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Discussion Starter #1
I'm getting ready to replace the stock Panasonic with a Northstar AGM, either 24F or 27F (haven't decided). I'm a pretty religious user of battery tender's, so would be buying an appropriate charger meant for an AGM, either CTEK or Batter Minder. Would regular use of the charger mitigate the lower voltage concerns related to charging the AGM from the stock charging system, or is it pretty much a given that I should be looking at the HKB voltage booster as well? I don't run a fridge, but I do have added lights and a winch. The FJ is 2014 and a daily driver.

I appreciate any input.
 

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If its a daily driver you have nothing to worry about and when you park it for extended times the CTEK would be the right addition.
 

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If I remeber correctly AGM batteries require more voltage than what the stock system puts out


Enter HKB

I have it and on a regular bassis it is at 14.6v and on cold days when the load is greater it is at 14.98v

Cheap insurance
 

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G'Day,
They are two different tools.
A tender will keep your new Bat in top condition when the FJ is parked.... the HKB only works when the engine is running ... and allows the AGM to become fully charged ...without the HKB the alternator will not keep the Bat fully charged ... so imho ...both are desirable
Cheers
Baz
 

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Discussion Starter #6
I appreciate all the input. I had a visit with the gal who works at the local Batteries Plus regarding their made by Northstar AGM batteries. They have a 20% off discount right now if I buy online and pick up at the store. We discussed warranty issues and she advised that the biggest issue is when folks install the AGM in a vehicle that does not have high enough voltage, allowing the battery to drop below a certain level. B+ won't warranty batteries if they are found to be undervoltage or something like that. She stated that's easily avoided by keeping the battery on a charger from time to time. They had a 24F there that was the exact same dimensions of my current Panasonic ( but 15lbs heavier), so it will fit easily with all the other electronics I've added in the engine bay.

My Bantam switch controller has a voltage readout that I can monitor on my cell phone. During my drive to the store it steadily read 14 to 14.2, with an occasional drop momentarily to 13.8. Sounds like a small bump from the HKB booster would be just what I need when I'm out in the back country and don't have access to a charger. I was a bit worried about some posts on the forum that described the higher voltage having an effect on the longevity of electronics in the FJ (bulbs mostly?) I could see buying that HKB module that has variable output, so I can run it at it's lowest boost when commuting and then bump it up when I'm going to be offroad for longer periods.
 

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I've been running an AGM with just a battery tender and never had any issues (without adopting any voltage up).
The "issue" would simply be shorter battery life. Until battery performance noticeably declines there is no easy way to tell if you have an issue or not.
 

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Currently contemplating the same issue. I missed the fine print when I upgraded to the Odyssey PC1500 battery 6 or so months ago and didn’t realize there was special charging recommendations. So far I see a vote for the charger, a vote for the module, and a vote for both.

Only reason I ended up here is because I am researching alternator upgrades. Mine seems to be on its way out and I’m wondering if the Odyssey battery charging demands caused it to overwork/fail. Or perhaps the components attached to it.. I too am running added lights and winch, plus occasionally the compressor.
 

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I have the one from HKB. I've had it for many years.

No issues with lights, etc.

I also top up the batteries every once in a while with a Nocco Genius battery charger/maintainer.

I've had the same Optima blue top for many years as well.... so it seems to be happy.
 

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I have the Northstar AGM battery in the 27F size . No fitment issues at all .
Also got the battery voltage booster from Demello Offroad . First one didn't work so Larry built me one because I needed one wired backwards . 2007 FJ . Great people to work with !
 

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All batteries have a specification on how much voltage each cell needs to be charged to for a nominal/equalized charge.

They also have a specification on the high charge voltage limit for each cell which should be followed also.

The life of the battery depends on keeping the charging between these two specifications.

The factory charging system is set up for this and that is why the Panasonic battery can last, like mine, at 8 years old and still chugging along.

If the AGM batteries need a little more voltage, add the part that ups the voltage to it, drive it regularly and your good to go.
 

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Discussion Starter #15
Well, I sure appreciate all the replies and discussion on this topic. I wrote to and received a nice email back from Leigh, who runs HKB and I'm feeling much better about the idea of trying the Mk3 voltage booster. Unfortunately, the forum discount for HKB is no longer in effect, but it seems a useful upgrade nonetheless. I was also curious about the state of my stock Panasonic and was surprised to learn that the battery my 2014 FJ shipped with seems to be a smaller version of what the older FJ's came with. My Panasonic is model 80D26L which I think barely has 600CCA. My ComeUp winch says I need a minimum of 650 CCA to be safe. So, I'll be picking up that "Northstar" 24F from Batteries Plus, because it will fit perfectly in that same space as my stocker and has 840 CCA.
 

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How about a solar panel on the dash plugged into the cig lighter. That is how I kept the dual batteries charged on my Powerstroke when it sat for months at a time. I have Autozone Platinum AGM batteries in both a my cars.
 

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Would regular use of the charger mitigate the lower voltage concerns related to charging the AGM from the stock charging system, or is it pretty much a given that I should be looking at the HKB voltage booster as well?
Why did you choose AGM? AGMs typically require a higher voltage to fully charge, so you'll need some higher-than-factory voltage solution - the voltage booster, the battery tender, or both - to get your AGM battery back to full capacity.

Did you buy the AGM battery because of its total energy capacity? Will you always be able to hook a battery tender up in-between times where you want the full capacity of the AGM battery?

If your answers to those questions are "yes," and "no," respectively, then you need the voltage booster so that your FJ's own electrical system can bring the battery back to full capacity.

Without that, the "only*" time the battery will be at full capacity is when you drive it out of your driveway after just taking off the battery tender. This may (allegedly, depending on the battery and the manufacturer) reduce the total life of the battery, but most importantly... if you bought a big AGM battery for its big capacity, you'll be missing out on something you paid for by not fully recharging the battery - just like only filling your gas tank 3/4 full instead of all the way.

My ComeUp winch says I need a minimum of 650 CCA to be safe.
Aha!

Your alternator cannot produce anywhere near 650 amps; if that's what the winch will try to draw (I don't know which winch you have, but my Warn M8000 will draw up to 435A at maximum load), basically all of that has to come from the battery. If you're thinking of a big battery to make sure that your electric winch will always have power to recover you when you need it, then you will want a fully-charged AGM battery in the middle of a trail (which is not right after you drove away from the battery tender), so you will want the voltage booster.
 

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Discussion Starter #18
Why did you choose AGM? AGMs typically require a higher voltage to fully charge, so you'll need some higher-than-factory voltage solution - the voltage booster, the battery tender, or both - to get your AGM battery back to full capacity.

Did you buy the AGM battery because of its total energy capacity? Will you always be able to hook a battery tender up in-between times where you want the full capacity of the AGM battery?

If your answers to those questions are "yes," and "no," respectively, then you need the voltage booster so that your FJ's own electrical system can bring the battery back to full capacity.

Without that, the "only*" time the battery will be at full capacity is when you drive it out of your driveway after just taking off the battery tender. This may (allegedly, depending on the battery and the manufacturer) reduce the total life of the battery, but most importantly... if you bought a big AGM battery for its big capacity, you'll be missing out on something you paid for by not fully recharging the battery - just like only filling your gas tank 3/4 full instead of all the way.



Aha!

Your alternator cannot produce anywhere near 650 amps; if that's what the winch will try to draw (I don't know which winch you have, but my Warn M8000 will draw up to 435A at maximum load), basically all of that has to come from the battery. If you're thinking of a big battery to make sure that your electric winch will always have power to recover you when you need it, then you will want a fully-charged AGM battery in the middle of a trail (which is not right after you drove away from the battery tender), so you will want the voltage booster.
That is an excellent summary. I chose AGM for the deep cycle ability to run my added lights and to power the winch if I have a need. The winch is a ComeUp 9.5 which draws 380 amps at full pull. I have several Batter Tenders in the garage which I use regularly on my motorcycles and the FJ. The one for the FJ is a 3amp charger and I installed the quick release cable end on the battery so I can easily plug the charger in whenever I pull into the garage. I've always had a thing about keeping the batteries topped off when I'm not driving.

I've also decided to order the Mk3 voltage booster from HKB. Seems to be well supported and designed in a way that shouldn't have any negative effects on the vehicles electronics.

Thank you again for everyone's input and discussion. I will post an update when the battery is installed and when I get the MK3. Apparently it can take several weeks for the booster to arrive from Australia. :)(y)
 

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I ordered mine on 12/09/2019 and it arrived on 12/30 via US certified mail.
I know it takes a while but (as usual) it is worth the wait as it keeps my battery fully charged and happy.
 
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