[kettlekev]

I have noticed that if my battery voltage falls below around 10.5v that my ignition output stops (no spark).

I have my dwell compensation running right down to 9v so it shouldn't be anything weird with that. As long as it is above 10.5v i get ignition.

I have engine protection OFF.

What else would it be?

[jonbill]

It might be the operating limit of the Speeduino.
Would you really want to put effort into making Speeduino work at 10v, rather than making sure that your supply stays at 12v+?

[kettlekev]

Jonbill

I dont disagree but sometimes when the battery is a bit low, I still get good cranking revs but the fairly high current draw drops the voltage. if it is the operating limit then that is good to know.

It seems like the ignition trigger signal just drops out around 10.5v.

[kettlekev]

It there anyway the speedy voltage reg circuit could be adjusted to go a bit lower?

[dzener]

Hello,
How is your electrical diagram? Did you calibrate the voltage reading in Tuner Studio?

[JHolland]

It there anyway the speedy voltage reg circuit could be adjusted to go a bit lower?

Any properly designed ECU should be able to operate down to around 7V during cranking. Which board do you have? The majority of Speedy boards have an LM2940 with a series diode, that will allow operation down to around 6.5V to 7V so it sounds more like a software/configuration issue.

[kettlekev]

I have a V4.0 speeduino board wired direct to battery via switch. I can see very clearly from the trigger log that when the battery gets below 10.5v the trigger stops and there is no spark. If I parallel another battery on and the volts stays above 10.5v then it is all good.

It is a bike project with a reasonable power draw and high starting amps so if the battery is a bit weak the volts can dip. Starter motor still turns at good revs, just no spark.

I don't have knowledge of the speeduino regulator wiring but assumed it was a 12v to 5v regulator so can't see why it would cut out. My crank trigger is a 12v one and fed from the on-board conditioner. Could it be related to that?

I cant see what in the software would inhibit crank signal? I have engine protection off and dwell compensation set down under 9v

How would calibrating the battery voltage in TS help? I am using a precision voltmeter to check the battery.

[LPG2CV]

Be cautious that what you are seeing is what Speedy is seeing. Check for grounds loops. Also ensure that the voltage at the coils, is the same voltage that speedy is seeing for comparison of voltage correction.

[Chris Wolfson]

If you have a weak battery and have it crank, the voltage will go well under 10.5 volt. If you use an oscilloscope, be sure to see sub 8v, maybe 5 or 6. The Speedy shows only the LAST voltage it measured, before rebooting.
Any time a piston reaches TDC, the battery voltage is at it's lowest point. Speeduino looses count or shut's down.
Your digital voltmeter only sees a random voltage, as it measures about 2-3 times per second, while you crank at maybe 2-4 rp-second with constant changes, depending on the number of cylinder's.
If you have an old, analog voltmeter, try it, the pointer will go up and down. Even that is not the full truth, but you get an idea.