Help Electrical Questions

Question 2: check this video from the DIY lithium thread

https://www.2fiftycc.com/index.php?threads/lithium-batteries-lifepo4-diy.9981/

IIRC he reckons the battery on his SV650 draws ~250 Amps on starting - the 12 volt 9Ah capacity is a measure of it's power density VA = watts which is a measure of power, not it's current capacity which is measured in Cold Cranking Amps - the current capacity dropping over time with age leads to batteries which cannot turn the engine.
The 30amp fuse is usually for the electrical system - the starter is routed straight through - no fuse

 

Question 1: check your numbers
@18000RPM the engine is doing 300 cycles per second

F = 4 x 18000/2 = 36000 - correct 36000/60 = 600 sparks per seconds - but same as cycles per second for each coil firing once per cycle,
300 ignition sparks per coil per second
0.0032 seconds per revolution
So that's 0.0032 seconds between spark events on each coil - but there's no points which is where you used to set/check dwell

Different situation to dwell on a car, however with an oscilloscope you could check the charge to coil saturation time of the ignition TCI through the rev range - it might not be reaching full saturation at 18000RPM - only thing you can say for certain is that the dwell time at 18000RPM is less than 0.0032 seconds because the transistor has to charge the coil and drop the voltage to zero in that time

 

You could achieve this relatively easily with a Dyno which can hold RPM, and a timing light with degree marks on the flywheel housing - work your way through the rev range and plot the advance.
A couple of runs and you should have a good graph

From other maps I have seen there is usually a boost in the advance just prior to where the engine comes onto the cam, which is usually
in resonance with the airbox as it also assists overcoming the slight flat spot.
Back down a bit to a gradual rise to redline then a cut usually to prevent massive over -rev

 

Witchcraft I tell you, it's witchcraft - the devil will get your soul

 

It's probably fine, you wouldn't use it for electrical engineering work, but to get a reading/readings for comparison perfect

 

Well looking at it this way, if you go to an ignitech, is there the potential to run 4 individual ignition channels?
Going to need to indicate to the system when it's at TDC cylinder 1 firing with a cam sensor of some manner. A hall effect sensor with a neodymium magnet is probably a good way to go.

If you can make 4 individual channels, there will be more current available for the individual coils on plug - those units will have specs for the dwell time to saturate sufficiently for high energy spark. The highest RPM values may be a compromise.

So as I said, 3.2 milliseconds is the absolute maximum time available to the system at 18K RPM, that may be less than ideal. Do they have a an oscilloscope available in your course? At least that way you could check the dwell currently in the OEM system with the OEM coils and program that. Check if it works through the range, then install the coils on plug

 

I've been trying to figure this out, too.

The best I have come up with is that bikes which used a flooded lead acid battery as standard can sometimes charge up to 15 volts, which is too much for a lithium. Requiring a regulator that limits output to 14.4v or 14.5v. Not sure how the stator works into the equation.

 

Typically a clamp-on amp meter nowadays. Lead acid batteries will provide current only limited by their internal resistance so 100A wouldn't be unusual. Lithium(LiFe) type have miniscule internal resistance and will provide huge current if allowed. In a motorcycle the current of either will be limited by the resistance of the starter motor.

 

Nearly all LiFe batteries have a built-in Battery Management System(BMS). These will limit the voltage applied to the cells and in most cases will also limit the maximum current that is able to be drawn from the battery. LiFe batteries I have seen also have a large fuse built in. Even without a BMS the LiFe batteries seem to do just fine in a car or motorbike. The problem occurrs when they are charged with a charger designed for lead acid. These chargers often have facility that corrects sulfation by overcharging at a low current. This kills LiFe batteries.

 

I don't know which type of R/R is better. I'm pretty sure the FZR alternator output is only rated as 19A so a R/R exceeding that value would be a waste. 5A would probably cover what you are looking at including the lambda heater. I have a bit of load on my bike and just have some R/R that was lying around, probably a standard FZR R/R. It has no cooling but I do have it bolted to an alloy bracket which warms up a bit. The bracket provides a heatsink and a good earth which is important. CCA and R/R ratings are totally separate. CCA is the current the battery is rated to provide for starting. The R/R is not involved. Once the engine is running and the alternator is generating electricity then the R/R rating comes into play and is simply the maximum it "could" output given sufficient input and an output load that can handle it.

 

I would highly advise against a standard shunt-type R/R for a lithium battery (I have destroyed at least 3 Lithium batteries figuring this out). I used a Mosfet R/R. I can't quite remember but I believe it has to do with the charging wavelength and amplitude. AGM batteries are pretty robust but lithium batteries are way more sensitive to the charging signal they receive. All the lithium batteries had a protection circuit to prevent incorrect charging.