Topic: Race batteries & charging units

[lordmoonpie]

A question for you racers running minimal batteries and electrics - when running, the sparks for my 750 are provided by a boyer bransden power box linked up to a normal rotor/stator generator. When cold, the power box doesn't produce enough juice to start the bike so I have to use a slave battery. Looking at the Li Ion batteries that Kayaker has posted, I was womdering if it's possible to connect these up to the ignition at the same point as the generator connections and so not have to lug around a large battery for starting only - I'd leave the Li Ion battery on the bike.

The question is, how would I connect it to avoid the generator harming the battery once the bike is up and running? I'm thinking some kind of diode to allow flow out of the Li ion battery but not back in. Any electrical gurus know a better or correct way to do this? The power box produces an output equivalent to a battery so a +ve and a -ve feed which connects straight to the ignition circuit...

[scottly]

Simon, please e-mail me a schematic of the bike your charging system came from.

[kayaker43]

I'm not sure what the Boyer Brandson does?? Will it allow you to run without a battery at all?

The Lithium batteries can accept your charging system output provided you still have the regulator/rectifier. Otherwise you can use it as an on board jumpstart battery with a big switch if you use the starter or a small switch if you kick/bumpstart. Just switch the battery out after starting.

Might be simpler to just run total loss ignition and the small Lithium battery?

[kayaker43]

Ok, I found it on the web, very interesting http://www.boyerbransden.com/pdf/Power_Box_Leaflet.pdf

Looks like a decent way to run a street bike without battery,.. except for the cold start problem mentioned?

For track use it still seems better to run total loss with a lightweight lithium battery. That way you can lose the 7+ lbs of lead battery and 5-7 lbs of stator coils, regulator and spinning rotor. Taking the rotor away makes a huge difference in how quick the bike revs. Cut down the cover for more cornering clearance too.

12-15 lbs weight savings, quicker revs and more cornering clearance, all for the price of a battery. Remove the starter and starter clutch for another 5-6 lbs. Remove the kickstart lever, shaft and gear for another 3 lbs,... I just keeps getting better

I'm looking for a lightweight street solution as well. The lithium battery of course but I would also love to find a mini charging system with a tiny rotor like the off road bikes use. Just enough to maintain a small battery, low power headlight and LED brake light.

[lordmoonpie]

You might be right kayaker - maybe total loss is the way to go but I wanted to remove the unreliability of a battery going flat from the equation, Happened too many times in races before where the bettery develops a faulty cell or something.

Maybe I just need a switch - start on the battery and switch to generated power fromt he powerbox and then remove the battery?

Scottly - check the link out that Kayaker posted for the schematic, they'll do a neater job than me of drawing it out LOL!

[kayaker43]

I'm still not sure why you are hesitant to let the charging system charge the battery? I don't think the powerbox or battery have a problem with that?

These batteries are so light you wouldn't need to remove it, just switch it out of the circuit.

[Phil]

Our friend Voxonda has some very small (L114mm X B35mm X H81mm) , "Super B 2300" lightweight lithium ion batteries on his site - used by World Superstock teams, I'm told. 450 gram and will last a race on the Ten Kate bikes! Recharges in 45 minutes, lasts for 5 years. Not cheap but must be the way to go?

[kayaker43]

Yes I saw the Super B batteries at Mid Ohio recently. I think they started with A123 cells but switched to K2. He was vague about details but did indicate that they have low voltage protection circuits which others don't have. Nice feature but that and the fancy case pretty much doubles the cost of the battery.

Lithium is here to stay and all will eventually have low voltage protection but for now a little self monitoring will save you a lot of money.

[lordmoonpie]

Thanks Phil, I thought about Rob's batteries they do look the part. Problem is electrics is my weakest spot so not terribly sure what to do here...
Think I'll head down the garage and do some therapeutic parts tidying

[scottly]

I'm still not sure why you are hesitant to let the charging system charge the battery? I don't think the powerbox or battery have a problem with that?

I agree, the power box provides the voltage regulator that will protect both the battery and the electronic ignition from over-voltage.

Or, you could go back to points, and run the output of the permanent magnet alternator through a rectifier directly to the coils. This would basically act as a magneto; spark energy would increase with RPM. 

[lordmoonpie]

I'm still not sure why you are hesitant to let the charging system charge the battery? I don't think the powerbox or battery have a problem with that?

I agree, the power box provides the voltage regulator that will protect both the battery and the electronic ignition from over-voltage.

Or, you could go back to points, and run the output of the permanent magnet alternator through a rectifier directly to the coils. This would basically act as a magneto; spark energy would increase with RPM. 

Thanks Scottly and everyone else - my only challeneg now is to choose a battery which is a whole lot less of an issue for my electronically challenged knowledge! 

[Phil]

I am certainly no expert. Are we saying that if we use Dyna ignition + coils (or Boyer equivalent) we need something other than a battery for a total loss system to work?

[kayaker43]

Nope, you just have to size the battery so it runs as long as you need.

The Boyer power box tries to trick your ignition system into thinking its a magneto so you can start without a battery. Then when its running, it powers the lights. The advantage is that you save the weight of a battery and have no run time limits. The disadvantage is that you get weak spark until you spin the motor fast enough, and the lights won't stay on when the engine is off. (some states require this) This is probably fine if your bike kicks and starts easy or you use powered rollers. you obviously can't use the electric start.

Total loss allows much more weight savings because you can remove the alternator, cover, regulator etc,.. It also has good starting spark. The disadvantage is limited run time depending on battery size.

I'm still considering total loss for a street racer. The new lithium batteries are so light you can build a good size pack that would run your ignition for 3-4 hours. A small low wattage headlight bulb could pass inspection but I would ride with it off. An LED brake light is negligible and wouldn't reduce run time much. Obviously no night riding but most of my joy rides and even commutes are only 1-2 hrs

[lordmoonpie]

When I get my Dyna 2000 system on I'm going to try and use only the power box for starting. If that fails, I'll use a slave battery and then work out where to store the battery for permanent mounting. In an ideal world, I'll just have the power box but it depends on whether I can start the bike reliably with it.

Kayaker - I am using powered rollers to start but the ignition issues in the first place are masking the powerbox contribution. Gotta wait for that Dyna 2000 to prove this once and for all ....

[kayaker43]

Remove the kickstart lever, shaft and gear for another 3 lbs,... I just keeps getting better

Duh,.. beware of free advice!!

I'm a 550 guy and was reminded that removing the kickstart gear on a 750 will disable the oil pump. 

Better leave that in there 

You can however remove 20 lbs of air from each tire. (kidding) 

[Sam Green Racing]

You could replace the air with Helium now that would make it light but don't over inflate the rear, the back tyre needs to touch the ground

Doug

Sam.

[lordmoonpie]

Remove the kickstart lever, shaft and gear for another 3 lbs,... I just keeps getting better

Duh,.. beware of free advice!!

I'm a 550 guy and was reminded that removing the kickstart gear on a 750 will disable the oil pump. 

Better leave that in there 

You can however remove 20 lbs of air from each tire. (kidding) 

No Worries Kayaker - my motor is sound 
In terms of weight saving the kickstarter has gone, the shaft cut down but as you say, gear left in place to drive the oil pump but the return pawl mechanism also junked. Gone is the starter motor and the 750 stator/rotor replaced with a 350 K4 stator rotor, gone is much of the crank web material too. I like lightening things, if only I could work the same magic on my gut! 

[Sam Green Racing]

Magic and miracle are 2 different things Simon m lord.

Sam.

[lordmoonpie]

Magic and miracle are 2 different things Simon m lord.

Sam.

After I work out how to do it Sam I'll be in touch - next challenge after that is how to get my hair to re-grow 

[Phil]

Any progress on this Lord Moonpie? I am following with interest but still plan to use Rob's little batteries + Dyna 2000 + total loss.

[lordmoonpie]

Some progress Phil - after spending a huge amount of time fabricating a tiny cradle to hide my dyna 2000 box under the seat, the wiring is almost done. I am going to static time her in the next week using a battery only and then see if she runs up OK. If so, I'll switch to the power box and see if it generates enough juice to runt he bike or whether I then have to add the lithium ion batteries and more to the point, have to find another cunnign place to hide them from sight!

Getting there slowly...

[somesuch]

Some progress Phil - after spending a huge amount of time fabricating a tiny cradle to hide my dyna 2000 box under the seat, the wiring is almost done. I am going to static time her in the next week using a battery only and then see if she runs up OK. If so, I'll switch to the power box and see if it generates enough juice to runt he bike or whether I then have to add the lithium ion batteries and more to the point, have to find another cunnign place to hide them from sight!

Getting there slowly...

Lithium ion provides the highest power density, but tends to be susceptible to charging/discharging rates. Litium Iron (Fe) is a more stable alternative, but somewhat lower power density. I decided to go with LiFe variety from Shorai. time will tell, so far very happy.

--Nick