Toyota RAV4 Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I purchased a 1999 RAV4 about 1.5 years ago for my college student. It was a one owner vehicle and appeared to be well maintained. Since purchasing it, we have replaced the shift cables, thermostat, radiator, rt. axle assembly, brake hoses, the entire exhaust system and the battery (twice).
My issue now is the alternator. The battery was replaced the first time about 4 months ago. It died within 2 months and was replaced under the warranty. We took the vehicle to the dealership and they said the alternator is putting out between 15-16v and should only put out 13-14 so it is overcharging the battery and killing it. They have recommended replacing the alternator. Before putting more $ into the vehicle, does this sound like a correct diagnosis? The car runs just fine otherwise. No loss of power, no dimming of the lights, ect.
Thank you for your feedback.
 

·
Super Moderator
Joined
·
11,099 Posts
Thread moved to correct forum.

Yes, the voltage is too high and may eventually ruin more than the battery.
Since I'm quite sure the regulator is built in to the alternator either it or the whole alternator needs to be replaced. If it was mine I'd just buy and replace the regulator, but then I have that ability. In your case you could have a re-builder do it, but considering the age of the car a new alternator might make the best sense.
 
  • Like
Reactions: aneumann

·
Registered
Joined
·
9,026 Posts
Agree with Dr. Dyno. I had a Ford back in the days when cars had generators rather than alternators, and that vehicle burned out generators every few thousand miles. At that point I didn't have the equipment needed to diagnose the problem and the incompetent Ford dealership simply kept on replacing generators rather than diagnosing the problem. Finally they did identify the problem as a defective voltage regulator - excess voltage and bad current regulation in general.

If it is possible to replace the RAV's regulator - may be problematic as Dr. Dyno points out - that should solve the overcharging problem. Otherwise, perhaps a rebuilt alternator could be the best solution, given the age of the vehicle.
 
  • Like
Reactions: aneumann

·
Premium Member
'99 RAV4.1, 3MZ-FE, E250F 4x4, Torsen Dif
Joined
·
2,163 Posts
It is an easy replacement, the alternator is very accessible and can be changed out easily and quickly with a few common hand tools. If you can live without the vehicle for a few days it's much cheaper to order one online or at least at an aftermarket parts place because it will be much more expensive at a dealer. I agree with the others, I would not rebuild a possibly 17 year old alternator. Replace those belts while you are there.

Pep boys has one free shipping and for an additional charge they will install it for 119.99 https://www.pepboys.com/parts/alter...99/TOYOTA%20TRUCK/RAV4/0/4-1998%202.0L%20DOHC

Another thing to think about, if you or a previous owner has upgraded or plan to upgrade the stereo or lights you may want to consider a higher output alternator than the standard 80 or 90 amp one.
 

·
Registered
Joined
·
1,064 Posts
...We took the vehicle to the dealership and they said the alternator is putting out between 15-16v and should only put out 13-14 so it is overcharging the battery and killing it. They have recommended replacing the alternator. Before putting more $ into the vehicle, does this sound like a correct diagnosis?...
Get a plug-in cigarette style LED voltmeter and confirm what dealer says. This one is like $3 on Amazon and free shipping. The cheapos may not be the most accurate, but should give useful relative readings. (Dr Dyno has recommended one before that also has a USB port.)

Would be good to monitor things before and after your alternator transplant also.
 
  • Like
Reactions: aneumann

·
Super Moderator
Joined
·
11,099 Posts
Agreed on the plug-in voltmeters! They are just SO handy for keeping an eye on the electrical system's "blood pressure." I probably have half a dozen of them around various places and at various prices. I say they all read within .1V of each other - plenty accurate enough.
 
  • Like
Reactions: aneumann

·
Registered
Joined
·
9,026 Posts
Agreed on the plug-in voltmeters! They are just SO handy for keeping an eye on the electrical system's "blood pressure." I probably have half a dozen of them around various places and at various prices. I say they all read within .1V of each other - plenty accurate enough.
How much, if any, voltage variation is there between voltage measured at the battery terminals with the engine running and voltage measured by the plug-in voltmeter? Am asking because on my motorcycle the difference is about 0.75 volt.
 

·
Registered
Joined
·
409 Posts
They are great, I have one in mine. However that rectangular-ish one in the photo above won't fit, as the socket is recessed, so get a round one, so it can go in further.

Mine goes up to 14.7 volts after not being used for a few days, but I think the alarm is draining current. It slowly drops the longer I drive, going to about 13.6.
 

·
Super Moderator
Joined
·
11,099 Posts
How much, if any, voltage variation is there between voltage measured at the battery terminals with the engine running and voltage measured by the plug-in voltmeter? Am asking because on my motorcycle the difference is about 0.75 volt.
The battery-to-12V outlet/cigarette lighter voltage drop will depend on the vehicle and other loads on the circuit but I wouldn't expect it to be more than .1 or .2V even with a usb charger in use. Likely within the accuracy of the voltmeter.
 
  • Like
Reactions: Blogson

·
Registered
Joined
·
9,026 Posts
The battery-to-12V outlet/cigarette lighter voltage drop will depend on the vehicle and other loads on the circuit but I wouldn't expect it to be more than .1 or .2V even with a usb charger in use. Likely within the accuracy of the voltmeter.

I've been thinking about getting a plug-in voltmeter for my RAV but would like to determine the voltage difference between the two meter probe points so will use my multimeter. I've taken the readings on my motorcycle with no load except for the headlight, taillight, and ignition system. I wouldn't expect there to be any measurable drop on the RAV because of a USB charger since the current draw with that on a car system is very near to zero and may even be un-measurable.
 

·
Super Moderator
Joined
·
11,099 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #13 ·
Thanks for the feedback everyone! I had the alternator replaced. Hopefully this is the end of major repairs for a while. I appreciate all the input. Will look into getting the voltage meter. Looks like a handy little device/tool.
 
1 - 13 of 13 Posts
Top