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maniac

Battery light on after exactly 17mins of driving - bad alternator?

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Hi guys

My girlfriends 2014 Aygo mk2 is having this weird problem, where the Battery light comes on after exactly 17mins of driving, everytime. The car has done 85.000km / 52.815miles.

Is the alternator dying, or is the Battery going bad? I did measure the voltage while running, dont remember the voltage though 😂 I believe it was nearly 14v, not around 12v.

Anybody seen this problem before? I read somewhere that Toyota's are notorious for corrosion in the alternator, which just needs cleaning, could that be as "easy" as that?

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Alternator is charging at 13.65v, mesaured directly on the output of the alternator. It is on the low side - should vi around 14.2v. It does charge the Battery, and it is able to keep the car running if I unplug the negative terminal on the Battery, but what does this alle mean? Is the alternater slowly dying? I mean, sure it works, but the Battery indicator on the dash is annoying, and when will it totally die.

Is my only solution replacing the alternator? Apparently they just dont last long, 52.000miles / 84.000km isn't alle that great 😞

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Can you get some diagnostic connected to see why the light went on?

The alternator should charge at around 14.4V or so, so yes 13.65 is at a low end, did you maybe had lights and radio on, maybe AC while it was measured?

Maybe clean and re tighten contacts on the Battery.

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Also check/clean the earth leads.  Don't run the engine with the Battery disconnected - you risk damaging the electrics.

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14 minutes ago, furtula said:

Can you get some diagnostic connected to see why the light went on?

The alternator should charge at around 14.4V or so, so yes 13.65 is at a low end, did you maybe had lights and radio on, maybe AC while it was measured?

Maybe clean and re tighten contacts on the battery.

I did all the "how to check if alternator or Battery is dying"-trix from youtube, meaning AC/lights/rear defogger/radio on an off etc. Car only, LED DRL's and no radio/AC/defogger = 13.65v directly on the alternator. Contacts cleaned, even tried another (newer) Battery. Didn't touch the earth though, but dont think they're bad.

4 minutes ago, Notoyboy said:

Also check/clean the earth leads.  Don't run the engine with the battery disconnected - you risk damaging the electrics.

I will check them, but dont think they are bad 😞 I know but it's a way of telling wether it's the alternator or Battery 😉 Doesn't do much damage.

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And yes, I do have a Delphi tester, just didn't plug it in yet. I will scan for codes when I get the time for it 🙂

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Alternator should produce at least 13.8V and up, so the output you have is on the lower end, even with DRL running, which considering it's led, is not a significant load.

You are probably right that it's on it's way out, i guess the 17 minute thing is more triggered by the onboard diagnostics, maybe go for a short drive and when it trigers the light, measure the voltage then. 

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9 minutes ago, furtula said:

Alternator should produce at least 13.8V and up, so the output you have is on the lower end, even with DRL running, which considering it's led, is not a significant load.

You are probably right that it's on it's way out, i guess the 17 minute thing is more triggered by the onboard diagnostics, maybe go for a short drive and when it trigers the light, measure the voltage then. 

My thought exactly. Actually I did that, it even comes on after exaclty 17min idling, still measures 13.65v. So wether its highway or idle, same thing. Probably the onboard diagnoistics measuring a voltage drop or something. Girlfriend did tell me that when I had fitted the newer (slightly cheaper) Battery, the light was on all the time when driving.

I strongly suspect that it is on its way out, but I do think that it is a strange behavior. Had my mate measure his Peugeot 108, and sure enough it was producing a bit more than 14v as it should.

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Hi Thomas, have you got a multimeter at all and with respect do you know how to use it, very available from shops or Amazon for as low as £10.00. Mike

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14 hours ago, Mike169 said:

Hi Thomas, have you got a multimeter at all and with respect do you know how to use it, very available from shops or Amazon for as low as £10.00. Mike

No, I just made up all these measurements......

 

Anyways, talked to a mate who told me that it's probably dying. Could be one of the brushes not touching correctly or something. Brushes and regulator can't really be serviced, so I might just find a good used alternator to throw on the car.

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Hi Thomas.

If you want to repair your alternator on a budget , cheaply, and are prepared to chance a few well in £'s in English money a few quid you can usually Google and buy just brushes for an alternator, just put on the make and the model number etc and for a small amount buy 2 brushes, a very possible reason about your troubles and usually you can change them easily, but, it may be a transistor or a diode in the 'circuit board' of the alternator in which case you have wasted your money on the bushes alone.

Personally I would just fit another alternator as the voltage you have quoted is far too low so something is not working properly and be prepared your car Battery may have a cell on it's way out so you might need a Battery as well. If you can find a Battery selling shop they usually have a 'drop test meter' and that will show if a cell is dying on your Battery itself.

It is not uncommon for both to 'die' together.

An easy alternator home Battery test is to park you car close to a wall when it is getting dark, turn your dipped headlights on rev up the engine a bit and see if the brightness of the headlamps increases and if this happens I would personally go for the Battery first and I suggest you don't buy the cheapest one you can as you get what you pay for again depending on your budget.

Actual genuine Toyota batteries are very competitive on price, usually will price match and last longer. 

Good luck, Mike. 

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Refurbished ones could be a better solution, some places might have them on stock will just give you the new one in exchange for your old one and some cash.

Might be a budget solution, and better than buying used one which might also die in near future.

As Mike169 said above,  the Battery could probably be affected by this.

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