Proper Maintenance of High-capacity AGM Batteries

With the recent purchase of a Northstar 92 amp-hour (ah) battery, I started to research how to properly maintain the battery in order to get my money's worth out of this purchase. Unfortunately, sulfation isn't something that is easily seen in sealed batteries such as an Absorbed Glass Mat (AGM). So, the old adage, "an ounce of prevention is worth a pound of cure" rings true.

In this post, we'll discuss what sulfation is, how it occurs, and how to prevent it. We'll also "talk technical" about the Tacoma's charging system and why it needs modification in order to keep this batteries fully charged.

What Is Sulfation?
Quite simply, sulfation is the term used to describe the build up of lead sulfur crystals in the battery. This is a naturally occurring chemical process in all lead-sulfur batteries, but the rate at which it occurs is accelerated when a battery is either constantly undercharged or in storage for long period of times. When there is a significant amount of these crystals formed inside of the battery, they impede the chemical process that produces energy. Over time, this reduces the available capacity of the battery thus "weakening" it.

How Sulfation Occurs:
As mentioned above, sulfation is, unfortunately, a naturally occurring process in lead-sulfur batteries. As the battery charges and discharges, lead sulfate crystals accumulate in the battery reducing it's capacity. This process can be minimized by charging the battery at the proper voltage and amperage. Just as well, failing to give the battery the correct voltage when charging accelerates the sulfation process.

The Tacoma Charging System:
crashnburn80 points out in his AGM battery thread, that the Tacoma's electrical system is setup to charge the flooded, lead acid batteries the truck ships with. As such, the Tacoma's average cycle charge voltage is approximately 13.80 volts. Unfortunately, the Northstar requires a cycle charge voltage of 14.40v to 14.80v which means that the Taco is undercharging the Northstar by 0.6v to 1.0v. As we pointed out above, the lack of proper charging voltage is going to cause accelerated sulfation which is going to decrease the lifespan of the battery.

Solutions:
For us third generation owners, we're unlucky in the fact that the alternator output is controlled by the ECU. This of course means we have to change the parameters in the ECU. In order to do this, you must purchase the Orangevirus Tuning cable. It's not cheap, but I take solace in the fact that the tuner allows access to most of the ECU parameters, so it has some versatility. Couple that with the logging feature and I'll stomach the cost.

In order to get the alternator to output the required voltage, you must change the parameters in the "Alternator Constant" map definitions. Specifically, Mr. Yeltzin recommends setting the 30-168 parameters to 94 in order to achieve a 14.36v output at idle and approximately 14.50v when driving. This is on the lower range of acceptable for the Northstar, but it is acceptable.

If you aren't willing to stomach the cost of the OV tuner, you can purchase a 10A charger such as the NOCO GENIUS10 and just plug the truck in as often as feasibly possible. It's better to supply the correct voltage to the battery when the truck is running, but a 10A charger will offset the sulfation process by keeping the battery at or above the recommended stable voltage of 12.70v.

Conclusion:
While the Northstar is a marked upgrade from the factory battery, it is a needy battery. It's not a cheap upgrade either. At $409 MSRP at my local BatteriesPlus compared to a $200 for a Toyota TrueStart replacement, the Northstar costs just over twice as much. You also need to spend $400 for the OV Tuner and, if you want to properly maintain the battery, $100 for the GENIUS10 charger and maintainer. Without tax, shipping, etc. you're looking at a minimum of $909 for this upgrade. Thus begging the question, why?

Piece of mind, really. With winter on the horizon, I'm doing everything reasonable to ensure that I can park my truck at work for eight or more hours in the freezing cold without draining the battery. I also have accessories that put an increased load on the electrical system and in order to compensate for that, I wanted a battery that had an increased capacity and could withstand deep cycles more frequently.

Just as well, it has been mentioned many times on this forum and others that the factory battery will die in a few years. In the nine months I've owned this truck, I've cleaned off a considerable amount of acid from the top of battery. That does not inspire confidence.

Hopefully this helps you make a decision if you're looking at a battery replacement. Even if you don't go with the Northstar, I recommend you consider looking at the supporting elements of an electrical upgrade such as the alternator output and a charger/maintainer.

Thanks for reading!

 

KDMax changed mine to 14.2 for my red top.

 

Great summary

Where are you located? I've thought about an AGM for the cold up here in Minnesota but I've only run into issues if I've let the truck sit for about a week or more, and even then I've had a jump pack on me so it fires right up. I also sit in the truck doing work while it idles quite a bit. An AGM second battery to power accessories would be handy to have, but I haven't gotten to a breaking point yet where the jump pack couldn't get me going again.

 

I live in the mountains of Colorado. It's not the ambient temperature that gets you, it's the 20mph+ winds coupled with freezing temperatures. I keep a

$100 NOCO GB40 1000A UltraSafe Car Battery Jump Starter, 12V Battery Pack, Battery Booster, Jump Box, Portable Charger and Jumper Cables for 6.0L Gasoline and 3.0L Diesel Engines, Gray

NOCO GB40 in the glovebox and check it every couple weeks, but I never want to use it for myself--I've stood outside in near zero weather enough to know that it's better to be inside of a warm truck than trying to jump start it.

The dual battery setup is definitely a nice to have if you need it. If I spent most of my day inside of my truck working, say in like police cruiser scenario, I would double up and run my accessories off of the secondary.

 

Nice write up.
With that cost, you can just buy a brand new battery every winter for the next five years.
I get the piece of mind (also wind has no effect on components like batteries) but, in all the years of living in the cold and snow, the only problems I had with batteries was when I did not replace them when needed.
Good luck man and I understand the need for justification lol.
I wanna buy a Tommy Bahama sweatshirt but I am can't figure out how to justify $129 per shirt over the $12.99 I pay for sweatshirts now.
Got any ideas?

 

The battery doesn't know the difference between 10° and 50mph wind and 10° and calm. There are chargers that can maintain/desulfate a lead acid battery of either chemistry for far less than $100. Lastly, one can buy a tune from a licensed tuner for ~$300-350 that will get them a corrected charge voltage and significant drivability and torque curve improvements. Just some additional info for future consideration.

The X2 AGM battery from Batteries Plus is a great value and rumors have it as a Northstar with a different badge and maybe some other small differences.

 

Its not a rumor. It says Northstar literally on the side of the X2 batteries

Good post. Your next issue when you up the voltage is that you should only up the voltage to charge the battery. Once it’s fully charged it needs to drop to a float voltage or you’ll burn the plates. Unless OVTune or whoever is tuning your alternator can detect the charge and then automatically fluctuate the voltage… you’re killing the battery life no matter if you change from the stock alternator output voltage. The RedArc BCDC has a proper charge profile for an AGM, but it only does that for the house battery. I wish we had a way to use them for a crank battery.

 

Okay. This explains the fluctuation of the stock values in the ECU from factory. I've also seen this in the battery monitoring app I use. When I took it off of the maintainer this morning, the voltage dropped to 13.01v before sharply rising to 13.98v upon start. Over the course of my commute into work the voltage hovered between 13.94v and 13.79v. With that in mind, maybe just keeping it on the maintainer as often as feasible and keeping the stock alternator voltage output is acceptable? The float voltage for the X2 is 13.50v to 13.80v.

 

Well, when you put it like that...

There's no denying the fact that this is a significant investment. As a matter-of-fact, this kind of upgrade doesn't make sense from a financial standpoint until you've owned the truck for at least nine years, assuming the factory battery last two years and you replace it at a cost of $200. And that's also assuming that you only have to replace the Northstar once at a cost of $409. And that's just on the cost of the battery alone, I didn't factor in a new tie-down, the charger/maintainer, and OV Tune.

As far as the Tommy Bahama shirts go, I actually own a few--they're nice shirts and they fit me well. But, like everything, they have a time and a place. I'll wear them at work or in the summer on an off-day, but I don't wear them when working on the truck. For that, I wear the shirt that is six years old, covered and oil, and been chewed on by mice.

 

Good info on the crystals but for $900 you can install a dual isolated battery system with charger and solar. 92ah is pretty excessive.

My factory battery lasted 5 years to include Colorado winters and we run winches, fridges, radios, lights etc from it.

I upgraded to a Deka 9A34R, pair it with a battery charger and will last a long long time.

EDIT:

2x Deka Intimidators - $500
1x Renogy 30A Charger - $275
1x Renogy 100w Solar - $175

$950 and you can monitor it from your phone.....

 

Haha! Sometimes it's just a question of quality. I am guilty of spending too much on quality when I would have been just fine with quantity. and the inverse is true too! I have bought repetitive items when the buy once, cry once mantra is a better way.
With vehicle batteries? I have no best answer.

 

IIRC the dealer can change your charging voltage with Techstream according to some threads I've read on TW.

Dunno what it costs or if true or not as I'm running an HKB booster on my gen 2, but worth checking into as a potentially cheaper and easier solution than buying a tune or doing it yourself I expect.

 

You certainly can go the dual-battery w/ solar setup at the expense of weight. If you're going to go this route, I would recommend this setup from OGE in order to put the weight of the second battery on the opposite side of the vehicle. And I completely agree that if properly maintained a battery will last the expected lifetime, if not longer. But, this is TacomaWorld and since when do we consider fiscal responsibility in any of our mods?

 

I love the OGE kit but not worth the price anymore. Can just retrofit a batt charger and boom you dont need the other stuff really

 

TechStream would almost certainly be able to modify the necessary parameters. The problem would be finding a tech at a dealer that would be willing to void your warranty for you.

The HKB boosters don't work on a Gen 3 as those vehicles alternators are controlled by the ECU. The HKB booster, as explained by crashnburn80, fools the alternator by making it see a lower voltage output that what it is actually putting out by applying a resistance across the ALT-S circuit.