New Battery, or not......

3 Mar 2013
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United Kingdom
I'm trying to decide whether to invest in a much better battery.......

Every Winter my wife's car battery goes flat when it's very cold if the car has not been used for about 3 days. I charge it up and then it's fine until it gets left for a period again. The car is mostly used for short journeys. I completely understand that this is not that unusual under the circumstances I describe; however, I am wondering whether getting a top quality battery will make a difference and be more tolerant of the circumstances that cause the current battery to go flat?

The battery has been replaced in the past but did not make a difference to this behaviour. The current battery has a starting power of 310 amps.

Anyone any experience of this and upgrading the battery? Did it solve the problem?

Thanks in advance!
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if the battery is going flat so quickly, then id suggest getting the alternator tested to make sure its charging the battery correctly. However, if it was faulty there would potentially be a light on the dash illuminated. Still worth checking it out though.

If the battery is being charged ok but still goes flat, then the battery is worn out. Its not normal for a battery to go flat so quickly. Is it a maintenance free battery or can you open the 6 covers on top and fill it up with deionised water? have you even checked for this??

what car is it and how big is the engine?

A larger battery with better capacity and greater Cold cranking amps will behave much better in colder weather, but the weather we have here is not really that cold that cars should struggle to start! this leaves me thinking that your battery may just be worn out. If your doing lots of short journeys, with heated screens turned on, blowers and radio and headlights etc it doesnt take long for a battery to go flat if its not being fully charged. Its best to take the car out for a decent long run at least once a week if it is a short journey car.

Putting a new larger capacity battery on will only aid in the length of time that it lasts before being flat, it wont solve the issue if the car is not being run long enough to charge the battery.
I would agree with the above. Connect a voltmeter across your battery, with the engine running it should read about 14.4 volts, much less and the alternator is not doing its job, if its OK I would suspect the battery.

Every time the battery goes flat it will shorten its life so if its done this frequently its probably had it.

This is winter

I will guess that the lights are used a lot, the HRW is used a lot, the heater fan is used a lot. Does the car do mostly short runs, or longer ones where the engine is mostly turning at a fair speed, and not idling at traffic lights?

Has a replacement radio or other electrical item been fitted? Is the light in the boot switched on?

You didn't mention how old the battery is

If you have a charger, you could top it up once a week or so.
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If its a ford it may have a heated front windscreen which draws a lot more current than the rear heated screen. This is a battery killer if not being charged correctly.
As above and check the alternator drive belt is tight.

You could try a solar cell charger in the front window to help keep the battery topped up? t connects to the power point (cigarette lighter) socket.
3 days is a bit premature for a battery to fail - I would suspect that there is a constant current draw somewhere.
You could try disconnecting one of the battery leads to see if it remains charged - you'll need the radio code though.
John :)
Thanks for all the replies.

I'm getting good voltage across the battery when the car is running so the alternator is fine. Electrolyte is all OK too.

When I put the battery on charge the gauge on the charger does not show it as completely empty - in fact it only needs an hour or so on slow charge to show full. Goes back in the car and all is fine again.

My hunch is that at 310 amps (lower than any of the batteries on offer from Halfords - budget through to best) it's just not got enough gumption when it's a little less than fully charged and the weather is at it's coldest.
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