Saturday, December 13, 2008

Batteries & Babbling

Up until recently, I've been fairly comitted to using LiFePO4 batteries. I was leaning toward ThunderSky 60AH, but the physical layout of the cells didn't look great in my mockup. Maybe one of the other suppliers would work better?

Therin lies the problem. Distribution channels for Lithium batteries are not established in the US. Sure there are dozens of people who will import them, but I'm not a big fan plopping down thousands of dollars for a product without support .

The only brands actually being sold in the US are from overseas based companies. The US based manufacturers won't even sell their batteries to a non-OEM manufacturer. Sure, they have a link on thier website to "tell us about your application", but what they really are looking for is someone ready to place a $500,000 order and wait a year for the product. I've exchanged emails with A123, Valence and EnerDel, just looking for more information, only to get the go-jump-in-a-lake reply. (In hindsite, I may have replied a little hastily to those emails.....)

The asian suppliers have thier issues too. ThunderSky doesn't have a decent BMS system, while LifeBatts are built-in and slick but very spendy. Interestingly enough, I have written to both and gotten prompt, informative replies.

So, I'm really stuck. Normally an EV conversion hinges on battery selection, and fitting the trays around them. What if my trays are more generic, allowing for multiple battery formats? It's easy to add spacers or mounting holes after the battery selection is made.

The key is still optimizing the use of space for batteries within the frame. So I still needed to grind a few thing off the lower frame rails. (For comparison, see the cardboard mockup, several posts back)

Sunday, December 7, 2008

Diversion into detailing

I know, I know..... I'm supposed to be mapping the frame geometry and working on the solid model. Unfortunately, other things (that pay the bills) have been dominating my time latley.

I did have a little time to sneak out to the garage and do some detailing on the frame, and experimenting with polishing various surfaces. I'm toying with the idea of turning this bike into a "street figher", because I can't bear covering up the frame.

The frame is an intricate combination of sand castings, die castings and extruded sections. Most of the less visible castings were not cleaned up very well, with rough parting lines, and even sprues still attached.

The steering head is a large sand casting and really needs some help. The sprue remnants were driving me crazy (have you picked up on the anal retentive tendancies), so I ground them off. I then used progressively finer sandpapers on the surrounding cast surface, and finished up with some 000 steel wool, and some Mother's aluminum polish.

The results aren't quite "mirror-finish", but pretty good for a rookie, IMHO. I may need to go one grade higher on the sandpaper and do "00" and then "0000" with the steel wool.
Hopefully, I will be able to get away for few hours sometime this week to get the dimensional layout done.