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  

wrote:

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 agree. See below

Merry Christmas

Roger
 

wrote:

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.

Forget the weight, a bag of spuds would be no heavier. Tonka is run most days, mainly to town or the gym but usually short journeys but a longer one into the country every week. If I fit a bigger capacity battery, there is no change to the charging rate, I will use the same output which the alternator will replace in the same way and in the same time. So why fit it? Simply put, insurance. During the cold spell I noticed that starting took  a little longer and if I had  more CCA at my disposal I would know that I had reserve power to hand. Your comment about R and D reminds me that when an astronaut was asked what worried him the most replied "everything on that rocket was supplied by the people who quoted the lowest price".

Merry Christmas

Roger

We are sort of saying the same thing, but I am being pedantic 
The alternator needs to match the load applied to the battery, but not the battery.
Fitting a larger battery is not an issue to the alternator and won't make any difference. The alternator is designed to cover vehicle load and top-up the capacity used during starting within a typical use cycle ( whatever that is). So large or small battery this will be covered as the load applied has not been changed in this instance.
They can be considered electrical petrol tanks. Large or small tank if you remove the same petrol out of each during a journey it takes the same time to pump it back.
It only starts to make a difference it you increase the load on the electrical system or totally drain the battery. At this point you need to increase the alternator output to keep within the "use cycle" or keep the engine running longer. 
So the alternator is matched  to the vehicle electrical load,   not the battery capacity.

But this still don't explain the need to go large, but no harm in it other than cost. 
Edit <<^^^^ Extra cranking time in cold weather - yes larger will help. Just drive around a little longer.

 

"Alternator matched to load", yes I agree. This situation reminds me that the Jimny has a small fuel tank which is not a problem if I stay local but it's a reminder that long journeys need investigation as to fuel supplies. I would think carefully about a long range tank. I am just off to Halfords to measure batteries and although my tank is three quarters full I will top it up on my way home. At this time of year, you never know.

Roger

I have often thought I would like a bigger battery to enable my 2ch Dash Cam to run longer in parking mode. In my previous car the same Dash Cam would run for a good few hours. Lucky if it runs for 10 minutes after turning off the ignition now.

I saw this a while ago and thought it might be a good upgrade, but haven't actually looked into it properly as it is quite a price.

Z.Mode have made an a fitting kit to suit the Optima Red 5Ah battery. 

HERE

Obviously you could just buy the same battery sepparately and fit it yourself.
 

I am not sure you will see any benefit from a battery twice the size, having that extra capacity is only really a benefit if you have large current flow when the alternator isn’t producing much power, e.g. winching, or parked up for long periods using power but not with the engine running.

If you do fit a bigger battery, you will probably have to replace the thick power leads for the starter as the originals might not be long enough and I wouldn’t attempt to joint them otherwise the resistance in the joint will limit the CCA or worst case get very hot due to the power loss.

If you use the car every couple of days your existing battery will be fine and the extra CCA won’t be needed, not in the UK anyway. You would be better off spending the money on a high performance battery like the Optima Red Top battery suggested by Soeley, than fitting another battery of the same technology, but twice the size.

Robin