[Geoff Vader]

?

[Adrian II]

5AH seems to be adequate for 12V kick start Bullets, I don't know if the CGT's fuel pump and ECU will need more.

Would this be a weight saving exercise?

A.

[Geoff Vader]

Partly Adrian, it’s also part of increasing the airbox size. I can actually fit the Hitchcock Li ion battery under my new airbox, but it’s a lot of cash if I can get away with a much smaller capacity one. Still look at Li ion for the smaller one.

[gizzo]

I borrowed the tiny battery out of the wife's xt225 for ages. It worked fine including starting the engine 130cca rings a bell?
If you're not going to e start, I can't see why a tiny battery would be a problem. As long as it provides enough amps to run the electronics until the engine starts, the alternator will take over when it's going.
I've started my 600cc pantah with a 2200mah lipo plenty of times. It's the size of a Mars bar.

Not that I'm saying you should run a lipo in your bike. Of course you shouldn't.

[axman88]

When I bought my bullet the previous owner had been running a teeny little 3Ah, 50 CCA Duralast GSX4L in it.

Similarly, my Honda VT1100C2, which is supposed to have a 16Ah battery, and only has electric start, was running with a 9Ah battery when I got that.

As stated above, the alternator does the job once the machine is started.  I'd measure the amp draw of the ignition and fuel pump, multiply that by a minute as a conservative estimate of extreme negative starting conditions, then make the baseline minimum battery capacity as 30 times that.   By this formula, the small 3Ah battery I mention above would support a 6 amp draw by the systems mentioned.

Or, you might start by seeing how much space you have to spare, then looking for the largest battery that fits in that space.

Another consideration might be lighting systems draw.  If you plan to ever be stuck by the roadside after dark, pushing or working on your bike, it's nice to have at least a couple of indicators blinking, for safety.

I think it's a good idea to make the India headlight conversion, so this can be turned off for starting, being stranded as mentioned above, and for other situations where it might be desirable.  It's not illegal in the US to turn it off, it's just illegal to ride with it off.

I think I've read here on the forum that somebody was able to get their UCE started just by kicking, but not sure whether that was with NO battery, or just a very dead battery.  I think if one had a capacitor in the system in place of a battery, one might accumulate charge by kicking, before switching on the ignition.  After all, the charging system is always connected, but the ignition switches all loads off.

[gizzo]

I think if one had a capacitor in the system in place of a battery, one might accumulate charge by kicking, before switching on the ignition.  After all, the charging system is always connected, but the ignition switches all loads off.

I think that's how the son in law's CRF450 works. It's fuel injected and computerised but it has no battery. It's a monster to start when it's been sitting a while but after that first start it's good all day. I think the capacitor takes a while to charge up that first time.

[Nasher]

I fitted a Shido Lithium battery in my GT535 a while back - it was a fair bit smaller (& lighter!) Than the original and came with spacers to fill up the battery box

It was less than £100 and holds it's charge so well that I can leave the bike for 3 months during the winter and it fires up on the starter motor way better than the original lead acid battery did after being charged!

[gizzo]

I fitted a Shido Lithium battery in my GT535 a while back - it was a fair bit smaller (& lighter!) Than the original and came with spacers to fill up the battery box

It was less than £100 and holds it's charge so well that I can leave the bike for 3 months during the winter and it fires up on the starter motor way better than the original lead acid battery did after being charged!

Same here. It's great. I think they come in pretty tiny sizes so should be able to get one that fits in the tail hump or something. That'd weigh almost nothing, too. I thought they'd sent me an empty box.

[axman88]

I think that's how the son in law's CRF450 works. It's fuel injected and computerised but it has no battery. It's a monster to start when it's been sitting a while but after that first start it's good all day. I think the capacitor takes a while to charge up that first time.

I bet the ECU and ignition are quite efficient, and the issue is producing enough pressure in the fuel rail so the injector can work.  Once pressurized, until it leaks down again, the fuel pump's electrical demand would be somewhat out of the picture.

A small, short fuel rail would be a good thing, on a system like this.  It seems like they could design a system that uses longer injector pulse widths at lower pressure, but it would complicate the fuel delivery system and require a different ECU program.  And injector's are all designed for about the same pressure, aren't they?  I've read that the earliest fuel injection systems modulated system pressure and not injector pulse length to control fueling.

Maybe he could add an auxiliary connector and use an external battery or DC supply to operate the fuel pump for a few seconds in the garage, to reduce startup kicking after hiatus?

[gizzo]

Maybe he could add an auxiliary connector and use an external battery or DC supply to operate the fuel pump for a few seconds in the garage, to reduce startup kicking after hiatus?

I'd never thought of that. And never heard of anyone else doing it. That's pretty smart. It wouldn't be very hard to do, either.

[Geoff Vader]

Thanks for the feedback guys. I think a Shido will be on order soon. It looks like there’s one around the size I want that still gives 180 CCA but is only about £80.

[KD5ITM]

Partly Adrian, it’s also part of increasing the airbox size. I can actually fit the Hitchcock Li ion battery under my new airbox, but it’s a lot of cash if I can get away with a much smaller capacity one. Still look at Li ion for the smaller one.

If you do the ACE air box kit mod, where you get the filter OUT SIDE of the air box, theres no need to make the air box any bigger.

Here is the youtube video of the ACE air box kit.

https://youtu.be/RAUPA27HeUk

[Geoff Vader]

With all due respect…

Rubbish!

[Arschloch]

With all due respect…

Rubbish!

Which management class have you been on. 

[Geoff Vader]

The one that many professional engineers attend, the one for dealing with BS.

Friends have always said I should have worked as a diplomat in the Foreign Office. 😇