AGM battery charge controller
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03_4x4Runner
Senior Member
Nothing is needed. I have been running my agm for two years now and 10 years on my old 4th gen with no problems.
Tuc4R
New member
The alternators on out trucks don’t put out enough amps to fully charge an AMG batter. That’s why it’s a good idea to top off your battery at least once a month. AMG batteries don’t like being discharged below 50% and 75% on cheaper batteries. I have a Noco battery maintainer I use every couple of weeks. This will prolong the life of you battery greatly!
There are many threads on this exact subject.
There are many threads on this exact subject.
Speedsurfer
New member
There are a lot of posts on this topic. After reviewing the information I felt that AGM batteries were better off charged at slightly higher voltage than than traditional FLA batteries. You could to this with a AC DC home charger like the CTEK 7002, a PWM or MPPT Solar charge controller, or a voltage boosting fuse like https://www.hkbelect.com/product/206-mk3-micro-blade-75a-electronic-fuse-version-2017/.
I actually have all 3 above and feel that your AGM batteries will probably last longer due to reduced sulphation if you keep charging them close to 14.5 volts as much as possible. This is especially true if you don't drive that much. That's not to say you couldn't get away without charging, but there are reports of people who killed AGM batteries within a couple years who did not charge.
I actually have all 3 above and feel that your AGM batteries will probably last longer due to reduced sulphation if you keep charging them close to 14.5 volts as much as possible. This is especially true if you don't drive that much. That's not to say you couldn't get away without charging, but there are reports of people who killed AGM batteries within a couple years who did not charge.
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it might not have been an issue on 4th gen, but you definitely need to do a couple things on 5th gen
voltage booster fuse is the cheapest solution- you can get them on ebay for <$30 or get the HKB fuse for $70; you can also get a charger to maintenance charge the battery at home when you can plug it in; or you can upgrade the alternator. I have the HKB fuse, I also tried the ebay fuse but the diode was on the wrong side so it wouldn't fit in the fuse box (if you tell them its a 4runner they can reverse the diode so you can install it in the other direction and it works, it's just an add-a-circuit with a diode attached)
there are 2 issues with upgrading to AGM- the additional capacity and the required charging voltage. AGM batteries require a higher voltage, usually around 14V+ and the 5th gen 4runner is usually only about 13.3V. Any of the items mentioned above will solve the voltage issue or minimize the impact. the second issue is the capacity, this is not an issue if you drive frequently but if you have a constant load on the battery, like a fridge that discharges the battery, and don't drive much, the alternator won't be able to fully recharge the battery in the limited amount of time. A high output alternator or maintenance charging can solve this issue. I recently moved and now have a short 10-15 minute commute but used to have a ~1hr commute. When I had the long commute I was generally driving enough to recharge the battery however now that I have a short commute if I don't have solar connected and don't maintenance charge by thursday or friday the battery is sufficiently depleted that i've seen the fridge shutoff.
voltage booster fuse is the cheapest solution- you can get them on ebay for <$30 or get the HKB fuse for $70; you can also get a charger to maintenance charge the battery at home when you can plug it in; or you can upgrade the alternator. I have the HKB fuse, I also tried the ebay fuse but the diode was on the wrong side so it wouldn't fit in the fuse box (if you tell them its a 4runner they can reverse the diode so you can install it in the other direction and it works, it's just an add-a-circuit with a diode attached)
there are 2 issues with upgrading to AGM- the additional capacity and the required charging voltage. AGM batteries require a higher voltage, usually around 14V+ and the 5th gen 4runner is usually only about 13.3V. Any of the items mentioned above will solve the voltage issue or minimize the impact. the second issue is the capacity, this is not an issue if you drive frequently but if you have a constant load on the battery, like a fridge that discharges the battery, and don't drive much, the alternator won't be able to fully recharge the battery in the limited amount of time. A high output alternator or maintenance charging can solve this issue. I recently moved and now have a short 10-15 minute commute but used to have a ~1hr commute. When I had the long commute I was generally driving enough to recharge the battery however now that I have a short commute if I don't have solar connected and don't maintenance charge by thursday or friday the battery is sufficiently depleted that i've seen the fridge shutoff.
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MikeYQM
New member
Thank you very much! I think the HKB is exactly what I’m looking for. I don’t have anything constantly drawing from the battery yet, but I do want to have my battery topped up for when I do.
I’ll also add solar prior to any major additions as well and keep charging it overnight on occasion with my batt charger.
Sent from my iPhone using Tapatalk
I’ll also add solar prior to any major additions as well and keep charging it overnight on occasion with my batt charger.
Sent from my iPhone using Tapatalk
my friend has AGM batteries in his lambo sport cars I installed them for him.
these vehicles do charge at a higher rate than the 5th gen toyota charging system. AGM batteries are the best . I do not put my vehicles to sleep in the off season so I use cheap costco batteries $80..
In winter when the cold temps hit the Toyota does charge at the normal higher volts .. 14-14.5 volts DC.. when I drive down south in the winter the Toyota volts do drop to 13.25 volts last winter I thought that the alternator was failing but that is how these operate.. in hot temps ac on the alternator drops the volts down. I use the scan gauge II to monitor the exact volts .
there are computer controlled charging devices that you can mount in your vehicles . I purchased 3 of these for my friend.. and I also got one for my boat battery that sits for 8 months.. boat battery still working good ..over 5 years old. the computer controlled charger charges 2 amps then when it senses it is charged it shuts down .. the it will come back on and check to charge it again. volts on charge do rise to the 14.5 vollt range.. cost on these are $25 USD.. small waterproof easy to place under the hood away from any heat ..
your vehicle isn't typical if it sees any kind of sustained 14.V+ charging
check your battery stats to see the max voltage, i doubt you would ever see anything above that. also, when checking your battery specs look for the temperature compensation.
for example my battery charging specs are 13.80 to 14.60 V at 77 degrees F. When temperatures are below 77 you actually need to increase the voltage, my temperature compensation is add 18mV per 1.8 F (and subtract 1.8mV per 1.8F in temps above 77). For my battery that works out to 13.62V-14.40V at 95 F or 14.32V-15.12V at 25 F.
My problem has actually been that in very cold temperatures even with the HKB the voltage is still too low until you drive enough that the battery can warm up a bit.
check your battery stats to see the max voltage, i doubt you would ever see anything above that. also, when checking your battery specs look for the temperature compensation.
for example my battery charging specs are 13.80 to 14.60 V at 77 degrees F. When temperatures are below 77 you actually need to increase the voltage, my temperature compensation is add 18mV per 1.8 F (and subtract 1.8mV per 1.8F in temps above 77). For my battery that works out to 13.62V-14.40V at 95 F or 14.32V-15.12V at 25 F.
My problem has actually been that in very cold temperatures even with the HKB the voltage is still too low until you drive enough that the battery can warm up a bit.
jrandom
New member
Just FYI the truck itself has a constant low amperage draw when it isn't running.
At the risk of being repetitive, search around a little bit there is already a ton of info to sift through.
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007Tacoma
New member
I mean... I think I see what the concern is, but then again I don't...
Okay. I am going to throw down some assorted musings...
...that's just what I am getting from my understanding. As Radiohead sang: "I Might Be Wrong".
Reason I stated all this is 2 part:
Okay. I am going to throw down some assorted musings...
- The 4Runner's (5th Gen) Alternator outputs ~13.3v regularly?
- Standard Lead Acid Batteries do not require more than 13v to charge.
- AGM Batteries require >14v to charge?
- Changing the 4Runner battery from Lead Acid to AGM is "okay" as long as you have higher charging voltage?
- The AGM battery will not fully charge without some kind of modification?
- A voltage booster fuse (placed in the ALT-S fuse slot under the hood) is the cheapest way to fix this.
- The Voltage Booster Fuse tricks the voltage controller and alternator to think more voltage is needed.
- The best way to fix charging an AGM battery is to use a trickle charger or battery conditioner.
...that's just what I am getting from my understanding. As Radiohead sang: "I Might Be Wrong".
Reason I stated all this is 2 part:
- Has anyone created a thread or how-to on making a voltage booster? ...or at least shown results of one on the 4Runner?
- I have been running a Batteries+ X2Power 24F AGM for past year. Am I damaging it by not using a voltage booster?
[MENTION=73851]007Tacoma[/MENTION]
1. yes
2. i don't know if that's a rule for all, but yes the stock charging is sufficient for oem or replacement batteries
3. generally, but some don't require as high a voltage. at 77 degrees mine requires 13.8-14.6
4. see the last paragraph of my post
5. correct, if your voltage is too low, it won't fully charge
6. it solves the voltage issue, not capacity though
7. it lowers the voltage of the circuit the alternator is monitoring by using a diode
8. the best way would be to replace the alternator, plugging into a charger is just a lot less expensive
1. you can make one with a diode and add-a-fuse, there are plenty of results including 3 posts above yours. I think this is the diode the ebay ones use. [MENTION=153545]LOLSNOW[/MENTION] went all fancy and added a pcb and switch to his.
2. yes it's very likely you are not fully charging the battery which can cause sulfation which will shorten the lifespan and capacity of your battery. i don't see any specs listed for your battery though to confirm, you may need to contact batteries plus
1. yes
2. i don't know if that's a rule for all, but yes the stock charging is sufficient for oem or replacement batteries
3. generally, but some don't require as high a voltage. at 77 degrees mine requires 13.8-14.6
4. see the last paragraph of my post
5. correct, if your voltage is too low, it won't fully charge
6. it solves the voltage issue, not capacity though
7. it lowers the voltage of the circuit the alternator is monitoring by using a diode
8. the best way would be to replace the alternator, plugging into a charger is just a lot less expensive
1. you can make one with a diode and add-a-fuse, there are plenty of results including 3 posts above yours. I think this is the diode the ebay ones use. [MENTION=153545]LOLSNOW[/MENTION] went all fancy and added a pcb and switch to his.
2. yes it's very likely you are not fully charging the battery which can cause sulfation which will shorten the lifespan and capacity of your battery. i don't see any specs listed for your battery though to confirm, you may need to contact batteries plus
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ChrisJHarney
New member
I just purchased a Battery Tender 3A charger/maintainer. It claims to self adjust for AGM batteries. I usually put it on the truck about once a month. Is this an acceptable method for maintaining the battery short of performing the volt boost mod or changing my alternator? Thanks.
03_4x4Runner
Senior Member
I still do not get it. As I said in the second post I have been running my Odyssey battery for 2 years with no mod and no problems. This thread got me curious on my charging voltage so I checked it several times. It is 13.8-13.9 every time. You would think that if something needed to be changed it would be sold by Odyssey or Optima. I do a lot of short trips and it cranks over very fast every time. I do not want to try to second guess what fuse or whatever to use.
Edit: After posting this I connected my Optima charger to the 4runner battery to see how long it would take to charge it to 100%. In the test mode it said battery was normal before charging and only took a few minutes to top it off. This is the charger I used. https://www.amazon.com/Optima-Digit...1541004512&sr=8-1&keywords=optima+charger+400
Edit: After posting this I connected my Optima charger to the 4runner battery to see how long it would take to charge it to 100%. In the test mode it said battery was normal before charging and only took a few minutes to top it off. This is the charger I used. https://www.amazon.com/Optima-Digit...1541004512&sr=8-1&keywords=optima+charger+400
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Odyssey's warranty card states it best: "For applications where an alternator is present, the alternator must deliver between 14.0V and 14.7V when measured at the Battery’s terminals"
http://www.odysseybattery.com/documents/US-ODY-WS-AA.pdf
By the way, I no longer carry the voltage boosters - they were a limited run since demand is not really that high for a booster that will only work for a 5th gen 4runner.
Louisiana Overland
New member
I have an odessey grp34 battery and have been running a dometic cfx50 24-7 in the truck now for about 4 months.
I installed the hkb voltage boosting diode.
Im currently living with my girlfriend and have a 40 minute drive to and from work. For the last two weeks i made two attempts to charge the battery with a noco smart charger. It runs its routine for a few minutes thrn shows 100%.
Prior to moving in with her I drove 20 minutes less per day. At that time it would take several hours to get the battery from between 75% and 100% to 100%.
The booster absolutely is needed with an agm. Your driving time per day will decide if you need any additional maintanance charging.
I installed the hkb voltage boosting diode.
Im currently living with my girlfriend and have a 40 minute drive to and from work. For the last two weeks i made two attempts to charge the battery with a noco smart charger. It runs its routine for a few minutes thrn shows 100%.
Prior to moving in with her I drove 20 minutes less per day. At that time it would take several hours to get the battery from between 75% and 100% to 100%.
The booster absolutely is needed with an agm. Your driving time per day will decide if you need any additional maintanance charging.
if you get that consistently it's not surprising you haven't noticed a decrease in performance, but that is not typical for 5th gens. Are you actually watching that while you drive or are you just testing with a voltmeter as a single sampling point? mine would often be about 13.8 shortly after starting up, but then when driving it drops down would stay in the 13.3-13.5 range. If you actually have a consistent 13.9 i probably wouldn't do anything either, it's not quite in spec but i'd bet it's close enough that any reduction in lifespan is marginal, but if you are only taking a single sample i bet your voltage is actually in line with the typical lower observations
