[Flat6er]

As you might know all by yourself - battery seems kinda small in Tribeca... Unfortunately I don't have luxury of garage and even electricity outlet at my home to regularly use charger, so I came up with this splendid idea about putting larger(and AGM) battery in.

When I was picking up people in airport two days in a row... guess what happened on second day?
Just when I wanted to leave - battery wasn't able to start the engine... On a plus side - I found out that airport has towtruck driving around and helping those in need(like me) with booster.


Stock battery
So. Original battery (from FSM -> General Information Section ->3 specifications.pdf (SPC2)) is - 52Ah (75D23L). Some technical information about it - https://technoluxpro.com/en/akkumulyatory/avtomobilnye/75d23l.html
Most important details are size(dimensions), capacity and CCA(cold cranking amperage):

• overall dimensions: height - up to 225 mm, width - 173 mm, length - 230 mm;
• CCA 510-630 amperes;
• capacity is 60-65Ah.

Choosing
In USA, catalogs call it Class 35 battery (230x175x225mm).
I looked up those "Class" sizes https://www.batteryequivalents.com/bci-battery-group-size-chart.html
I thought that I might be able to put in Class 24 (260 x 173 x 225 - longer by 30mm). They have the same price as Class 35, but have a bit larger capacity.

After asking fellow Tribecians on drive2.ru ( Габариты аккумулятора и время "засыпания" — Subaru Tribeca, 3.6 л., 2008 года на DRIVE2 ) - I got information that some people even have installed 300mm long batteries (though one end is somewhere in front fender and other is ON engines head cover), but that sounded unacceptable to me.
Also asked around about different manufacturers - turns out Optima is not recommended (video explaining it -

), Interstate batteries also not. DieHard were recommended to me - so I bought that.

In the end, got myself DieHard 24F-AGM, 710CCA, 70Ah. Since this is not Class 24, but Class 24F - it is another 13mm longer.


Conclusion
Installed product:

Distance to engine block looks good (for me), for more "comfortable" distance I would suggest to use Class 24.

Distance to left headlight is also acceptable, but definately - wouldn't recommend going bigger battery.
As a minor disturbance - original plastic/cardboard pan, which is put underneath battery is to small to fit properly.

 

[06b9beca]

I have run a Diehard Gold 35-2 in the Tribeca for about 5 years now so it is getting due for a change. Now my SG Forester XT has the same battery. I wonder if I should out the Diehard 35-2 Gold in to my Forester and do what you did.

What is the real difference between the Gold and Platinum?

I was reading on the Forster forum that an AGM battery is not always the best bet if the electrical system (charging voltage) is not modified.

('03-'05) - AGM battery for my Forester XT?

Hi; I own a 2004 Forester XT. I need to replace the battery (which is only the 2nd one the vehicle has had). I am considering an AGM battery, but am not sure whether this vehicle's charging system is suitable for AGM. Then there is the problem of fit. Would an AGM battery fit my car? The only...

www.subaruforester.org

 

[Flat6er]

1) About platinum and gold differences - no idea, just read the specs.

2) AGM Batteries: Pros and Cons - this list of pros and cons about AGM.

3) About charging voltage mod:
"long story short" = nonsense.

"short story long"
I recently took out battery from Tribeca to test my new battery charger (like 30-35bucks on Amazon - takes into account outside temperature, detects agm, 7 (or 8?) stage charging) - my battery measured 13.1 or 13.2volts...

that guy, Alex(?), says:
"Unlike a conventional wet battery, which reads 12.6V when fully charged, the Optima AGM (Absorbed Glass Mat) battery reads 13.1V when fully charged. We decided this battery could benefit from a higher charging voltage. ".
Personally, I don't see how this correlates(chargING voltage to chargED voltage), because when properly charging battery there are multiple stages of that process, which take into account more than this one parameter:

Explanation of Charging Stages on MEAN WELL Intelligent Battery Chargers | ADM MEAN WELL Power Supplies

MEAN WELL’s intelligent battery chargers are usually available with two or more selectable charging stages.

www.power-supplies.com.au

 

[Flat6er]

@06b9beca also - excerpt from FSM:
Regulated voltage
14.1 — 14.8 V [20°C (68°F)]

so, assuming you add 0.5V to your generator now - 14.8+0.5 = 15.3... from that CONS list I mentioned earlier "They are sensitive to overcharging and high voltages "... desulfatization uses higher voltages (though I am not sure how much applicable to AGMs), but for normal charging 15.3V seems excessive.

 

[06b9beca]

Thanks. I just ended up with a regular group 35 Costco battery...they didn't have the AGM battery. Makes me wonder what I pay membership for. I took the 5 year old Die hard gold and moved it to the FXT. I got a nice charger from Amazon too to accompany my harbor freight one. This has the desulfate setting. I was able to save one battery but two were toast. Pays for itself.

 

[Flat6er]

costco.com shows interstate batteries agm, though it looks more like motorcycle batteries.

nice to have tools... and garage

 

[06b9beca]

Little bastard of a Costco battery is dead in just 15 months. Wish I didn't get one.

 

[Flat6er]

may be you weren't taking care of it?
warranty?

 

[06b9beca]

may be you weren't taking care of it?
warranty?

Warrantied it. Should have gone more than 14 months.

 

[jimihimisimi]

TLDR - Almost all the AGMs batteries are made in a handful of a few manufacturing locations around the world, the main thing that changes is the brand's stickers on the outside. It's the Company-on-the-sticker's job to do QA/QC on the battery cells they are getting, and some companies are better than others about quality.

Also, buy batteries from China if you can find them vs batteries manufactured in other countries, at least for the near-future. Detailed below

RANT:

I design equipment that runs off AGM batteries at my job. Biggest issue post-pandemic is that a lot of the manufacturing of these batteries was moved from China to other countries over the last few years: I saw new locations such as Vietnam, Thailand, etc. During this time there was a big push on getting product out and much less emphasis on getting product right.

At my company we were/are seeing quality issues between the original batteries and the new units. The battery vendors swear up-and-down that the batteries are equivalent, but our own internal testing showed that the plastic on the newer models was lower quality than the original. We did hot/cold tests and temperature cycling tests to verify this and saw plastic deforming under some scenarios. This was about as far as we could go without cutting batteries open - I would bet that there would be similar issues with lower-quality materials used inside of the batteries as well.

We had so many field-failures on newer batteries that we were sending out Chinese batteries that were 1-2 years older as they were more reliable, which is crazy when you take into the account that the lifespan of an AGM is 3-5 years.

As far as charging - make sure you have an external battery charger that can detect an AGM and charge it accordingly. In terms of the car charging circuit - a good AGM battery that is designed for a car will be able to charge off the voltage coming off the alternator.

Desulfation - best to avoid it rather than try to cure it. Make sure the battery does not sit for extended periods of time so it doesn't self-discharge to the point of sulfation. If you drive around your car every day then there is absolutely no point to try to desulfate. Additionally, the 'research' into desulfation is fairly inconclusive - there is not really a peer-reviewed article from a reputable source that discuses methods and outcomes on how to best do it. In my experience sometimes the batteries were able to be used after a desulfation pulse-charge and sometimes they were still bad. Contrasting this to a conventional charger and the outcomes were about the same. I did not see big differences in available-charge that are touted, both methods appeared to perform the same. Note: the capacity of the batteries we use are smaller than an automotive batteries, so maybe it is an issue of scale.

For example, here is an article on desulfation Link to article. It is incredibly short and their methodology of testing is dubious: it does not talk about the sample size of how many batteries they use, and it also does not go into details of how many Coulombs they put into the conventional vs desulphated tests. If they pushed more charge into the batteries during the pulse-charging then of course they are going to see more amperage available when cold-cranking... Anywho, I am going to stop now.

 

[06b9beca]

TLDR - Almost all the AGMs batteries are made in a handful of a few manufacturing locations around the world, the main thing that changes is the brand's stickers on the outside. It's the Company-on-the-sticker's job to do QA/QC on the battery cells they are getting, and some companies are better than others about quality.

Also, buy batteries from China if you can find them vs batteries manufactured in other countries, at least for the near-future. Detailed below

RANT:

I design equipment that runs off AGM batteries at my job. Biggest issue post-pandemic is that a lot of the manufacturing of these batteries was moved from China to other countries over the last few years: I saw new locations such as Vietnam, Thailand, etc. During this time there was a big push on getting product out and much less emphasis on getting product right.

At my company we were/are seeing quality issues between the original batteries and the new units. The battery vendors swear up-and-down that the batteries are equivalent, but our own internal testing showed that the plastic on the newer models was lower quality than the original. We did hot/cold tests and temperature cycling tests to verify this and saw plastic deforming under some scenarios. This was about as far as we could go without cutting batteries open - I would bet that there would be similar issues with lower-quality materials used inside of the batteries as well.

We had so many field-failures on newer batteries that we were sending out Chinese batteries that were 1-2 years older as they were more reliable, which is crazy when you take into the account that the lifespan of an AGM is 3-5 years.

As far as charging - make sure you have an external battery charger that can detect an AGM and charge it accordingly. In terms of the car charging circuit - a good AGM battery that is designed for a car will be able to charge off the voltage coming off the alternator.

Desulfation - best to avoid it rather than try to cure it. Make sure the battery does not sit for extended periods of time so it doesn't self-discharge to the point of sulfation. If you drive around your car every day then there is absolutely no point to try to desulfate. Additionally, the 'research' into desulfation is fairly inconclusive - there is not really a peer-reviewed article from a reputable source that discuses methods and outcomes on how to best do it. In my experience sometimes the batteries were able to be used after a desulfation pulse-charge and sometimes they were still bad. Contrasting this to a conventional charger and the outcomes were about the same. I did not see big differences in available-charge that are touted, both methods appeared to perform the same. Note: the capacity of the batteries we use are smaller than an automotive batteries, so maybe it is an issue of scale.

For example, here is an article on desulfation Link to article. It is incredibly short and their methodology of testing is dubious: it does not talk about the sample size of how many batteries they use, and it also does not go into details of how many Coulombs they put into the conventional vs desulphated tests. If they pushed more charge into the batteries during the pulse-charging then of course they are going to see more amperage available when cold-cranking... Anywho, I am going to stop now.

Good read actually. I ended up getting an Interstate AGM Group 35 battery for my 04 Forester XT since it really sits alot. It is waiting for me at a Costco that is about 60 miles from my house. Thoughts there? After what you wrote, I shall look at mfg. location and date of manufacturer. Thanks.

 

[jimihimisimi]

Good read actually. I ended up getting an Interstate AGM Group 35 battery for my 04 Forester XT since it really sits alot. It is waiting for me at a Costco that is about 60 miles from my house. Thoughts there? After what you wrote, I shall look at mfg. location and date of manufacturer. Thanks.

Here are a couple good primers that are quick reads. FYI I am not affiliated in-any-way with PowerSonic other than having tested a couple of their batteries:
What is a Sulfated Battery and How To Prevent It - Power Sonic
Complete Guide On How To Charge A Lead Acid Battery - Power Sonic

If your AGM sits a lot in cold weather it will self-discharge a lot slower than if the battery sits in hot temps (internal resistance of the battery goes up with colder temperature - that is why its hard to get cold-craking amps out of a lead acid battery, but it also means that the battery will hold a charge longer). Because of the importance of temperature on lifespan, I cannot give a specific time on how long is OK to let the battery/car sit (3-6 months in winter weather could be OK whereas 3-6 months in summer might be too much).

Easiest way would be to read the 'resting' (car not started) voltage of the battery with a meter. If it is getting close to 12.6 volts for an AGM, then it is time to charge it.

Also, if you do need to let the battery charge, LET IT CHARGE. The voltage will start to 'roll off' and it may look like the charger is done, but leave the charger on the battery for a good 8+ hours. Undercharging a heavily-discharged battery can severely reduce the batteries lifespan. For reference, here is a sample Datasheet with a 'Charging Characteristics' curve which shows that the volume of charge vs the charge time on the graphs on the second page.

 

[Flat6er]

Good read actually. I ended up getting an Interstate AGM Group 35 battery for my 04 Forester XT since it really sits alot. It is waiting for me at a Costco that is about 60 miles from my house. Thoughts there? After what you wrote, I shall look at mfg. location and date of manufacturer. Thanks.

when I was choosing my battery - Interstate wasn't top candidate (according to workshop I use). Die Hards were commented to be best option

 

[06b9beca]

when I was choosing my battery - Interstate wasn't top candidate (according to workshop I use). Die Hards were commented to be best option

Oh I agree. My die hard golds were the best...freaking inflation though. 🙂

 

[jimihimisimi]

Oh I agree. My die hard golds were the best...freaking inflation though. 🙂

I think the Die Hard Platinums (AGM) are the same internals as the Duralast Platinum in the Tribeca size (35 Group). Both carry the same warranty

I have been happy with this battery - already passed the 3 year mark. Left the dome light on a few times and we were able to charge it back no problem.