So with my real charging need being about 15% of the total capacity, I will need about 3,600 Watts from these little panels, so I figure ... 5 days in Winter if I'm lucky? Something like 1-2mi/day in Winter maybe? Booya! I'm gonna make it...

My big question is this.... how am I going to custom diy (on the skinny) the boost converter these panels will need to direct DC-DC charge this batterey. (F a charge controller more complex than a manual on/off switch and a voltage read-out)

I can't even figure out what the nominal charging voltage is for the drive batterey on a 2011 Th!nk ~ not much information out there since they were discontinued so quickly...? But I figure I will get the voltage once I pull the seats out and get in there. So with my two panels in series I will need to go from 36V to... ? (Guessing something in the 250-400V range?)

Only needs to be 200W beefy... maybe 400 watts, because I might plug it into some more panels when it's parked at home. I just don't know enough about electronics to really understand this buck/boost converter schematic I downloaded. I don't understand what components I would need to change/adjust to modify the parameters I am trying to effect. So help me self-learn! Where can I get some basic electronics learning materials which might include for-dummy in depth explanations of this type of circuitry?

I have heard of brilliant people like Duncan making their own motor controllers, and I am so inspired by this! I am not there yet, but I also don't feel terribly far away in my e.skills. Maybe DIYing a 400W Voltage Boost converter would be in the scope of salvaging components from TVs / microwaves? Perhaps it would be an approachable entry-level project compared to motor/speed/regen controllers, and sound synthesizers?

So help me help myself! Any advice or ways to get started? I have these panels on hand ... The only thing stopping me, from retiring this petrol-genny, is a little know-how and hopefully a very little $. :)
 

·
Registered
Joined
·
45 Posts
a boost converter is your best bet for efficiency. many of the hybrid car inverters have boost converters in them. That would cover the power stage side of things. You would then need some control system for measuring input and output current/voltage and firing the gate.

the boost stage in a gen 2 Prius inverter igbt has a gate drive built in and fairlyeasy to interface to

if you are to account for conversion losses, your going to be looking at maybe 180 kw at best. You are going to want to double or triple your power generation, the panels are going to put of a peak of 100w each. dose not mean 100w consistently.

some sort of buffer, capacitor bank or battery will help.

idealy you want to maintain the smallest input to output ratio possible. A 90v solar system will be much more efficient that boosting a 18v one
 
1 - 2 of 2 Posts
Top