Anyone know how to change alternator output for AGM battery

No problems for me with AGM batteries and temps below zero for five months of the year. Even down at -50° they still started the truck.

 

I've never ever had a problem with Diehard AGMs.
Never.

 

Isn't it the Lithium batteries that are not very cold temp tolerant?

 

Never heard of a special alt for AGM. I've run them for over 20 years without issue(in Toyotas). Most last over 10 years, but one died at 8 years(diehard platinum).

Full voltage for a car battery is 12.6~7 volts. So if a charge is higher than that, it should charge fine.

 

I got 11 years out of my last Odyssey, stuck it in place and didn't have to do anything special, it was good to go.

 

I’ve had an AGM since May and through the Texas summer heat. My alternator has no problem keeping the AGM battery charged to 100%. I test it with my Schumacher charger on AGM mode and it won’t charge it because it’s already at 100%. Not sure this is a real problem that needs requires a higher voltage solution? I’m also not sure what my alternator output is but it keeps me charged to 100%.

 

Lipro batteries cost 80 dollars for my R/C cars and can catch fire, why would you want one for a truck.

 

You can save over 100 pounds of weight on a group 31 two battery system by using lithium instead of lead acid.

 

The 2017's don't have an alt-s fuse.

 

I'm wondering if the OP is confusing "battery charger" and alternator.
Who told you that you need a high output alternator?? My other car is over 20yrs old , stock 130a alternator and charges fine. If you have a lot of power draining accessories , then yes.
Battery charger does need an AGM option . A normal charger CAN overcharge an AGM without an AGM option. An AGM charger charges low and slowly.
I've had the Diehard AGM down to 2% . So low that the charger cannot detect it being a 12v . A normal battery would've been toast. I had to boost it to 12v to start charging. That was 3 years ago. The same battery is still in the car but on Battery Tender with desulfator. No problems.

 

No confusion. The Taco regulator is ECU controlled and tops out at 13.5V, if I recall correctly. You need north of that to not shorten the life of an AGM, like your Battery Tender does.

 

LiPo's and similar LiFE, and a a few other formulations cannot handle cold temps and actually drop voltage, and amperage draw available.. while they do have long lifespan (draws down below 50%, and the amount of amperage avaliable, as well as lifetime deep charging cycles it has... typically a LiPo will habdle around 2000 deep cycles before death.. where some lead acids, and AGMs will only handle 500-800 deep cycles.

ALL batterytypes have different charge cycles for a trickle, and float charge to keep them topped up. the downfall is that the voltage required for an AGM, and LiPO battery is much higher than what our "smart alternators" are capable of. they will typically output 14.5v @ anywhere from 30-100AMPs (stock 2016 v-6 with A/C is rated for 100AMPs output) however this is an optimal output, it does not account for extra exuipment running/charging off this system.. lots of LiPO's speciffically will require 14.7v+ to reach a full charge.. while you can get away with running and charging them to 14.5v only they will eventually damage the battery, and leave you with un-usable capacity for that expensive LiPO, or LiFE battery you bought...

one way around this is to run a dual battery setup with a DC to DC charger such as this one... this only helps if you want to run a house battery setup... which means separate batteries, and different wiring setups... not for your "starting battery"

$540 REDARC 40A in-Vehicle DC to DC Charger with MPPT — Dual Input for Solar & Alternator Charging, Green Power Priority - 12 or 24V Battery Charger Suitable with AGM, Gel, Lithium LiFePO4 Batteries

https://www.amazon.com/REDARC-BCDC1240D-Dc-Dc-Charger-12V40a/dp/B077JR6NH5/ref=sr_1_4?crid=67FPBPJ4MHX3&keywords=dc+to+dc+charger+redarc&qid=1575485149&sprefix=dc+to+dc+charger+red%2Caps%2C169&sr=8-4

 

For what it is worth, I have an Odyssey group 65 AGM in my truck. I installed it back in 2015 in July/ August of 2015 I believe and it has been kicking ever since without an ALT-S mod to the circuit. I tested it recently and with a spec of 950 CCAs out of the box when it was new, it tested to 804 CCAs. Granted, this test was done with my style driving which is 10-12 of vehicle on activity highway driving, which is usually not enough time to properly charge a battery. I have the ALT-S mod in mind, but I can't really justify it at this moment because of the test results.

In short, if you buy a quality battery, given how the Toyota charging circuitry works, you may never end up having to worry about it, as 4 years is damn good service life out of any modern day battery, and we all know how garbage today's vehicle components are these days.

 

What is the charging voltage on the 2nd Gen? I'm assuming the ECU controlled regulator is a 3rd Gen 'feature?'

 

Anywhere between 13.3-13.7 normally, though I do sometimes see 14-14.3 on the charge. It is sort random when it does that though.

 

That might be why you are seeing the longevity? The voltage that I have seen on mine is rock solid at something sub-optimal for AGMs. It doesn't move once the motor is above idle.

My bike with a MOSFET reg sits nicely at 14.2 according to a DMM. I have an onboard voltmeter, but it samples too quickly. It was good for spotting the OE shunt-type reg when it was dropping volts though.

 

Typical charging voltage is 14.2v or roundabouts.. it is controlled by the voltage regulator which is typically in the alternator housing itself (there are some ECU controlled alternators out there.. they are pricey too...) the ALT in our tacomas is designed to shutoff charging for fuel economy..... it will charge with 13.7-14.3v unitl it sees that the battery will return a signal showing about a 12.6v charge state.. it will then shut off and discontinue charging until voltage drops again due to accessories being used, radio, lights, cooling fans, etc... an AGM will like to see 14.7-14.9v to charge... it will accept the 14.2-14.3v charge, but will never "fill" the battery to capacity, couple this "never full status" as well as cell degredation (typical to see anywhere from 70-80% loss in amperage, and you have effectively negated the $300-400 you spent on that extra capacity, and or Ah storage.. add in freezing temperatures that rob amperage, and you may wind up in a no crank situation.... so be selective on what battery type you get.. its all about choice really... honestly I'm looking at the northstar 27f, or possibly getting a 31... and eventually expand my 12v system to involve the dc to dc charger, and a house battery for all my camping needs, and device charging responsibilities.

 

Edit: Didn't realize this is a 3rd Gen. thread...

this mod applies to 1st and 2nd gen only


A 5 dollar diode and voltage sense wire relocate is one would ever need to sufficiently provide the proper voltage to maintain an AGM battery(s)...

 

My other truck is a '91 Dodge Cummins with a truck camper. I recently installed a CTek DC to DC charger (it takes input from both solar panel and alternator) and it has 2 separate very thin wires for AGM batteries but specifies a "smart alternator" is required. One wire goes to the batt neg terminal, the other to the truck's ignition.

While I have 2 new AGM house batteries, my '91 Dodge has a firewall mounted, separate from the alternator, not very smart voltage regulator so I didn't bother hooking up the AGM wires. I guess I will settle for plugging in a 120v smart charger when electricity is available for the truck camper.