ECU resets during cranking

[He Man]

I have a 4 gauge wire that connects to the starter that custom built and its mated to a ballstic 12cell LiFePo battery.

The voltage drops enough to cause the gauges to reset after the bike has attempted its cranking procedure and fails. As i'm writing this, i should probably check to see if the fuel pump is repriming to verify if its indeed shutting off and turning back on.


What is the minimum ECU voltage before it shuts off?

[tangoman]

if battery goes under 9.5 when bike is starting time for new battery

[FrankenDuc]

That'd be nifty to find out at what voltage it resets!  What voltage are you running (RMS) during cold cranking?  (how about voltage at the ECU power connections?)

My guess is it would have to handle down to ~8v.  I don't know much about the packs being put in bikes, but my guess is yours is a 4-series 3-parallel pack, so ~16v peak charge, 14.4v nominal, and ~8.4v @10% charge.  Internal resistance of the battery will drop its output voltage to around the 8.4v minimum level during "rapid" discharge.  I'm guessing the pack is designed for the CCA current to be near (for weight) but not beyond the "rapid" discharge level (otherwise it heats up, catalyzes, and catches on fire )

Looking through a Magnetti Marelli catalog I found on the web ( ) it looks like many of their parts (where they give a range...) are spec'd at 13.5v or 13.6v nominal and 8-16v or 8-18v range. a few of their aesthetic bits are 9v or 10v minimum, but their engine control units appear to be 6-18v - hard to believe you're dropping to 6v during cranking though...  Unless connector corrosion, etc., is coming into play.


~Doug

[Howie]

Most motor vehicle computers shut down below 9 volts, although once started, 12 are needed for proper running.  I'm not sure about the Marelli, but I imagine similar to insure starting.

What does the voltage across the battery drop to while cranking?  How is the cranking speed?  Have you tried jumping the bike with a known good battery?  Open cell voltage on your battery over 13.2you will get to a volts?  Have you checked voltage drop across all connections including ground?

Unfortunately I have yet to find an official load test for a lithium ferrous battery, but I think your usual cranking test should work good enough.

http://www.ballisticparts.com/tech/charging.php might help you with battery charging.

This may also help.  http://www.shoraipower.com/s.nl/it.I/id.5/.f  Scroll down and you will get to a chart on open cell voltage/ state of charge.  Also, keep in mind you will not get to full charge without a balancing charger.  

Ah, while typing frankenduc posted some good info!  Thanks!

My offer stand to go down to Brooklyn and take a look.  Give me a call.

 

[FrankenDuc]

BTW - I totally lied in my last post  , I don't know where I got 2.1v/cell at high discharge from but it's actually more like 2.7~2.9v/cell, so a four cell series pack would be >~11v.  On the bright side, if I recall correctly, bad things still happen below ~2v

[greenmonster]

Was runnin w a slowly discharging battery.
At 9,5V, it started stuttering & running erraticly on my 907 w a WM P8.

[He Man]

Sorry for the slow response. Just been Busy.

Howie, to address some of the stuff in the email, yes im going to probably wire in a manual switch to shut the head light off.

Ive been ridding more with it the past few days and have gotten more aquainted with LiFePo batts, leaving the HID light on for a minute doesnt help much at all. You need a high current to help it "warm up" which requires you to crank the bike.

The first crank, runs for about 5 seconds before the ECU shuts off and resets. I wait about 10 seconds for the batt to recover and i try again, and the bike stumbles a bit. After another 10 seconds, it can run through the full 15 second cycle and it may or may not start. on the 3rd try, she finnaly fires up.

the batt never has that weak feel. you know like the lead acid batts that have that "trying to spin the starter" sluggishness.

What i am afraid of is hurting the ECU from having so many on off cycles.

[Howie]

Forgot, HID, 20 watts less.  Strong cranking but the ECU shuts down...    Maybe check voltage to the computer and battery voltage simultaneously while cranking?  It no longer sounds like a battery/ starter circuit to me.  Also try running an extra ground wire for computer?  You have my curiosity going.

 

[TheoRex]

My 2009 M1100 has done this a few times.  It happened when I let the bike sit for a couple of weeks and tried to start it.  So far it has not happened when I have kept it on the battery tender.

[Bill in OKC]

I have a 4 gauge wire that connects to the starter that custom built and its mated to a ballstic 12cell LiFePo battery.

The voltage drops enough to cause the gauges to reset after the bike has attempted its cranking procedure and fails. As i'm writing this, i should probably check to see if the fuel pump is repriming to verify if its indeed shutting off and turning back on.


What is the minimum ECU voltage before it shuts off?

Have you balance charged your battery?  I saw on the Ballistic website that they sell a special charger.