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209 Posts
Discussion Starter · #1 ·
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 -
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.

In USA, catalogs call it Class 35 battery (230x175x225mm).
I looked up those "Class" sizes
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 ( 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.

Installed product:
Tire Automotive tire Light Motor vehicle Synthetic rubber

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

Book Publication Font Art Motor vehicle

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.

765 Posts
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.


209 Posts
Discussion Starter · #3 ·
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:

209 Posts
Discussion Starter · #4 ·
@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.
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