Battery Sate of Charge and ECU Function

[Yamasledder]

I know this isn't new but I feel I need to post my experience with battery condition and ECU function.
My battery is 2 years old in my 2014 RTX N/A and I put it in the sled for the season just 3 weeks ago as snow conditions haven't been good for sledding here. The battery voltage was 12.3 and it started the sled fine as the ambient temperature was -5 C. Fast forward 2 weeks and I decided to take it ice fishing. It seemed to crank slightly slower but I didn't check the voltage. Ambient temperature was -7C. By the way,I have had the most recent flash done a year ago and been quite happy with it. As it was cranking it seemed to fight the starter so I stopped cranking it. ( prime symptom of ignition timing too far advanced) I then cranked it again and it was popping through the exhaust. ( prime symptom of late ignition timing) I tried it a third time and it started but stalled. On the fourth attempt, it started and ran fine. My first thought was; here we go again with the kickbacks and backfiring. I used it that day and it started and ran fine the rest of the time I used it. Fast forwarding another week; I decided to go sledding with my son today. I thought I'd better check the battery voltage before I trailered it out to the staging area and it read 11.4 volts which is a low battery. I put the charger on it for 2 hours and then left home. I went to start the sled and it cranked so slow that it was obvious that it was not going to start. I went and got a new battery, installed it, checked the voltage and it was 12.6 volts. (fully charged) The ambient temperature was -26 C and it had been down to -31C the night before so this thing was well chilled right through. It cranked at a good speed and started/ran perfectly for the whole time that I used it.
For riders that are having starting issues after the latest flash, I strongly suggest that they check the condition of the battery before anything else. The engine management computer on these things is very sensitive to voltages that are anything but 12 volts or more. The battery doesn't have to be discharged much below 12.6 volts and the computer doesn't seem to know what it should be doing. Once the engine is running, there aren't any issues because the charging system is has increased the electrical system voltage to over 14 volts.

 

[GR8BBQ]

Good post, thanks! I think what you are describing is why several of us were thinking that a voltage regulator to keep the ECU voltage boosted to 12v even when the battery voltage drops (especially when cranking in the cold) might help.

This thread is worth a read:

Cold starting | TY4stroke: Snowmobile Forum | Yamaha - 4 Stroke
https://ty4stroke.com/threads/cold-starting.150939

Discussion of the voltage regulator specifics start around the bottom of page 8 of that thread.

Definitely worth keeping the battery and connections in tip-top shape if nothing else.

 

[Mike P]

I know this isn't new but I feel I need to post my experience with battery condition and ECU function.
My battery is 2 years old in my 2014 RTX N/A and I put it in the sled for the season just 3 weeks ago as snow conditions haven't been good for sledding here. The battery voltage was 12.3 and it started the sled fine as the ambient temperature was -5 C. Fast forward 2 weeks and I decided to take it ice fishing. It seemed to crank slightly slower but I didn't check the voltage. Ambient temperature was -7C. By the way,I have had the most recent flash done a year ago and been quite happy with it. As it was cranking it seemed to fight the starter so I stopped cranking it. ( prime symptom of ignition timing too far advanced) I then cranked it again and it was popping through the exhaust. ( prime symptom of late ignition timing) I tried it a third time and it started but stalled. On the fourth attempt, it started and ran fine. My first thought was; here we go again with the kickbacks and backfiring. I used it that day and it started and ran fine the rest of the time I used it. Fast forwarding another week; I decided to go sledding with my son today. I thought I'd better check the battery voltage before I trailered it out to the staging area and it read 11.4 volts which is a low battery. I put the charger on it for 2 hours and then left home. I went to start the sled and it cranked so slow that it was obvious that it was not going to start. I went and got a new battery, installed it, checked the voltage and it was 12.6 volts. (fully charged) The ambient temperature was -26 C and it had been down to -31C the night before so this thing was well chilled right through. It cranked at a good speed and started/ran perfectly for the whole time that I used it.
For riders that are having starting issues after the latest flash, I strongly suggest that they check the condition of the battery before anything else. The engine management computer on these things is very sensitive to voltages that are anything but 12 volts or more. The battery doesn't have to be discharged much below 12.6 volts and the computer doesn't seem to know what it should be doing. Once the engine is running, there aren't any issues because the charging system is has increased the electrical system voltage to over 14 volts.

Your diagnosis is close. What is actually happening is a very dramatic VD (voltage drop) from the supply wire feeding the fuse block, ECU, fuel pump, starter solenoid and more. Everything works fine as long as the battery and ALL components are textbook. I'm pretty sure the ECU has a working voltage as low as 9.5 volts DC.
I have powered the ECU with an independent supply voltage as a test. The motor turned over faster and fired within 3 cranks when cold. I had to remove the extra battery because of warranty issues. I may take a second look at setting up a second power source or increase the wire size feeding the fuse block.

 

[GR8BBQ]

I may take a second look at setting up a second power source or increase the wire size feeding the fuse block.

Voltage regulator should accomplish the same from the main battery without needing a secondary source or larger wire.

 

[Yamasledder]

Your diagnosis is close. What is actually happening is a very dramatic VD (voltage drop) from the supply wire feeding the fuse block, ECU, fuel pump, starter solenoid and more. Everything works fine as long as the battery and ALL components are textbook. I'm pretty sure the ECU has a working voltage as low as 9.5 volts DC.
I have powered the ECU with an independent supply voltage as a test. The motor turned over faster and fired within 3 cranks when cold. I had to remove the extra battery because of warranty issues. I may take a second look at setting up a second power source or increase the wire size feeding the fuse block.

Yes. I believe you're right on this. My battery was under 12 volts at rest. I would guess that it was likely down near 6 volts while cranking. The ecu just can't operate properly under these circumstances.

 

[blueironranger]

9.5v while cranking seems to be the low limit of the ECU is what I’ve found/tested. Even with a fully charged fresh battery I’ve seen the voltage drop below that on a -25*f morning for the first crank. On the second crank the engine usually spins a bit faster and the amp draw is lower and voltage higher so it will fire up. Thankfully I don’t ride at -25*f much though I have thought about adding a pigtail that’s stick out of the seat so I can hook up a Lithium boost pack on frigid mornings.

 

[Carla 123]

9.5v while cranking seems to be the low limit of the ECU is what I’ve found/tested. Even with a fully charged fresh battery I’ve seen the voltage drop below that on a -25*f morning for the first crank. On the second crank the engine usually spins a bit faster and the amp draw is lower and voltage higher so it will fire up. Thankfully I don’t ride at -25*f much though I have thought about adding a pigtail that’s stick out of the seat so I can hook up a Lithium boost pack on frigid mornings.

Yup got the pigtail hanging out the back of my seat cause mine just wont go below -15 f

 

[YukonMP]

blueironranger/Upton44 ... you guys are onto it as far as I'm concerned. If there is any question about my sled starting I just boost it. It is easier on me and easier on the sled. Why run down a battery and wear out a starter cranking multiple times for extended periods. At the temps you guys are talking about these little batteries are down 30 to 40 percent before you even touch the key.

 

[Mike P]

Voltage regulator should accomplish the same from the main battery without needing a secondary source or larger wire.

The stock OEM voltage regulator is not able to add voltage to a circuit. The regulator is only a factor after motor is running.
During engine star-up the amount of current required to crank and successfully start any motor is a fixed number. The conditions in which the current is to be delivered are the variable:
temperature
battery charge
fuel delivery
control voltage
timing, and a lot more.

By adding a secondary source, in my case a rear earth lithium ion battery, I was able to supply the ECU with a constant 12 volts. The VD was eliminated at the ECU and motor fired. I have read of others using capacitor type devices that work in much the same way with great success.

A little something about voltage regs.
https://itstillruns.com/automotive-voltage-regulator-work-5024418.html

 

[GR8BBQ]

The voltage regulator is not able to add voltage to a circuit. The regulator is only a factor after motor is running.

The Pololu voltage regulator I am talking about certainly will add voltage to the circuit. It does not need the motor running to produce more voltage than the battery itself has. The on board battery can be at 5 volts and the output of the voltage regulator will be a solid 12v. Before the motor even starts. Granted it won't produce the same amps, only a couple of amps, but that's enough for the ECU.
Put this device in line with the ECU and no matter what the battery voltage drops to when cranking, the ECU will see 12v. This should keep the ECU for going "brain dead" due to voltage drop out on cranking.
https://www.pololu.com/product/2577

 

[Mike P]

The Pololu voltage regulator I am talking about certainly will add voltage to the circuit. It does not need the motor running to produce more voltage than the battery itself has. The on board battery can be at 5 volts and the output of the voltage regulator will be a solid 12v. Before the motor even starts. Granted it won't produce the same amps, only a couple of amps, but that's enough for the ECU.
Put this device in line with the ECU and no matter what the battery voltage drops to when cranking, the ECU will see 12v. This should keep the ECU for going "brain dead" due to voltage drop out on cranking.
https://www.pololu.com/product/2577

I thought you were referring to the stock VR. The Pololu will work fine as well.

 

[D&C&S]

The Pololu voltage regulator I am talking about certainly will add voltage to the circuit. It does not need the motor running to produce more voltage than the battery itself has. The on board battery can be at 5 volts and the output of the voltage regulator will be a solid 12v. Before the motor even starts. Granted it won't produce the same amps, only a couple of amps, but that's enough for the ECU.
Put this device in line with the ECU and no matter what the battery voltage drops to when cranking, the ECU will see 12v. This should keep the ECU for going "brain dead" due to voltage drop out on cranking.
https://www.pololu.com/product/2577

Is this unit in use just when engine is cranking or all the time when engine is running. Is it powered up from
battery when key is off.

 

[GR8BBQ]

Is this unit in use just when engine is cranking or all the time when engine is running. Is it powered up from
battery when key is off.

Depends how you wire it up. It could be wired up with a switch. It would be preferable to do so as there would be a draw if you put it in line. It's not a plug and play product specific for sleds today; it's just a component that could help us.