New Battery

Post by **Oakey** » Tue Feb 28, 2006 12:31 pm

Just bought a new battery 1098 car, the supplier was not sure what to sell me at first asked if it was like a mini - yes sold me an exide 30 amp/h
is this ok?

Post by **simmitc** » Tue Feb 28, 2006 12:46 pm

It should have a generic type "038" with round posts. Available as "standard" "heavy duty" etc and with 2, 3, or 4 year guarantees; so plenty of variation. What might affect it is if any owner has changed the battery clamps for a differnt sort, but you'll have to look at the wiring to find that out.

Post by **rayofleamington** » Tue Feb 28, 2006 1:05 pm

30Ah is a bit on the low end but you'll probably never notice the difference. AFAIK the mini had round terminals too so it should not be a problem.
If you commute in very heavy traffic in winter and still have the lovely dynamo you may find the battery gets drained a little quicker than an 038 but again not a lot of difference - a new 30Ah battery is likely to be far better than an old 38Ah battery ;-)

Post by **Oakey** » Wed Mar 01, 2006 6:27 pm

Thanks lads, maybe I should have consulted my manual first

Post by **minor_hickup** » Wed Mar 01, 2006 10:11 pm

The minor has a large battery box, would it make sense to fit the largest possible battery as mine is on the way out and will replace it soon? Or would this be a silly idea?

Post by **bigginger** » Wed Mar 01, 2006 10:38 pm

I have to say that that's what I do - but I don't know if it's a silly idea, it just LOOKS better

Post by **minor_hickup** » Wed Mar 01, 2006 10:54 pm

I was just wondering why people didn't fit the largest battery possible? I thought maybe the dynamo couldnt charge or thered be some rational explanation. So what size of battery do you use?

Post by **bigginger** » Wed Mar 01, 2006 10:57 pm

I also don't use a dynamo except on the car I haven't changed the battery on, so the answer again is - don't know! Surely though, the dynamo doesn't care about the size of the battery that it's charging?

Post by **minor_hickup** » Wed Mar 01, 2006 11:00 pm

true, maybe its just an issue of expense

Post by **Shawn** » Thu Mar 02, 2006 6:53 am

I've got a big (modern) 11 plate unit in place. It looks a bit better than the baby 9 plate I had before - and spins the starter heaps faster!

Post by **chickenjohn** » Thu Mar 02, 2006 9:01 am

minor_hickup wrote:I was just wondering why people didn't fit the largest battery possible? I thought maybe the dynamo couldnt charge or thered be some rational explanation. So what size of battery do you use?

I changed the ailling battery last year on the Traveller- my local "Partco" knew exactly which battery was needed- just asked for one for a 1969 Morris Minor, positive earth, I did ask them about a larger battery (as I'd measured the battery box) but they said it would invalidate the 3 year guarantee, and they were of the opinion that this particular battery was "beefy enough anyway!."

maybe thats why.

Post by **rayofleamington** » Thu Mar 02, 2006 9:04 am

The minor has a large battery box, would it make sense to fit the largest possible battery as mine is on the way out and will replace it soon? Or would this be a silly idea?

A dynamo will struggle to charge it properly if it is too big. The flip side is that it will last longer in Winter before going flat (as long as it is charged properly in the first place)
With an altenator, it is fine to fit a bigger battery however you are unlikely to get any benefit from the extra ££s as an 038 is fine and will be fully charged using an alternator.

Post by **bigginger** » Thu Mar 02, 2006 11:42 am

So, as I thought, it's all down to looking better

They were cheap too...

Post by **Kevin** » Thu Mar 02, 2006 12:20 pm

Well I replaced mine with one for the Metro VP version as it was only a couple of quid more and it really does wizz over, but I take rays point that a dynamo can struggle to keep it fully charged but after 18 months I have had no problems at all and as it came from Costco for £30 for a Bosch I am more than happy.

Post by **Cam** » Thu Mar 02, 2006 12:42 pm

The battery will only take what it needs from the dynamo. Usually it does not take much more than about 4 amps when it's getting low which the dynamo can easily cope with. The problem is when it's totally flat it might want a bit more current but the dynamo can usually cope. The best way to think of it is that the battery is a bucket. The dynamo just adds a little trickle to keep it topped up, so the bigger the battery, the more 'reserve' you have. Of course if you have lots of electrical accessories and draw more than the dynamo can supply then the bucket will start to empty and so eventually you get a flat battery. That's a simplistic explanation but usually helpful.

To be honest, a lot of the 'behind the counter' bods in motor factors know very little about battery physics or detailed auto electrics. So they just go on what they have been told. Which is: this battery for this car. Any deviation from this and they invalidate the warranty.

Too small a battery can cause problems (not enough cold cranking amps - so sluggish starting in the cold) and poor reserve so it flattens quicker, but going bigger you eleminate these problems.

Post by **lowedb** » Thu Mar 02, 2006 1:37 pm

Good explanation Cam. I use the water tank analogy a lot for explaining leccy things.

Considering the 'dynamo will struggle' it's best to think of it as having a bigger bucket, but keeping the same size tap to fill it from. If the bucket is kept well topped up then all is fine. If you take more out of the bucket than the tap is putting in, the bucket will empty, but the bigger bucket will take longer before it's empty. Once you've emtied it, it will take the same tap longer to fill it back up, but I wouldn't put that as it struggling, and it certainly won't do anything any harm.

Post by **bigginger** » Thu Mar 02, 2006 1:58 pm

That's what I thought - and I used the same analogy in my head too

The same one is used when you're being taught how the anti-skip in a CD player works too...

Post by **Cam** » Thu Mar 02, 2006 4:18 pm

Mmmm buffers...

Post by **bigginger** » Thu Mar 02, 2006 4:21 pm

Yup - or buckets

Post by **lowedb** » Thu Mar 02, 2006 7:01 pm

Or indeed bucket brigade delay lines. Remember them anyone?