2013~2016 My 2016 would not start this morning

Anybody know how to test the voltage of the alternator? I want to rule out that I'm not losing voltage in the wiring between the alternator and the battery.
Usually there's a port (screw) on the alternator that you can test positive voltage but I can't seem to find anything.
 
Anybody know how to test the voltage of the alternator? I want to rule out that I'm not losing voltage in the wiring between the alternator and the battery.
Usually there's a port (screw) on the alternator that you can test positive voltage but I can't seem to find anything.
Just find out where the big battery wire attaches, and that stud is where you probe to test. The wire is probably mostly out of sight, and you might need a mirror or inspection camera to find where it comes into the alt.
 
no.2

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Anybody know how to test the voltage of the alternator? I want to rule out that I'm not losing voltage in the wiring between the alternator and the battery.
Usually there's a port (screw) on the alternator that you can test positive voltage but I can't seem to find anything.
OP,
The video I posted shows you how.
 
OP,
The video I posted shows you how.
Thanks, but that video had a nice convenient point to probe. It even had a nice plastic cover to pop up. No such thing on the CX-5 alternator. There's a electrical connector that plugs into the alternator but none of the wires are exposed. I will try to bury the probe down into the connector to see if I can get a reading off that
 
Thanks, but that video had a nice convenient point to probe. It even had a nice plastic cover to pop up. No such thing on the CX-5 alternator. There's a electrical connector that plugs into the alternator but none of the wires are exposed. I will try to bury the probe down into the connector to see if I can get a reading off that
I don't have a picture of your model's alternator connector available, but most all of them have a removable protective cover that goes over the stud connector. On my '20, it's a plastic flip up, but some have a rubber cap. So you should be able to easily get the cover off, in order to access the stud for testing.
 
I don't have a picture of your model's alternator connector available, but most all of them have a removable protective cover that goes over the stud connector. On my '20, it's a plastic flip up, but some have a rubber cap. So you should be able to easily get the cover off, in order to access the stud for testing.
Yeah, that's what I thought too. It looks like it has a standard plastic connector (like a wire harness). I tried inserting the probe down in it but couldn't get a reading.
When my wife gets home I want to compare the alternator setup on our 19 GTR against the 16 and see if there's any differences. I will probably just take it back to the dealer and complain about the battery going dead and let them test the system.

It did start this morning but now I'm afraid to take it anywhere since I don't have one of those jump packs.
Also I checked voltage again this morning, not started battery was 12.5v. Started and running for 10 minutes 13v. Still too low.
 
... . Started and running for 10 minutes 13v. ...
Ok, I thought you had indicated that the running voltage was always 12.5V, but now you're saying that's not the case. The 13V means the alt is definitely doing some charging, but it's unclear why it's not coming up close to 13.5 in that amount of time. The fact that it's charging might also be the reason for no codes or warning lights. Is your vehicle still under BB warranty? If it's not, you might be paying for a hefty diagnostic charge from the stealership.
 
13V with alternator running is too low.
Did you measure that at the battery terminals or the alternator?
If there is a big difference between these two numbers, then, you could have a connector problem from alternator to the battery. If not, it could be a bad alternator. 13V is low.
 
13V with alternator running is too low.
Did you measure that at the battery terminals or the alternator?
If there is a big difference between these two numbers, then, you could have a connector problem from alternator to the battery. If not, it could be a bad alternator. 13V is low.
Measured at the battery but I believe that's the wrong place to check. The battery probably won't show more than 12.6v because there's a voltage regulator that keeps the battery voltage from going too high. I checked our 19 while running and it was sitting at 12.5/6. I was expecting the voltage to be higher when the engine was running and it probably is at the alternator. Logically the system should keep the battery around 12.6v and 12.6v volts is fully charged. I'm just going to have the dealer check the charging system and be done with it.
If they do a load test and the battery comes up bad then they should replace the battery for free. If it turns out the alternator is bad (unlikely) then I'll have to pay to replace.
 
wlong01,
Not quite true.
While alternator is running, the voltage taken at the battery terminal should range from 13.6V to 14.6V depending on vehicle.
Higher voltage is needed to charge 12V battery effectively.
Not too high, but not too low, either.
13V is low.
 
12.6v is a fully charged resting battery. Immediately after charging it's not unusual to see up to 12.8 for a period of time.

Nominal running voltage for most cars hss always been 13.8, but my Chevy charges up to 15v when it detects a weak battery.

I bought a Smart charger that charges up to 14.9 to fully charge AGM batteries and help desulfate the plates.
 
wlong01,
Not quite true.
While alternator is running, the voltage taken at the battery terminal should range from 13.6V to 14.6V depending on vehicle.
Higher voltage is needed to charge 12V battery effectively.
Not too high, but not too low, either.
13V is low.
I tested our 2019 running and it was 12.5/6v. This vehicle has no problems starting plus the battery is less than a year old. I'm taking the 16 in to the dealer tomorrow for them to look at the charging system so I'll see what they say.

note: It's possible the multimeter is off, it's an old one with analog readings.
 
Took it to the dealer this morning for a charging system test. After two hours they said everything is fine. All tests were where they were supposed to be.
They have no explanation. Suggested if it happens again have it towed in.
 
Took it to the dealer this morning for a charging system test. After two hours they said everything is fine. All tests were where they were supposed to be.
They have no explanation. Suggested if it happens again have it towed in.
Thanks for the update. May be there’s a light which was on overnight and caused the battery drained out? But the accessaries and lights should get turned off after about 30 minutes to prevent this happening.

A couple of months ago my faithful 1998 Honda CR-V failed to start in the morning. I found the newly installed 3-month old Costco Interstate 51R battery was totally dead (~ 0 V). I took the battery to Costco and got a new one. Once installed and drove around there’s no issues. But I noticed the brake lights seemed to be lit after I parked the CR-V under the bright sun. Did some diagnosing and looked like the brake switch was out of adjustment and let the switch closed all the time. The problem was even if I turned the switch to the closest to the metal stopper the switch was still closed. Thinking there’s no way the gap between brake switch and stopper suddenly getting so wide and out of range for adjustment, I eventually figured out there’s a plastic / rubber pad missing on the metal stopper which makes the gap became so wide. Somehow the pad was disintegrated due to age. Went to my Honda dealer and was told this’s a very common problem on all Honda’s. And every Honda uses the same plastic / rubber pad on metal stopper and eventually it needs a new one when the pad is worn out causing the brake lights on forever until the battery dies.
 
Took it to the dealer this morning for a charging system test. After two hours they said everything is fine. All tests were where they were supposed to be.
They have no explanation. Suggested if it happens again have it towed in.
If you don't mind sharing, can you post what they charged you for those 2 hours?

Also, the dealer techs have the proprietary Mazda M-MDS tool, which provides access to all of the Mazda-specific OBD parameters, which most other tools cannot read. So did your paperwork show any of those M-MDS valves which relate to the battery and charging system? (it would be SOC and a bunch of other battery parms)

And did they indicate exactly what they would do next if your vehicle was towed back to them with a dead battery?
 
To be honest, trying to diagnose your problem without a DMM (digital multi meter) is pretty much a waste of time.

If you don't want to pay the dealer big bux you will have better luck if you get a meter that is accurate to a tenth of a volt minimum.
 
If you don't mind sharing, can you post what they charged you for those 2 hours?

Also, the dealer techs have the proprietary Mazda M-MDS tool, which provides access to all of the Mazda-specific OBD parameters, which most other tools cannot read. So did your paperwork show any of those M-MDS valves which relate to the battery and charging system? (it would be SOC and a bunch of other battery parms)

And did they indicate exactly what they would do next if your vehicle was towed back to them with a dead battery?
They didn't charge me anything. Maybe because they sold me the battery or maybe because I have both my CX-5's serviced there. They're a pretty good dealer and have been around forever.
Maybe they looked in our records and saw that we bought a RX-7 and a 626 from them.
They did not give me any paperwork although the service advisor showed me two pieces of paper with the test results on them.

They just said if it fails don't try to jump it, have it towed in and they will evaluate it in that condition.

Anyway, I bought a battery tester and it's showing 12.8v sitting and 14.0v running. Jumps to 14.1v when the headlights are turned on.

Only thing I can think of is something didn't go to sleep after the car was turned off.
No interior light was left on because I have the interior lights set to OFF and I check the cars in the garage before I go to bed just to make sure nothing is on.
 
... They're a pretty good dealer and have been around forever. ....
I have a dim view of auto dealer service (all makes), based on many negative reports over the years on these forums. But I'd also be willing to concede that at least some of them are not out to gouge every last dime they possibly can out of the owners, and it sound like yours is in that group.

Hopefully this incident was a one-off, and you won't need to come back to this thread again.
 
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