The NorthStar AGM Battery + Voltage Booster Upgrade

The NorthStar AGM Battery + Voltage Booster Upgrade

This thread covers upgrading to the best AGM battery available and modifying the voltage regulator via plug and play fuse to charge the battery at increased voltage, as required by spec on an AGM. Side benefits include brighter halogen headlights and higher flowing fuel pumps for supercharged applications.

Best AGM Battery
3 big heavy weight names constantly come up in the high performance AGM battery space, Opima, Odyssey and NorthStar. There are other brands out there that make AGMs as well, but this thread will focus on the top 3 names in the industry.

Update! Odyssey has since acquired NorthStar. The same NorthStar 27F discussed here is now available as the Odyssey ODX-AGM27F. This is the exact same battery, specs, housing, just with a different color and different sticker. Odyssey did not previously make a 27F. The same battery is also still available though Batteries Plus as X2Power.

What is an AGM battery and why does it matter?
AGM stands for Absorbed Glass Matt. These batteries are maintenance free, they are sealed (non spillable), they have a higher power density than a flooded lead acid battery, they are typically more reliable with a longer life span. AGMs can charge much faster and have the ability to deep cycle. An AGM is superior in every way to a standard lead acid battery.

Understanding battery sizes
The 2nd Gen Tacomas came with battery size 24F for non-tow package trucks and 27F for tow package (TRD) trucks. The 3rd Gen Tacomas only received the smaller 24F batteries. It is possible to mount a larger 27F in a 24F tray, these were interchangeable on the 2nd Gen. It is also possible to mount a larger group 31 battery in place of either, though group 31s are large and heavy, it is recommended to get a group 31 battery cage from an aftermarket vendor.

The best way to evaluate what you are getting is looking at the data.

Battery Data


Battery Data Notes:
*Stock specs are based on value replacement Toyota TrueStart batteries. OEM battery specs are unpublished. 18mo warranty is replacement warranty, they pro-rate in tiers after than for 42 mo. The TrueStart Batteries are likely much higher performance and quality than the OEM included with the vehicle.
*NorthStar offers a 4 year warranty, buying BatteriesPlus X2 labeled NorthStars is cheaper and extends the warranty to 5 years.
*NorthStar claims 900 charge/discharge cycles in publications, but if you look at the data details that is 50% change rate, the other brands use 80% charge rate. NorthStar 80% change rate spec is 400.
*Odessey batteries do extreme vibration testing and pass but do not provide a multiplier value like Optima and NorthStar.

Looking at the specs, it is pretty clear NorthStar is the superior product. The NorthStar 27F has over 2x the reserve capacity of the OEM 24F and almost 2x the CCA, while also beating out every performance spec of the larger group 31 Optima. And if you have a 2nd Gen the 27F is factory size. If you have a 3rd Gen, fitting a 27F should be no problem.

If you are looking to go big with a Group 31 battery, Odessey and NorthStar are much more equally paired. However, in every spec where there is a difference NorthStar comes out ahead. Note that even the 27F is significantly heavier than stock, and group 31 batteries are even heavier. Tray and support cracking has been reported with heavy batteries and off road use, something to consider.

Looking at every measured metric, NorthStar AGMs are the best battery on the market.

Some Optima background
Optima was made in the USA. In the early 2000s Optima was purchased and the new parent company cut cost and moved production to Mexico. There was some overlap in the mid/late 2000s where both the US factory and the Mexican one were producing batteries. In 2008 I think the parent company closed USA production and shifted all production to Mexico. The Mexican made batteries that are said to not be of the quality the Optima brand was built on. While the USA plant closed in 2008, there was still stock of the USA made batteries that likely lingered around for a little while before eventually all being sold and replaced with Mexican made ones.

I had a yellow top that I purchased in 2005 for winching on my Wrangler Rubicon. That battery was a trooper and did great on long hard winch pulls in well below freezing temperatures. I kept it for 8 years across several vehicles before eventually selling it with a vehicle. I would no longer buy an Optima and instead run a USA made NorthStar AGM.

Selecting a battery size
27F vs Group 31. The NorthStar 27F is 20lbs over stock for a 2nd Gen while offering substantial gains across all spec'd metrics. Going to an even larger Group 31 NorthStar does offer more power, but I would only consider doing so if one really needed the additional reserve capacity. The additional added weight at 76lbs on the front battery tray is a lot and certainly doesn't help the Taco lean. With the deep reserve capacity, one might consider a single Group 31 NorthStar as an easier alternative to a dual battery setup. For my use I chose a 27F NorthStar.

Charging Voltage
AGM batteries require a higher charge voltage than lead acid. Since the Tacoma is calibrated to charge lead acid, that means the charge voltage is insufficient. Lead acid may charge at 14.0v-14.4v. I measured my 4.0 2015 Tacoma hot charge at 13.91v idle, and 14.02v rev.

Right on the NorthStar AGM battery, cycle service charge 14.4v-14.8v.



Very clear the 14.02v charge voltage is insufficient, meaning the AGM battery must be maintained on a plug in wall charger for proper AGM health or the alternator voltage must be boosted. If the charge voltage is not sufficient, battery sulfation will occur and reduce the performance and life of your AGM battery.

Voltage Boosters
These devices work by effectively tricking the alternator voltage regulator into seeing less voltage than it is actually producing thereby causing it to compensate to produce more. So in a simple example if you want to increase the voltage by 0.5v, you cause an artificial 0.5v loss on what the voltage regulator detects and it compensates by raising the voltage an additional 0.5v giving you a net gain.

The Alt-S Circuit <-Needed for this mod
The Alt-S circuit is the circuit used by the voltage regulator to monitor voltage at the battery and adjust accordingly. You can read more on the Toyota Alt-S circuit here. This simple mod is only works in vehicles where the Alt-S circuit exists for the voltage regulator to control the voltage.

In some newer vehicles like the 2016+ Tacomas, the voltage is regulated by the ECU, meaning no voltage regulator Alt-S circuit to spoof. The ECU can be reprogramed for 3rd Gen using OV Tune and likely others, see post #3821 here for details.

HKB Electronics Voltage Boosters
There are a lot of methods to do this mod. I am not interested in hack solutions, I wanted something safe, proven and polished. If this mod goes wrong there are a lot of expensive electronics at risk. HKB Electronics out of Australia offers specifically designed plug and play voltage booster kits for the Tacoma for this exact purpose. Australia has some of the best 4WD companies on the market due to their environment, it is not surprising it is an Australian company to offer this product.

HKB Electronics offers two different products for the Tacoma, a 'fixed' 0.5v booster or an adjustable booster 0.2v-1.0v in increments of 0.2v. Unsure which to get, the obvious answer was clearly buy them both so I can test them and tell you guys which is better.

The AGM specs 14.4v-14.8v cycle service charge (aka alternator charge). Meaning that is the operating voltage target window that we want to adjust the alternator charge voltage to. Based on stock measurements it looks like 0.5v increase minimum.


HKB Adjustable voltage booster


To install, you simply replace the fuse in the 7.5A 'Alt-S' location (shown in upper left) with the modified voltage booster in your under hood fuse box. Basic plug and play.


Adjustable voltage booster shown mounted and set to +0.8v. (0.4v-0.6v recommended)


Here is a photo of the 0.5v booster installed.


Testing
I originally measured the voltage with a multi-meter off the battery. The results I got were somewhat misleading. The problem was the data provided by a multi-meter is a fixed point in time, and charge voltage fluctuates over time. I needed to determine the peak charge voltage baseline so I can then make the required adjustment to set it to 14.6-14.8v, but I cannot accurately tell where the peak is with the multi-meter. I really needed to track the voltage over time so I knew the highs and lows of the data to determine the voltage setting more accurately.

So I logged my stock alternator charge voltage settings over time.



I checked the voltage monitor for accuracy with my multi-meter, it specs to be within 0.03v. I confirmed it meets spec, it reads 0.03v low. In the big picture that is a very small delta but good to know.




I then set my booster up to +0.6v and logged more data.




Over several days the peak voltage recorded was 14.69v, and being 0.3v low, that means peak voltage is 14.72v, up from 14.09 recorded (14.12 actual). I then sent this data off to NorthStar, and they agreed the settings look optimized and no further adjustments were necessary.

Based on my 2015 Tacoma 4.0 130A alternator, the HKD Electronics booster set to +0.6v provides measured maximum performance benefit without overcharging the battery. The 0.5v booster would also do well at 0.1v less, meaning ~14.6v which would also just make it into the optimal 14.6-14.8v charging range specified by NorthStar.

While these settings worked on my truck, you should test to confirm what works on yours to avoid overcharging. If using a multi-meter, it is best to test your truck on cold start after sitting for an extended time such as overnight, as the voltage output will be highest then.

If you are interested in knowing more on charging systems, this is a good overview of how voltage regulators, alternators and batteries work together in the charging system.

Battery Data Logging
I really wanted to log voltage data over time to better help me track and tune my battery and charging performance. After hunting for some products to accomplish this, I found this

$29 Battery Monitor BM2 BM3 Bluetooth 4.0 Wireless Battery Tester 12V Automotive Battery Load Tester,Automotive Charging and Cranking System Monitor Digital Battery Analyzer for Android & iOS

bluetooth battery monitor.





For only ~$32 this provided far better insights to my charging system performance than my $100+ multi-meter, because it gave me the running history over time. This is what I used to share the charging voltage plots earlier in the thread. Note that for best performance, you want to install this on-top of the battery. My picture above is somewhat temporary positioning for testing. If you install alongside the battery the low power bluetooth signal will not be able to broadcast through the lead battery, causing very directionalized range performance. The power draw for the monitor is 1mA, so you don't need to worry about it draining your battery. It also stores up to 30 days of data on board and then will sync it when you are back in range so you don't have any gaps in your data logs.

Battery alarms
Bonus features for those that run camping gear off their batteries at night, or just like more data, it has multiple adjustable power alarms so can have it notify your mobile device at a power percentage level. You can also monitor your battery charge in real time if you are curious on the charge status. It will also notify your mobile device of any abnormal start conditions.

Battery Tie Downs
The Northstar batteries do not fit the OEM tie down well, it is a very tight fit. The top of the battery is too wide causing the tie down to need to go underneath the battery handle as shown in earlier photos. There are aftermarket tie downs that resolve this issue, here are a few:

@Coupe sells adjustable battery tie downs on TW.
Rogue Off Road battery tie down
Off Grid Engineering battery tie down

Headlight Boosting
Halogens increase exponentially to the power of 3.4 with voltage increase, meaning the voltage booster upgrade is substantially beneficial to halogen output. Running some basic math:

Calculated: (14.65v/14.02v)^3.4=1.16 aka a 16% increase over pre-boost voltage.

Measuring actual lux
14.0v = 2014 lux
14.7v = 2335 lux
15.9% measured increase over pre-boosted stock.

0.1 increase difference in theoretical vs calculated is impressive to say the least.

Where to buy:
HKB Electronics of Australia
Adjustable voltage booster
Fixed 0.5v voltage booster

BatteriesPlus
X2 Power NorthStar Batteries (10% off buy online and pickup in store)
24F NorthStar
27F NorthStar
31 NorthStar

 

Another awesome write up! End of the month I’ll order up the booster. How’s the headlight temperature now with the extra voltage?

 

@crashnburn80 will this work on a 19 4runner? I put the 31m from the 17 Tacoma to a 194runner.

 

Good information! Now for this old fart's breif history lesson:

Back when I was a kid, cars had mechanical voltage regulators. It was fairly easy to open one up (most had 2 screws just for that) and adjust the charging voltage. There were some aftermarket voltage regulators with an external adjustment that was even easier. Up until the mid 1950s, most automotive electrical systems were still 6 volt. Really.

There were 8 volt batteries readily available from aftermarket suppliers, so it was fairly common to replace the stock 6 volt battery with an 8 volt, and adjust the charging voltage accordingly. This was not done to make the lights brighter, but to help the anemic starters of the time. The reduction gear starters that are so common now didn't exist then.

The trade off of having a better performing starter, with the roughly 33% increase in voltage was drastically reduced light bulb life. ALL of the lights, not just the headlights.

So, everyone needs to keep this in mind. No, this 16% change isn't nearly as drastic, but it WILL result in reduced bulb life. As long as people are aware of that, no problem.

 

Great write up as usual...I was wondering if something like the NOCO BLSOLAR5 would do the same job since it’s a little more cost effective?...would be great to hear your thoughts on this.

 

Have 2 of those batteries, guess i need the voltage booster.
Guess ill have to order one when i return from Kuwait.

 

Maybe I’m missing something, but the BL Solar5 appears to be a VERY different product. It’s a solar panel charger that you would use when parked to maintain a battery. It’s a standard battery charger, just solar.

The voltage boosters raise the voltage of your alternator while the truck is running, changing your charging voltage while your drive which (among other things) makes an extra at home battery charger/maintainer unnecessary when running a AGM battery.

 

I’ve got a question: why not use a Northstar/BatteriesPlus X2 24F battery? It still has significantly more Reserve capacity (160 vs 90/130) and higher CCA’s (840 vs 530/625) than either stock battery, but is 11 pounds lighter (and only 9 pounds heavier than stock instead of 20 pounds heavier) and $50 cheaper than the 27F.

 

Thanks for the great write-up, as always, @crashnburn80!

You wouldn't happen to know if/where one of these could be installed in a 1st Gen (2001), would you? (Thinking of my son, who's running a Northstar 24F.)

EDIT: According to HKB, the same unit will work in 1st Gen. Just gotta figure out where to plug it in...

Personal preference.

 

Looks like these are a little cheaper (~$86 + ~$19 S&H = ~$105) via HKB's eBay presence, with free shipping on additional units.

 

@skierd ... thanks for your input...I am aware these are VERY different products and I’m not an expert like @crashnburn80 ... but it seems to me that both products achieve the same goal of fully charging the battery... one does it when the truck is running and other does it when the truck is parked...after spending $300 on a battery, I was just looking for a more cost effective way to get the same results...
Aloha!

 

Good question. I did not test temp, I'll do that and add the data to the thread.

If your fuse panel has the 'Alt-S' slot, it should work. I would advise running your own voltage tests with a multimeter to dial in the correct voltage if using the adjustable voltage booster.

Bulb life will be reduced, by much more than the output gained. So this is somewhat of a balancing act. You could use the 0.5v booster or the adjustable set to 0.6v to get the minimum necessary charge voltage and slightly better bulb life, which would still be an improvement over stock charge levels.

The solar charger is designed for lead acid batteries, so the charge voltage is not likely at AGM required levels. This doesn't mean it cannot charge an AGM battery, but it will not serve the same purpose or function as the voltage booster. If concerned about cost effectiveness, even the 0.5v booster, while just slightly on the low side will significantly improve the charge voltage for the AGM over stock.

All good points! The NorthStar 24F would be a great battery choice for stock replacement. Typically it seems many looking at AGMs are often looking for greater capacity to support running aux gear like fridges or high loads like winching, etc, which is why I focused more on the larger sizes. Nothing wrong with staying with the stock 24F though, as you point out specs are improved across the board while saving weight and cost over the 27F.

The prices on HKB's site are in AUD! I should have pointed that out. The AUD to USD conversion is currently .72, meaning purchasing from them directly is also $86. Although ebay purchasing would make it a bit easier for many.

 

@crashnburn80 is there a preference over which one to buy? Just the fuse or the one with the dip switches?

 

I have a group 31 X2Power in my truck so I am going to have to do this too. I also have an Group 24 Optima house battery that is disconnected when truck is off. Is there a way to have the Optima trickle charge the X2Power up to the voltage required? to maintain a good charge???

 

Following as I dont trust my factory battery much down here in So. Florida. Coming up on the 3yr mark for it.
Gotta check my panel, but this looks like it should work in a 3rd gen also?

 

The adjustable one allows you to dial it in. The fixed fuse version gives you a fixed bump. The data I shared was from my truck, based on my trucks measurements the adjustable one was a better fit. Either one will be an improvement over stock. The 0.5v booster will likely be fine for many but the adjustable one allows you to set it in the sweet spot.

I’m not sure I follow. If you have the correct charge voltage, you don’t need to trickle charge the X2 Power, that is typically done as maintenance when the vehicle does not support the correct charge voltage.

My OEM battery died at the 3.5 year mark. The mod will work for 3rd gens as well.

 

UPDATE: Based on the research of a bunch of folks in this thread the concern below isn't anything to worry about. In fact in this case the booster should increase the life of the battery.

Original post follows:

Erm... I could be wrong but this seems like a bad idea. AGM does not like being held at its cycle charge voltage once full - will result in drastically reduced battery life. Even more so in a hot climate. Indeed for “cycle applications” you want the higher charging voltage but a starter battery is not a “cycle application” at all. A starter battery is much closer to a “float application” in which the battery is almost always near full charge. In fact some AGM manufacturers recommend doing exactly the opposite of what you have done here - they want you to check that the alternator voltage meant for a flooded lead acid isn’t going to be too high a float voltage for the AGM.

Again, I could be wrong for sure but from what I’ve read you’ve gotten this backwards. In the rare case you use that battery in deep cycle then you’ve helped. For the 99% of the time it wants the float voltage instead you are sending the battery to an early grave with the boosted voltage.

 

I think you are right. I was focused on cycle charge, but agree starting is typically closer to float. Cycle charge voltage boost would then be to charge the battery after it has been drawn down, not for maintenance. That isn’t a differentiation the OEM alternator is not going to make. I’ve removed the voltage booster purchase links for now.

Edit: After discussions with NorthStar directly, the above concerns are unfounded. In-fact AGMs in automotive use should see regular charge voltages of 14.6-14.8v, meaning you must use a standalone wall charger or add a voltage booster and tune it to see peak voltage in the 14.6-14.8v range.

 

I agree with the above assessment and have removed the voltage boosters from the thread as I do not want to have people mistakenly follow something that would harm their battery, making this really just a battery comparison thread. I'll add info about mounting cage options for the Group 31 batteries and the adjustable aluminum tie downs for the Northstar since they do not fit well in the OEM bracket.

 

Well crap, I really liked this thread I was looking forward to doing something to make my battery system better.

Here is what I found on Northstar
Will there be a list of vehicles that we do not want to sell product into because of their alternators?
No, the number of vehicles and systems that exist today would make it difficult to identify, manage and update a list on a regular basis. So instead we have set charging the charging parameters of between 14.1 volts and 14.8 volts as an acceptable charging range. So long as the battery charging remains within these tolerances the battery will perform to its engineered specifications. It is recommended that for every application the customer test the charging voltage to ensure it is within the acceptable limits.

For my optima battery:
Recommended charging information:

• Alternator:
  • 13.65 to 15.0 volts, no amperage limit.
• Battery Charger:
  • 13.8 to 15.0 volts, 10 amps maximum, approximately for six to twelve hours.
• Cyclic Applications:
  • 14.7 volts, no current limit as long as battery temperature remains below 125°F (51.7°C). When current falls below one amp, finish with two-amp constant current for one hour.
• Rapid Recharge:
  • Maximum voltage 15.6 volts (regulated), no current limit as long as battery temperature remains below 125°F (51.7°C). Charge until current drops below one amp.
• Float Charge:
  • 13.2 to 13.8 volts, one amp maximum current, time indefinite (at lower voltage).
  • Strictly adhere to all limits.

I am thinking 14.1 to 14.8 should be good for me any time. Now I have to check