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I have Odyssey but you should also consider northstar
SDCementTacoTruck
3️⃣ Silver
I'm thinking of going with the genesis off-road duel battery kit. Other duel kits place the 2nd battery where I already have a air compressor so this solution looks pretty solid. I also really like the features, including accessory hook up and boost for jumping yourself which may come in handy if overlanding.
I intended to go group 31 but then my battery died and the best I could do with little time was a 27f yellow top from O'Reillys. Minor trimming to the tray was necessary. I'm happy with it and haven't needed more as far as truck mods go. We do have two group 31s in the trailer though...
I also find myself ready for a battery upgrade. From this thread and others I'm seeing this is what people are running:
I did see a good question from zweisman about the need for tray modification with the 31s. Is that necessary?
- yellow top 27f
- northstar
- Odyssey marine group 31 agm
- Odyssey Extreme Group 35
I did see a good question from zweisman about the need for tray modification with the 31s. Is that necessary?
Heh, looks like it fits fine to me!
I've had great luck with both Odyssey and Optima, but also have ran the NAPA Legend Premium AGM Batteries. Depending on their cost at your local NAPA they can be a good value. I think they are rebranded DEKA.
GhostChilly
2️⃣ Bronze
Is an alternator voltage mod required for these larger deep cycle batteries to charge properly?
GrandmasKid
1️⃣ Getting Started...
That's the question I can't find an answer to. I've searched the web and the service rep at my local Toyota dealership didn't think the alternator output is controlled by the ECU, but from what I read on the internet it is. Also, odly the dealership didn't want me to buy a Tpyota Truestart battery. I have trust issue when it comes to Toyota dealerships. I'm not at all sure how I'll replace my stock battery on my 2021 Off Road when the time comes.
AGM's want more voltage than the stock alternator puts out. It will die earlier and never be fully charged at stock output. It can be changed with a OV/VF tune. Not sure how else it can be done on the 3G, but there are various ways to accomplish it on other vehicles. You can routinely hook up a battery charger. I already have the tuner, so I just use that.
I've gotten way more longevity out of my AGMs after changing my alternator settings with VF Tuner.
I wondered the same thing.
Toyota will recommend the TrueStart Battery. It is AGM. It's known AGM requires higher alternator output.
They offer a 2 year replacement warranty. Then years 3-7 the warranty is pro-rated to 50% if the dealership installs it, so I guess that's half off the next battery. Are there any Toyota vehicles that have higher alternator output from factory?
Just a word of dissent: You don't need to change the voltage for the AGM. It's a starter battery, not a house battery. It should never need to get above float charge, which is in spec for the stock alternator output. 14.6 is the fast charge voltage and batteries don't like to be at that voltage all the time. A proper charger will vary the charge voltage depending on the state of charge of the battery. The charging system in a car is constant because it's just meant to maintain a charge, not fast charge.
If you have a second battery that is an AGM you would want to have a charger that can vary the input voltage so that it can keep it fresh because presumably, you'll have a load on it when the engine is off.
I'm getting my info from an electrician who works on off-grid solar systems and a friend who runs AGMs in 6 different vehicles with no modifications.
I just installed an Optima Red Top (because it was the only thing available) without mods. If it dies early, I'll come back and admit my mistake.
-M
If you have a second battery that is an AGM you would want to have a charger that can vary the input voltage so that it can keep it fresh because presumably, you'll have a load on it when the engine is off.
I'm getting my info from an electrician who works on off-grid solar systems and a friend who runs AGMs in 6 different vehicles with no modifications.
I just installed an Optima Red Top (because it was the only thing available) without mods. If it dies early, I'll come back and admit my mistake.
-M
There’s a lot of real evidence that shows not fully charging an AGM severely cuts it’s lifespan.
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Smitty
6️⃣ Aficionado
Well if that's the case, what's the best battery we should put in our rigs?
A good quality lead acid battery? I already had OV tune, so I was able to change the charging voltage. Another not so convenient way would be to top an AGM off with a charger. You also aren’t able to utilize the amp hours you pay for with an AGM if you can’t fully charge it. So the question becomes, is the extra money worth it for advantages you can’t fully utilize?
Supposed to last longer and have lower standing discharge rate. They are more durable to shock and vibration. Recharge faster. Then they are typically 30% lighter. Less Taco Lean. More level. Look cooler. Because looking cool is all that matters.
I did find this article: AGM Battery Charging: Stages – workshoppist.com (https://workshoppist.com/agm-battery-charging-stages/)
It states: " Never hold an AGM battery at the absorption voltage longer than about 15 hours, as this risks overcharging the unit. A smart charger steps down to float automatically; a regular charger must be disconnected."
If anything maybe set your alternator to a "slightly higher" float voltage per the battery spec rather than the 14.6 range absorption voltage.
Nevertheless, all this discussion about voltages for the starter battery has convinced me that I definitely want a second deep-cycle battery with a proper charger to run my loads when the engine is off. Specifically, the 12v fridge that I run in my truck. In my experience, running a fridge overnight or while parked for extended periods discharges the battery a lot, necessitating it needing a proper charge cycle, rather than just maintaining, which the vehicle doesn't really do.
-M
It states: " Never hold an AGM battery at the absorption voltage longer than about 15 hours, as this risks overcharging the unit. A smart charger steps down to float automatically; a regular charger must be disconnected."
If anything maybe set your alternator to a "slightly higher" float voltage per the battery spec rather than the 14.6 range absorption voltage.
Nevertheless, all this discussion about voltages for the starter battery has convinced me that I definitely want a second deep-cycle battery with a proper charger to run my loads when the engine is off. Specifically, the 12v fridge that I run in my truck. In my experience, running a fridge overnight or while parked for extended periods discharges the battery a lot, necessitating it needing a proper charge cycle, rather than just maintaining, which the vehicle doesn't really do.
-M
GrandmasKid
1️⃣ Getting Started...
This is frustrating and a bit strange to me. My '21 Tacoma Off Road came with a barely adequate battery, a Clarios 582 CCA Group 24F. I use it mostly for towing a small camper and light "Off Road" (really on slightly rough road and a couple of beach surf fishing trips). Anyway I noticed the "Check Charging System" message popping up when I first got it and was told by the dealer that it just meant the motor wasn't running and I was draining the battery so I should just turn the car off so as to not drain the battery too much. OK, so I buy a multimeter and start digging around. After two years and only 16K miles of towing/camping/light off roading, and turning electronics off as soon as I can after the motor stops running, I find by my meter a reading of 12 volts after sitting overnight. So, I think my lead acid OEM battery is getting weak and I start looking for a replacement because I like to stay ahead of problems and I know what it's like to be stuck out in the boonies with a dead battery. It wasn't any fun. Toyota for some reason (I suspect money) decided to put a low capacity non-AGM battery in their "Off Road" built for towing and the AC outlet in the bed, truck. Searching around on the internet I read that the deep cycle AGM ideal batteries require more voltage than my vehicles alternator puts out. Figuring my dealer would know what to do I talk to the service rep. at my last free maintenance that came with the truck. He doesn't want to sell me a Toyota TrueStart battery. Instead he offers an AGM battery branded by someone I never heard of for $239 plus tax. When I mention that my alternator only pushes out 13.6 volts and I've read that's not enough to fully charge an AGM battery he doesn't seem to know what I'm talking about. So thinking that maybe I don't know what I'm taking about I go home and do more digging on the internet. Several places I read that on 3Gen Tacomas the alternator voltage delivery is controlled by the ECU. I had mentioned that to the dealer service rep and he told me the alternator voltage is not controlled by the ECU. Who do you think is right? Isn't it strange that for the most popular small truck in the USA there doesn't seem to be a straightforward answer as to how to best replace the battery? Maybe if I keep my battery on a trickle charger I can squeeze more use out of it without getting stuck and the answer will seem clearer later. If I need a tune to boost the voltage output of my alternator would that void my Toyota warranty? Any insight into this issue will be greatly appreciated.
Well one of your questions is easy, I think that I am right. You don't need to change your voltage output for an AGM. And float charging at the absorption voltage is bad.
-M
GrandmasKid
1️⃣ Getting Started...
So far it's looking to me like if I replace with an AGM I would just fully charge with my house AC charger set on AGM charging every once in a while. Someone suggested once a month. Is it right float charging at 13.6-13.8 volts while driving is OK for an AGM? Perhaps the better thing to do is just forget about going with an AGM and go with a good lead acid. I just don't know yet. Thanks for your reply. I won't overcharge an AGM as I hear that's a quick way to ruin them. I wonder if the voltage regulator inside the alternator is smart enough to adjust to whichever type of battery suggested by retailers we put into our trucks. That would be great.
I slowly killed at least two pairs of Optima Yellows and Odysseys in my last third gen before I started looking deeper (heh) into what was going on. If you are only using an AGM for a starting battery and not using it for any off-grid power, maybe you can make it last. But draining down an AGM with lights, fridges, etc, and then not charging it with a proper profile afterward slowly kills it in my experience. And even though I had a dedicated starting battery, I still had issues with the Tacos low charge voltage on that battery.
What I did was edit the alternator settings in VF Tune, it's still not 100% perfect, as you can't really do a proper profile, but I just increased the charge voltage to like ~14.2 ish from high 13's or whatever it was at.
So far, I've been on the same pair of AGMs for 30K miles leaning into them pretty hard. Like 48+ hours running a fridge without starting the truck hard.
My other suggestion is to toss a 50-100W solar panel on the truck and let a solar controller keep your AGMs topped off. Or just plug the truck into a good charger every week or so.
I'm not an electrical engineer (or any kind of engineer), so this could all be wrong. It's just my experience.
What I did was edit the alternator settings in VF Tune, it's still not 100% perfect, as you can't really do a proper profile, but I just increased the charge voltage to like ~14.2 ish from high 13's or whatever it was at.
So far, I've been on the same pair of AGMs for 30K miles leaning into them pretty hard. Like 48+ hours running a fridge without starting the truck hard.
My other suggestion is to toss a 50-100W solar panel on the truck and let a solar controller keep your AGMs topped off. Or just plug the truck into a good charger every week or so.
I'm not an electrical engineer (or any kind of engineer), so this could all be wrong. It's just my experience.