T135 Carado - Fiat Ducato Alternator & Battery issues

[Keatingray]

Hello, I have a 2020 Carado T135 on a Fiat Ducato 2.3 Multijet chassis. The starter wouldn't engage recently and it turned out the battery was flat, the result of it not charging and the assumption was tat the Alternator. My mechanic changed the Alternator, but it still won't charge even with the new alternator fitted. My mechanic is at a loss, so if anyone has any knowledge that could help it would be greatly appreciated.

 

[The Coops]

Battery knackered would be a good place to start ( no pun intended) get it checked, you may have just bought an alternator that was not required!

 

[Jake Royd]

A battery can show say 12.7v after resting from charging and appearing ok. As soon as you apply a load your down to 10v. If so the battery has had it.
Get a load test done on the battery.

 

[L' Hobo]

Hello, I have a 2020 Carado T135 on a Fiat Ducato 2.3 Multijet chassis. The starter wouldn't engage recently and it turned out the battery was flat, the result of it not charging and the assumption was tat the Alternator. My mechanic changed the Alternator, but it still won't charge even with the new alternator fitted. My mechanic is at a loss, so if anyone has any knowledge that could help it would be greatly appreciated.

As it's a Ducato, the first thing to check is the Earth strap!

 

[Keatingray]

Hi all, thanks for the replies. Yes, the battery has been tested and it appears fine. He also did the earth strap but to no avail.

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[fred_jb]

Have you measured the battery voltage with the engine running? Even with a smart alternator it will change from the engine off reading to somewhere around 14V before dropping to 12.5V or so. If you are seeing that then it would seem that the alternator is trying to charge the battery, so if it failing to charge then it could be a faulty battery.

On the other hand if you see no change in battery voltage when you start the engine then there may be a problem with the wiring from the alternator, including any fuse. Probably worst case would be a smart alternator which the ECU is failing to turn on for some reason.

Most modern vehicles have some sort of sensor or shunt attached to the battery so that the ECU can monitor it, so it could be a fault with that.

 

[GeoffnDee]

Was it both the engine to body and battery to body earth straps that were checked/replaced and is the alternator output connection at the starter motor main supply cable ok. or the alternator may have its own fused connection at the positive starter battery terminal plate.