12v battery

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Discussion

trickywoo

Original Poster:

12,722 posts

242 months

Wednesday 5th March
quotequote all
This falls well into the cool story bro category but some may find it interesting.

The short version is that I had a battery showing a solid 12.6v that had never been discharged but it wouldn't handle any current.

The long version.

I had a Yuasa made in Japan battery in my motorbike. Its 2 1/2 years old. I haven't used the bike since September but put the battery on an optimate charger once a month or so.

Over the winter it never needed more than a few minutes charge and always went double green on the charger.

A couple of days ago I started the bike for the fist time in 5 months and all was well. Went for a 20 minute ride.

Next day the battery wouldn't even turn the bike over. Put it on the optimate charger and it took a couple of hours to go green. Still wouldn't start the bike. Tested it with a multimeter which showed 12.6v even after trying to start the bike (lights and ignition on OK). I then gave it a stronger charge at 14.4v for 30 minutes and back on the optimate which said all well over a test cycle of a couple of hours.

It still wouldn't start the bike. The really strange thing is even a few minutes running the headlight it was still showing 12.6v. The same again after spending a cold night in the shed.

I was kind of thinking a bike problem at this time but I put a new battery in today and all is well.

What I've learnt is that you can't trust a battery showing 12.6v to be good, you can't trust an optimate charger and you can't trust a Yuasa battery.

paul_c123

374 posts

5 months

HealeyV8

436 posts

90 months

Wednesday 5th March
quotequote all
Yep had same with car battery had plenty of volts but no amps. I didn't have anything but a multimeter so drove me nuts for a while, thinking it might be coil or something else. You need a proper battery tester.

trickywoo

Original Poster:

12,722 posts

242 months

Wednesday 5th March
quotequote all
paul_c123 said:
Thanks for that. Looks a nice tool to have.

Belle427

10,217 posts

245 months

Thursday 6th March
quotequote all
I have a Yuasa that is dying on a car but that drops to 12.1 volts overnight, still cranks the car ok but is on borrowed time. Probably 3 years old.
They are supposed to be good batteries from what I have seen.
I have a similar battery tester to the one linked to, they are ok but it does not tell me the battery needs replacing on this particular occasion.
It has worked well on some other cars though.

ssray

1,175 posts

237 months

Thursday 6th March
quotequote all
Most bike batteries are sized as small as possible, not unusual to fail early, they have no room internally to absorb a warped plate etc.

What bike is it?

trickywoo

Original Poster:

12,722 posts

242 months

Thursday 6th March
quotequote all
ssray said:
Most bike batteries are sized as small as possible, not unusual to fail early, they have no room internally to absorb a warped plate etc.

What bike is it?
Its one of the bigger batteries you get but its still small relatively - its a 14 size. Its on a KTM 1290 so turning a big engine plus the electronics its just disappointing the optimate didn't flag any issues.

TimmyMallett

3,009 posts

124 months

Thursday 6th March
quotequote all
If you left it on the bike then in the month, it could actually flatten. A voltage doesn't give you a true guide on a battery's health. So if it does flatten in a month and you do that repeatedly, it can kill it. A lot of battery chargers 'green' is only monitoring a voltage drop over a short period, they don't check it's cranking voltage.

SystemOfAFrown

76 posts

32 months

Thursday 6th March
quotequote all
The Optimates are a triumph of marketing over function tbh. They are a decent enough maintenance charger but all the guff about battery testing on the gold series is just that. It can't apply the kind of load required to check for cells with internal resistance starting to increase, and even if it could it doesn't have the required kelvin probe setup to measure voltage under load.

kestral

1,928 posts

219 months

Friday 7th March
quotequote all
trickywoo said:
This falls well into the cool story bro category but some may find it interesting.

The short version is that I had a battery showing a solid 12.6v that had never been discharged but it wouldn't handle any current.

The long version.

I had a Yuasa made in Japan battery in my motorbike. Its 2 1/2 years old. I haven't used the bike since September but put the battery on an optimate charger once a month or so.

Over the winter it never needed more than a few minutes charge and always went double green on the charger.

A couple of days ago I started the bike for the fist time in 5 months and all was well. Went for a 20 minute ride.

Next day the battery wouldn't even turn the bike over. Put it on the optimate charger and it took a couple of hours to go green. Still wouldn't start the bike. Tested it with a multimeter which showed 12.6v even after trying to start the bike (lights and ignition on OK). I then gave it a stronger charge at 14.4v for 30 minutes and back on the optimate which said all well over a test cycle of a couple of hours.

It still wouldn't start the bike. The really strange thing is even a few minutes running the headlight it was still showing 12.6v. The same again after spending a cold night in the shed.

I was kind of thinking a bike problem at this time but I put a new battery in today and all is well.

What I've learnt is that you can't trust a battery showing 12.6v to be good, you can't trust an optimate charger and you can't trust a Yuasa battery.
https://www.youtube.com/watch?v=tsJUuLu1cw0

You don't need a max/min multimeter just make sure when you crank the car you can see the multimeter, rest it on the windscreen.