How do I check the charging circuit?

[thornton_chris]

I got some really useful information when I posted this (http://forums.sv650.org/viewtopic.php?t=49216) yesterday. It looks like I may need a new battery but as suggested in the replies I thought it might be worth checking my charging circuit before I part with my money.
Does anyone know how to check this?

I can check that the batery is sittting at or around 12v but surely this doesn't prove that it has charged properly. Do I not need to check the current supplied by the charging circuit?

Any ideas?
Chris

[Sid Squid]

First charge the battery and check the voltage across the battery terminals, (not immediately after disconnecting the charger, you'll get a falsely high reading), should be about 13V, much less and the battery is past it's best, do this first as some supposed charging system faults are duff batteries.

With the lights on and the engine spinning at 5000rpm there should be a reading of between 13.5 and 15V at the battery, if the reading is above 15V the regulator doesn't, if it's below 13.5V either the regulator is toasted or the alternator or wiring is goosed. This is a good rule of thumb test, but does assume that your meter is reasonably accurate, if you're not convinced your meter is accurate try this:
Ensure the battery is fully charged, start the engine, turn on the lights and rev the motor to about 5000rpm, what you're looking for is a rise in the reading of at least a volt, and when the engine speed falls back to tickover that it's still either equal to or preferably a bit above whatever reading you got from the battery alone.

[suzsv650]

i told u in ur last thred

[Viney]

And hes been told in this one. Now let that be the last of it ;)

[Warren]

First charge the battery and check the voltage across the battery terminals, (not immediately after disconnecting the charger, you'll get a falsely high reading), should be about 13V, much less and the battery is past it's best, do this first as some supposed charging system faults are duff batteries.

With the lights on and the engine spinning at 5000rpm there should be a reading of between 13.5 and 15V at the battery, if the reading is above 15V the regulator doesn't, if it's below 13.5V either the regulator is toasted or the alternator or wiring is goosed. This is a good rule of thumb test, but does assume that your meter is reasonably accurate, if you're not convinced your meter is accurate try this:
Ensure the battery is fully charged, start the engine, turn on the lights and rev the motor to about 5000rpm, what you're looking for is a rise in the reading of at least a volt, and when the engine speed falls back to tickover that it's still either equal to or preferably a bit above whatever reading you got from the battery alone.

if the battery is only half charged, will you get a reading of 6.5V ?

im not fooling around, just trying to get my head around voltage, amps, watts, and multi meters and stuff.

[Razor]

No, if you ever get that it's completely flat or has a dead cell.

Read this http://en.wikipedia.org/wiki/Ohm's_law

and this http://auto.howstuffworks.com/question324.htm

and this too http://en.wikipedia.org/wiki/Lead-acid_batteries

[Warren]

First charge the battery and check the voltage across the battery terminals, (not immediately after disconnecting the charger, you'll get a falsely high reading), should be about 13V, much less and the battery is past it's best, do this first as some supposed charging system faults are duff batteries.

With the lights on and the engine spinning at 5000rpm there should be a reading of between 13.5 and 15V at the battery, if the reading is above 15V the regulator doesn't, if it's below 13.5V either the regulator is toasted or the alternator or wiring is goosed. This is a good rule of thumb test, but does assume that your meter is reasonably accurate, if you're not convinced your meter is accurate try this:
Ensure the battery is fully charged, start the engine, turn on the lights and rev the motor to about 5000rpm, what you're looking for is a rise in the reading of at least a volt, and when the engine speed falls back to tickover that it's still either equal to or preferably a bit above whatever reading you got from the battery alone.

so why have i got to wait until the battery is fully charged before i carry out this test ?

and approx how long would it take me to charge the battery (riding time, with lights on, no other electric device attached )

[Warren]

First charge the battery and check the voltage across the battery terminals, (not immediately after disconnecting the charger, you'll get a falsely high reading), should be about 13V, much less and the battery is past it's best, do this first as some supposed charging system faults are duff batteries.

With the lights on and the engine spinning at 5000rpm there should be a reading of between 13.5 and 15V at the battery, if the reading is above 15V the regulator doesn't, if it's below 13.5V either the regulator is toasted or the alternator or wiring is goosed. This is a good rule of thumb test, but does assume that your meter is reasonably accurate, if you're not convinced your meter is accurate try this:
Ensure the battery is fully charged, start the engine, turn on the lights and rev the motor to about 5000rpm, what you're looking for is a rise in the reading of at least a volt, and when the engine speed falls back to tickover that it's still either equal to or preferably a bit above whatever reading you got from the battery alone.

so why have i got to wait until the battery is fully charged before i carry out this test ?

and approx how long would it take me to charge the battery (riding time, with lights on, no other electric device attached )

what measurement is needed to tell how much drain an electrical application will have on a battery ? ie. heated grips.

[Baph]

what measurement is needed to tell how much drain an electrical application will have on a battery ? ie. heated grips.
That would be Amps (Ampere's). The amount of electricity per second.

Heated grips IIRC, draw 4Amps (max) at 12volts, could be wrong on that though. Your starter motor, draws around 75Amps.

You need to put the system under load to get an Ampere reading though. So fire her up & stick the lights on.

I can't remember the specific values, but I did post somewhere on the forum. If you haven't found it by morning, I'll try find it. Basically, I went to town one day with my bike, and stuck the multimeter everywhere I could (oooeeerrr) under different conditions.

But now, is home time...

[Warren]

aah baph to my rescue :)

so your saying that i could find out how much charge is remaining in my battery using a multi meter ?

[Warren]

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 ?

[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 :wink:

[Warren]

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 :wink:

ok new battery on its way.

[Baph]

Sorry Warren, only just seen this thread again. :oops:

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 :)

[Warren]

Sorry Warren, only just seen this thread again. :oops:

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.

[Warren]

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]

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 :lol:

[Baph]

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

[Warren]

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 :)

[roger]

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.

[ejohnh]

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 :)

Sounds like it always was the battery. 6 years is an old battery. When you dump the acid into the battery(presuming that is what you got(a kit)) there will be a lot of charge in there. I changed my battery last week and I put it on charge for an hour. I could see it was full of juice though because the charger could only pump less than an amp flow into it.

John

[Warren]

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.

i have a CBR,
that is something i have thought about, but straight after charging the battery,. the starter sounds fine.
my voltage drops to 7.5 across the terminals when i start the bike.