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Discussion Starter · #1 · (Edited)
I know there have been many issues with slow starting, etc. that have been resolved with a new battery and now I know why.

I've been on the road for a month so luckily this happened the night before I got home not just after I left.

The RAV had been starting & running fine for my bride including the other evening when she had stopped at the beach in Westerly RI and then at Walmart. But at Wendy's it would only make a clicking sound with the interior & dash lights blinking as she turned the key to start. An apparent instant failure. She left the RAV at Wendy's, got a ride home and drove my Accord.

This morning she dropped me off with a jump box. I started the RAV easily with it. Went to Walmart and bought a MAXX 24F. With no tools to install it there I brought it home, car still starting fine on the old battery.

Ran some tests on the old one which seemed to crank over like you could drive down the road at 40 mph on it. Hydrometer test showed the two end cells were weak/dead. Center four including the one keeping the visible indicator blue = OK tested good.

I removed the fuel pump relay so the engine couldn't start and ran cranking voltage tests. The 12 volts with the key on dropped to about 8.5V as it cranked over quite well for about five seconds. It did the same for another five second crankover. The third try resulted in no crank accompanied by the clicking & lights dimming. So what's happening is two weak cells are only contributing a few tents of a volt instead of the normal 2V. Then after a short time the bad cells can't cope anymore and probably reverse dropping the voltage way down.

So the confusion factor is how well the starter works at a low voltage thereby giving no hint of impending no-starts.


BTW, the new battery right off the shelf with no charge added held at 11.8V and cranked the engine over like 80 mph!
 
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Hydrometer test showed the two end cells were weak/dead. Center four including the one keeping the visible indicator blue = OK tested good.
Interesting observation. Lets think what's different in the outside cells. More heat transfer from engine compartment, me thinks. Like I said before, engine heat kills RAV4 batteries.
 

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Discussion Starter · #3 ·
Interesting observation. Lets think what's different in the outside cells. More heat transfer from engine compartment, me thinks. Like I said before, engine heat kills RAV4 batteries.
Agreed, at least on the end toward the engine. Not sure about the other end, but the center cells are probably insulated from the heat best.

As I recall from other batteries in the past it's often an end cell that fails first. And usually one cell dropping causes a no-start or at least noticeably poor starting on other cars & trucks. Apparently our RAV4s still start with deceptive ease with a VERY weak battery that puts out under 9 volts.

A cranking voltage test would probably be the best early indication of impending instant demise.

I bought our RAV4 used so it's possible the battery was the original Toyota 80D26L-MF. Six years sounds like a new record!
 

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Won't those battery blankets like in VWs help with insulating the battery from the engine heat? If there is room, maybe adding the blanket will extend life on the fresh new battery?
 

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Insulation does not insulate forever - as soon as the insulating material heats it transfers heat to the insulated object, although more slowly than if the insulation were not present. So it would be more effective for short trips and/or in cooler atmospheric conditions than on a longer one with engine and/or atmospheric heat present for a longer duration.
 

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Won't those battery blankets like in VWs help with insulating the battery from the engine heat? If there is room, maybe adding the blanket will extend life on the fresh new battery?
I actually thought about it, but never did anything about it. RAV4 has a rudimentary heat shield made of plastic, but not very effective of course.
I made a heat shield from reflective bubble wrap in my other, older car, but it looks cheesy.
 

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I would think a ram-air duct with flap controlled thermostatically might works. Definitely easily a DIY project with foil dryer duct and plastic intake port. Hottest outside air is still cooler than inside engine bay.

In the South, a control flap is probably not even needed due to no deep freeze temperature.
 

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Discussion Starter · #8 ·
Its pretty obvious that carmakers give no more than token attention to battery heat exposure. All the heat from the radiators, both engine and A/C gets dumped under the hood on a virtually unprotected battery. Even ram air wouldn't help in summer city traffic. The real answer would be to locate the battery elsewhere. I know that's done in some sports cars but even then its more for weight transfer than battery life. Guess batteries just don't rate!
 

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I check the fluid in my battery every month and it has only needed water (distilled) twice so far. And the level in the cells closest to the engine are no more evaporated than the other cells. I don't think heat is a problem.....unless you don't check the water level..then it's your fault.


Tom
 

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Its pretty obvious that carmakers give no more than token attention to battery heat exposure. All the heat from the radiators, both engine and A/C gets dumped under the hood on a virtually unprotected battery. Even ram air wouldn't help in summer city traffic. The real answer would be to locate the battery elsewhere. I know that's done in some sports cars but even then its more for weight transfer than battery life. Guess batteries just don't rate!
Fred, you mentioned that the battery which failed was a Toyota, but was it actually a Furukawa? If so, given the number of posts about Furukawa failures yours must have at least come close to setting some sort of record, especially used in a V6.
 

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Discussion Starter · #11 ·
I don't think heat is a problem.....unless you don't check the water level..then it's your fault.
None of the cells were low on water. I don't believe underhood heat is the primary cause of loss of water. That's caused by overcharging which is pretty rare. I had it happen to the battery on my camper, probably due to my setting the charger voltage to a constant 24/7 14.1 volts to keep the lights nice and bright. Battery didn't like it at all so now when I'm on "shore" power I disconnect the battery.

Heat just somehow accelerates the degradation of the cells. I'm sure one of our battery experts has more information but I believe the optimum temperature for battery life is 0F or below.
 

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I have extensive experience with wet cell batteries in telephone company power plants and yes, heat is their mortal enemy. While cold is better than hot, I'm not sure 0F or lower would be good for CCAs.
I agree that the under hood area is probably the worst location for a battery, but don't know why car makers insist on keeping them there.
 

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I agree that the under hood area is probably the worst location for a battery, but don't know why car makers insist on keeping them there.
1. Shorter cable run to the starter.
2. Safer place if there are vapors or leakage.
3. It is a convenient place for maintenance.

On the other hand, under the seat or in the trunk has advantages:
1. better weight distribution
2. cooler environment.
 

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If heat was a big problem with battery life then the zillions of car owners living in year round hot areas would have a LOT less battery life than we living in cold/hot areas. I never heard of problems with battery life in hot parts of the country.

Tom
 

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If heat was a big problem with battery life then the zillions of car owners living in year round hot areas would have a LOT less battery life than we living in cold/hot areas. I never heard of problems with battery life in hot parts of the country.
When you check, you will hear a lot about that.
 

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I never heard of problems with battery life in hot parts of the country.
How would you if you are from OH? A couple of years ago I did a poll here that showed that effect, especially for V6.

That is in line with this:
 

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Discussion Starter · #17 · (Edited)
Fred, you mentioned that the battery which failed was a Toyota, but was it actually a Furukawa? If so, given the number of posts about Furukawa failures yours must have at least come close to setting some sort of record, especially used in a V6.
Yes it was a Furukawa. May have been from when the car was new since the original owner sold it because he was making a lot of PA-FL trips, likely easy on the battery, and wanted something with better mileage.
 

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How would you if you are from OH? A couple of years ago I did a poll here that showed that effect, especially for V6.

That is in line with this:
That's an accurate map! I'm right on the border of the orange/red and the battery in our Altima died a week ago. It was 39 months old!!
 

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Discussion Starter · #19 ·
That's an accurate map! I'm right on the border of the orange/red and the battery in our Altima died a week ago. It was 39 months old!!
Yeah, and how about the blue spot in Arizona where a couple hundred miles makes two years difference! Looks like its near the Grand Canyon.
I'd sure like to know the source of that map!
 

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