XSeries-forum

I’ve tested the battery charge in the E70 and it came to 56% over the last 5 days. I’m not running it daily more like once or twice a week and prior to purchase it was sat on forecourt for 6-8 weeks. I was wondering if the battery is now bad and needs changing.
Seen some at eurocarparts. Which make is best Exide or Bosch and what is Bmw oem?
Is installation straightforward or do you need to reset car on dealer software ?

Bosch and Exide are OK, and so apparently is the Halfords AGM equivalent (which is also cheaper). Any battery more than 6 years old is on its way out. Mine is 8 and almost certainly dying. OEM could be Varta or a US built battery. There was an issue with Bosch suffering premature failures (S5 & S6 families) a few years back, but not many reports these days

Unfortunately changing them isn’t as simple as you would hope. The E70 (and beyond) are fitted with Intelligent Battery Systems which change the charging according to the age of the battery meaning the car has the battery coded to it. The IBS needs to be told there’s a new battery, it’s type and capacity/rating.

It’s a quick job to do, but you need something like Carly to do it. I expect Halfords can also do it too but I haven’t checked.

Not doing can result in the battery either being over or undercharged, and shortening its service life.

IBS systems seem to be fitted to pretty much everything these days. It’s part of the emissions reduction technologies across many manufacturers.

Get a smart charger and charge it up if you are not using it much ,no battery is going to be too happy sitting discharging for a week at a time in a car. I've the opposite problem using it far to much as clutch bearing went on my wife's car !

Took it to Ford garage.
They said the recharge was Good and battery voltage was 12.1volts off.
I asked for price of new AGM. He quoted £135 fitted.
Cheapest I could find at Eurocarparts with 45% off was £175 without fitting .
I’m not sure why ISTA is saying charge over 5 days averages 57%. A Good battery recharge is 80%.

ECP have never been cheap for batteries and £135 is a good deal.

If your battery isn’t the original one, it’s just possible that the IBS system wasn’t recoded when the battery was replaced so has the wrong profile. Just a thought. 12.1V sounds low if the car is asleep, you should still see 12.8V approx on an AGM with full charge.

The battery is the original one and last replaced at 0km which means it’s never been replaced.Its AGM.
Garage said 12.2 is normal. Not sure I believe them.
12.1 after been sat on drive overnight without a good run but average charge at 53%.

What’s the charging voltage?

You should be seeing 14.6V to 14.8V for AGM.

Incidentally, 12.1V is fine for the old flooded cell (wet batteries), however AGM type run higher than that - and hence need higher ‘bulk’ charge rates that get over the flat battery though once charged the volts can drop to around 13.8V to maintain the battery state in use.

I’ll have to find my multimeter. It’s a pain getting to battery each time to unscrew everything. So to test it’s one positive one terminal to red wire and where do you attach the black wire.??

To check it under the bonnet there are two points - and it’s where it should be checked as the cables run there too. There is a negative mount up front, close to the +ve point. Looks like a 17mm nut just sat in its own and to the right and forward of the charging point,

Any good bit of metal will do though.