Build Session 18 (180 mins): Forward Battery Rack, Fabricating Supports

Yes, I finally finished the rear battery rack and am now working to complete the forward battery rack. When complete the rack will hold 32 160ah thundersky batteries or 8 Lead Acid batteries.

First I cut the 4 lengths of 2 inch flat bar for the four U supports...

Then I bent the four pieces into U shapes using the torch and a few clamps...

The four U supports are complete. They will be welded two on each side.

Then I cut and bent the two longitudinal supports.

And thats it...in the next session I will weld them in place and finally be done with the rear battery racks!

Build Session 17 (60 mins): Rear Battery Rack Complete

Yes it's been a while since my last post. Work is extremely busy right now but I will attempt to make some amount of progress and post at least every week or two. We'll see...

This month I was able to complete the rear battery rack. I made some size modification on the original design to maximize the space for additional LiFePO4 batteries. My current plan is to purchase 45 Thundersky 160ah batteries. I will install 32 of the cells in the forward rear boxes and the remaining 13 cells in this rear box. I estimate the the rear box will hold 34 which I plan to use in the future if I add more cells for a higher voltage system.

Removing the rear cross member support...

Cross member removed...

Working on the final two rear rack supports...more bending.

I made two just like this...

And installed one on each side as depicted below...This will keep the batteries away from the rear shocks.

Lead Acid or LiFePO4 (lithium Iron Phosphate) batteries?

In a previous post I indicated that I would most likely purchase the the Trojan T-145 Deep Cycle lead acid battery http://www.trojanbattery.com/Products/T-1456V.aspx. They are supposed to be one of the best deep cycle sealed lead batteries. They are relatively cheap (approx. $3000 total for 24 batteries). Unfortunately, they are also EXTREMELY heavy weighing in around 1700 pounds. Added weight will decrease range and performance. Based on my calculations and verified by several EV'ers that I have contacted I may only see a range of 40 miles using lead acid batteries.  While this may be enough to support much of our daily driving it just doesn't feel like enough for me. Especially when you combine the fact that these lead batteries require regular maintenance (watering) and will degrade over time when not fully charged.  


There may be an alternative... Lithium Iron Phosphate batteries. This battery technology suffers from none of the pitfalls that I mentioned for lead acid batteries and contains many times the amp hour capacity. Plus lithium phosphate cells are 20% of the weight of lead acid batteries which will increase performance. 


I have been researching Lithium batteries for a couple of years and many of you may remember that Jared and I built custom A123 Lithium Nano-phosphate battery packs for our electric bicycles a couple of years ago. The batteries were extremely successful but a lot work, soldiering, etc... In addition, the A123 cells are very expensive. To achieve a range of 75 miles in my S10 EV I would need well over $20,000 worth of A123 cells that must be surface welded "soldiered" into custom packs.


Recently, however, I have rediscovered a potential alternative. Thunder Sky (http://www.thunder-sky.com/products_en.asp?fid=66&fid2=70) LFP cells. I did a little research on these cells a few years ago but found several people who were having problems with some cell batches. However, apparently, newer versions of these cells are popping up in a few Electric Vehicles around the globe and appear to be performing quite well. 
The cells are manufactured in China. I have contacted their primary distributer and it seems that I could get my hands on these 160 amp hour LiFePO4 cells for about $9,000+ shipped to nearest SEA port. I estimate about 75 to 100+ miles range for this amount. Plus no soldiering hundreds of little cells as the Thunder Sky cells are manufactured in large form factor. Just 45 cells will be tied together with bolts and electrical cable. I'm considering purchasing even higher amperage 300 amp hour cells which would cost more but could increase my range to possibly 200+ miles. Yes, I'm drooling...


Anyway, I have been reworking my battery rack design to accommodate either battery technology in case I actually get my hands on some of these cells. :)

Adapter plate is here...

A couple of weeks ago I sent the clutch disc from my S-10 (actually I ordered a new one and sent that) to a machine shop specified by EV-America. They disassembled the disc and  milled out the a the center portion of the adaptor plate assembly from 1/2 inch 6061 aluminum. In the near future I will attach this plate to my S-10 transmission, take some measurements, and then mill the transmission mating holes for attaching the plate. Then I plan to cut down the excess around the corner and perhaps follow the contours of the transmission bell housing. After that I will attach the Advanced DC 9 inch FB1 electric motor to the adaptor plate and transmission.

Build Session 16 (90 mins): Rear Battery Rack Welding Cross Member

Yes, I'm still working on the rear battery rack. :) One more day and I should have the rear rack finished.

First I prepped the flat bar cross member that I bent yesterday. I'm using the wire attachment on the Makita to remove the rust.

Prepping the frame...

Measuring the distance at the top of the new cross member to make sure that its slightly more (1/2 inch) than the 31 inches at the bottom of the cross member. This will allow the battery box to slide in easier. The cross member is clamped into place and I tapped it into position with a hammer.

Then I welded the cross member into place.

In case you're wonder what welder I'm using...

It's a Lincoln Power Mig 140c Welder. I'm not using MIG right now just .035 inch Flux Core Welding Wire and it seems to be working great for this application. The bottle on the back of the welder currently is Argon which I use when I am welding aluminum. I use argon with the spool gun pictured below.

.035 inch Flux Core Welding Wire

100 SG spool gun used for welding aluminum and other types of metal.

Anyway, back to business here...Then I wire brushed the area where the flat bar cross member supports meet, clamped them together, and welded all three of them in place. That's it for tonight.

Build Session 15 (45 mins): Rear Battery Rack Cross Member Bending

Not much time again tonight...but it was enough to cut and bend a piece of 3 inch flat bar for the rear battery box rack. This piece will provide cross support for the rear battery rack. The flat bar is 1/4 inch thick. I cut it 68 inches which turns out to be a 1/2 inch or so to long (I'll fix that tomorrow when I weld it in place).

I convinced my oldest son Matt to step away from his laptop long enough to work square up this piece and help me bend it.

Using the torch to heat the steel...

Matt is learning how to use the torch...he did a great job!

Me...trimming the acetylene...

Preparing for the third bend...

Not much leverage so Matt used the sledge on this bend...

The new 3 inch cross bar sitting in place... I plan to trim the ends down an inch and weld it in place tomorrow.

A video of Matt using the torch.