[rich46]

Is/are the battery/ies lead/acid or the light weight kind ?

 

[rich46]

I suggest you keep disconnecting stuff from the ECU. Wait. Battery voltage stays in the 12v range until you hit the starter button? It only plummets when you try to start the bike? Once you let go of the starter button, the voltage goes back up the 12v and up? What year is the bike and how many miles are on it?

With your battery the problem is something other than the battery (IMHO) FYI in general all the super lite ones tend to have a high voltage spike within 30 to 60 seconds of turning the ignition switch on. We have a battery sponsor and our rep calls this the warm-up time. LOL I know it does sound counter intuitive but even my multimeter shows the voltage rise. Good luck with your problem; I'll go back to work on the vintage racers where there is very few circuits to worry about. With all the interlocking circuits; ECU's and ECM's I'll head to someone whom is conversant this tech.............still I'll bet they can't balance a set of carbs by ear. CHEERS !

 

[rich46]

@rich46 thanks for the info on the voltage spike. that's interesting.

Hello Winston. Just a wee bit more. The Rep (do keep in mind that IMHO rep and salesman are quite similar) told me that when you turn on the key switch that excites the battery. The electrons begin to move faster and in 30 to 60 seconds they will be up to their max. Not totally trusting I removed a battery from a proper lithium battery charger and let it rest over the night. In the morning it had 12.8 volts. Placed in the motorbike and connected (was a race bike with out even a charging circuit) and retested after after about 1.5 min. it took to install and test the multimeter read 14.1 volts. Not a perfect test and there could be other factors but that's what we saw on the meter.

 

[rich46]

Winston, Being a simple guy I'd first take my test light and go through all the accessories and switches (side-stand,horn,turn-signals) to see if anything is hot that should not be with the key off. I'd then pull apart the switches so I can get to the small circuit boards and do the similar test. I have had the same issue with a Honda Goldwing and a Kawi touring bike and found the trouble there; the result of a wire being chafed by electronics without proper install by the owner. Something is drawing electrons from somewhere so I always start with the most easy to repair. If the trouble is there you replace or repair a wire or switch takes less time and will most probably cost the least. If the trouble is within the more complex components then go with God and good fortune.

With things such as wiring troubles remember the old adage "when you hear the sounds of hoof beats look first for horses not Zebras " I only say this because your trouble seems rather simple in that your battery is not crashing, there's no smoke and the wrenched thing starts from time to time. Now it may be some demon in the ECU but at least hope not.
I have had one faze of the starter motor go bad from time to time so when the starter is in one spot the thing will not start or is hard to start; put the motorbike in gear and bump the thing a bit against the Bendix and try again and off you go. I don't even know if this is even relevant in modern motorbikes and one would think you'd be getting some proper error message on the clocks if this was the trouble but it's a thought..

 

[rich46]

I love the term methodical and will start to include same in my personal description. I always thought I was just lazy and was taking the easy way.

 

[rich46]

Hi Winston,
when you are performing the test , do you recall how long the ignition / 10 a fuse is live total time in minutes to reach 10 v from 12.87, ,
It is possible to measure the actual current drawn by measuring the voltage across the fuse,
there is a calculation matrix depending on type of fuse, i use an amp hound when checking muliple fuse boxes to save time,
out of interest what other additional electrics are added and how are they powered/ controlled
have they been in use when the bike intermittently fails,
what journey times frequency in the days before the non start,
what battery voltage is displayed when the non start occurs without cranking ,
apologies for the questions, trying to help,
Forest

Just a wee reminder our modern motorbikes with the new generation of ECM's and ECU's pretty much are at an end of function when the voltage drops below 9.5 volts. The lithium batteries will often not even be able to pick-up a charge from your charger when they get below 5 volts. You can sometimes trick them by using jumper wires and wiring them in parallel using a trickle charger. All the same the days of babying a engine to start with TLC and luck when the battery is down are over. You pretty much need a full charge to get all the electronics (ECU,etc) to kick-in and the bloody thing to start. My Racer is DTTW (dead to the World) when the battery is at 9.55 v. I know because I had it out in my shop with the seat off so I tried a battery off a racer that was at 9.55 v. Light (some) came on but otherwise nada.

 

[rich46]

Just a wee reminder our modern motorbikes with the new generation of ECM's and ECU's pretty much are at an end of function when the voltage drops below 9.5 volts. The lithium batteries will often not even be able to pick-up a charge from your charger when they get below 5 volts. You can sometimes trick them by using jumper wires and wiring them in parallel using a trickle charger. All the same the days of babying a engine to start with TLC and luck when the battery is down are over. You pretty much need a full charge to get all the electronics (ECU,etc) to kick-in and the bloody thing to start. My Racer is DTTW (dead to the World) when the battery is at 9.55 v. I know because I had it out in my shop with the seat off so I tried a battery off a racer that was at 9.55 v. Light (some) came on but otherwise nada.

OH ! by the way when I put the R 9 Racers proper battery in at 13.1 vit fired right up happy as a clam.