24V Electrical System ?

[farmerj]

Hi all,

We have another thread going on "hard to start 2018s". I know that my bike will start just fine if you put enough power to it - a while back I tried 24V and it cranked and started instantly.

The problem was, it didn't take long to fry the starter. But my test was inconclusive - the starter may already have been failing, and in my elation I may not have left enough time between starting tests to let the starter cool sufficiently.

So I recently went to try it again. This time instead of adding a 12V battery I used a 7.4V battery from a RC car, thinking that maybe it would add a bit of power - and it fit so well in the airbox. It doesn't seem to help at all (contrary to the suggestion here - https://thumpertalk.com/forums/topic/1155753-24-volt-starting-for-gncc/)

Why is that? Do you have to have a full 12V for the two batteries to "add" to each other? Or are there insufficient amps in the RC battery to contribute power?

I admit my electrical ignorance and thank you for enlightening me!

Jeff

 

[blitz11]

How did you connect the batteries each time? In series or in parallel?

If you connect your RC battery in parallel with the 12V bike battery, the RC battery will not increase the voltage to your starter, and it won't contribute any current unless the voltage on the bike battery drops to 7.4 volts.

If you put another 12 volt battery in parallel with the stock battery, you will increase the current available to to the starter motor. when you go to start it, the voltage is less likely to "sag," and the additional current will allow the motor to spin closer to its max speed for that voltage.

If you put the batteries in series, then you will have the voltage increase, and the starter motor will tend to spin faster (speed = Kv*voltage). Higher speeds will demand more current, but the additional batter can supply that as well.

w/o knowing how you wired the battery in, it's hard to say what's up.

 

[Neil E.]

I expect he just put them in parallel. To properly do a series hookup requires some cable work. Ideally both batteries should have the same current output when connected in series. A small battery would choke the current flow if paired with a large battery. The small battery would likely overheat.

 

[(F5)]

So I can't help applying the razor principle here. What if you had a 3rd battery?

2022 will of course need 4 just to shift off the showroom floor.

 

[farmerj]

Thanks for the replies, guys. The second battery is in series, negative pole to "output side" of solenoid and positive to starter.

https://store.schnitzracing.com/24-volt-starter-wiring-diagram/

https://www.youtube.com/watch?v=goO4VHemPbY

Neil, this is probably the answer!
A small battery would choke the current flow if paired with a large battery.

 

[farmerj]

And another question...

I currently have a 240 CCA Antigravity (9 amp). They make a 12V 120 CCA battery in a "small case" (6 amp).

So do you get more starting power from a 24V system with a 240 CCA battery and a 120 CCA battery in series; or from a single 360 CCA battery?

And Neil - does the smaller 12V 120 CCA battery "choke the current"? (I don't know if it's the difference in Volts or Amps that creates the problem...)

Thanks,

Jeff

 

[Neil E.]

Let's assume all the other parts of the system are in good mechanical condition. In a series circuit you have common current. The small battery would act as a load on the bigger battery, so the larger battery would drop voltage. The combined circuit might only deliver 18 volts at 8 amps.

I'd choose the 360 CCA 12 Volt battery. I get the reasoning behind increasing the voltage to the system. I've done this a few times with 6 volt cars in the winter time. Jump the 6V battery with a 12V battery while the engine is cranking. That way the 12V is pulled down and the car's electrical system doesn't get zapped with the full 12V. At cold temperatures there is some headroom for component heating due to excess voltage.

Another consideration is battery charging. The bike will typically put out 14-15 volts so the 24V combination is a problem. The best way to see if a larger battery will help is to jump the bike with a car battery. If this this works every time then a bigger battery is a good fix.

Most starter issues relate to how much current actually gets to the starter windings. Perfect grounds and heavy cables plus a good relay are the only ways to prevent voltage drop.

 

[farmerj]

Thanks Neil. I have a few things to try and will report back at some point in the future!

Jeff

 

[fred99999au]

I'd be more concerned about the current going through the RC battery.

In testing a chinesium Kato starter on my 18 GP300 I used a clamp meter on the cable and measured a peak current of over 300 amps before the smoke leaked out of the starter.

I doubt if the RC battery would carry that without exploding.

 

[farmerj]

Just to report back and finish up this thread - the idea of using a 7.4V RC battery came from the link in my first post, but it is not a good idea

With the Antigravity ATZ-8 first and the 7.4V RC battery second in series, the voltmeter read 5.3V.

With the RC battery first and the ATZ-8 second, I got 19.8V.

So Neil is right, the smaller battery chokes the larger one if it is second in the series. Additional problems have been mentioned above, and would include needing a special charger for the RC battery. And it can't be placed "first" anyway, or it will be charged by the 12V charging system on the bike and the battery will be damaged.

The right way to do a 24V system is shown in the video in Post #5 above. Two small case Antigravity AG-401 batteries will fit in the 2018-19 GG battery compartment, and - as mentioned in other recent threads - will likely make you happy!

 

[farmerj]

I will add that numerous experiments by myself and others suggest that in this scenario, for whatever reason, throwing high CCAs at the problem doesn't help. Yes, often going from the wimpy stock battery to 240cca solves the problem. But beyond that, in this application there seems to be diminishing returns. We have gone directly from 800cca car batteries to the starter, and still got just a "thunk". But 24V creates spin. Just fwiw.

 

[Neil E.]

Interesting. The only difference I can see is that 24V would push the RPM higher and the extra speed would do a better job of camming out the bendix.

 

[(F5)]

So who's going to try 36?

 

[Neil E.]

Or 48? LOL @ F5.

 

[SpirosZ1000]

220AC directly from the plug....
Is the next thing I am going to try if the damned thing wont work after replacing everything related to starter.( last things coming these days).
And if not as I said..... 220AC and little fuel.
Nice torch it will be

Ps. With my 2015 EC 300 never had the slightest problem for almost 3 years I kept the bike with as I believed the same parts installed on the starter mechanism.

 

[fred99999au]

Anyone tried the new bendix cover with the needle roller bearing?

I have a spare cover which will be fitted with a BK1210 bearing this week by a mate. Bit of a bodge job but at AUD$8 not including the bendix cover which I bought ages ago, might just do the trick.