Car battery? Is there a difference from where you buy?

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Fred99

13684 posts

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#1968241 5-Mar-2018 12:27

We've got a 1998 Mazda MX5, purchased as a used import. I just took a look at the battery that came with the car when we bought it 10 years ago. It looks like it's got a date stamp on one of the terminals "04F", so I guess that could mean 2004. Anyway, the battery is at least 10 years old, it's unlikely it was brand new when we bought the car, so it's probably 14 years old - and it's still going strong. (Not superstitious - but touching wood as I type that anyway).
I'd read that some people had got well over 10 years life on the original Na MX5s, which came out from about 1989, these had Panasonic brand batteries. The battery in our MX5 is a "FB - Furakawa Battery" brand. It looks like a perfectly standard sealed lead-acid battery. Only thing I can think of that's different, is perhaps the battery is larger than you'd expect to find in an 1800cc car these days, but also the battery is in the boot, so there'd be some voltage drop over the long cables to/from the starter and the alternator, but I'm unsure how that could affect battery life.

It leaves me with the nagging thought that the makers can make long-life lead acid batteries, and have known how to do this for decades, but choose to make batteries that don't last very long by design.

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RunningMan

7948 posts

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#1968329 5-Mar-2018 16:05

Supercharge seem to have a good reputation as well as 40 month warranty. Bit more expensive though.

http://www.superchargebatteries.co.nz/

Bung

5421 posts

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#1968556 5-Mar-2018 21:58

Fred99: The battery in our MX5 is a "FB - Furakawa Battery" brand. It looks like a perfectly standard sealed lead-acid battery. Only thing I can think of that's different, is perhaps the battery is larger than you'd expect to find in an 1800cc car these days, but also the battery is in the boot, so there'd be some voltage drop over the long cables to/from the starter and the alternator, but I'm unsure how that could affect battery life.

With the MX5 they probably did it to get the weight disttibution right but I've had older cars where it was just to get the battery out of the heat in the engine bay.

Fred99

13684 posts

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#1968683 6-Mar-2018 09:02

Bung:
Fred99: The battery in our MX5 is a "FB - Furakawa Battery" brand. It looks like a perfectly standard sealed lead-acid battery. Only thing I can think of that's different, is perhaps the battery is larger than you'd expect to find in an 1800cc car these days, but also the battery is in the boot, so there'd be some voltage drop over the long cables to/from the starter and the alternator, but I'm unsure how that could affect battery life.

With the MX5 they probably did it to get the weight distribution right but I've had older cars where it was just to get the battery out of the heat in the engine bay.

That really might be it - it's surely at a more constant / cooler temperature. I seem to recall some cars in the past would have the battery stored in a compartment separated from the main engine bay. I also had a 24v Nissan diesel 4WD for 18 years, went through several sets (probably 4) of (expensive) batteries. This had 2 x 12v batteries in series, one battery would die with basically no warning, the other would seem to be perfectly okay. It was always the battery on the side of the engine bay where the exhaust was that would die first.

MikeAqua

7608 posts

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#1968737 6-Mar-2018 09:26

I find that quality batteries last longer in vehicles stored outside (in cooler areas). For inside storage I haven't noticed much difference.

I've had good service out of Hella, Century and Exide batteries over the years.

The Exide battery in our Pajero (stored outside)for example is at least 7 years old as well as regular starting (3.2L diesel) duty it regularly powers other 12v devices some of which are high drain.

Mike

Senecio

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#1968741 6-Mar-2018 09:30

My wife has an Audi A1 with the battery in the boot. Pretty sure its done for packaging as hers is the twin charged version so not much room under the bonnet with a turbo and supercharger in there. Interestingly it has a 770 CCA battery for a 1.4L petrol. My 2L Diesel seems to make do with a 350 CCA battery.

MikeAqua

7608 posts

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#1968782 6-Mar-2018 10:41

tripper1000:

mclean:

Cars like BMW/Mercedes/Audi have battery management computers which are sensitive to battery quality. You don't want to buy a Supercheap battery for cars like this, and it definitely isn't a case of simply unbolting the old one and putting a new one in.

Some BMS systems need to be reset when you fit a new battery. If your car has a BMS you'll need to google weather it needs resetting and how to do it.

What is the purpose of BMS systems in ICE cars - i.e. what 'problem' do they solve?

Mike

Fred99

13684 posts

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#1968786 6-Mar-2018 10:42

Senecio:

My 2L Diesel seems to make do with a 350 CCA battery.

That Safari I owned was an import, the "NZ New" versions (Patrol) had a single 12v battery. As a straight 6, it didn't actually take much to crank over. Seems counter-intuitive with such high compression and a large engine, but a cylinder at TDC on the compression stroke would be pushing down simultaneously as another cylinder was being compressed - so it balanced out. When turning it over for example when setting valve clearances, I'd do it easily with a 3/8" drive ratchet on the crankshaft nut. It's a shame that straight 6s are more or less a thing of the past. I suspect that as an old-school and indirect injection engine, battery grunt was needed to reliably glow it - more than just the grunt needed to turn over a large engine. And that was the problem when a battery died, if the engine was cold, push-starting it wasn't going to work.

mclean

578 posts

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#1968815 6-Mar-2018 11:40

MikeAqua: What is the purpose of BMS systems in ICE cars - i.e. what 'problem' do they solve?

I know the BMW ones do this, and probably lots more:

The charging rate is managed according to the type and age of the battery and how it is performing. Apparently this optimises the charge and keeps the operation in a "safe zone" which extends the battery life.

If you change from a normal LA to an AGM battery it knows to adjust the charging profile automatically, otherwise you will toast the AGM battery.

The most visible benefit is that monitors the battery performance so that you get a early warning on the dash of any problem well before it actually fails.

The computer keeps an on-board record of the battery history for the life of the car, which might not be much use but it's certainly interesting.

All this depends on properly registering each new battery install.

MikeAqua

7608 posts

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#1968912 6-Mar-2018 14:11

mclean:

[If you change from a normal LA to an AGM battery it [the BMS] knows to adjust the charging profile automatically, otherwise you will toast the AGM battery.

That bit sounds like a useful feature.

Mike

Aredwood

3885 posts

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#1970947 7-Mar-2018 23:51

MikeAqua:

What is the purpose of BMS systems in ICE cars - i.e. what 'problem' do they solve?

It is often to reduce fuel consumption / emissions.

Under engine braking, the alternator voltage is increased to quickly charge the battery and cram as much energy into it as possible. At other times, the alternator output voltage is reduced, to use that stored power to run electrical loads. Less alternator load means less fuel consumption and emissions.

But this type of BMS puts alot of extra stress on the battery. So it is debatable as to whether you would save enough money on fuel expenses to cover the cost of extra battery replacements.

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