The original battery in my June 08 Octavia has had it it seems. Three times I have been caught out in the morning this week with a failure to start, and there was no sign of signficant recharge after a decent run (going by the indicator when I parked up after the trek to work and the sluggish cold starts when I set off home a few hours later).

So I just ordered a new one using the euro parts discount for Briskoda members, £62 for a tidy Bosch one with a 4 year guarantee - pretty pleased with that.

Just wondering how much the battery might have affected fuel consumption as its been quite high of late. I'll be taking in to Portsmouth next week so I will get an idea then if the new battery makes any difference.

Cheers

Adam

Edited 14 July, 201213 yr by adamal

Not an expert, but the only way I could see any possibility, is that the alternator working harder to charge your duff battery (like having heater fan, rear window etc on) and inturn needing more engine power thus reducing fuel con. Would have thought very little noticeable difference though.

It could affect fuel consumption if the alternator is having to put out a heavy current all the time into a battery that will refuses to charge.

The greater the current it has to supply, the more force the alternator's stator will generate to oppose the turning of the rotor. In turn, this will make it harder for the engine to move the alternator drive belt. This effectively makes the alternator act like a brake on the engine.

It's the same effect that you get when you have lots of other heavy current draw electrical stuff running, like A/C. So, at a wild guess, it could have around 5% effect on the mpg.

Edit: Jerbear - our posts overlapped! Gues we are in full agreement here!

Edited 14 July, 201213 yr by skodacarman

Yeah that was my thinking, lets hope so as I'm not overly happy with my fuel returns of late. Cheers both

I had a similar scenario. Original battery about 7 yrs old. Had an issue when camping of car not startingand taking a few attempts. Finally did tho'. Also took a few cranks on other occasions. Checked batt with voltmeter in the morning and it registered 10.7V! Time for new battery. Got similar one to you from Eurocarparts. There has been a very slight increase in mpg. E.g. Short run into work 3.5m mostly up hill now 30.5mpg. Before 27/28mpg. Not massive. Starts better tho'.

The alternator on a diesel is rated at about 1kW which is about 1.36hp. That is at max load, but you couldn't put that kind of power into a failing battery.

That seems small compared to 140hp, but of course if you are cruising along at 50, the engine may be generating as little as 30hp.

Useful to know that, thanks

It could affect fuel consumption if the alternator is having to put out a heavy current all the time into a battery that will refuses to charge.

The greater the current it has to supply, the more force the alternator's stator will generate to oppose the turning of the rotor. In turn, this will make it harder for the engine to move the alternator drive belt. This effectively makes the alternator act like a brake on the engine.

It's the same effect that you get when you have lots of other heavy current draw electrical stuff running, like A/C. So, at a wild guess, it could have around 5% effect on the mpg.

Edit: Jerbear - our posts overlapped! Gues we are in full agreement here!

Skodacarman, you put it so much more eloquently than me ..lol.