KR-E ...lectric

**imdying** · 20th December 2010, 15:36

So if somebody else was supplying the dollars, you reckon you could build another 250 powered by LiFePO4s?

K14, your 4 cell will be 2.3AH, but it'll probably have a 10 second discharge rating of close to 120A. Kick arse

**bogan** · 20th December 2010, 15:46

Originally Posted by imdying

So if somebody else was supplying the dollars, you reckon you could build another 250 powered by LiFePO4s?

Hells yeh

Probly make a pretty sweet bike for around 5K + donor frame I reckon, theres a guy near welli who has done one with a lot better spec'd batteries, you may find that interesting http://www.astara.co.nz/Astara/Elect...e_project.html

**k14** · 20th December 2010, 15:46

Originally Posted by imdying

K14, your 4 cell will be 2.3AH, but it'll probably have a 10 second discharge rating of close to 120A. Kick arse

Yeah it is written on battery, I will have a look when I get home from work. Sounds about right though. I have read that there are some dodgy A123 counterfeit batteries out there that are made in China so you have to be careful for that. I just got the battery off a guy in the states that makes them himself. Cost me just under $100. Easy way to save 2kg of high up weight.

I was reading up about making up your own A123 spot welding machine a few months ago, I am assuming you'd have to do that for all the 60 batteries? Wait a few years and A123's will be cheaper and a lot more prolific. You'll probably be able to get them for $5 each because the next greatest thing will be invented. Keep the thread up to date cause it is fascinating reading. Something I wouldn't mind having a stab at in the future. Best thing I can think of is plugging it in at work to recharge it

**bogan** · 20th December 2010, 15:52

yeh, makes buying a123's a bastard if it's off ebay. Some manufacturers make their cells with threaded ends now, so you just get some copper bar and wire em up with that, lot easier for the one-off projects. I think at the moment we can get a123 or a similar brand 10ahr cells for around 20NZ+shipping. Think I'll be pluggin mine in at work just so i can make it home again

, which will probly mean I can't knock off too early if it's still charging

**imdying** · 20th December 2010, 15:52

Originally Posted by k14

I have read that there are some dodgy A123 counterfeit batteries out there that are made in China so you have to be careful for that.

Not too bad for your application probably. As I understand it, mostly they're just down on the peak discharge (say only 80A) which isn't important on your race bike (no starter)

**k14** · 20th December 2010, 15:58

Originally Posted by imdying

Not too bad for your application probably. As I understand it, mostly they're just down on the peak discharge (say only 80A) which isn't important on your race bike (no starter)

Nah I still have starting system on race bike. I actually bought two 4 cell batteries and was toying with the idea of going total loss and removing the rotor from crank. But the starter clutch is part of the rotor so that would mean either getting some rollers or crash starting every time. Both of which I am firmly against! A guy on another forum did a test with a 600 and on his 8 cell he got 27 minutes running before it died. On a few of the tracks here that could get you into trouble if a race is red flagged. You'd have to go 12 cell to be sure and then get a set of rollers. Both of which are out of my budget! So just the 2kg saving for me. I am also assured that they are genuine A123 cells.

**imdying** · 21st December 2010, 14:03

Originally Posted by bogan

Hells yeh

Probly make a pretty sweet bike for around 5K + donor frame I reckon, theres a guy near welli who has done one with a lot better spec'd batteries, you may find that interesting http://www.astara.co.nz/Astara/Elect...e_project.html

Cheers for the link. Feel free to relate some of the things you've learnt from your project, would love to hear about it.

**bogan** · 21st December 2010, 14:22

Originally Posted by imdying

Cheers for the link. Feel free to relate some of the things you've learnt from your project, would love to hear about it.

the main thing I learnt the hard way, is it's easy to design a high current motor controller in theory, but bloody difficult in practice! But I learnt a heap about electronics trying to make one.
it's really easy to do a conversion if you just buy off the shelf parts, if anything the wiring is easier and simpler than whats on a bike anyway. In fact mechanical experience to get the bits to fit an line up is far more important than electrical.
always have an e-stop that is guaranteed to work, otherwise the bike is very hard to slow down in the case of a controller failure.
and also the more generic experience of putting in a quality effort and getting quality results (it surprising how many think they can halfass the effort and still get quality at the end of it).
oh, and little alphanumeric display screens may look good in a well lit shed, but you can't see shit when on the go!
and I'm hoping to learn that with some minor tuning you can reduce the rolling friction significantly, but tests for that will be next year.

**avgas** · 18th January 2011, 09:35

any updates yet?

**bogan** · 18th January 2011, 09:48

yeh, took a caliper off and dropped almost 30% of the power needed to cruise at 50kmhr. So I'll be ordering new pistons and seals all round as there is still significant friction in the brakes. Haven't done much serious testing yet, as the battery charger I made started smoking (completely over power electronics, don't work as the book says they should!) I've since ordered a 48v power supply from china which should just replace the smoldering mess part of the charger and work all good once it gets here, could be a while as it's on the slow boat I think!

**avgas** · 18th January 2011, 10:32

So are you running 4 batteries now?
How much was the 48v charger? Also be very careful with it - as most people don't realize that 48v supplies are usually designed for comms which is reversed polarity (-48vdc). But I don't think your would stuff that up - knowing you you have ordered a specific charger for electric drives.

**bogan** · 18th January 2011, 10:36

nah, charge voltage on the 36V pack is around 42-44V anyway. Not sure what you mean about reversed polarity, I just got a cheap 5A supply from china bout 50 bucks, got a bit of adjustment in the output voltage which should take the load of my charger circuit a bit.

**bogan** · 27th January 2011, 15:59

Got the charger installed and almost tuned properly. Chinese POS which could be described as a semi assembled kitset with limited instructions, a component has come free and mashed off another little one, as well as the trimpots being tuned to fuckery, few hours of circuit diagnosing had it fixed though. Wasn't able to drop down to low enough voltage so blew some fuses, fixed now I hope. Is great as I just take off the pillion seat, unroll 3pin plug cord, and plug her in

Did a wee bit of range testing, 9km and expecting that to need about 9ahrs top up. Got the go slows at about km 7, so pulled over for a bit to check nothing was on fire, went fine after that so I think the battery voltage had dropped too far and the controlled started current limiting it. I can program the controller to be more agressive on the cells, but hoping that won't be needed.

Realised I never put an indicator dash light back on, so will have to sort that asap so I don't leave it on and get run over. (edit, is done now)

All in all, getting closer to completion

**ducatilover** · 27th January 2011, 16:56

Awesome stuff dude!!!!!!

**bogan** · 23rd February 2011, 19:30

another update

I've been to massey and back twice on it, charging at massey takes about 3 hrs, one way trip is about 8ahr so could make it return without, but easier to charge at both ends.

The brake lines weren't hacking running only a single caliper (double pressure equals a lot of expansion) so went back to twins. Pity I didn't figure it out before ordering seals, so one is running old seals and missing one dust seal, will sort it with my next order. Stopping power is good, and no discernible increase in energy used.

Both trips have had wee issues with it cutting out, one was a dodgy micro-switch (bypassed now), the other I'm not sure of but may have been the microcontroller (bypassed now) or some iffy wiring (it all looks soldered pretty good though).

Had to adjust the rear suspension as the weight distribution must have changed enough to cause it to top out over most bumps.

Fucking rain caught me out last night as it was charging too, but don't think anything shorted/damaged in the 20s of thundershower it took me to get to the wall switch.

Also I hit 58kmhr on the way home last time, new top score

I wasn't even in full crouch behind the fairing so I reckon it'll be good for 60 next time

If it gets there and back next commute, will get rewarded with a few months rego, and perhaps some crash bungs