2003 TXT custom lithium/solar setup

[nas]

Here is a little write up on the solar/lithium setup I just finished up.
I used 21 individual 12v 20amp hour cells that are internally voltage regulated for a minimum of 8v cutoff and max 14.4v cutoff so no need for a battery controller. There are 7 cells paralleled in each bank(rigid box) for 12v at 140 amp hours per bank x 3 for 36v. I then built a custom aluminum frame with 8 solar panels with inline diodes to a 72v streetlight digital self cooling solar controller that is programmable set to max 42v then it keeps running but will only charge once voltage drops below 42v.
Ive been playing with this setup for around 6 months on another junker cart and I have never had to plug it in since I started granted I dont run them all day long everyday but in essence it is a 100% solar setup. Im getting around 20 miles on a full charge if I drive it 20 miles nonstop(around the block on dirt road a bunch of times) but if I drive a few miles then sit for a bit then a few miles it never runs out of juice. The solar charger when the batteries are under 38 volts will run at about 4 amps constant then trickles down to .1 amp when its back up around 42v. The solar panel is thermally protected with 4 micro fans underneath when the sensor hits 120 deg. the fans kick on to ensure max performance. Just thought Id share in case anybody else has considered this.

[Dixie Chopper]

Originally Posted by nas

Here is a little write up on the solar/lithium setup I just finished up.
I used 21 individual 12v 20amp hour cells that are internally voltage regulated for a minimum of 8v cutoff and max 14.4v cutoff so no need for a battery controller. There are 7 cells paralleled in each bank(rigid box) for 12v at 140 amp hours per bank x 3 for 36v. I then built a custom aluminum frame with 8 solar panels with inline diodes to a 72v streetlight digital self cooling solar controller that is programmable set to max 42v then it keeps running but will only charge once voltage drops below 42v.
Ive been playing with this setup for around 6 months on another junker cart and I have never had to plug it in since I started granted I dont run them all day long everyday but in essence it is a 100% solar setup. Im getting around 20 miles on a full charge if I drive it 20 miles nonstop(around the block on dirt road a bunch of times) but if I drive a few miles then sit for a bit then a few miles it never runs out of juice. The solar charger when the batteries are under 38 volts will run at about 4 amps constant then trickles down to .1 amp when its back up around 42v. The solar panel is thermally protected with 4 micro fans underneath when the sensor hits 120 deg. the fans kick on to ensure max performance. Just thought Id share in case anybody else has considered this.

Really cool. I probably don't want to know how much it cost to set up LMAO

[nas]

Thanks the whole lith/solar setup cost right around 3k but the batteries are rated at 2000 full cycles compared to I think 300 full cycles for lead acid batteries. Im guessing the lithiums will outlast the cart.

[Dixie Chopper]

Originally Posted by nas

Thanks the whole lith/solar setup cost right around 3k but the batteries are rated at 2000 full cycles compared to I think 300 full cycles for lead acid batteries. Im guessing the lithiums will outlast the cart.

That's not as much as I expected. So you're running 36V? How's the power compared to lead acid batts?

[ThreeCW]

Great project ... it looks like you are taking lithium to another level with your use of solar. Congratulation on your build

Can you post some more information on your batteries and perhaps a few photos of what is inside your battery cases?

[nas]

Yep running 36v on this cart and Ive got another ezgo shuttle with the same setup but 48v with 12 solar panels opposed to the 8 that are running the 36v cart. Both have the same solar controller which will handle 0-72volts. Before I did the lift and 23" tires I had the stock tires on it and it wouldnt move on my rock driveway it just threw rocks and spun tires everywhere. Now with the big tires and losing 300LBS of battery weight it flat gets with it. My driveway is about an 1/8th mile and really steep and it will run 16mph up the driveway no problem at all so Im not sure if its the batteries that helped out so much or if it is the weight saving. Its also still got the stock motor and fleet controller in it but it feels like they are both upgraded now.

[nas]

Here is a pic of one of the li-phosphate cells that is inside the cases. There are 7 of these in each case wired in parallel with 1/4" spacers in between each cell and the case walls to keep them cool. Each 12v case has 2 terminals then wired in series to get my 36v or 48v. I check the temp on the cases and wires constantly with a laser and Im yet to see any increase in temp. on discharge or charge since I started working with them. The other pic is the under side of our solar panels and to show the fans and such. I plan on putting a thin plastic cover over the bottom to hide the wiring and fans and to create a wind tunnel for cooling.

[nas]

Here is a pic of the 48v shuttle. I plan on custom fabbing a 10" lift with 28" tires on this one. There are 12 solar panels on it and Im going to add 4 more over the back which will charge another 12v lithium bank under the front seat for powering a winch, stereo, lighting, amps, ect. that way the accessories wont draw on the main battery pack. I mounted the solar controller on the top above the drivers head(green box in pic) and will be moving it back down under the seat because the fan in the controller is loud enough you cant carry on a conversation lol. I will post more pics of this one when I get closer to finishing it . Its got to be completely disassembled painted lifted, rewired and a bunch more stuff but it should be done in a few weeks.

[BobBoyce]

I love what you've done! I built a Solar cart years ago. I replaced the roof with 3 large solar panels in series. I put the charger away and never had to use it again. I just left it parked in the sun. I put a battery cutoff switch so if the batteries were getting low, I could disconnect them to keep from discharging them too much. I could drive about 5 MPH from panel power alone. I typically just parked it and let it charge while I fished or took a nap, and it was ready to go again in a bit. I had a 20A analog Amp meter mounted on the underside of the roof so I could watch how much current was flowing from the array. I had that cart for a few years. When I sold it, I took the panels off and put the roof back on. I gave the buyer the charger with it.

Bob

[nas]

Playing with this solar stuff is pretty cool. I played with wind turbines few years back but didnt know much about solar until I started actually getting my hands on the solar stuff about a year ago and Im still learning every day.