Hi All

I had a total battery failure on Sunday - everything fine, then total inability to power dashboard lights or starter (could hear the relay and the solenoid clicking). No alternator light before or since.
Have now replaced it, but there are a number of threads on batteries citing potential for other underlying issues.
SO - my quick question to all of you is ...
"When you have had a flat battery, and replaced it, did you find an ongoing underlying issue, or was it cured by fitting a new one?"

Thanks in advance - wondering how much digging to do at this stage!

id look for why no alt light in dash ,unless the d+ plus wire has 12v at it with ignition on alt wont charge

Have you checked for a bad earth

Many a battery has been replaced unnecessarily

Normal battery failure mode is to lose its capacity, but maintain cranking amps. This means it will continue to start the car, but maybe slower and slower until one day, usually a cold morning after a short journey - click-click-click.

Before replacing a “flat battery”:
Check terminals
Check alt charge voltage
Check starter circuit - key, relay, solenoid, voltage drop tests on cables
Check for parasitic draw, ie a faulty component sapping power when it should be off.
Knackered starter.

I find that roughly 2/3 of the time, its the battery, the other 1/3, one of the above. Write the date of fitting on the new battery.

Thanks all so far. Just to clarify, i had total unpredicted battery failure which didn't hold its charge after a run, so i replaced it. Just wondering how many of the scare stories about underlying problems are genuine.
The 2/3 v 1/3 figure is very helpful.

IanSG19 said:

i had total unpredicted battery failure which didn't hold its charge after a run,

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The wife's BMW convertible battery just suddenly failed to start the car last weekend. It was fine, but over a few days it started cranking the engine slower and slower every start. The alternator output measured 14.2 Volt with the engine running. I thought I'd charge the battery, as the car is only used in the summer. After a week on my battery conditioner, where it's showing 13.6 Volts, the battery simply refuses to deliver the current needed to crank the car.

So I've fitted a replacement and all is well so far.

So yes, a battery can suddenly suffer failure, where it behaves like it's fully charged, but can't deliver the current needed to crank the vehicle.

When the battery finally expired on my FL2 it was pretty rapid. One week the car started fine, the following week it turned over a bit slower and seemed reluctant to start, by week three all I got was 'clunk clunk'. In the battery's defence I will say this was the onset of winter.
I took the battery out and measure the voltage . . . 12.7Vdc. "That's not shabby," I thought, so took the battery to the shed and put it on my 20A smart charger.
It came up to full charge in less than an hour, which could leave one to believe all is well. Not so. Although the volts were fine, the battery couldn't deliver enough amps to turn the engine over.
So I put the battery back on the charger and selected 'Reconditioning Mode'. This charges the battery waaayyyy above the 14.4Vdc your alternator will chuck out and the battery will fizz like a newly opened can of pop, except it's not CO2 but Hydrogen gassing off. Three things to remember:-
1) Don't do this when the battery is fitted in the car; your car's electrics won't like it.
2) No naked flames or mobile phones anywhere near the battery; unless you're an idiot.
3) Don't peer down the battery cell top-up holes (if extant) unless you like Labradors and white walking sticks.

What reconditioning does is blast the lead-sulphate build-up off the plates, freeing up lead surface area, making for a once again efficient battery. Albeit one on its last legs.

I bought a new battery, but the old one is still doing sterling service on an electric outboard delivering 10 to 20 amps for between 1 to 1/2 an hour.

Rank Amatuer said:

One week the car started fine, the following week it turned over a bit slower and seemed reluctant to start, by week three all I got was 'clunk clunk'. In the battery's defence I will say this was the onset of winter.
I took the battery out and measure the voltage . . . 12.7Vdc. "That's not shabby," I thought, so took the battery to the shed and put it on my 20A smart charger.
It came up to full charge in less than an hour, which could leave one to believe all is well. Not so. Although the volts were fine, the battery couldn't deliver enough amps to turn the engine over.

Click to expand...

That's basically the same scenario as the wife's BMW battery last week.

Voltage is fine, but virtually no current capacity at all.

This evening I thought I'd try a 10 Amp load with a Watt hour monitor connected. Off load the battery was showing 13.4 Volt. Under a 10 Amp load, the voltage plummets to just 9 Volts, so the battery really is dead as a dead thing.

Shout out for the Ctek MXS 5.0 intelligent charger - it gave me another three years out of my Defender battery that would not hold a conventional charge and kept letting me down. The desulphate and recondition/destratification modes made the difference.

The opposite of a shout-out for anything made by Ring Automotive. I keep being given stuff made by them to repair, and they’re awful.

I've had a battery be ok one day and dead the next..

Mine on the FL2 was a little different - went through winter no problems - but last week just leaving the Autobox in Neutral whilst cleaning out the handbrake was enough to make it chug and fail to start - did the same when I did the job again using new drums and linings - but a nice new Bosch S5010 fitted before I did the bloomin' job for the third time with new springs clips and pins cured that problem- Oh - and I now have a working handbrake that does not scrape in reverse at slow speed....
The battery that came off was the original - nine years old.

In answer to your question: No. Replacing the battery on our FL1 has not identified any underlying issues.

That said, there were no non-battery related issues to start with so I didn't expect to find any problems after I put a larger battery in. It appears that mine gave up cells gradually after a month of cold starts in sub zero temperatures. The major problem that caused was the alternator running/discharging all the time to back-fill the current required to run the engine and systems. Eventually burnt out the alternator and got dash lights (windings actually on fire at the side of the road!)

Recovery being a very last resort for me, I left it where is was until the following dawn (-3 degrees celsius). Then proceeded to whip off the aux belt and drive the 7 miles home. S***e battery, no alternator charge, no power steering and no water pump meant getting home before overheating. Only recommended for those with balls/ovaries of steel.

Battery now lives in a nice, cosy cooler bag to reduce exposure to cold temperatures.

guineafowl21 said:

Shout out for the Ctek MXS 5.0 intelligent charger - it gave me another three years out of my Defender battery that would not hold a conventional charge and kept letting me down. The desulphate and recondition/destratification modes made the difference.

The opposite of a shout-out for anything made by Ring Automotive. I keep being given stuff made by them to repair, and they’re awful.

Click to expand...

That's a +15 from me for the Ctek M200 20A charger. Brilliant bit of kit. Ctek are very good and popular with the boating fraternity.

Also agree with your comment re. Ring chargers. Utter rubbish. I put a scope on mine and the DC had a helluva lot of ripple on it.