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While dynoing my car this weekend a guy with a 16 club sport Miata immediately noticed my battery and couldn't believe how large it was, after looking at his I see why! His battery and tray were 1/2 the size and likely 1/2 the weight. Wondering if there is any reason the tray and battery wouldn't work in our cars. Anyone have any insight on this?
 

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I think the "gram strategy" means that the MX-5 battery is the minimal they could get away with, and based on how many are reporting dead batteries after 3 or 4 weeks of no driving, I would stick with Fiat's choice, unless you plan on using a Battery Tender while parked for extended stays.
 

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I pulled the stock Fiat battery and put in a group 51R battery in its place. I was able to use the existing hold-down hardware and the terminal clamps fit perfectly with no mods necc. I have not had any problems. The longest I have left it is two weeks and it fired up without any hesitation. If I park the car for the winter I will definitely put on a tender. Group 51R was about 2/3 the size of the Fiat and 12 lbs less.
 
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I pulled the stock Fiat battery and put in a group 51R battery in its place. I was able to use the existing hold-down hardware and the terminal clamps fit perfectly with no mods necc. I have not had any problems. The longest I have left it is two weeks and it fired up without any hesitation. If I park the car for the winter I will definitely put on a tender. Group 51R was about 2/3 the size of the Fiat and 12 lbs less.
Did this also help give access to the oil filter without having to disconnect the EC intake?
 

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Did this also help give access to the oil filter without having to disconnect the EC intake?
It did!. It's almost easy now to get to the oil filter. However, I have the V1 intake which uses the stock airbox. I believe the other versions ( V2, V4) might have a different shaped intake tube so you may not gain as much room as you do with the V1.
 

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The reason the FIAT's battery is bigger is because they're more stuff sucking electrons afterthe engine shuts off (the turbo cooler). A tiny battery will go bad faster with that kind of post-stop power drain, and if the battery's too small, it will simply drain it too much to start the next morning. I've researched battery options, and I think we'll be sticking with the OE battery until I'm ready to finalize a trunk-mounted "accessory" battery, and then we'll do a Li-poly battery under the hood and a Pb-acid powersports battery in the trunk for outside of race season.
 

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I can back this up. The MX5 battery is “marginal” for the job. My RF’s battery is absolutely DEAD after about 12 days idle. It’s ridiculous really.
 

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I can back this up. The MX5 battery is “marginal” for the job. My RF’s battery is absolutely DEAD after about 12 days idle. It’s ridiculous really.
Remember the government PSAs about "ghost loads" like brick transformers you leave plugged into the wall all the time? Looks like the car manufacturers are getting worse and worse about ghost loads on their cars with these ultra-techno gadgets. I don't think an old-school turbo timer would require a floor scrubber battery, :laugh:
 

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I'm sure there's a modern equivalent with equal or more capacity and equal or more cranking amps, and in a smaller package. I believe there was someone put in a smaller battery, which is an off the shelf, type with the equivalent capability.

I don't think you'll shed a lot of weight, without sacrificing capability in one form or another, but the physical dimensions is going to be smaller.

The baseline for the OEM battery are most likely capacity and cheap (or, rather, cheap and then capacity).
 
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I'm sure there's a modern equivalent with equal or more capacity and equal or more cranking amps, and in a smaller package. I believe there was someone put in a smaller battery, which is an off the shelf, type with the equivalent capability.

I don't think you'll shed a lot of weight, without sacrificing capability in one form or another, but the physical dimensions is going to be smaller.

The baseline for the OEM battery are most likely capacity and cheap (or, rather, cheap and then capacity).
51R battery group.
 
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I'm sure there's a modern equivalent with equal or more capacity and equal or more cranking amps, and in a smaller package. I believe there was someone put in a smaller battery, which is an off the shelf, type with the equivalent capability.

I don't think you'll shed a lot of weight, without sacrificing capability in one form or another, but the physical dimensions is going to be smaller.

The baseline for the OEM battery are most likely capacity and cheap (or, rather, cheap and then capacity).
There's more than that, but I haven't dug into the Spider's battery to know for sure. They may also have chosen that battery because of thicker plates. More surface area (thinner plates) means more cranking "juice" but thicker plates can withstand deeper cycles. Having built EVs and some small off-grid solar/wind systems, I've learned a bit about picking batteries. And if they were smart about the 124 in terms of reliability, they'd choose one about the size of the one that's in there, with fairly thick plates for better, slightly deeper cycling. It's too bad they didn't just make some space on the dash and put a solar panel on it ;)
 

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There's more than that, but I haven't dug into the Spider's battery to know for sure. They may also have chosen that battery because of thicker plates. More surface area (thinner plates) means more cranking "juice" but thicker plates can withstand deeper cycles. Having built EVs and some small off-grid solar/wind systems, I've learned a bit about picking batteries. And if they were smart about the 124 in terms of reliability, they'd choose one about the size of the one that's in there, with fairly thick plates for better, slightly deeper cycling. It's too bad they didn't just make some space on the dash and put a solar panel on it ;)
While that makes sense to a certain extent, on a typical car, there's no need for a deep cycle battery. I know the coolant pump runs after shutdown, and even a lot of cars run their cooling fans for a period of time after shutdown, it's not taking that much energy from the battery. Indeed, if you 'deep cycle' a car battery, how will you subsequently get it started?

Maybe the design allows for a flatter power delivery with a rapid drop off; like you said, a 'little bit of deep cycling' if there is such a thing. The small pump may take more current than your average cooling fan (in fact, it'd be nice to know where that thing is - it seems like a nice point of failure).

(EDIT: Not trying to be combative, here, just trying to see what the real reasoning is for such a boat anchor, and when it fails, what the options are for replacing it, pitfalls, benefits, etc. maybe it just won't matter, but obviously there's concern about storage, since these cars often are not used over winter).
 

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I don't know how much current the pump uses, but it's physically pretty small. The entire assembly is smaller than a can of single serving soup.

There are quite a few people in the 500 Abarth community running tiny batteries without problems, so I don't think it would be a big issue in this car.

Greg
 

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Don't undersize.

IMO it is best to keep the larger battery, capacity capacity capacity. I've noticed that I have replaced batteries on the order of about 5 - 7 years and my first impression was that this battery may not make that timeframe. Lower capacities may leave you on the road in failure....or decrease battery lifetime at a minimum.

From a current standpoint there are many things drawing current on this vehicle. The turbo cooling uses about 4 Amps for the duration it operates. Not insignificant. Electronic shutdowns and "follow me" lighting can also be significant loads.

In my opinion the weight of the battery is not a "ghost load" rather a necessity in light of the power requirements.

AND! My important reason to not undersize the battery....

I play my car radio when parked, top down, at many camping events, tailgating events, I also use a 110VAC converter........ Your mileage may vary but this is how I use the vehicle!

Don't undersize.

Full disclosure, I did characterize the current draw at shutdown. I was concerned because I installed a buried 12V USB C charging port and one of my requirements was that it was always active even if the car was turned off. When the vehicle is completely into the lowest current state it draws about 100 mili Amps. That's not much but over months of non use it could be catastrophic for the battery.

http://www.124spider.org/forum/81-w...day/19554-always-high-current-usb-c-port.html
 

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You make some good points, but as an automotive instructor I'd like to clarify a couple of things:

A ghost load has nothing to do with battery weight. It refers to electrical loads that are drawing current from the battery when the engine is off. Keep alive memory in the various modules, the ECM, BCM, Infotainment, etc...etc...

Anything more that a 30 to 40 milliamp draw, engine off, used to be considered excessive. If you consider the amp/hour rating of the battery you can calculate how many hours it would take to drain it at a given ghost load, or parasitic draw. Inactivity for a couple of months may do it.

So yes, I totally agree, I'll keep my heavy battery....My Fiat is inactive for weeks at a time quite often, but never fails to start. Cheers.
 

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I thought I might want a smaller battery to help assist with removing the oil filter, but after performing my first change this weekend, I found it to be no big deal.
 
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You make some good points, but as an automotive instructor I'd like to clarify a couple of things:

A ghost load has nothing to do with battery weight. It refers to electrical loads that are drawing current from the battery when the engine is off. Keep alive memory in the various modules, the ECM, BCM, Infotainment, etc...etc...
Sorry, re read and for some reason I was thinking he was referring to the weight as the unnecessary load. As for the other loads you mention...they are all essential in my pursuit of happiness, every time I get in the vehicle! Hardly Ghostly!

Unseen current drains, ghost, I get it! Now I understand his use of the term. My understanding is that a "Ghost Current" is that power lost to heat due to inefficiencies. For example, your charger when not connected to your phone but plugged into the wall still takes power, precious little, but that inefficiency is reflected in heat, a overhead energy use and you get nothing for it. I'm ok with the thought that Casper the friendly ghost is cooling my turbo and keeping my radio stations organized. That is useful work.

Here are the car battery details.

Battery: Q85, “start-stop” battery, 520 CCA, 65 Ah [20 hr rate], 52 Ah [5 hr rate], 37 lbs

This specification says that the battery can deliver 520 cold cranking amps for a very short period of time. (30 seconds without a drop below about 7V I think.) The CCA spec is just for starting. The 65 Ah @ 20h rate means that the battery is specified to provide a current of 65Ah/20h, or 3.25A. This means that the battery can supply 3.25 A for 20 hours without denting the battery Voltage. Alternately 52 Ah @5h rate means that it can deliver 52Ah/5h or 10.4 Amps for 5 hours. These are just "strength" numbers that indicate a relative rating for battery to battery comparisons. It is sometime argued that you could proportionally adjust those number for different current drains. This is the best that you can do but it is not overly accurate. Lead Acid battery capacity depends on rate of drain, elapsed time, temperature and a host of other physical and chemical reactions.

So, using one rating there is 3.25*20 Ah = 65 Ah, the other is 10.4*5 Ah = 52 Ah. These numbers make sense, at a larger discharge rate there is less capacity or less Ah (Ampere Hours). It can deliver 3.25 Amps for 65 hours but when pushed to 10.4 Amps it will only last 52 hours.

The best we can do is a proportional analysis, know that there are inaccuracies. A vehicle drawing 100 mA in sleep current could proportionally see 65 Ah / 100 mA = 650 hours = 27 days before a defined discharge state. Using the alternate rating, 52 Ah/100mA = 23 days. These seem like realistic numbers. Know that the current drain of 100 mA is 32.5 times less than the 3.25 A rating so you can expect better numbers than a month, probably.

According to the specification the battery will run down after about a month of non use!

Sounds obvious to me.
 

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why is everyone so obsessed with replacing their battery, if you save 20# of sprung weight what will be your benefit. nothing unless you are running laguna seca raceway in the new scca spec 124 class for road racing. the difference in any way shape or form will be miniscule and unnoticed by a driver. when your battery fails if you want to put a smaller battery in your car, ok, find a group 51r battery with the same amperage, but you will now notice the difference. if weight savings are so important, you can drive around using $ 5.00 fill ups and have a greater weight reduction. at a weight of 2400# the reduction of weight by 20 -30# is nothing.
 

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why is everyone so obsessed with replacing their battery, if you save 20# of sprung weight what will be your benefit. nothing unless you are running laguna seca raceway in the new scca spec 124 class for road racing. the difference in any way shape or form will be miniscule and unnoticed by a driver. when your battery fails if you want to put a smaller battery in your car, ok, find a group 51r battery with the same amperage, but you will now notice the difference. if weight savings are so important, you can drive around using $ 5.00 fill ups and have a greater weight reduction. at a weight of 2400# the reduction of weight by 20 -30# is nothing.


What

are you kidding me? 30lbs in a 2400 car is HUGE, that is 1.25% of weight, especially on the driver side, front of the car Helps with left to right, and F/R Weight distribution!
 

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why is everyone so obsessed with replacing their battery...
Haha! you are right, I think people obsess about things that are quite inconsequential. The battery may or may not be one of those things.

However, if nothing else, it's darned fat and ugly from the 70s!
 
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