Dual Battery Setup : LiFePO4 vs AGM vs Deep Cycle, Lead Acid, etc

Octanejunkie

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@Mike_taco4x4 Just do a Deka AGM. They seem to be one of the better options for the price these days.
I held off one day on Rock Auto and they dropped price on the battery by $5 but shipping got cut in half. I ordered the Deka 9A34R for $210 delivered

I spent the $$ I saved on a battery tray to hold the larger battery in place
 
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I've run an AntiGravity LiFePO4 for about a year now in my daily driver 2nd gen taco. Maybe a couple dozen starts around 10 degrees or less a few of them into the negatives, but only this past winter so far. A handful of 3hr+ drives. Makes the starter sound like its on the roids too, cranks quick. LiFePO is much more stable than the older lithium battery styles like you guys are referring to, especially with a good battery management system built in like the antigravity ones have. Lotsa sportscars have them as factory options now
Don't get me wrong tho, i think i'm one of the first few to get one for a taco so knew i was taking a bit of a risk trying it out. And i'm not sure how it would handle quick temp drops like yall get in the desert but idk if that'd be any different from me running mine on cold days with it in the stock spot
 

Stairgod

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I've run an AntiGravity LiFePO4 for about a year now in my daily driver 2nd gen taco. Maybe a couple dozen starts around 10 degrees or less a few of them into the negatives, but only this past winter so far. A handful of 3hr+ drives. Makes the starter sound like its on the roids too, cranks quick. LiFePO is much more stable than the older lithium battery styles like you guys are referring to, especially with a good battery management system built in like the antigravity ones have. Lotsa sportscars have them as factory options now
Don't get me wrong tho, i think i'm one of the first few to get one for a taco so knew i was taking a bit of a risk trying it out. And i'm not sure how it would handle quick temp drops like yall get in the desert but idk if that'd be any different from me running mine on cold days with it in the stock spot
What provisions does that battery have for temperature controlled charging? What modifications did you do to your charging system to keep that battery happy during recharging?

Any drop in replacement LiFePO4 HAS to have a built in BMS otherwise the battery go kaput very quickly.
There are plenty of DIP batteries these days and some have built in heaters for cold temp charging, but without a reliable way to boost charge voltage up into the 15v range there is not way to realize the long cycle life of that chemistry
 
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dirtyjerz
What provisions does that battery have for temperature controlled charging? What modifications did you do to your charging system to keep that battery happy during recharging?

Any drop in replacement LiFePO4 HAS to have a built in BMS otherwise the battery go kaput very quickly.
There are plenty of DIP batteries these days and some have built in heaters for cold temp charging, but without a reliable way to boost charge voltage up into the 15v range there is not way to realize the long cycle life of that chemistry
No mods; thought about a voltage monitor of some kind but i haven't even checked it once yet to see how it does :noidea: (at this point i'm a little nervous that i'd start having problems as soon as i did start keeping an eye on it). No idea if it does anything to control temps when charging either. Not sure that's an issue with the newer FePO4 types
And quite a few didn't have BMS when i was looking around. Braille is the big dog company for automotive and theirs don't. Same with many of the ones made more for solar power storage. 50/50 from what i saw. I guess those are all just meant to be put on a tender anytime they're not in use
Maybe i'll look into a voltage booster of some kind
 
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i have this in 40 amp hour configuration
I got a little charger/tender thing with it just in case but haven't used it yet
 
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Stairgod

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No mods; thought about a voltage monitor of some kind but i haven't even checked it once yet to see how it does :noidea: (at this point i'm a little nervous that i'd start having problems as soon as i did start keeping an eye on it). No idea if it does anything to control temps when charging either. Not sure that's an issue with the newer FePO4 types
And quite a few didn't have BMS when i was looking around. Braille is the big dog company for automotive and theirs don't. Same with many of the ones made more for solar power storage. 50/50 from what i saw. I guess those are all just meant to be put on a tender anytime they're not in use
Maybe i'll look into a voltage booster of some kind
At least they have a BMS. Definitely do not have any temperature based charge protection though.
The biggest clue about their set up is the 7-9 year life expectancy.
To be honest that is pure garbage. A probably set up system with that battery chemistry should at least double that life.
The biggest draw is obviously during starting and that does drain the battery quite quickly, but if properly sized that will still be less than a 50% DOD. And if kept within 75% max charge and 25% max at discharge a battery set up with that chemistry will do almost 10k cycles.
Solar set ups that do more than 50% DOD are still looking at near 7500 cycles.
Be interesting to see your results with that battery. Keep us informed.
 
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At least they have a BMS. Definitely do not have any temperature based charge protection though.
The biggest clue about their set up is the 7-9 year life expectancy.
To be honest that is pure garbage. A probably set up system with that battery chemistry should at least double that life.
The biggest draw is obviously during starting and that does drain the battery quite quickly, but if properly sized that will still be less than a 50% DOD. And if kept within 75% max charge and 25% max at discharge a battery set up with that chemistry will do almost 10k cycles.
Solar set ups that do more than 50% DOD are still looking at near 7500 cycles.
Be interesting to see your results with that battery. Keep us informed.
I think you got it all figured out there. It's a bit of overkill so starts are easy and don't drain it much. Pair that with driving hard/lotsa revs basically anytime there's no cars in front of me (often out here in the hills) and prioritizing light weight with pretty much every mod. My alternator always has it's chances and the battery probably doesn't get stressed much

Even if that is a short life the cost of buying a one year battery every year or so was exactly the same at the time i got it. Probably a bit more now since the AG price hasn't changed but i'm sure inflation hit regular auto parts store shit. Good trade off to remove some weight and lighten up the stress on the front fender. That's what sold me --and i did pick up like a tenth mpg and it was enough the butt dyno felt it in handling and acceleration improvements so i'm happy

I'll post updates for sure. Any ideas, advice, links to stuff that could improve the setup would be much appreciated as well. Like i said i understand i'm already takin a bit of a risk with this so i'm down to experiment some more, especially if doubling the life of it is really in the cards. And your input is always good in general. Could maybe even spitball a few requests to the company like a little add-on heater for winter n shit like that
 

Octanejunkie

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That Antigravity seems impressive at 16# and $800+. I'm super curious and can always move my 50# AGM to the cargo area to save weigh up front
 
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That Antigravity seems impressive at 16# and $800+. I'm super curious and can always move my 50# AGM to the cargo area to save weigh up front
You could run the agm in the cab with a fuse box completely separate and just keep enough extra cable to switch between either if one goes out and you need to use something or start the truck
 

Octanejunkie

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You could run the agm in the cab with a fuse box completely separate and just keep enough extra cable to switch between either if one goes out and you need to use something or start the truck
I was thinking about a 4-way.switch like this

I could use a switch like that as a theft deterrent/house battery switch and toggle to charge both batteries on demand vs full time charge both batteries
 
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Arcticelf

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I was thinking about a 4-way.switch like this

I could use a switch like that as a theft deterrent/house battery switch and toggle to charge both batteries on demand vs full time charge both batteries
 

Mike_taco4x4

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Octanejunkie

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Chatted with Antigravity today, their batteries cannot be wired in series or parallel with other battery technologies. Also, their automotive batteries cannot be used for high draw applications, like winching.

Here is what they recommend for a dual battery heavy-draw application, like my intent.

Primary battery, something small like ATX30-HD or Group 51R

Secondary battery, for high draw like winching, they recommend a deep cycle, I told them I'm going to use an AGM.

They recommend a battery isolator, and while they don't sell one, I found several online. Example:
Screenshot_20220525-094705.png

I'm leaning toward the ATX30-HD under hood with the Deka AGM in the back with the Delco 140A alternator charging both through an isolator in the engine bay. That will allow me to cable the winch off the AGM off the isolator as well as my OBA compressor in the rear off the AGM.

The ATX30-HD has 4 terminals which means it will fit in any post orientation, and the "unused" terminals can be used for a solar panel for secondary charging or be capped off.

Heres what this project looks like, financially:
ATX30-HD battery $560
Standard Terminals $14
Battery Isolator $100 (estimated)
Deka 9A35R $200
Battery tie down $50
Delco 140A alt $114
Wire, connectors ~$120

Thoughts?
 

Stairgod

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Chatted with Antigravity today, their batteries cannot be wired in series or parallel with other battery technologies. Also, their automotive batteries cannot be used for high draw applications, like winching.

Here is what they recommend for a dual battery heavy-draw application, like my intent.

Primary battery, something small like ATX30-HD or Group 51R

Secondary battery, for high draw like winching, they recommend a deep cycle, I told them I'm going to use an AGM.

They recommend a battery isolator, and while they don't sell one, I found several online. Example:
View attachment 79015

I'm leaning toward the ATX30-HD under hood with the Deka AGM in the back with the Delco 140A alternator charging both through an isolator in the engine bay. That will allow me to cable the winch off the AGM off the isolator as well as my OBA compressor in the rear off the AGM.

The ATX30-HD has 4 terminals which means it will fit in any post orientation, and the "unused" terminals can be used for a solar panel for secondary charging or be capped off.

Heres what this project looks like, financially:
ATX30-HD battery $560
Standard Terminals $14
Battery Isolator $100 (estimated)
Deka 9A35R $200
Battery tie down $50
Delco 140A alt $114
Wire, connectors ~$120

Thoughts?
Blue Sea Systems Automatic Charging Relays (ACRs) https://www.amazon.com/dp/B001VIXLRO/ref=cm_sw_r_awdo_77RDA0MH9B8MEFEGAZQ1
This. Will isolate and allow you to self jumpstart at the flick of a switch
 

Stairgod

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Blue Sea Systems Automatic Charging Relays (ACRs) https://www.amazon.com/dp/B001VIXLRO/ref=cm_sw_r_awdo_77RDA0MH9B8MEFEGAZQ1
This. Will isolate and allow you to self jumpstart at the flick of a switch
And.... typical LiFePo4 batteries have both a high charge and discharge rate. Perhaps because of the relatively small capacity of the battery they do not recommend it for winching.
Using an isolator between the batteries is neither series nor parallel connection. There is no reason you could not use their battery as a house and leave the chassis battery as an AGM, aside from my earlier comments about LFP batts liking higher charging voltages which apparently is not an issue with their battery chemistry.

When I get a spare moment I want to call them and chat
 

Octanejunkie

Just another jagoff with a 4x4
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Pretty close to a final plan to use a single charging system for a dual battery setup leveraging two different battery chemistries, AGM and LFP, separated by an isolator.

Leaning towards the REDARC SBI 212 isolator
I've had several conversations with them, as well as other vendors, and their product seems the most aligned with my goals and can definitely handle the type of amperage I would be looking at

Here's my current wiring diagram proposed plan. I have to lay it all out on the vehicle and double check all wire lengths against gauges and capacities. All critical load fuses are ANL blade type

4runner Dual Battery LFP+AGM.png

The only only things I need left to order are the lfp battery, 2/0 wire and lugs, and the relay.
 
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Octanejunkie

Just another jagoff with a 4x4
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Made some decisions, threw some money around

REDARC SBI212 is ordered!
I decided not to go with the D (dual charge) version and keep it simple. I can always add solar as a secondary charge for my house battery and not worry about charging the start battery off solar

Decided against LiFePO4
Cost and concerns by several about mixing chemistries, so I sourced a lightweight AGM (18#) and triggered the purchase of a Braille B2618 - now I have 2 AGM batteries and fewer concerns about charging.

My schematic is posted above and based on my mock up of the wiring, the 2/0 run should be under 15 feet long, total length

Additionally, I pulled trigger on Blue Sea AGM fuses and holders
150 AMP between the alternator and start battery
200 AMP between the Isolator and each battery circuit

Once the Redarc Isolator arrives I will finalize the installation locations, wire paths and battery hold downs in fore and aft.
 
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Octanejunkie

Just another jagoff with a 4x4
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What about monitoring?

Voltage and or State of Charge?

Redarc has a dual volt gauge, pricy for what it is, Blue Sea has them, too, I was looking at this Ironman gauge

12V Dual Battery Monitor Display

Only the Blue Sea 1830 does do SoC, specifically...

On the better-than-nothing side, there are plenty of these out there
Digital Voltmeter Rocker Style Dual Voltage Monitor

Anyone run something like this in a dual battery setup? Any recommendations?
 
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