Battery - when to replace

[mawallace]

I've discovered on my VW Golf that there is a feature which shows you the state of the battery. This morning, as an example, it says:-

"SOC 80%"

So, a few questions:-

- what percentage is deemed to be an acceptable one before you change the battery?
- should you measure it after a car journey or first thing in the morning?

[Scrump]

That % SOC means little to me.
When to replace a battery is usually informed by the voltage the battery shows after being left for a while.

[gmaz]

SOC means state of charge and is just how "full" the battery is.

Batteries work best best 20% and 80% full, i.e. being able to charge and discharge quickly so its probably just the management system limiting the capacity.

[Spare tyre]

I typically just replace them when it lets me down or starting become slower, that said do it before the end of summer, probably wait for a decent euro car parts discount code,

[Scrump]

Sorry, I should have been clearer. I realise SOC means state of charge but I can’t see how that relates to whether or not to replace a battery.

[Pastie Bloater]

Scrump said:

Sorry, I should have been clearer. I realise SOC means state of charge but I can’t see how that relates to whether or not to replace a battery

It doesn't really. As you said if the battery can't hold charge then it would need replacing. On the flipside if it is holding charge but can't output (e.g. start the car) it needs replacing.

OP your 'state' of battery is just charge, not life remaining or 'health' or anything like that.

Edited by Pastie Bloater on Wednesday 26th May 17:27