KISS Dual Battery Upgrade

[TeCKis300]

@Mogwai makes a good point.

Another concern to suitability of that battery:
- Operating temp. Specs say charging between 32* and 113*F. That's not very accommodating of underhood conditions

 

[radman]

Searching hasn't yielded any results, but has anyone tried using dual batteries in the stock location? I'm wondering if I could fit a smaller auxiliary LiPO battery next to a smaller lead acid one? Thinking this Renogy next to a group 26. Or something small that would work as a starter battery.

That is the complete opposite of KISS

 

[drftsub]

I ran my Battleborn to the rear of the rig specifically for the heat issue, every desert trip I go on will have underhood temps exceeding allowable.

 

[catastrofe]

There’s been a lot of discussion on batteries and battery systems. Here’s my attempt to offer an easy button. The task of a battery first and foremost is to offer power and reserve capacity. There’s many battery setups and systems talked about. But perhaps some of those are solving a problem that really isn’t there, or need complexity to solve a fundamental shortcoming of an architecture as laid out. Some may judge this as not sophisticated, at least from a traditional expo POV. I’d say KISS, with reduction of complexity and dependencies to be its greatest advantages. That’s ultimately cheaper, easier, more effective, and reliable than anything out there.

1) 2x lead acid batts (matched batts, buy at same time)

AGMs are not the right solution here. Flooded lead acid is what’s fundamentally compatible with the alternator/regulator and underhood temps. As large or small as you like. Deep cycle (hybrid) batts preferably. I’d say that 2x group 27s are more than most people will ever stretch when setup like this. Most may not even need 2 batteries and can get away with one larger battery with the expo options below.

2) Wire these batts in parallel to make one big bank

Wire with heavy 0/2 gauge. One big bank has advantages to maximizing usable capacity and huge current draws. It also keeps cycle depth low, prolonging usable life (lasting potentially 8+ years, unless you live in super-hot places like Arizona which kills any battery/setup). “But, house and starter batt”…. I’ll get there in the expo section.

3) Wire the vehicle to the batteries in cross fashion. Positive to (+) terminal on one battery. Negative to (–) terminal on other battery.

This is a key optimization for long battery life. Move the chassis ground to the battery on the other side. This is important to keep the batteries balanced. Otherwise, there will be voltage offsets and micro-currents causing premature wear.
View attachment 1853542


That’s it. No fuss. Always charged. Maximizes the batt capacity possible for every device, with huge current capability.


Expo options

4) If one has continuous draw devices that operate after engine shut down (i.e. fridge, heavy lighting, house draws, etc.), they should be wired to a distribution point that is tied to the batt with a low voltage protection mechanism. This protects the batts and ensures starting reserves, which addresses the reason for house/starter batt setups.

5) If one wants to monitor voltage accurately in cab, add a USB cig lighter adapter with voltage readout ($10). Some even have low voltage alarm functions.

6) If one wants to support continuous draws for long parked durations, add a solar panel/charger tied directly to the bank. Something that makes enough output to support whatever particular draw. 50-100W can typically make the system last indefinitely, unless one has a particularly large draw.

7) Protection from battery bank failure. Carry a standalone lithium-ion jumper pack that typically doubles as a USB charger. It has the benefit of helping any expo friends in trouble, vs a built in battery jumper solution.

Merry Christmas!

Great write-up. I'm thinking of going this route, but I'm unsure about which batteries to use since they should both be the same. The OEM cranking battery is a 27F (I believe) but mounting that same size on the passenger side is probably too involved for me. Can you suggest a user-friendly solution along with an appropriate battery tray (I like the Slee but it's Group 35)?

 

[RET2]

Merry Christmas!

Great write-up. I'm thinking of going this route, but I'm unsure about which batteries to use since they should both be the same. The OEM cranking battery is a 27F (I believe) but mounting that same size on the passenger side is probably too involved for me. Can you suggest a user-friendly solution along with an appropriate battery tray (I like the Slee but it's Group 35)?

Let me ask the obvious question, why do you need 2 batteries?

 

[catastrofe]

Let me ask the obvious question, why do you need 2 batteries?

I’m concerned that running additional accessories from the cranking battery isn’t “ideal”. I do carry a jump pack, but when camping off-grid I’d like to have some additional peace of mind.

 

[TeCKis300]

Merry Christmas!

Great write-up. I'm thinking of going this route, but I'm unsure about which batteries to use since they should both be the same. The OEM cranking battery is a 27F (I believe) but mounting that same size on the passenger side is probably too involved for me. Can you suggest a user-friendly solution along with an appropriate battery tray (I like the Slee but it's Group 35)?

Merry X'Mas to you too!

I still run the single stock 27F battery. For car camping, I use a portable Goal Zero 1000, to run things like a warming blanket on winter nights and to charge various electronics. I've used the portable battery with built in inverter to brew huge pots of coffee for my camping group.

To @RET2 s point, depending on your capacity needs, I'd use the following sizes:
1) Upgrade single 27F to single Group 31
2) Upgrade to 2x 27F
3) Upgrade to 2x 31

 

[catastrofe]

Merry X'Mas to you too!

I still run the single stock 27F battery. For car camping, I use a portable Goal Zero 1000, to run things like a warming blanket on winter nights and to charge various electronics. I've used the portable battery with built in inverter to brew huge pots of coffee for my camping group.

To @RET2 s point, depending on your capacity needs, I'd use the following sizes:
1) Upgrade single 27F to single Group 31
2) Upgrade to 2x 27F
3) Upgrade to 2x 31

Thanks.

I keep a portable fridge in the back of the LC, and was planning to run it from a lithium power pack charged by both solar and the 120V rear outlet. 12V out of the PP to the fridge, solar on roof.

I'm adding some lighting to my roof and can't think of a practical way to use the PP for this application, which is why I started contemplating a 2 battery layout. I could charge the batteries via solar and eliminate the PP altogether.

I'm still not sure how I'd fit a 27F or 31 on the passenger side. . .

How would you handle the two different loads (fridge and lighting)?

 

[tbisaacs]

Thanks.

I keep a portable fridge in the back of the LC, and was planning to run it from a lithium power pack charged by both solar and the 120V rear outlet. 12V out of the PP to the fridge, solar on roof.

I'm adding some lighting to my roof and can't think of a practical way to use the PP for this application, which is why I started contemplating a 2 battery layout. I could charge the batteries via solar and eliminate the PP altogether.

I'm still not sure how I'd fit a 27F or 31 on the passenger side. . .

How would you handle the two different loads (fridge and lighting)?

similar to @TeCKis300 I run a single 27f and a lithium goal zero for my ARB fridge. For “camp” lights I have a bunch of the GZ usb string lights and they are awesome. USB rope lights are also great.

The GZ isn’t strictly required for them, you can run them off of any 12v outlet for a really long time.

 

[Chrisleduc1]

For “camp” lights I have a bunch of the GZ usb string lights and they are awesome.

I haven’t seen these?? Link?

 

[tbisaacs]

I haven’t seen these?? Link?

Light-a-Life Mini USB Light

short USB light with 110 Lumens and collapsible diffuser for lantern or area light. Chainable with up to 4 LED lights, pairs with any Goal Zero power bank. Carabiner included for hanging. Additional colored shades can be purchased for customization. features LIGHT-A-LIFE MINI HIGHLIGHTS Bright...

www.goalzero.com

They are really well made, have two brightness levels, extra long chords, and interchangeable "shades". 4 of them strung together on hi sips about 10 watts. I carry an Anker external battery pack (made for cell phones) and plug in the lights if I'm away from the truck and it will power them basically all weekend.

 

[TeCKis300]

How would you handle the two different loads (fridge and lighting)?

I assume you want these things to run after ignition off. That will require you to run a new power distribution circuit directly from the battery. I'd recommend to run one from the battery with a low voltage disconnect so you never run the risk of fully depleting battery bank.

Something like this:

Victron Battery Protect Install

I've added a few accessories that allows power draw when the vehicle is off. I don't plan to ever install a dual bank battery system so I'll always be drawing from the single starting battery bank. Wanted to ensure it cuts off loads leaving enough starting power. Even with a dual bank, it's...

forum.ih8mud.com

 

[toadshade]

I have the dual battery set up stock in my diesel. (Surprisingly enough, there is a 4g wire connecting the two batteries in parallel and it runs behind the radiator. I agree it is not the best place for it). I read this thread hoping to get a possible answer to a question about the alternator. If my engine is on and I am drawing more Ah than the alternator puts out, am I taxing the alternator, effectively short circuiting the battery path all together, or is it a cumulative amp draw across the batteries plus the addition of the extra juice from the alternator? I plan on doing away with the 24v starter and using the KISS method with my two existing batteries. But I am also hoping to draw 1500 watts so I might have no choice but to go bigger. That is why I am worried about my alternator. I plan on getting a bigger one, but is it better to run the vehicle or charge depleted batteries? The draw will be quick and infrequent.

 

[TeCKis300]

Not completely tracking what you're asking as I'm not familiar with what the 24v starter and what your existing parallel configuration is.

The stock alternator is I believe a 180 or 200 amp continuous unit. Assuming 180 amps * 12V = 2160W capability. I'm simplifying this as alternators usually output in the 13-14V range. If a load were to exceed its output capacity, the output voltage would drop. If low enough to battery output voltage, the draw would then be supported by the alternator and battery together. Flooded lead acids are capable of huge bursts of power too, as noted by their cold cranking amps (CCAs). For a single batter, momentary starting current could be in the realm of 600-900CCAs, 7200-10800W. Combine that with the alternator output, 1500W bursts shouldn't be a problem.

I believe there is readily available higher output alternators on the market too.

 

[toadshade]

There are some monster alternators out there. Not quite that high on the stock alternator though. Quick search gave me 80 amps, ~960 watts. That is what worried me. But if the batteries and alternator are working together and not short circuiting, then I agree, I would have no problem.

 

[TeCKis300]

There are some monster alternators out there. Not quite that high on the stock alternator though. Quick search gave me 80 amps, ~960 watts. That is what worried me. But if the batteries and alternator are working together and not short circuiting, then I agree, I would have no problem.

You're in luck as I'm pretty sure the 200-series is fitted with a 180 amp alternator.

2008-2022 Toyota Alternator 27060-38050 | LaGrange Toyota

2008-2022 Toyota part # 27060-38050 - Alternator

toyotaparts.lagrangetoyota.com

 

[toadshade]

Never thought of that. Nice. Much rather go OEM. I need to check fitment.

 

[toadshade]

This is just a random thought after reading this article and you guys seem to know what you are talking about. It came up a few times that the second battery would not charge to full capacity since it was second in line. By changing the negative leads, you could reverse the batteries and charge in reverse. If you set up a simple switch, could you alternate the batteries manually and charge both to full capacity? If so, I could think of a simple contactor setup that could do that on its own over some interval, or switch every time the car is started or something. Kind of getting away from the KISS, but this is pretty simple. Let me know if I am wrong, or if there is already a device that does this.

 

[BigMF]

similar to @TeCKis300 I run a single 27f and a lithium goal zero for my ARB fridge. For “camp” lights I have a bunch of the GZ usb string lights and they are awesome. USB rope lights are also great.

The GZ isn’t strictly required for them, you can run them off of any 12v outlet for a really long time.

I would like to avoid the dual battery setup if possible. For multi-week trips (admittedly in the distant future for me), do you think running something like the Goal Zero for the fridge would work long term?

This may belong in the SQOD thread but I'm new to mini-fridges, power packs, solar, etc:

1. Can you use the 115V port in the back to run the fridge while the truck is running during the day and run the fridge at night from the power pack while camping?
2. How do you charge the power pack during the day if it's powering the fridge?
3. Can you run the fridge and charge the power pack at the same time while the truck is running? Is there enough "juice" to do both simultaneously on one battery and stock alternator?

I'm a long way off from any of these things but like to ponder and research far in advance. Additionally, it might also help me while I plan the wiring for my upcoming compressor project.

 

[tbisaacs]

I would like to avoid the dual battery setup if possible. For multi-week trips (admittedly in the distant future for me), do you think running something like the Goal Zero for the fridge would work long term?

This may belong in the SQOD thread but I'm new to mini-fridges, power packs, solar, etc:

1. Can you use the 115V port in the back to run the fridge while the truck is running during the day and run the fridge at night from the power pack while camping?
2. How do you charge the power pack during the day if it's powering the fridge?
3. Can you run the fridge and charge the power pack at the same time while the truck is running? Is there enough "juice" to do both simultaneously on one battery and stock alternator?

I'm a long way off from any of these things but like to ponder and research far in advance. Additionally, it might also help me while I plan the wiring for my upcoming compressor project.

Goal Zero (or similar) is a pretty idiot proof solution. You can get more power by building your own, but it won't be plug and play. The lithium goal zero units have all of that sorted for you. I plug my Goal Zero into the inverter in the back of my LX and it charges while I'm driving. If I'm at camp I unplug from the inverter and plug in my 100w solar panel. The fridge runs the whole time.

The larger lithium units have some "advanced" options for charging. Depending on how long you intend to be stationary - they may benefit you:

• MPPT charging module - will optimize the charging from your solar panel and in some cases charge much faster
• Yeti Link - allows you to wire your Yeti directly to the trucks alternator for much, much faster charging while the truck is running (but won't drain when truck is off).