alternator voltage

[xdarkox]

hi everyone
Year ago I bought mazda protege 1.8 ES, and I had charging light on dash ever since.
I've been driving my car like that for a year ,about 15k miles.
voltage on battery with car off is 12.90V
when running without load 13.5
with lights and heater blower 12.4

My thoughts are that some dummy probably put alternator that is from protege 1.6 which uses alternator of 70Amps,my car need one that is 80amps.

question is :For how long am i gonna be able to get away with this,is the battery gonna drain eventually,coz its been a year.

I am also going to buy one of the Mitsubishi electrics 80 amps alternator soon,are the others like bosch,nsa,denso equally as good.

and my last question,it looks to me that i am gonna be able to pull alternator out from under the car, there is some room, because i saw that some people were saying that they had to pull axle to get to it.

Appreciate any input ,Thanks

[goldstar]

hi everyone
Year ago I bought mazda protege 1.8 ES, and I had charging light on dash ever since.
I've been driving my car like that for a year ,about 15k miles.
voltage on battery with car off is 12.90V
when running without load 13.5
with lights and heater blower 12.4
Appreciate any input ,Thanks

Obviously, something is wrong if the indicator lights up.
However, assuming your voltmeter is correct, most sources state a battery can be considered fully charged if its output is 12.6V, engine off.

According to the FSM:
B+ voltage should be 13-15V with engine running and the following electrical loads: headlights, blower motor and rear window defroster, with a nominal voltage output of 13.5V.

Maximum current output = 77A @ 2,000 rpm.

Back-up (dark) current = 20mA maximum.

In my own car with a known good electrical system and an accurate digital voltmeter, after the engine reaches operating temperature the reading varies between 14-14.6V regardless of electrical load (OEM audio system).

Since with lights and blower motor on your output is 12.4V, the battery is not being charged here indicating either a faulty alternator or one with too little output as you state. I wasn't aware that the 1.6L alternator was only rated at 70A.

Happy Motoring!

[D323]

Load testing can be done for free by many local auto parts stores. Of course that typically means you will have to remove the alternator and take it to the store to be bench tested. Yes I have heard/read from various sources in the Mazda community that the passenger side axle must be removed to access the alternator. I never had to remove the alternator from my protege 5 when I had it so I couldn't tell you for sure.

Most shops have a load tester that tests the alternator while the car is running (its part of the PM we do on all squad cars) to circumvent you wasting your time removing a good alternator. Its possible that the alternator itself if ok, but the voltage regulator or the diodes are going bad (internal to the alternator, requiring its replacement anyways...) causing it to struggle to keep up with demand when all of the accessories are on.

[99es]

You do not need to remove the axle to remove the alternator. I changed the one in my daughter's 99ES, and you do need a little patience as well as some twisting and turning. As I recall, I had to loosen the support bracket from the block to the intake manifold to help facilitate matters.

[xdarkox]

i'm gonna get it out,no way axle removal, 99ES and 2000ES are identical cars

[meGrimlock]

can i verify my problem here? is this a bad alternator or battery?

• hard starting in the morning. it struggles for a few seconds like it has a dying battery.
• radio intermittently cuts off, then turns back on
• when radio cuts off, warning lights on dashboard pop up for a split second
• no distinct loss in engine power, car continues to drive normally
• yesterday could hear a high pitched electrical whine when the radio cut off, as i was slowly going up the levels in a parking garage (headlights on, window defrost on). this time, the RPMs dropped, but i could not reproduce this symptom.

new battery installed in 05/2011, Exide Orbital ORB75DT-108 Sealed VRLA (AGM). with the car off, the battery tested at 10.5 volts. turned the car on and fluctuates between 13.8 and 14.5v, same with headlights on. thanks
-meGrimlock

[xdarkox]

In that case has to be the battery since when you measure voltage on the battery itself should read 12.3 - 12.8 (unlike yours 10.5), if it shows 14V when car is running than alternator is fine.

[D323]

14v is no guarantee that the alternator is good. It could be dumping AC current (diodes going out) and still read 14v. AC current makes DC electronics act weird.

When a shop load tests they also measure the diodes. Load test is the best method for finding starting/charging issue. From there I would look for a loose ground or poor connection somewhere.