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So a couple times i have had issues with my rav not wanting to start. One minute it will start fine then the next it won't. It did it for a few days back around August then not again till last week. I replaced the positive terminal clamp and all seemed fine until today. While cruising down the highway i noticed my voltage was at 12.5v for most of the drive except when i completely let off the gas, then it went up to 14.5v until i accelerated again. What would cause this?

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Year, model, miles?
 

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So a couple times i have had issues with my rav not wanting to start. One minute it will start fine then the next it won't. It did it for a few days back around August then not again till last week. I replaced the positive terminal clamp and all seemed fine until today. While cruising down the highway i noticed my voltage was at 12.5v for most of the drive except when i completely let off the gas, then it went up to 14.5v until i accelerated again. What would cause this?

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Why did you replace the terminal clamp, was it corroded? I'd start with a load test(not just a VM test)of the battery.
 

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also good to know is the age of the battery. They don't last forever and if you're is original (doubt it) I'd be inspecting that first. As was said earlier, a load test on the battery is necessary (not just simply determining output volts).
 

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Discussion Starter #6
I replaced it cuz the one i had on was getting pretty old and felt kind of cheap. I did do a load test back in August when it first did this to me and it was fine

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Ok, so just to confirm, I'd do the load test again and make sure the cold cranking amps (CCA) is solid. If that's confirmed, next to check is the alternator, (cables and attachment) along with drive belt, tensioner and alternator output as well. You may need to go to a shop or auto parts place to have them check the alternator.
 

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Discussion Starter #8
And just on my way home it held steady at 14.2 volts. Will still have the battery/charging properly tested though

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...While cruising down the highway i noticed my voltage was at 12.5v for most of the drive except when i completely let off the gas, then it went up to 14.5v until i accelerated again. What would cause this?
So you must have a voltage monitor maybe plugged into the 12V outlet for continuous, right?
If you got the number of zeros right, 410,000 km translates to 255,000 miles, and if it's the original alternator, I'd suspect its brushes are about worn out.
 

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Discussion Starter #10
Yes there are 409,625km. I have installed a volt meter in place of the cigarette lighter. I'm sure it is the factory alternator. I've been eyeing up a 250 amp alternator but would that be too much? I have an aftermarket sound system and plan to add a bigger amp and another sub

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IMO a 250A alternator is too big and might lead to melted wires. As I said on another thread somewhere around a 20% increase is probably safe.
 

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So if you venture over to the rockauto website and look here ..
http://www.rockauto.com/en/catalog/toyota,2007,rav4,3.5l+v6,1434677,electrical,alternator+/+generator,2412

you'll see that they have a few 150 amp alternators that appear for the towing package. Having read that I'd be inclined to say that you'd be safe to go to 150 IF you have the towing package on your 2007 although trying to draw too much current thru undergauged wires is pretty dangerous. I'd be talking to the folks at the car audio place regarding the amp you intend to run as they'll likely have some sensible info (and I'd follow their lead).
 

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Discussion Starter #14
Ok so since my last post regarding this topic i have replaced the battery but the low voltage is still showing on the gauge and as it warms up, it's becoming more frequent. It starts good every time now that i got a new battery though. But while I'm idling in park it shows 14.0v

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Ok so since my last post regarding this topic i have replaced the battery but the low voltage is still showing on the gauge and as it warms up, it's becoming more frequent. It starts good every time now that i got a new battery though. But while I'm idling in park it shows 14.0v
You definitely need a new alternator.
 

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Discussion Starter #16
That's what i was worried about. Not looking forward to disassembling the front end

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seems like the voltage rectifier on the alternator is shot, voltage is only good on some rpm ranges.. Had the same problem on my previous car, voltage was only good at idle, and from 3000 to 4000rpm, outside of that it was <12v.
 

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Discussion Starter #18
It's not so much a specific range of rpm as it is load. When the voltage is showing 12.5 volts I'm on the highway or accelerating but as soon as i start slowing down it jumps back up to 14.1-14.5

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Discussion Starter #19
I have also realized today that when driving and my voltage drops to 12.5ish volts and i turn my lights on then the voltage bounces back up to 14.

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I have similar issue on Rav4/2006/Limited/I4 engine. few days ago the Battery light flashing, I took it to the mechanic, he said it is alternator, because the Voltage drop to 12.5V some times. I wish I did not take it to him at once, Cost me $570 (I asked him for a good brand not cheap). I placed the digital indicator after that repair in my lighter to monitor the Voltage. Seems like nothing changed, some times Voltage drops to 12.5 or 13.1 and similar to other stories in here, it is OK for a while after engine starts (showing 14V) and then start to drop after some minutes. I cleaned the battery connectors, Removed and sand the area of ground cables around the batter(2 wires which is going to the battery "-" pole). it is not better. the battery was changed 1.5 Years ago when my first alternator died(original one). That is not battery, and the alternator is brand new, still same issue. I am very suspicious about the Ground, because I find when I turn my light one step ON, this issue goes away, I get 14V consistent. BUT this does not happen when I push the brake (brake lights)/ or when A/C is on/or Fan On . ONLY when I turn the handle one turn or more to turn on lights, the Voltage correct itself and fix on 14V. Based on this experience, when I feel it is been long that I indicator does not show 14V, I turn light to charge my battery and the Battery light does not goes ON or avoid battery discharge. I should add, after alternator change the battery light i snot on or flash any more.
Since I did not see any conclusion on this thread, I thought share my story and ask for Help or any extra information if some one have, I have ordered a 5 point Ground wiring to install but not received it yet...... and I have searched this issue and lots of similar stories that after few minute the Voltage drops.
 
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