Programming a new car battery??

It isn't as big a deal as it sounds, or need not be.

Some cars have a charging algorithm which can be adjusted if a different spec battery is fitted. Fit the same spec battery and you should be fine.

I'm not sure which cars, someone mentioned BMWs to me but I expect there are others.

Some cars won't accept a new battery unless you hook it up to a computer to tell it you've fitted it.

All to do with smart charing and start / stop systems.

BMW have been doing it for years now.

Oh. In that case BMW's been struck off my list of new cars to look at when I'm due to buy a replacement come September. Life's complicated enough already.

That is why I buy second hand. You can look at reliability and user reviews, something you can't do for new.

I also aim for a vehicle model that is being discontinued or undergoing some change, hoping that many of the bugs would have been sorted.

It needs to know the capacity of the battery for rather obvious reasons.

Even a like for like replacement? (Same spec.)

Yes, there is a current sensor in series with the negative terminal. It's used to measure the current in/out of the battery and thus its state of charge. Important in the new world of stop/start engines . . . The cars relevant ECU has to be reset otherwise the stop/start wont work.

look here:

I have a new BMW on order (X1 PHEV) - the starter battery is the least of your worries if one of those goes wrong!

Yes, even like for like.

It works out the battery degredation over time, as Dave has pointed out, it needs to know the capacity and predicted health of your battery - mostly so you can guarantee it will re-start when it stops!

Ok, thank you.

I'm less than convinced this is an 'improvement' ;-)

I do wonder what difference in fuel economy this makes in the cars concerned.

I assume that is behind it all and it is linked to the dreaded ?smart alternator? issue.

The latter crops up in various motorhome forums in relation to charging the leisure batteries in newer motorhomes.

I became aware of the battery programming issue when an acquaintance mentioned he?d had a battery fail in a newish car. He wanted to replace it with a larger capacity one but was warmed about it would need a visit to a dealer etc. I thought he got round it by fitting a like for like replacement but perhaps I am mistaken.

I have seen a manual that mentions charging voltage, where the battery under normal circumstances is held at 90% capacity. And then topped up when the engine is on the 'overrun'.

It seemed a simple criterion of voltage and there are many references to the relationship between terminal voltage and state of charge depending on the chemistry.

In this instance I wouldn't have an issue in putting in place a larger capacity battery.

I would thought the ultimate would be to use the alternator as a motor in a pseudo hybrid capacity if ultimate fuel consumption was the aim.

In many instances the battery tray is limited in size, and the like for like replacement is probably optimum for physical size in terms of price. If one of larger capacity existed I would get that instead.

Likely just as much to do with emissions. An engine idling is at its worst for those. So makes sense to switch it off.

Devices that can be both motor and generator often combine the worst aspects of both.

Thanks - guessed it had to be something sophisticated.

Isn't it all down to detailed design? The integrated motor assist (IMA) unit on Honda hybrids seems pretty good to me. Starter, alternator, and assist motor all in one unit on the crankshaft. Obviously, you want it to be reliable but surely it's better than having an alternator and starter motor hanging off separately, each with their own drive? (My Jazz does have a conventional starter and battery in case the separate battery fails, but only as a backup).

So the car is so smart it can tell how long it's going to be before you take it for another run? Wow! :-D

If there's one *genuinely* valuable feature I'd like to see introduced (or re-introduced in this case) it's the starting handle. For me that would be a truly useful addition. But sadly it's never going to happen for obvious reasons. :-(