2012 RX350 AWD 123K miles. My battery is starting to get weak. (My wife left the lights on for 5 minutes, and when she came back, the car wouldn't start--just clicked). I jumped the battery, and it started, but I have a feeling the battery needs replacing soon. I notice that most battery places recommend an AGM battery. What's in there now is a standard lead acid that came with the car when I bought it 2 years ago with 93K on it. Any suggestions as to why or why not to go with AGM?

 

My personal opinion is that the AGM batteries are not worth the extra cost. A good lead-acid battery will last 5 years or more.

And yes, leaving the lights on for 5 minutes should be no problem for a battery, so yours is very worn.

 

Well worth the cost as long as you search for a good deal. Most I have ever paid for an AGM battery is $156. They are so much more capable throughout the power range. Everything on the vehicle works smoother and faster, especially the power windows. I have AGM batteries in my 2013 Subaru Outback 3.6R and her 2006 Jaguar XK8. When the time comes for a new battery in her 2015 RX350, it will get an AGM as well.

 

AGM is a whole lot better but a whole lot more money. It's not what I use, but it's just a personal preference.

 

I once read the Bentley BMW manual that said AGM batteries are meant to be stored in the trunk away from a hot engine bay because they don’t like hot temperatures. As a result, they have to have a vent tube for toxic gases. They’re great at lasting a long time and are capable of deep discharges without issues. In addition, they don’t have any liquid acid inside as they’re made out of fiberglass.

So with that in mind, if the car has a battery under the hood, go with lead acid. If it’s in the trunk like on Hybrid models, go with AGM.

 

I would go with an AGM battery if you can pick one up for cheap at Costco or something like I did. My original battery died after 6 years, so I took my 2-year-old budget AGM out of my Highlander as a donor for the RX (swapped it out for a big 94R Chrysler battery I was given). My original battery was a measly 585 CCA, while the budget AGM is 710 CCA. Scored extremely well on the battery load tester in the Battery Health and Internal Resistance department before going into my RX. Starts the car real easy during the winter months and should hold up very well to our bipolar Canadian weather over the years.

 

I'm new here though not new to the AGM vs Lead Acid Battery matters. The experience Ive had with the AGM battery related to two BMWs we previously owned & purchased used. Up here in Maine, known for beautiful summers but cold and snowy winters, both BMWs, a 530xi and an X5 parked out doors year round required AGM battery replacement at about 11 years old. Have extensive previous experience with lead acid batteries which don't seem to last more 3-4 years here, at best. The only caviat is the BMW operating system has to be told a new AGM battery was installed so that the alternator/regulator supplies the correct voltage when/as needed. Lastly these batteries include a small vent hose that vents to the outside of the car.
Lastly, AGMs are more expensive then their lead acid competitors but their longevity is well worth the extra expense, ie; 1 AGM battery over 11 years vs 4 lead acid batteries over 11 years.

 

I'm running AGM in my winter car since it gives better cold cranking it stays viable down to about -35 C. Lead acid at those temps has a serious drop off in power. On the flip side I have an AGM battery in my Lexus that is only driven in warmer weather that battery is going bad so there might be something to the theory that AGMs don't like heat. Battery in the Lexus is 6 years old in my winter car about 8 that battery if still healthy. IMO if you live in a mild climate and/or don't need cold weather cranking power get a lead acid.

 

Battery on our 2013 lasted eight years, and we have temps down to -30 F, so I'm not complaining...

 

 

Thanks, everyone, for your input. There are pros and cons for going with either battery. Personally, after looking at specs, reading all the posts and other things, I have decided to go with the traditional lead-acid battery. I think the AGM's are more designed for those cars that shut the engine down at a complete stop, and restarting when you push the pedal to go; i.e. hybrid like RX450. That kind of driving puts a lot of strain on a battery. Living in New Jersey doesn't really have the cold weather like the far north part of the country, nor does it have the hot humid summers like the deep south. If it gives me 5-6 years, I'll be happy..

 

Not intending to nit-pick but just in case any reader may be mislead ... RX -hybrids do not have the starter that uses 12v battery.
Salim

 

Thanks, Salim! Not owning a RX450 (yet) I was unaware of them not having a starter. I just remember that where I worked, it was recommended to purchase an AGM if you had one of the newer vehicles that the engine quit when you came to a full stop, to save gas.

 

I haven't used an AGM but for me it would depend on price... I live in FL and guaranteed every 4 (MAX 5 ) years I need to replace the battery.
So for me longevity in heat is the major factor, and I haven't read anything that convinces me that AGM is any better.
Good luck.

 

I was recently researching a new battery for a friend and noticed a big marketing push for AGM through Interstate/Costco. I remember a few years ago AGM was solely meant for Start/Stop systems and European cars with batteries in the trunk, but now it seems they’re selling them like the “better” or “best” option and the lead acid is the “basic” one. Is there a shift in the industry to get away from lead acid and go all in on AGM?

Like I mentioned in my previous post, I read about AGM only being recommended in certain applications and not liking the extreme heat of an engine compartment, so I’m a little baffled by the marketing.