Car battery ratings question

shauncr91

shauncr91

shauncr91

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My car battery is on its last legs (Had to charge it twice since the weather dropped and it was the same last year) so looking at a new one and have been tempted to get a lightweight one instead but don't want to spend a fortune.

I've been looking at this one but don't really know what stats are important on batteries? My standard one if 540CCA which I gather is one of the main factors to consider but some people online seem to be using batteries as low as 220CCA on big cars so I'm a tad confused.

Any help greatly appreciated, it's for a 2.0 Fiesta ST btw.
 
I don't think you need to spend £89 on a battery for a start. Just put your reg into halfords/eurocarparts/the myriad of online battery retailers.

CCA is cold cranking amps so the more, the better in cold weather. You don't need to go crazy with it though.
 
I'd get one that can at least supply something close to the CCA of the standard battery, but there is no point getting one that is rated higher, it won't make any difference. Starter motors can easily draw a couple of hundred amps, so if you get a low CCA battery it will probably work ok when it is warm, but it might struggle to turn the engine over in cold weather.

The amp hour rating isn't so important, as the battery is usually kept fully charged by the alternator, so you could get a lower rated one if it is cheaper, although to be honest there isn't any good reason for buying anything other than one with the recommended spec, or at least close to it. You can probably get one for £40-50.
 
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If you're building a competition car where every kg counts and the usage pattern is totally different to a road car then a lightweight battery can be worth it. For normal road use then just fit a standard replacement
 
As above - any with the manufacturers spec will be fine. I looked into 'race' batteries previously to save ~9KG of weight, but if you do a bit of reading you'll find they don't like low drain, IE alarms, dashcams, central locking etc. which means if you don't use the car very regularly the battery will flatten. Whereas standard batteries are designed for that kind of use and generally have a higher capacity vs their CCA.

Looking on Halfords you can get a battery for a Fiesta ST for ~£60 with CCA 500amps and 56Ah, as opposed to that with only 18Ah.
 
For your everyday car just pick up a halfords jobby, AH isn't very important unless you like to play with your radio for long periods with the engine off etc. Ive been in the car audio business for a number of years and built some installs that require multiple batteries running huge power, Just try and get one to match the manufactures specs, you can use one with less cranking amps if will work but the battery life will be greatly reduced. AGM batteries are the best but you really only require those for modern stuff with stop and stop that require regular cranking etc. for everything else a good old lead acid from halfords should last years.
 
Thanks for replies so far.
One thing I forgot to mention is that I'll also be relocating the battery to the spare wheel well so that's a driving factor in wanting a smaller battery :)

kaiowas said:
If you're building a competition car where every kg counts and the usage pattern is totally different to a road car then a lightweight battery can be worth it. For normal road use then just fit a standard replacement
Click to expand...
The car is far from a competition car but I have done quite a bit of weight saving on it so far so the potential 8-10kg of weight to be saved is rather significant hence why I really want to get one.

unrealrocks said:
As above - any with the manufacturers spec will be fine. I looked into 'race' batteries previously to save ~9KG of weight, but if you do a bit of reading you'll find they don't like low drain, IE alarms, dashcams, central locking etc. which means if you don't use the car very regularly the battery will flatten. Whereas standard batteries are designed for that kind of use and generally have a higher capacity vs their CCA.

Looking on Halfords you can get a battery for a Fiesta ST for ~£60 with CCA 500amps and 56Ah, as opposed to that with only 18Ah.
Click to expand...

I don't really know what could drain the battery on my car apart from the alarm and central locking on mine, there's no big ICE install or cameras etc so I imagine I could get away with less powerful battery?
Car gets driven 5 days a week too so that should keep it topped up enough.
 
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The name/number is the physical dimensions - e.g. 063 = 207mm x 175mm x 175mm.
The CCA is how much oomph it has to start the car. Bigger is better. Particularly so for a big engine or an engine with a high compression ratio as they're harder to turn over.
The Ah is how much power it has for leaving the lights and stereo powered up without the engine running.

For my Clio 182, I stuck in a Bosch S5 063 when the original 9year old Yuasa one died. Same physical dimensions as the original, but 520CCA and 52Ah - spins the car over way faster than the original. 5 Year Guarantee and cost £55.

The Westfield has got that exact Odyssey battery you linked to. Partly because of the weight, and partly because of the small physical size. Because racecar. The battery only has something like 220CCA, and after a few failed cranking attempts it runs out of juice. The battery barely has enough CCA to start the high compression engine, and we had to fit a custom made starter motor to increase the spin speed. Note that as an AGM battery, you need to switch your CTEK charger to the special AGM charging mode.

For a road car, I definitely would not recommend getting a lightweight battery - the hassle really isn't worth it. If you're relocating the battery to the boot, the weight shouldn't matter anyway as the rear axle has naff all weight on it in a FWD anyway.
 
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I'd just get a Varta, Yuasa or Bosch battery, something decent and stick with that.

I know the 'racing' batteries will save you some weight and gain you some track day scene points but nothing I have read suggests they last very long.

How does your car feel under braking now as well? I imagine its pretty lively under braking/turn in if you've stripped out most of the trim (which I recall you mentioning before), with the majority of the weight being shed over the rear? Especially with the rear anti roll bar you've got installed...I know my Fiesta ST was pretty twitchy from the rear with similar mods as you've got, without stripping out extra weight at the back.

Moving the battery to the boot seems sensible to help balance weight distribution but I wouldn't be rushing for a lightweight one.
 
If you use it 5 days a week and it needs charging, assuming it's not a battery under 3 years old, then it's probably just due replacement.


http://www.eurocarparts.com/mobile/...a4eaf97ccd8b2ebe8ec2456b9af73f7c07c123&000020

If you think it's draining, then look up on YouTube.. Parasitic draw test. EricTheCarGuy has a good guide on how to do one. Just need a multimeter and socket set to remove the battery terminal
 
The battery is the same one the car left the factory with to my knowledge so it'd make sense that it's due for replacement, it's fine during the year even after I left it for 2 weeks but in winter it can be dead after 2/3 days. Thanks for the suggestions everyone, I think I may just stick with a standard battery then and get a tray/box to mount it in the boot :)
 
You talk about saving weight by putting a smaller battery in the boot, but then how much will all that 0 gauge cable weigh when you run it back down to the engine bay?
 
Le bump

I decided to stick with a standard battery due to the responses on here and potential problems cranking over in cold weather.

I still want to relocate the battery however to help put some weight over the rear end and was wondering if people could help me locate what bits I need in order to connect the new cable to the existing ones in the engine bay, I assume I need some sort of a junction box to connect the cables safely? Can't seem to find anything like this online though.

Planning to use the standard battery tray/box for the time being instead of buying a new one.
 
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