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...ting-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-v...iring-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