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Old 05-21-2018, 07:43 PM   #1
cmiovino
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Default "Lighter" weight battery that starts in winter

Battery died in my 2004 WRX autocross car. I had a Duralast Gold rated at 640 CCA and 38lbs for the last 7 years.

I was initially going to replace it with another Duralast Gold, but prices have skyrocketed to $158 with the core replacement. The regular Duralast option ($129) is only 500 CCA and weighs the same.

I saw group 26R is a direct replacement for the stock group 35 and is only 28lbs.... but has 575 CCA. It's also only $129. It's overall dimensions are about 1" off every side.

Are there any other options out there for "lightweight" batteries that would still work in winter? All the Odessey and Braille ones are around the 350CCA or lower range and I doubt that would work the few times I do snowcross events or take it to a meet in the winter.
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Old 05-21-2018, 11:31 PM   #2
mrsaturn7085
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PC680 has always been my go-to. The only problem is you sometimes get a bad one (2 of the 6-7 I've had were immediately exchanged after a day) - be sure the seller is local and has replacement's on-hand.
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Old 05-22-2018, 01:36 PM   #3
cmiovino
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Quote:
Originally Posted by mrsaturn7085 View Post
PC680 has always been my go-to. The only problem is you sometimes get a bad one (2 of the 6-7 I've had were immediately exchanged after a day) - be sure the seller is local and has replacement's on-hand.

I've seen these posted around in my research, but they're only rated at 170CCA... isn't that terribly low to be used even at 32 degrees F?
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Old 05-22-2018, 09:08 AM   #4
JazzyJake
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I use a PC925 in my Forester XT. I daily drove it for 2 years with that battery, then the car became an occasional car when I began DD'ing my BRZ.

I've only had to charge it once when the car sat for 3 weeks in the winter, outside. Otherwise no issues, I try and drive it every week.
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Old 05-22-2018, 01:37 PM   #5
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Originally Posted by JazzyJake View Post
I use a PC925 in my Forester XT. I daily drove it for 2 years with that battery, then the car became an occasional car when I began DD'ing my BRZ.

I've only had to charge it once when the car sat for 3 weeks in the winter, outside. Otherwise no issues, I try and drive it every week.

What temperatures are your winters? 330CCA was lower than what I was expecting would be needed in the winter.

Edit: I see it's rated at 26lbs... at that rate, I could get the 550CCA Duralast for $129 for 28lbs.
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Old 05-22-2018, 04:03 PM   #6
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Assuming you stay with the same chemistry (lead-acid), the relationship between size and CCA will be consistent. You want smaller and lighter, you're giving up capacity. No way around that.
You could go for an alternate chemistry like Li-ion but they are much more expensive and have so far proven to be somewhat unstable in an automotive application (i.e. sometimes they blow up). No way I'm touching one of those at this point.
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Old 05-22-2018, 05:01 PM   #7
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Originally Posted by Mulder View Post
Assuming you stay with the same chemistry (lead-acid), the relationship between size and CCA will be consistent. You want smaller and lighter, you're giving up capacity. No way around that.
You could go for an alternate chemistry like Li-ion but they are much more expensive and have so far proven to be somewhat unstable in an automotive application (i.e. sometimes they blow up). No way I'm touching one of those at this point.
This is fairly inaccurate - in terms of lead-acid batteries, downsizing a cell usually revolves around making the case smaller yet equally or more robust as well as increasing the purity of the reactive materials. Both of which increase cost. Granted, you're not going to chop a lead-acid battery's mass in half and get the same CCA - improvements like those require an entirely different chemistry (i.e. Lithium).

Lithium on the other hand, has much more ground to cover in terms of development. I attended an A123 Systems seminar where they discussed the gains they were able to make over ~6 months when they were working with Porsche on the Le Mans car. Long story short - they saw an approximate 50% improvement in capacity for a given cell mass through experimentation with electrolyte chemistry. Amazing what a motorsport budget can give you.

Lithium as a car battery works pretty well these days but the problem is generally the cost (assuming a reputable brand). For what you get, it's just not worth it. The other problem is reliability - the additional protective circuits required to use Lithium are just more things that can fail. You have to prevent over-charge, over-discharge, shorting, excessive draw, excessive heating, etc. Lots of things to pay attention to while a lead-acid cell will just sit there and take the abuse. LiFePO₄ is probably a better choice for a car battery - not as energy dense as the more common lithium polymer/ion cells, but it's a little easier to manage.
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Old 05-23-2018, 06:37 AM   #8
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Quote:
Originally Posted by mrsaturn7085 View Post
LiFePO₄ is probably a better choice for a car battery - not as energy dense as the more common lithium polymer/ion cells, but it's a little easier to manage.
FWIW, I've been using the Shorai LiFePO4 batteries for 4 years now. I use the 5 lb version and don't have cranking issues though I live in the South. That said the car starts on morning in the teens. You can't let them sit for months though like an LA battery, more like 10 days to 2 weeks at most before starting but you also need to buy the Shorai battery charger which works very well if you aren't going to be starting the car for a while. The downside of course is price, like $290 for the battery and around a $100 as I remember for the charger. The car is not my DD though I have been impressed by the battery.
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Old 05-22-2018, 05:40 PM   #9
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Just to muddle this up a bit......LiON and LA usually require different charger profiles. So, consider that.

Yes, lithium usually has a higher power density....good thing.
They tend to be lighter for same amps......good thing.

Need a correct charger profile, while not a huge issue, something to consider.
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Old 05-23-2018, 04:57 PM   #10
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Originally Posted by Charlie-III View Post
Just to muddle this up a bit......LiON and LA usually require different charger profiles. So, consider that.
If you are considering a reputable brand of Lithium battery, this should be handled internally on the pack - if not, you should not be considering the brand in question.

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Originally Posted by Mulder View Post
I want my cars to start during the "polar vortex" and to be able to listen to the radio/stream music/talk on the ham transceiver for more than a couple of minutes without being stranded.
If your alternator is in good order, the battery shouldn't ever care about the latter.
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Old 05-22-2018, 05:55 PM   #11
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Agreed there may be some wiggle room with construction methods and some tweaking of the materials, of course at a penalty of increased cost. But I think we're basically on the same page as far as a really substantial reduction in size while maintaining a similar output requiring a change in chemistry.
IMO, and this is just MO and others may feel differently, unless the car is used in serious competition where the weight of the battery actually makes a difference i say put the heavy battery in with the higher CCA and reserve. I want my cars to start during the "polar vortex" and to be able to listen to the radio/stream music/talk on the ham transceiver for more than a couple of minutes without being stranded.
And FWIW I do keep a Li-ion jumper pack in the tool bag. Got that a while back and finally had occasion to try it recently, it works.
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Old 05-28-2018, 12:04 PM   #12
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Quote:
Originally Posted by Mulder View Post
I want my cars to start during the "polar vortex" and to be able to listen to the radio/stream music/talk on the ham transceiver for more than a couple of minutes without being stranded.
I was considering a lighter battery, like the 925.

Ended up going with a pc1200mj. 38lbs. It's got some serious juice.

It sat at the airport for 60 days and cranked right up at about 25f.

Pretty common to be double digit negative temps where I live in the morning in January/February. It spins the engine well.

There are times when it's a survival situation if the car won't start, figured the extra weight was worth it for me.
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Old 05-22-2018, 08:10 PM   #13
Ernest
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Isn’t there a Miata battery that is lighter and still good for winter. My memory fails me.
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