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2015 forester
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Discussion Starter #1
I have a 2015 Forester, I already cycled the battery twice, the first time was fine, but when I used the load tester to test this time, the dial did not bounce back to the "OK green area", however the car still starts: "OK green area"
Do you think the battery is at its end of life?

Compared to batteries from my other cars, I feel like Subaru's battery does not last long.
I tested battery based on this: diagnosis
 

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2015 forester
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Discussion Starter #5
2017 2.5i Fozy CVT
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Yes,,, whatever your fab skills will allow as long as you can use the existing cables, as before.
I was able to find some threaded rod and mating nuts so I could fashion some longer holddowns to accommodate an inch taller battery. I used the existing "crossbar" part of the holddown.
I monkeyed around with the tray, as well, as the new battery was an inch wider, as well.
Look around and you'll find easier choices than mine to fit with minimum fab, yet have higher CCA than the stock factory setup.
 

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2015 Forester Premium CVT
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If this is OEM battery, replace it. You are past overdue, irrespective of what the meter says. Don't know where you are located but I wouldn't want any battery issues in the winter. I installed Costco Interstate battery last year. The remote start was hit or miss the year before.
A friend of mine who has the same Forester as mine got stranded on a road trip when they stopped for a coffee.

You can use different size (wrong size) battery as long as you can align the OEM wires with them. Take a look at the chart here https://www.jegs.com/Sizecharts/bcigroup.html for physical dimensions of the battery. I am unable to find the chart where it lists polarity and location of the electrodes as well. I would go to the store and spend some time looking at the batteries. You will notice in some cases the polarity of the electrodes is reversed so you will not be able to use OEM wires as is. Those are not a fit for your vehicle.

@Makingforestergreatagain, Which group battery did you install? I tried a little larger battery, don't remember the group no. (24F) but the battery fit is so tight in 2015, I could not fit anything other than what the car came with.
 
2017 2.5i Fozy CVT
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@Makingforestergreatagain, Which group battery did you install?
..............
24F
Height of batt is almost 8.5" as measured to bottom of battery tray.
Factory tray has locating nubbins that mate into car sheetmetal. I cut it down( removed the shoulders) and plastic epoxied it onto the bottom of a generic plastic battery box that I also cut down to make a tray.

Dims on tape
20190915_093711.jpg

20190915_093807.jpg
 

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2015 forester
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Discussion Starter #9
Yes, mine is still the original OEM, I want to set a record :) to be the longest battery lifespan. I probably should replace it, last year my Forester could not start at the airport waiting area, I asked a few people to provide a jump, many people did not want to help, only the 5th person I asked agreed to give it a jump. Yes, I used a couple batteries from Costco, they are great. Walmart batteries are cheaper than Costco, I tried those from Walmart, I think they are fine.

If this is OEM battery, replace it. You are past overdue, irrespective of what the meter says. Don't know where you are located but I wouldn't want any battery issues in the winter. I installed Costco Interstate battery last year. The remote start was hit or miss the year before.
A friend of mine who has the same Forester as mine got stranded on a road trip when they stopped for a coffee.

You can use different size (wrong size) battery as long as you can align the OEM wires with them. Take a look at the chart here https://www.jegs.com/Sizecharts/bcigroup.html for physical dimensions of the battery. I am unable to find the chart where it lists polarity and location of the electrodes as well. I would go to the store and spend some time looking at the batteries. You will notice in some cases the polarity of the electrodes is reversed so you will not be able to use OEM wires as is. Those are not a fit for your vehicle.

@Makingforestergreatagain, Which group battery did you install? I tried a little larger battery, don't remember the group no. (24F) but the battery fit is so tight in 2015, I could not fit anything other than what the car came with.
 

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2015 forester
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Discussion Starter #10
This is very helpful, you saved my time to experiment it.

Now to get the best deal with the same price, see if you agree with my arguments:
1. the outer dimension may not be as important.
2. as long as CCA is higher, the biggest may not be the optimal. This is because to get a higher CCA, you may just need to increase the effective area, i.e. thinner plates and more plates, this higher CCA may not mean that the lifespan is longer.
3. may be it should be the weights. The walmart site lists the $50 battery weight as
65: 47.2 lbs
24F: 44.4 lbs
higher weights mean more lead plates and acid, hopefully this will be a better indicator.
 
2017 2.5i Fozy CVT
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Dims are not important as long as you can fab, though think it advantageous if you can still use the existing crossbar often factory holdown.

Lead purity is important. Better batteries, such as Northstar, have a higher purity.

CCA is not an indicator of longevity...only indicates starting power. Deep cycling a starting battery greatly shortens life.

s/b ".... use the factory crossbar holddown.

..

higher weights mean more lead plates and acid, hopefully this will be a better indicator.
When comparing different sizes in the same brand, yes, but the better AGM (absorbed glass mat)batteries have plates of higher purity lead, which, I think, leaves them less prone to sulfation.
But, AGM batts are not a good choice for hot climates
 

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2018 Forester XT Limited CVT
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to get a higher CCA, you may just need to increase the effective area, i.e. thinner plates and more plates
To get more contact area, they often use a mesh instead of plates. You can see that deep cycling electrodes made of mesh is going to quickly dissolve the electrodes or enough of them to make most of the electrode simply drop into the bottom of the battery. And when you recharge the battery you don't have any control over how the metal reattaches to the electrodes, so if you get a thin part at the top, and then drive over a speed bump, your electrode is going to go clunk into the bottom. Best practice is to not deep cycle a starting battery.
 

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2015 forester
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Discussion Starter #13
When comparing different sizes in the same brand, yes, but the better AGM (absorbed glass mat)batteries have plates of higher purity lead, which, I think, leaves them less prone to sulfation.
But, AGM batts are not a good choice for hot climates
AGM is expensive. If the walmart $50 can last 5 years, then it beats a $100 battery that can last 8 years (because 2*5=10 years). So the cheapest wins. After price, the second factor should be the weights for the same brand and type of batteries, I think.
 

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2015 forester
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Discussion Starter #14
I have had to charge the battery before one cycle (not deep cycle). After I could not start at the airport waiting area, I felt I had little choice but to deep cycling.
So this is interesting, which choice will provide longer lifespan:
1. deep cycling, knowing it will speed up its life
2. not deep cycling, knowing it may die next morning. When you are frustrated, you will may a call to replaced it sooner.

To get more contact area, they often use a mesh instead of plates. You can see that deep cycling electrodes made of mesh is going to quickly dissolve the electrodes or enough of them to make most of the electrode simply drop into the bottom of the battery. And when you recharge the battery you don't have any control over how the metal reattaches to the electrodes, so if you get a thin part at the top, and then drive over a speed bump, your electrode is going to go clunk into the bottom. Best practice is to not deep cycle a starting battery.
 

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Discussion Starter #15
To "deep cycle" a battery is to discharge it to a greater depth of discharge, meaning to discharge it more, before recharging it.

When you discharge a battery, in each battery cell, metal flows from one electrode, through the electrolyte, and attaches to the other electrode. When you recharge the battery, the same thing happens in the reverse direction.

When electrodes are new, they are whatever shape the manufacture makes for that style of battery. The electrodes could be thick plates for deep cycle batteries, or meshes for starting batteries, or somewhere in between. As you discharge and recharge the batteries, the electrodes slowly change from whatever manufactured shapes, to blobs. There are other things that happen as a battery ages, like stratification etc that are beyond the scope of this discussion.

I think starting a typical car discharges a typical battery by about 3% (we could probably look this up). But if you discharge a starting battery slightly more than that, you could end up with the electrodes dissolving more and becoming structurally weaker.

In this case, your battery should have a longer lifespan if you don't deep cycle it. (This means something different than installing a deep cycle battery in the car.) And all batteries have a finite lifetime. When you change the battery will likely be influenced by how much trouble it is for you to change the battery and/or how much trouble it would be for you to get stuck for a bit of time while you went and changed the battery. Once I was changing a battery and found that one of the ring terminals on the cabling was cracked, so I had to run to the store again to get more parts. But if you need the car to be reliable, like you're visiting someone in the hospital every day or doing other stuff that's important, it may be beneficial to change the battery before it completely fails.
Good explanation. I think maybe in my case, what I had done may not be defined as "deep cycling". I don't have a professional deep cycle equipment. As shown in the video, after I charged full according to the hydrometer (at this point, if I start the engine, it will start fine,) I use the load tester to see if the 100A discharge would make the dial turn back. I will discharge it if the test fails.

I only had to do this one or two cycles, I did not have to do this many times. I did not use the 6A setting, only the 2A setting, I hope it only had minimal abuse.
 

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Discussion Starter #16
Another question I have: many people say the lifespan is 3 to 5 years, should the lifespan be measured as the number of times the charge-discharge cycle? If I don't use the car, does the battery age?
 
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Flooded Lead acid batts start to discharge from the moment not being charged.

AGM batts, by comparison, can hold a charge for months... the better ones anyway-Northstar/Odessey
 

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Discussion Starter #18
would flooded one last short than AGM in California climates? It looks like AGM is a lot more expensive, if it does not last longer in my state climate, then I should get flooded one.
 
2017 2.5i Fozy CVT
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Depends where in Calizuela you are:

IMO...Mountains-:yes get a plate type( not coiled Optima style) AGM.
DESERT clime... - no,as AGM are not as tolerant of heat.
 
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