Diagnosing dead battery vs charge leakage etc?

[Freddyfruitba...]

My car suddenly refused to start the other day due to a flat battery; I stuck it on charge overnight which apparently worked OK, next day it started fine. But the following day - same problem - as if I'd left the lights on overnight or something (I hadn't).

I assume this is likely to be a dead battery in need of replacement (it's about 5 years old)? But if so, why did it charge up OK? And could the battery actually be good but being drained somehow (ie, so a new battery would just suffer the same fate?) How to tell?
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KC100->CB100N->CB250RS--------->DL650AL2->R1200RS->R1250RS

[Riejufixing]

[Suntan Sid]

Had the same problem a few weeks ago.
Car wouldn't start, charged the battery up, off we went!
Couple of days later same thing, but this time we needed to leave the car in an airport car park for a few days, so it was new battery time.
Went to the local motor factors and told him what I wanted, he asked "how old the battery was", "8 years old" I said.
He laughed and said "you're lucky, they normally last 5 or 6 years"

I didn't fit the new battery straight away, stuck with the old one, and kept the new one in the boot. The old battery was flat after four days in the car park, so put the new on.

Charged the old one up again, it lasted a couple of weeks.
From fully charged, if you attach a meter, you can see it losing charge, about half a volt every couple of hours.
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"Everybody needs money, that's why they call it money!"

[Nobby the Bastard]

The easy way to tell if there is a drain or the battery is fucked is to disconnect the earth and then charge it up. If it's still charged a couple of days later the battery is fine. If not its not.

Edit: fixed all the dyslexic typing.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Riejufixing]

[steve the grease]

Worrapens is that the material from the battery plates falls off over time and forms a conductive sludge in the bottom of the battery. This then internally shorts the cells, running the battery down. time for a new one. I bet it gets warm when you charge it.
Plus with a new battery the engine turns over faster , for ages longer , improving starting.
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All the above is my personal opinion, you can see my lips move, but I'm talking out of my arse.
I've been riding, and fixing , bikes for 50 years, in that time the more I learn, the less I am absolutely sure of.....

[MCN]

[doggone]

It's probably the battery, considering the age of it just get another at this stage.
A cheaper test of sorts would be to borrow another known good used one if at all possible.

[Tankie]

Check to see if any internal light remain on e.g boot light
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Always learning, everyday is a school day

[megaross]

Test for a parasitic draw. Get your multimeter, black lead to com, red to amps and set it to measure amps.

Disconnect your negative cable and connect your multimeter between that and your battery. Leave it to settle it's tits down if it's a modern car with loads of electronics.

If you've got a draw over 50ma (ish) then it's got a parasitic draw (start pulling fuses to find out where from).

If not then your battery is probably toast, you can do a time analysis on that by disconnecting the battery and measuring the voltage every couple of hours. It'll become obvious fast if that's the case.

Annoyingly I once had a parasitic draw that was intermittent, two wires were shorting in the boot turning the light on but only if the car had shaken them into position so it didn't show on the tests, I only found it by chance. That was fun to find
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'07 Tiger 1050

[Nobby the Bastard]

It's still much easier to see if the battery stays charged if its disconnected.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050