HDI Battery

[BiG K]

If you get a hammer out and flatten the lip closest to the headlight on the battery tray, you can fit an 096 comfortably which is more powerful.

How much CCA (which is what I'm assuming you mean by power) do you really need for a humble 4 pot diesel though?

My HDi has only got an 065 in it from a petrol 306/Xsara and that cranks the engine over strongly even on bitterly cold winter mornings.  Whilst I wouldn't recommend buying one of those new - it's only on mine because I had it left over from a car I broke a couple of years back - it does show that you don't need a massively overkill battery.

Approximate capacity, size and price (based on Lion battery from ECP for the sake of comparison) of the various options:

065 = 52Ah, 460CCA and 242x175x175mm.  £44.
027 = 60Ah, 480CCA and 242x175x190mm.  £56.
075 = 60Ah, 520CCA and 247x175x175mm.  £47.
096 = 75Ah, 640CCA and 278x175x190mm.  £69.

Whilst it's not a huge amount in the grand scheme of things, going for an 096 is nearly 50% more expensive than a 075 and I'm not convinced you'll see much benefit.

If you shop around, even a little, a 096 is only a tiny bit more. Like this Exide Premium for £50 http://www.ebay.co.uk/itm/311601723770

Batteries work better when they are warm, so the colder it gets, the less current it can provide. Starting an engine requires a lot of current, over a very short time. Meanwhile, cold engines are harder to start, requiring more power to get them going.

As batteries age, their internal resistance increases, reducing CCA. Total capacity decreases at the same time. This is why a newer battery can start your car in any weather, even if you leave the sidelights on overnight, while an old battery might only start the car when fully charged, in good weather.

Starter batteries are optimized for short-duration, high-current draws, followed immediately by recharging. They are built with thinner plates with more surface area, which speeds up the chemical reactions that release the energy. If you draw them down to 1/2 charge, and then leave them like that for a while, hard crystals will form on the plates, which won't re-desolve easily on recharging. That reduces capacity and CCA over time.


So a larger battery will still degrade & provide the power you require for longer & allow you to use the accessories in the car for longer before you damage it, at the expense of a tenner or so and a kilo or two of weight.

Peugeot must have had a good reason to fit a bigger 027 over a 065, most likely, they didn't want their customers breaking down within the warranty period or shortly afterwards.