Batteries

[mobylette]

Just a general post about batteries. I fitted a Hankook SMF Car Battery 12V 62AH in 2019, has been perfect since and kept charged with an optimate trickle charger. Yesterday it was flat as a pancake and showing 0.6 volts! Wouldn't take a charge so dead. I know modern batteries can suddenly fail, so not that surprising. What did surprise me was a 2015 battery removed from my old Fiesta 3 years ago . It had been sitting on the concrete garage floor untouched. Thought I would check incase it was usable, voltmeter showed 12.6 V !!. Swapped it in and good to go. Amazing. Perhaps something to do with it being a"stop/start" spec. No idea really, but well chuffed

[geoberni]

I fitted a Hankook SMF Car Battery 12V 62AH in 2019, has been perfect since and kept charged with an optimate trickle charger. Yesterday it was flat as a pancake and showing 0.6 volts!

That's very strange.The only way to get that low is to have a dead short across the terminals.
Below around 11.5v is generally regarded as Fully discharged for a 12v automotive battery, depending on the actual type.
For example:

.
I wouldn't use that Trickle Charger again until you've tested it out.

The example of your old battery, just sat there unconnected to anything, is the sort of figure I'd expect.

[simmitc]

Some years ago in a daily use Ford Mondeo, I drove around 200 miles in daylight in good conditions and with no previous symptoms on the car, no problems. Stopped outside a newsagent for a couple of minutes. Back to the car, completely dead, no power anywhere. Analogue meter across the battery terminals and the needle hardly moved. Ford Assist (the RAC) arrived with a new battery and everything perfect. Every other time a battery has been on the way out, it has always shown warning signs, but not that one.

[mike1864]

If I've got my sums right, simmitc's fully charged 40Ah battery would have had to deliver 14.4kW to discharge itself in two minutes. Something would have got really hot, eg the wiring!
I suspect the battery could have slowly died over that 200 miles, the car's vitals (since starting) having been maintained just by the alternator.
Going back to the OP, I agree with geoberni. Don't use the trickle charger until it's tested. Or if that's not possible, check it's delivering around 14.5V. Did you have a separate meter for that 0.6 volt measurement? Or was it on the charger's own display?
There's a school of thought that trickle charging is a waste of time in the automotive arena, where the battery usually gets fully charged by the end of every journey. Even a month's lay-up should see it still well charged (depending on any parasitic features such as alarms and radios).

[mobylette]

The 0.6 measurement was taken with a separate test meter. I can't really check the optimate charger as it wont deliver a charge unless it senses it is attached to a battery. I have another old battery which I put on charge with a standard charger & would only charge to 11.8V. If I connect the optimate it then rises 13.4V across the terminals , so presume its working OK, can't think of another way of testing it.

In any event, as that Ford battery has sat happily for 3 years, I won't worry about keeping the optimate connected at all times. Will just keep an eye on battery voltage.

Thanks for your comments

[mike1864]

As per geoberni's chart, the 11.8V unit is essentially dead.
Incidentally, I recently had a "fully charged" (12.7V off load) battery that wouldn't even turn the starter. Connections and cabling were fine. The issue of course was that it had gone high resistance internally. Plenty of V, but no A.

[Bill_qaz]

A battery discharge tester is useful tool. You can have full voltage but battery cannot provide amps needed by starter.
The tester applies a load and tells you if battery is healthy.
Many types are available but a simple tester for home use is not expensive.

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