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Discussion Starter #1
I am not sure if this topic has been covered bin another post. My 2014 MDX's (FWD Advance w Ent) battery died last Saturday. I purchased the MDX as a CPO in 2015 and have gone through 3 batteries so far all replaced under warranty. However this last one dealer said I was on my own. So I purchased a group 24F from Costco. Stock battery is an AGM and the one from Costco is a standard wet battery. Any issues with going non AGM that you guys a re aware of? I know the MDX is heavy with electronics especially my version so am not sure if I should return the Costco one and get an Acura one. Thanks!
 

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Normally I wouldn't be concerned, but you've gone through 3 AGM batteries in 5 years? Would seem like something else is going on here. Does the car sit without being driven for a month or two at a time? Do you sit in the car with the engine off, but the ignition on or in accessory mode frequently for more than 30 minutes? Just trying to think of ways you might be stressing the battery.
 

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Have you call other Costco location and find out if they have AGM battery available? Quick search shows Interstate Batteries does have AGM one for Costco.

I assumed your warranty expired, that is why Acura / dealer is not offering free replacement. But if you buy a new battery from Acura this time, it should have Standard battery warranty (3 years free replacement and up to 100 month pro-rated). With the rate that you replacing battery, it falls into 3 years free replacement no matter you get it from Costco or Acura. So I will pick wherever is more convenience.

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Normally I wouldn't be concerned, but you've gone through 3 AGM batteries in 5 years? Would seem like something else is going on here. Does the car sit without being driven for a month or two at a time? Do you sit in the car with the engine off, but the ignition on or in accessory mode frequently for more than 30 minutes? Just trying to think of ways you might be stressing the battery.
Thanks for the reply. This is my daily driver with occasional radio after the engine is off. Dealer does all services and they have not reported any issues with charging system. Will have them re check at next oil change.
 

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Have you call other Costco location and find out if they have AGM battery available? Quick search shows Interstate Batteries does have AGM one for Costco.

I assumed your warranty expired, that is why Acura / dealer is not offering free replacement. But if you buy a new battery from Acura this time, it should have Standard battery warranty (3 years free replacement and up to 100 month pro-rated). With the rate that you replacing battery, it falls into 3 years free replacement no matter you get it from Costco or Acura. So I will pick wherever is more convenience.

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Thanks for the reply. Yes I actually purchased the H6 AGM battery but the terminals would not fit the top of the battery. The terminals on my MDX have addional electronic components and the way the top of the battery case is designed there is limited space around the post as you can see. I had to return it and go with the 24F one. Although we purchased Acura Care it does not cover the battery. I thought of just going to the dealer and getting an Acura brand one, you are right both have 26 month replacement albeit I am sure the Acura will be more expensive. If there is no issue with a wet one ill stick with it.
 

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There are differences between FLA (flooded lead acid) batteries and AGM (absorbed glass mat) batteries. They have different charge profiles (i.e. voltage vs. time), and crucially different internal resistance. AGMs are capable of charging faster and at higher voltages, and providing more current under load. AGMs are also more robust against vibration and over-discharge. In an automotive application it is common to regulate the alternator to a single voltage, as for the great majority of the time the alternator is running when the battery is being used. I would really like to know if the voltage is the same with the MDX model with AGM as for the other models with FLA; if it is the same then I would be tempted to install an AGM in my Base model. I would never replace an AGM with an FLA as the AGM does perform differently, and would be able to withstand a lower discharge level and can charge/discharge at higher rates. Not all AGMs perform the same. In the U.S. market I would opt for one made by East Penn Mfg, which is sold under many brand names; it has very good technology - cheap is not the way to go.
 

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There are differences between FLA (flooded lead acid) batteries and AGM (absorbed glass mat) batteries. They have different charge profiles (i.e. voltage vs. time), and crucially different internal resistance. AGMs are capable of charging faster and at higher voltages, and providing more current under load. AGMs are also more robust against vibration and over-discharge. In an automotive application it is common to regulate the alternator to a single voltage, as for the great majority of the time the alternator is running when the battery is being used. I would really like to know if the voltage is the same with the MDX model with AGM as for the other models with FLA; if it is the same then I would be tempted to install an AGM in my Base model. I would never replace an AGM with an FLA as the AGM does perform differently, and would be able to withstand a lower discharge level and can charge/discharge at higher rates. Not all AGMs perform the same. In the U.S. market I would opt for one made by East Penn Mfg, which is sold under many brand names; it has very good technology - cheap is not the way to go.
Good info thanks for the reply. I went with Costco because it was convenient, and I did not realize I was dealing with a AGM battery until after I had installed. Thanks for the detailed info.
 

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After much searching I found that the MDX 14-15 use a standard Group 24F battery. I was sure I saw an AGM sticker in the batery i took out but maybe I was wrong. After the 2016 MY they started using the AGM battery. I suspect it has to do with the auto stop/start feature those models years had built in. Thanks everyone for the detailed info.
 

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In an automotive application it is common to regulate the alternator to a single voltage, as for the great majority of the time the alternator is running when the battery is being used.
It's becoming more and more common for alternators to vary the voltage they output depending on the need - the so called smart alternator. I'm not sure if Acura is doing this on recent models or not. I know my 2014 doesn't have a smart alternator.
 

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I am aware of, and have used, smart regulators on my boat. I just didn't know if they were used in cars generally or MDXs specifically.
 

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More and more cars are using them, yes. Not sure how they work, but I think it involves a clutch in the alternator, not a regulator. I just see it as a potential problem point. The idea of the clutch is do disengage the alternator entirely and have less mechanical load on the engine - all in the effort to eke out every last mpg.

I worked at a Mercedes dealership for a while in 2018 and they definitely have them.
 

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That is a strange solution. Smart regulators can turn off all current to the alternator field coils, leaving very little friction. Adding a clutch to stop the alternator from turning would buy very little in additional friction reduction; I wouldn't have thought is was worth the extra complexity. OTOH a clutch added to a standard alternator with internal regulator makes some sense: I don't see much advantage to smart regulators in automotive applications. Smart regulators are typically used in deep cycle applications where the battery is discharged then recharged, and the recharging is done with a relatively brief elevated voltage to reduce the run time, and with longer run times the voltage is reduced. Autos are constantly charging and discharging at the same time and so are more appropriate for a constant voltage. Also, note that the batteries in modern cars are very small and not intended for extended discharging without the engine running.
 
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