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Mistake getting Optima battery ?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by our1vue, May 3, 2017.

  1. our1vue

    our1vue Member

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    I replaced my 5 year old battery with an Optima yellow top. I noticed the OEM battery was 45 AH 325 CCA.
    The Optima was 38 AH 450 CCA. I'm wondering how the 7 AH difference translates to how long the
    car sit in a parking lot and still start. Did the Gen 2 come with a 38 AH battery ? Thanks for any
    help and wisdom.
     
  2. bisco

    bisco cookie crumbler

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    from everything i've seen, the optima will drain slower, and revover more easily from deep draining. but idk what ah represents.
     
  3. mjoo

    mjoo Senior Member

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    AH stands for ampere-hour. It's a relative measure of how long a battery lasts and is close to [time discharging] * [amps drawn].

    I'd assume that since the battery isn't being used to crank the engine that the energy stored might be greater than 38 AH. But that would require more research on my part. Batteries generally have more energy if discharged at a slower rate.
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Good question!
     
  5. Siward

    Siward Active Member

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    I bought a MotorMaster battery in Canada and it has a higher Ampere-Hour of 46, but a lower CCA (Cold Cranking Amps):
    upload_2017-5-4_9-33-14.png

    I guess the Optima is better in the winter with the higher CCA (cold cranking amps).
     
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Canadian Tire, eh? Yeah I might go with that next time. My first experience buying a CT battery was when our son was stuck, with their Civic Hybrid. Told them the car, they had an exact-fit Motomaster on hand, and it went very smoothly. They had a very sweet electronic battery tester (I'd brought along my Solar BA5, but deferred to their device), which showed their battery to be in very good condition.

    I have this in my notes:

    Canada Tire battery:
    MotoMaster Eliminator Ultra AGM
    Product Number: #010-5122-6
    Manufacturer's Product Number: ELU-S46B24R
    (rebadged Exide battery)

    I think the 325 CCA is about the same as the OEM Yuasa.

    Have the Optima Yellow Top in there now, the one with higher CCA but lower Amp Hours.
     
    #6 Mendel Leisk, May 4, 2017
    Last edited: May 4, 2017
  7. David Beale

    David Beale Senior Member

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    NO! Oh, sorry. CCA has NO meaning for a Prius. Because the Prius DOES NOT crank with the 12V battery. Usually a higher CCA means larger intercell connectors and/or better designed connectors. Larger intercell connectors in a lead acid battery usually means more water loss (the connectors often will cause hydrolysis, breaking the water to H2 and O2). "Parasitic water loss" would be a good term.

    A-Hr rates are measured with a constant load, for example, the "20 Hr rate" mentioned on the above spec. sheet. They discharge the battery to "low charge" at a rate that will take 20 hrs to complete. For that battery, the discharge rate would be the AHr capacity divided by 20, or 2.3 Amps. "Low charge" has a different meaning depending on the type of lead acid battery. A "starter battery", optimized for high current discharge, can't take as low a discharge as a "float battery". In the Optima line, the yellow top is a "float battery" or "deep discharge" battery. The red top is a "starter battery". They also make a blue top "marine battery", which in my understanding is half way between the yellow and red top types - it can high current start, but can also deep discharge. DO remember, even if you have a "deep discharge" battery, it will -still- suffer some damage from deep discharge events. Mainly because you can't reliably stop the discharge at the optimum low charge level.

    For a Prius you want a battery with low internal losses, CCA who cares, and long life. It would also be nice if you could add distilled water after a few years of use, but I guess that's asking too much. ;) The A-Hr rating is not all that important, though a lower number would mean it could "go low" on retained charge sooner. But a difference of 15% probably won't be noticeable in actual use. The change in capacity as it ages would be greater.

    I noticed that "the other" high quality (read expensive) battery manufacturer, Odyssey, now makes AGM+ batteries. These are really sealed, though I suspect they still have an explosion proofing vent system. They do recombination of the O2/H2 internally to help limit the pressure that would be generated by hydrolysis. So there must be a catylist in there as well. Neat, but expensive. I think they run in the $350 range for a "Prius sized" unit.
     
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Are you still on the OEM battery David? Got a replacement battery in mind?
     
  9. David Beale

    David Beale Senior Member

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    I replaced mine last year with a Canadian Tire Exide Ultra AGM. The original ran out of water, as all my batteries seem to, at about 3 years into life. If I can't add water they fail. The Prius GIII battery was glued together. I suppose I could have forced it open, but I got lazy.
    My 2007 FJ Cruiser still has the original Panasonic battery in it, and still ran fine last winter. It ran low on water at 3 years to no surprise to me, and recovered fully when I filled it back up with distilled water. It has screw out caps! But it's also under-hood, of course. I don't think it's AGM. Looks conventional. I would buy another of those in an instant, if I could find one! Or one for the Prius with a vent tube. :whistle:
     
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  10. Currahee

    Currahee Member

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    What's with people adding water to the AGM batteries? They're meant to be relatively dry and the original Yuasa explicitly says "Never add water." It's the first thing written on the top.
     
  11. David Beale

    David Beale Senior Member

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    AGM batteries aren't "dry". They are lead acid batteries with the electrolyte held in a glass matt, but it still must fully wet the plates. They come with liquid above the matt. The water in the electrolyte still gets broken down by hydrolysis and lost out the vent tube.

    Of course the battery manufacturer doesn't want you to add distilled water! If you do you could mess up and add too much, add dirty water, or something else dumb. We are, after all, "the great unwashed public". Anyway, if you don't/can't add water you have to buy another battery from them sooner. Assured sales!
     
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Any ideas on when, how an how much water to add to agm battery?

    With a completely conventional regular battery it is so much easier: readily accessible caps, electrolyte level clearly visible and level marks on case side.
     
  13. David Beale

    David Beale Senior Member

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    With Pearl's battery I added distilled water when the battery started to look like it was going to fail (watching the voltage drop to 11V or lower from overnight sitting on the scangauge - press the red circled button on the scangauge to get it to read without putting the car in "ready"). I added water until it was just above the glass matt.on each cell (only two cells had enough - the centre two). I then charged the battery until the charger indicated it was "charged", and left it on trickle for a few extra hours. I got two more years of use, for five total. Not good but acceptable.
    As already posted, Pearl S' battery was glued together. I suppose I could have drilled holes but then I would have had to figure out how to make plugs. I gave up in disgust and just bought a replacement. Partially because Canadian Tire had them on sale. Ended up paying less than $150 Can. with rebate and the $20 they gave me for the old battery. Bonus, I also got a $50 "gift certificate"! But wait, there's more! ;)

    With both vehicles that was at the 3 year point. Three years for a lead acid car battery that doesn't -actually- crank the engine is UNACCEPTABLE! Are you listening Toyota? Find a better supplier!
     
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