Lightweight racing batterys

[STYLER]

12v 2300mAh LiFePo4 batteries Dont know if this is of any interest to anyone, but i thought i would throw it out there anyway!!

Heres my home made battery using x4 12v 2300mAh LiFePo4 battery cells removed from a 36volt Dewalt battery. It is suitable for 400cc bikes as you all know by now.



These batteries are the original version of the ones you will find in the racing batteries but do the same job according to: http://www.customfighters.com/forums/sh ... hp?t=31183

I followed these great and simple instructions when dissassembling the 36volt battery and connecting the wires:
http://www.rcgroups.com/forums/showthread.php?t=587606



With these 10 cells you can easily make x2 square 4 cell packs without adding connecting tabs, or you can do x1 8 cell pack, x2 4 cell rows with added welded tabs.



I only had to cut one link (where the white arrow points to in the previous photo) to get this nice little 4 cell pack. The excess tabs can be bent up slightly away from the cell terminals to weld the pos and neg wires on, this stops the cells from getting hot!!



heat shrink over the connections.



I covered the cells in 100mm wide (200mm total diameter) heat shrink wrap.



6 cells left, ill keep them and use make another 4 cell pack when i get another 400



Not bad aay!! 350 grams is a little bit lighter than the normal 2.6kg battery!! using only the most accurate, cutting edge scales!!!



My bike needs head bearings doing and the gsxr K5 600 forks,calipers etc ive bought to be fitted before i can test on the road, but the bike started and ran a few seperate times using it, so fingers crossed!!

Stuff used:
Dewalt 36 volt battery bought from ebay for peanuts when you consider what your getting!!
25 watt solder iron and solder wire with built in flux (for attaching + - leads to cells)
Old spare power cables with connectors - you can use standard battery 8 gauge/10 gauge cables etc.
Black cable heat shrink tubes.
Vapextape 100mm wide clear heat shrink, i bought 2 meters for £2 with free, quick postage!! They sell connecting tabs, cables, etc - Great site for batteries!
http://www.vapextech.co.uk/cgi-bin/sh00 ... %23a90#a90

[Drunkn Munky]

Nice DIY job there

My package from durbahn has arrived

nice proper connection kit inc

[STYLER]

Someones always got to go one better!!! ha

Thats some serious cable/ quick release connector gear.... must weight more than the cells!!

Youve just gotta love Durbahn, we are not worthy!!!

Its a good job my battery only cost £16 to make as my NC is emptying my bank account...FAST

I turned my battery around and found this label... strange

[Drunkn Munky]

Quality You've out done me there with the HRC sticker. Wish you'd posted this a few days ago, my bank account wouldnt be so light.

The durbahn kit is porn tho, where do you mount yours out of interest?

[Morespeedvicar]

The durban kit looks like its got the connection for a ballanced charging unit, can the Lipo cells be used without balance charging?
Do they charge ok as bikes only output 14volts and the batterys have a 14.4voltage?
And Styler do the dewalt cells crank the bike ok or do the welded tabs get hot?
Sorry for the questions i just building one at the moment, and havent figured out a way to make a balencing circuit which will allow cranking current though yet!

Cheers
Ian

[tanto]

STYLER - thanks! This is outstanding. Great write-up. Great result.

As described, this is the most cost-efficient weight saving idea possible for the NC30, or any bike for that matter. Karma, man!

[fourfingers]

The LiFePo4 cells have better tolerance to over-voltage (while charging) than LiPo chemestry, and are supposed not to explode...as Lipo on overvoltage. Balancing the cells once a week should be safe enough.
LiFe min 2v nom 3.3v charged 3.6v max 4.2v
LiPo min 2.5v nom 3.4v charged 4.2v max 4.2v
Balancers are ready available from model shops, just have to make sure they are LiFePo capable(most designed for LiPo different cutoff voltage).
I am not aware of any balancer that actually lets current through, they monitor each cells voltage and drain excess voltage with resistors,until they are level with the other cells in the pack, so no problem cranking the bike.

When soldering please use a +60w iron (hammerhead tip best for this job) so it takes just a few seconds to melt. Otherwise you will probably end up heating the battery for too long... not good.

[tanto]

Further investigation into sources for Lithium Iron Phosphate batteries has lead me to:

4S1P A123 Battery Pack Type I $48.00

That's $48 for a 380g four cell Lithium Iron Phosphate battery which should be sufficient to start an NC30.

Time to read up on the synchronous balance chargers over on RC Groups, and the manufacturer's information.

BTW, some Lithium Iron Phosphate batteries on eBay may be of different quality, their average weight is around 40g. v. 70g. for the better quality batteries.

[tanto]

Now I've got the bit between my teeth...

There's a ton of information out there in the RC forums about LiFePO batteries, chargers, balancers, et al.. Too much to read, even in one Sunday. Nonetheless, two things stick out:

(1) Safety. These Lithium batteries must be taken seriously; the question is should we be fitting them inside fireproof safety bags on the motorcycle?


LiPo Guard Lithium Battery Storage/Charge Bag from BRC Hobbies

(2) It's important to note that there's a difference between Lithium Polymer (LiPo) and Lithium Iron Phosphate batteries. I'm unclear which is "best" for bikes (see EPBuddy's 4S1P A123 Battery Pack and BRC Hobbies Extreme Pro 2200 4S and Durbann's A123 LiFePower 2.3 Ah battery).

It's quite possible some companies, such as BRC Hobbies in the UK, or EPBuddy in the US, might be happy to supply a special battery for 400GB'ers, with the appropriate connectors, a balanced charger, etc. for NC30/35's. Any takers?

[fourfingers]

Tanto, dont dare to use Lipo on your bike, they will simply explode if not properly charged.

Another important thing you should be looking at is discharge rate.
A123 :
continuous discharge: 26c (2.3Ahx26= 60Ah aprox)
burst discharge(10sec): 52c (2.3Ahx52= 120Ah aprox)

4S1P will be able to crank the engine. If you need higher current you will need 4S2P.
If you are planning on total loss just add batteries in paralel to achieve your desiered current rating.