How do I check the charging circuit? - Page 2 - SV650.org

23-12-06, 12:27 PM

ok, here's the score,

battery in bike, engine off, - im getting 12.5 volts.

turn the engine on, lights on, and stick it at 5k revs, i get 14.5V

but as im starting the bike, the voltage drops to 7v

so what does this tell me ?

23-12-06, 02:44 PM

if ure battery is only 'holding 12 ish' its prob goosed ,the voltage will drop upon pressing the starter ,its normal as theres a lot of power going to the starter to start the engine ,sounds like the reg.rec/cgarging circuit is doing its job but the battery is not doing its,change the batt

25-01-07, 08:27 PM

Quote:

Originally Posted by jim@55

if ure battery is only 'holding 12 ish' its prob goosed ,the voltage will drop upon pressing the starter ,its normal as theres a lot of power going to the starter to start the engine ,sounds like the reg.rec/cgarging circuit is doing its job but the battery is not doing its,change the batt

ok new battery on its way.

26-01-07, 01:06 AM

Sorry Warren, only just seen this thread again.

I agree, sounds like the battery is on it's way out. I assume you've had starting problems after the bike has been stood for a while?

If you're still having issues with the new battery, start a new thread & that should get my attn

26-01-07, 07:08 AM

Quote:

Originally Posted by Baph

Sorry Warren, only just seen this thread again.

I agree, sounds like the battery is on it's way out. I assume you've had starting problems after the bike has been stood for a while?

If you're still having issues with the new battery, start a new thread & that should get my attn

nope, the bike gets used every day, 2 journeys to work every day , with the lights on thats about 1.5 miles, thats about 5 mins riding each way.

26-01-07, 07:09 AM

its getting worse by the way, the battery needs charging every other night, (i am only charging it for about half an hour at the time, as i dont want to cook it, my charger is not a trickle charger, just a standard gel motorcycle charger).

and the battery is 6 years old too.

i only noticed this after i fitted my inforad, but since disconnecting it, im still having the flat battery syndrome.

jambo · 26-01-07, 10:12 AM

Ok a quick point, starting your bike takes a large lump of the charge out of a battery. Riding puts it back in, I have heard a ball-park figure of about 10 miles to put all the charge back in, I'd assume a little less would be fine, but I've bump started a bike from flat and seen it run 6 miles, park up and be unable to start again without another bump (that was with a new battery) so if you're starting every mile and a half you may just not be putting enough back in.

The figures for your charging system seem about right to me, so the battery may well have had it if you're properly charging it up and then unable to start it again after a day or 2.

Note: You can easily check voltage with all connections in place (as you have done) as it's measured in parallel to the battery. If you want to measure current (ampage) the Ammeter (multimeter) has to be in series with the battery (i.e. between the -ve terminal and the black lead that connects to the battery) so that all current has to flow through the ammeter to give a reading. Because of this most people can only use it to measure current while the bike is off as your standard £4 multimeter will not pass the 75A needed to start the bike without melting

26-01-07, 10:19 AM

Quote:

Originally Posted by jambo

Ok a quick point, starting your bike takes a large lump of the charge out of a battery. Riding puts it back in, I have heard a ball-park figure of about 10 miles to put all the charge back in, I'd assume a little less would be fine, but I've bump started a bike from flat and seen it run 6 miles, park up and be unable to start again without another bump (that was with a new battery) so if you're starting every mile and a half you may just not be putting enough back in.

Exactly my thought as soon as I read Warren's post explaining the situation.

Short runs will never be good for the battery, or the rest of the engine to be honest. Buy a battery, leave the bike at home, and walk the 1.5miles :P

26-01-07, 06:00 PM

Quote:

Originally Posted by Baph

Quote:

Originally Posted by jambo

Ok a quick point, starting your bike takes a large lump of the charge out of a battery. Riding puts it back in, I have heard a ball-park figure of about 10 miles to put all the charge back in, I'd assume a little less would be fine, but I've bump started a bike from flat and seen it run 6 miles, park up and be unable to start again without another bump (that was with a new battery) so if you're starting every mile and a half you may just not be putting enough back in.

Exactly my thought as soon as I read Warren's post explaining the situation.

Short runs will never be good for the battery, or the rest of the engine to be honest. Buy a battery, leave the bike at home, and walk the 1.5miles :P

i would love to, but taking the bike means i get an extra 30 mins in bed.

cool, new battery arrived today, which is nice.
now do i need to charge it or prepare it in any way before sticking it in the bike ?

ive got a 60 mile ride tomorrow

26-01-07, 09:27 PM

I agree, it's the battery.
But regs are prone to failure, and...

It's unusual, but the problem can also occur with a tired starter motor.
Basically the starter draws way too much current while your battery is OK, so the headlights are bright when the engine isn't running (battery voltage about 11.5 volts or so); but when you try to start it the voltage drops dramatically.
You can check the starter motor, it's in the electrical section of the workshop manual.
Brushes are available, but the rotor cannot be replaced as a spare. Buy the whole thing from a breaker.

26-01-07, 10:12 AM	#17
jambo Member Mega Poster Join Date: Aug 2003 Location: Croydonia Posts: 5,376	Ok a quick point, starting your bike takes a large lump of the charge out of a battery. Riding puts it back in, I have heard a ball-park figure of about 10 miles to put all the charge back in, I'd assume a little less would be fine, but I've bump started a bike from flat and seen it run 6 miles, park up and be unable to start again without another bump (that was with a new battery) so if you're starting every mile and a half you may just not be putting enough back in. The figures for your charging system seem about right to me, so the battery may well have had it if you're properly charging it up and then unable to start it again after a day or 2. Note: You can easily check voltage with all connections in place (as you have done) as it's measured in parallel to the battery. If you want to measure current (ampage) the Ammeter (multimeter) has to be in series with the battery (i.e. between the -ve terminal and the black lead that connects to the battery) so that all current has to flow through the ammeter to give a reading. Because of this most people can only use it to measure current while the bike is off as your standard £4 multimeter will not pass the 75A needed to start the bike without melting __________________ Modern motorcycles are bloody brilliant, enjoy it while we can

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Circuit Gearing	chardy	Mini-Twins	3	12-04-09 06:52 PM
charging system check - values	steveg	SV Talk, Tuning & Tweaking	4	17-02-08 07:21 PM
Brands GP circuit	Jdubya	Track Days	2	12-06-07 02:52 PM
Crash.NET - Circuit-by-circuit with Dani Pedrosa.	NewsBot	News	0	04-04-07 04:10 PM
Weird charging circuit values	andyb	SV Talk, Tuning & Tweaking	11	05-04-06 11:19 AM

23-12-06, 12:27 PM	#11
Warren Guest Posts: n/a	ok, here's the score, battery in bike, engine off, - im getting 12.5 volts. turn the engine on, lights on, and stick it at 5k revs, i get 14.5V but as im starting the bike, the voltage drops to 7v so what does this tell me ?

23-12-06, 02:44 PM	#12
jim@55 Guest Posts: n/a	if ure battery is only 'holding 12 ish' its prob goosed ,the voltage will drop upon pressing the starter ,its normal as theres a lot of power going to the starter to start the engine ,sounds like the reg.rec/cgarging circuit is doing its job but the battery is not doing its,change the batt

26-01-07, 01:06 AM	#14
Baph Guest Posts: n/a	Sorry Warren, only just seen this thread again. I agree, sounds like the battery is on it's way out. I assume you've had starting problems after the bike has been stood for a while? If you're still having issues with the new battery, start a new thread & that should get my attn

26-01-07, 07:09 AM	#16
Warren Guest Posts: n/a	its getting worse by the way, the battery needs charging every other night, (i am only charging it for about half an hour at the time, as i dont want to cook it, my charger is not a trickle charger, just a standard gel motorcycle charger). and the battery is 6 years old too. i only noticed this after i fitted my inforad, but since disconnecting it, im still having the flat battery syndrome.

26-01-07, 09:27 PM	#20
roger Guest Posts: n/a	I agree, it's the battery. But regs are prone to failure, and... It's unusual, but the problem can also occur with a tired starter motor. Basically the starter draws way too much current while your battery is OK, so the headlights are bright when the engine isn't running (battery voltage about 11.5 volts or so); but when you try to start it the voltage drops dramatically. You can check the starter motor, it's in the electrical section of the workshop manual. Brushes are available, but the rotor cannot be replaced as a spare. Buy the whole thing from a breaker.