bighit mac

[Lussy]

Inspired by Timmas frame welding I have 'upgraded' a big hit frame. The more I read and learnt about welding aluminium I became uncomfortable with loss of strength and need for heat treatment to achieve suitable yield levels. I had an alloy box build around the frame and headset with the aim of looking as though it is part of the frame. I then epoxies it to the frame. And repainted in 'gun barrel grey'. The bike is powered by 14s7p of LGD1, build in 2s7p packs with a peak output of 40amps and cruise of around 15amps. The motor is 'upgrade MAC. I made custom battery mounts out of a chopping board and used copper wire braid and bike tube rubber and heat shrink to secure. The jury is still out on the battery pack build by this method, but so far so good. Also linked the internals of the battery box with rubber sheet to insulate in case of a short.
Overall I'm stocked with the final result, just need to finish the battery balance leads, charge port, tidy handle bar wiring and secure the battery box covers......
View attachment 2
Cheers Matt

 

[spinningmagnets]

Well done, sir!

 

[deffx]

Looks great

What voltage are you hot of the charger

I'm running 14s lipo, seems to be the sweet spot for the 8 turn Mac

How many Ah do you have on board?

It sure is prettier than mine

 

[litespeed]

Very Cool!

Tom

 

[Lussy]

deffx,

See the link below for some info on the LG cells. Rated at 2C, 3 ahr each giving 21ahr total at ~ 52V

http://endless-sphere.com/forums/viewtopic.php?f=14&t=52346

Cheers
Matt

 

[teklektik]

Quite an ingenious battery box... well done!

Not sure how you epoxied the box in place, but if issues develop you might try some of this KBS epoxy putty. I have used the POR-15 variety and it is great stuff. The POR-15 putty got more expensive and their competitor (KBS) has other competing products that I've found equal to the POR versions - so their version of the putty seems like a pretty good bet.

 

[Danos]

Nice build, what's your performance like?

 

[Lussy]

Not expecting any epoxy issues, as the box was very tight on the frame without epoxy. The design means that the box sits on top of the top tube and is snug around the headset.
Regarding the performance the Mac cruises at about 40kmph. The batteries sag about 7 to 5v at full current but give the full 3amp hours each.

Cheers matt