Rapid Battery Drain

[Bunzena]

Hi. Have fitted a brand new battery as bike wouldn't start.

Voltage showing on dash as 11.9 - and this corresponded to a multimeter reading too. Was original battery - 5 years old. Always been on a tender - but ho hum.

New battery [which has been fully charged] shows initial voltage [with ignition on] as 12.6 - and bike starts. However after 5-10 minutes voltage has dropped to around 12.0 volts and bike won't turn over.

There's no apparent heavy or even parasitic drain other than the LED lights. But can't see how these would have an impact in such a short time.

My suspicion is that the Regulator/Rectifier may be kapput?

Bike is a 5 year old NC750X - low mileage.

Any thoughts on what could be happening?

[Rob W]

What does the multimeter say when the bike is running?
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'90 TS50 > '04 Senda 125 > '91 ZXR400 > '90 CB-1 > '04 GSX-R1000 > '96 Bandit 600 > '89 ZXR750 H1 > '96 GSX-R750 SRAD > '98 RR-W Fireblade > '98 T595 Daytona > '03 Hornet 900 > '04 Fireblade > '16 GSX-S1000F (x2) > '23 XSR900

[Bunzena]

Thanks for response/question.

Registers around 14.4v steady.

So seems to be charging.

Haven't pulled the Reg/Rec out of the bike yet [it's in an awkward location] - so haven't tested it.

But suspicion is that the diode may have failed?

[A100man]

could be a duff new battery - does it charge off the bike?
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Now: A100, SRX250, XJ598, FZ750, SL1000

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600, Skorpion, GT 250

[Bunzena]

I did think it might be the new battery - but the retailer [who was very pro-active] sent a new one I fitted this morning [after charging].

Had exactly the same issue.

When newly fitted and charged - showed a static 12.6v

After 30 minutes had fallen to 12.3v - now [6 hours later] at 12.1v

So there's a significant drain. I have heated grips and fog lights [using factory harness] - but they've been onboard for a while. The bike is garaged and has no corrosion. Earths look good.

So - and I'm guessing - the Reg/Rec may be playing up. Dodgy diode.

The Reg/Rec an absolute pig to get at. Petrol tank has to come out, rear mudguard, brake light, and multiple body panels off. Previous nakeds have always had the Reg/Rec in the airstream.

[Easy-X]

Do you have a multimeter with a current setting? A decent one can handle 10amps but with ignition off I'd only expect 10 to 100mA. Be interesting to see what the drain is just sitting there. Also try disconnecting the reg/rec and see if it affects things.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Bunzena]

Thanks Easy-X

My multimeter does have a current setting. But I'm not sure it's working.

With the ignition off it's not registering any drain at all.

I guess that's possible?

Getting to the Reg/Rec is a shocker - been at it an hour or so - and still not able to get access to it.

[A100man]

[Bunzena]

Good thinking A100man.

I have a more modern multimeter on the way that might reveal more.

In the morning - I shall start pulling fuses...

[jeffyjeff]

Don't forget to check the fuses in your multimeter. Contacting the leads to a live circuit with the meter set to measure Amperes will blow the meter fuse instantly. As far as I know, most multimeters will not indicate a blown fuse on the meter display, and a blown fuse will prevent the meter from measuring current.
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History shows again and again how nature points out the folly of men - BOC