What's the biggest battery you can fit in a Gen.4?

As the subject says

I have just fitted a new battery in Viv's Audi and I kept the old one for w/shop use. I measured it and compared it to the one in Tonka and with a bit of work I reckon I could make the Audi one fit. It's more than double the CCA and nearly double the A/H, but it's made for stop start and the terminals are the large size so I would need to check the specs on other makes but maybe someone has already done the homework and can point me in the right direction.

Cheers.

Roger

Unless you match the alternator with the bigger battery you run into potential issues with over working the alt which could over heat it and kill it prematurely. If however you are looking at a supplementary battery on a split charge system for additional loading that's different but really still needs a bigger alt.

Why do you want a bigger battery?

I don't believe a bigger battery will require a matched alternator. Your larger battery just has more storage AH and CCA available, the components connected to it won't suddenly use any more. Your alternator simply replaces what's been used from the battery during starting / storage, so unless you run the larger battery flat starting it won't take any longer to replace what's been used when the engine eventually runs. The maximum alternator out is fixed, large or small battery that's the most it can achieve.
So yes it could potentially run for longer if you use more of the storage capacity it's larger size grants you, but in reality is this is unlikely to cause it any issues.

That's good old fashion dumb alternators of yesterday.

I believe the G4 is a smart alternator, if you do swap the battery I assume you may need to let the ECU know the new AH / CCA so that it can determine the correct output to keep it full. Failing to do so may result in a flat battery. Best check this statement and if the ECU software is happy for you to go large. I don't know anymore, it's all getting complicated. Good luck.

 

I might agree with that if he were wanting to increase capacity by 10 or 20 percent but doubled is going to have implications, firstly the additional unnecessary weight and depending on vehicle usage patterns if the car isn't being run for long periods the alt is never going to have enough time to fully recharge the battery which will quickly result in it being incapable of starting the car. Suzuki put a lot of r and d into matching the alt and battery so that they work efficiently with the rest of the vehicle. Just changing the battery because it seems small is undoing that efficiency.

wrote:

Why do you want a bigger battery?

During the recent cold spell, charging the 8 year old battery on the Audi took 1 hour whilst the Jimny took 4, so I started to think that a bigger battery would be a sensible option. The fact that the old battery was sitting on the bench led to the inevitable idea "would it fit". In
reality, although it will, I would hope that I would not need to go that far. The standard Jimny battery has 330CCA and some batteries are available, said to be direct replacements, that boost the CCA to 400. Now that is just over 20% and would, realistically, be all that I need but I am a POF (pedantic old fart) and I like to explore all the options, so I will take me back to Halfords in the new year and measure the batteries they have on display, mainly Yuasa to further my ideas.

Merry Christmas.

Roger