christcorp

Is anyone using an agm battery in their 2007-2010 Lexus es350? Is the alternator output 13.5-14.2 normal charge voltage enough for the agm battery? Research shows agm likes 14.4-14.9 for main charging and 13.5-13.9 for trickle. My high on my alternator is around 14-14.2.

tolian21

What is the reason to use AGM battery? My understanding it will work fine, but I would not pay more for it

christcorp

The cost isn't that much more (assuming you don't go to a car part store like autozone, oreilly, etc). As Sam's Club and Walmart the AGM is about $30-$40 more depending on the model. But I live in cold country half the year, so better battery in low temps would be nice.

But I am still concerned about the alternator. MOST places I've researched on AGM batteries, it wants around 14.4-14.9 volts for main charging, then when fully charged, it likes a normal 13.6-13.8 volts give or take.

My 2007 ES350 alternator when first starting up, pushes around 14.1-14.3 volts. Once fully charged driving at night with lights on, it's around 14.0 volts. At low RPM in town it will go as low as 13.4-13.5

Just not sure this is good for an AGM battery
Thanks
Mike

Clutchless

It will probably be just fine with your alternator. I have an AGM battery in my Sienna and after 2 years all works perfectly, although I never checked alternator output. I just knew I wanted an AGM.
Or get a new alternator.

christcorp

Clutchless, I appreciate the reply. Not knowing what your alternator puts out, it's hard to tell. If the voltage is lower, it will still charge, but will take much longer. Not an issue if you drive a decent distance daily. e.g. 20-30 minute drive to work each morning and evening. But if you do mostly 5-10 minute driving in town, the AGM battery wouldn't be happy if it's only getting say 13.8 volts most of the time.

I'll have to do some more research with the battery manufacturers directly.
Thanks
Mike

Oro

Here is a very recent thread with discussion of pros/cons of AGM at the moment. There was some insightful commentary by others.

https://www.clublexus.com/forums/gx-...ery-again.html

I am leery as we have been getting very poor performance and longevity out of AGM batteries in motorcycles and powersport products the last few years. Friends, too - not just my odd observation.

Also, some modern cars have variable output alternators. It intentionally drops voltage when not needed (high state of battery charge). I honestly don’t know if that applies to your car or not; maybe someone else does. Your readings MIGHT be normal. On an older car, they would be marginal at best.

ESh

It can power the accessories for longer. Your alternator is fine but I don't think you need it.