Hi guys

I have a 2012 Mazda 5 with istop so has two batteries.
Do these Mazda's have a smart alternator and if not how does the charging system work with the two batteries?

The reason I need to know is that I use a leisure battery in my boot that I need to take out to charge so would be really handy if I could change it from the car.

I was thinking about using a split charge relay and maybe connecting it to the smaller battery but I read somewhere that the split charge relay may not even be necessary at the car already has the capability to change multiple batteries.

 

The ECU will see the extra battery a one and will over tax the alternator. This may cause overall charging system problems? But I am guessing based on how I know the ECU controls the charging rate.

This may be a better answered question with an Automotive Electrical service shop ? But my guess is that they may recommend an aftermarket alternator upgrade . I would suggest a power Bastards but you would need to contact them direct for application with your year Mazda and model.
I run one because of a very high end stereo system and it was a great investment. Prior to getting one I was needing to replace my battery about every 14 months.

https://www.powerbastards.com/default.asp

 

Thanks for the reply 👍

So the battery charging is controlled by the ECU (I've never seen that before)?

Does that mean we have a smart alternator?

Did you have the two battery (istop) Mazda 5.

 

Any Mazda I have seen uses one battery and it's expensive due to the high CCA rating compared to a std car without Istop.

 

First *it is common for almost a decade or more and
No it is *controlled by the ECU so nope not a "smart alternator" just an alternator old school type sorta only better quality and reliability.

 

I have the istop model and it has two batteries, one large battery and one smaller battery.

 

That's interesting. Are they in close proximity to each other? All the Mazda's I service have 1 battery the newest is only 3 years old.
Ah I think yours is the mild hybrid with a starter/generator system.