Interesting observation when charging battery

[roundle1979]

I've had a 2018 Mazda CX9 GT AWD since new.

I typically 'top off' my cars' batteries when it starts to get cold. I have a NOCO Genius battery charger/maintainer.

I started with my 2018 GTI which has a 12 month old Interstate AGM, same age as my CX9's battery. My NOCO turned 'green' (i.e. full) in about an hour. Meanwhile, the CX9 has been plugged in for 10 hours and is still charging. Admittedly, the NOCO is only 1.5 AMP so no exactly a powerful charger.

Both cars are used in a similar fashion. Lots of short trips with the occasional longer trip. The fact that the CX9 needs 10+ hours to top off the battery leads me to believe that the way the car is programmed (i.e. the car does not properly top up the battery) has something to do with the weak battery life).

My CX9 is on its 4th battery. The GTI got it's 2nd just 12 months ago.

Thoughts?

 

[BoomerZoomr]

I have two NOCO chargers… a 1 amp and a 10 amp. When I charge the battery (because we don’t drive it much) in my wife’s Mazda6, the 10 amp model will show fully charged pretty quickly. If I use the 1 amp charger I usually leave it overnight. Checking the voltage can provide insight. Even though (I think) all NOCO chargers are also maintainers, I would consider your small charger more of a maintainer than a charger, where a full size car battery is concerned. I would get a 5 or 10 amp charger for actual charging a depleted battery.
Your CX9 seems to be going through a lot of batteries. If those were quality batteries, you may have an issue with the vehicle.

 

[roundle1979]

I have two NOCO chargers… a 1 amp and a 10 amp. When I charge the battery (because we don’t drive it much) in my wife’s Mazda6, the 10 amp model will show fully charged pretty quickly. If I use the 1 amp charger I usually leave it overnight. Checking the voltage can provide insight. Even though (I think) all NOCO chargers are also maintainers, I would consider your small charger more of a maintainer than a charger, where a full size car battery is concerned. I would get a 5 or 10 amp charger for actual charging a depleted battery.
Your CX9 seems to be going through a lot of batteries. If those were quality batteries, you may have an issue with the vehicle.

First three were Mazda OE batteries from Mazda (including the original that was factory-installed). The current one is an Interstate from Costco.

While I do not expect the NOCO to be fast (I mostly use it for maintaining marine batteries over the winter), I was suprised that my other cars seem to keep themselves 'topped off' while the CX9 clearly does not.

 

[youri]

I have only changed my battery once on my 2018. And that was last year. I expect it will last me at least 4 years.

 

[Speed3.5]

First three were Mazda OE batteries from Mazda (including the original that was factory-installed). The current one is an Interstate from Costco.

While I do not expect the NOCO to be fast (I mostly use it for maintaining marine batteries over the winter), I was suprised that my other cars seem to keep themselves 'topped off' while the CX9 clearly does not.

What accessories have you installed since you've had the car, some accessories do drain the battery.
Either way you can check for battery drain, check youtube for examples and try it yourself.

Check if battery voltage when in idle is 14 to 14.5VDC