'99 100 Series - Dual Battery Setup by OVRmag

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G

GerLC100

Joined
Jan 10, 2024
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Location
Bay Area, CA
I'm about to think about my dual battery setup. One comment ahead: once I read DCDC, BCDC, VRS, ... my brain somehow has a hard stop, so I need proper guidance so my hands can do mechanical work :-D

Targets:
- run roof rack mounted LED lights at the campground
- add some USB outlets in the rear (for phones and smaller 600-800mAh RC batteries)
- possibly add solar and fridge in the very future (no plans right now, but you never know)
- winch
- if easily possible connect both batteries for jumping or winching

I'd switch the current main battery when buying a house battery, so I'd go for a group 31 main and group 35 aux.

I found this setup that seems to provide all (most?) of what I want:
www.ovrmag.com

OVR Project Land Cruiser 100: Everything You Need To Know About Its Dual Battery Setup

As our budget build OVR Toyota Land Cruiser 100 Series vehicle project marches forward, it was inevitable that we installed a dual battery setup. Learn how and why ours is setup they way it is.
www.ovrmag.com www.ovrmag.com

Thoughts on my end:
- I understanding the Redarc BCDC works on all alternators
- Redarc BCDC seems to give all options to add on
- Optima will likely not be my choice
- don't like the touchscreen and would rather have mechanical buttons

Main questions as of now:
AGM or Lithium?
Lithium seems to be a bad idea in the engine bay and for AGM I keep reading about not fully charging?!? Is the Redarc getting around this?!?
 
Your winch should run off your main battery so that is generally not a big consideration unless you can link you batteries or start from your second battery
 
I read that already fairly often. I think background is that the direct connection from the alternator to the main provides more power than going to the second via any kind of BCDC or whatever. 80-90amps come from the alt, but only 25/30/40 (whatever) is being provided by the chargers
 
I asked because I set them up to pull from both batteries, or which ever one is currently tasked with starting and operating the engine. For winching I want a marine switch or gigavac / rincon contactor that puts the batteries in direct parallel and by-passes any smart charging device.
 
I think what he wants to say is: don't run your winch off a single aux battery, but go for direct main or parallel main+aux.
 
Your targets are not the same.
Part of them are simply consumption devices - LEDs, chargers, winch.
And part, (a bigger part imo) is the use/operation of the batteries - binding both batts to start the vehicle, charging both batts efficiently, using one or both for high-current devices like a winch.
You're missing control of the charging, expected consumption rate of the devices, and if you're serious, real-time monitoring of it all.

Also, location of the batts.
Are we talking two engine room batts, one of which is wired out to the rear of the vehicle to power just consumption devices?
Or are we talking the main engine room batt, with a second batt in the rear - charged by the alternator, or solar, or shore power - to power consumption devices other than presumably a front-mounted winch?

For starters, you want to match battery sizes. If two engine room batts, you want two of the same size, same make if possible.
Secondly, lithium has it's place but it's your own risk how you use it.
Some say it's as safe as the children who mine it.
Others say not so much.
Up to you to decide. AND it requires a different charge profile compared to WLA or VRLA AGM.

Distance between batteries plays a part. An expensive BCDC charging two engine room batts is a waste of money. A BCDC charging two batts at either end of a vehicle is a far better use of the tech imo. It eliminates voltage drop and enables the use of less expensive wiring and fusing over the charge circuit.
 
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My plan is 2 batteries in the engine bay (so I think no lithium).
I‘d like to keep the 1yo main, get perhaps an Odyssey aux and once main is done get a second Odyssey.
If needed I‘m also ok to get two Odyssey right away if that makes sense.

My main idea:
Run roof rack mounted lights on the campground
Connect main and aux when winching or to jump start.

I already mounted the slee dual battery tray, so position is clear.
 
For starters, apologize for the length of this response. Just trying to highlight the mains.

The batts can be odd-matched at the beginning just to ensure the whole system works after implementation. Easy to get a matched pair thereafter. Just don't expect long-term, nominal charge performance until they are matched.

Battery charge/use:
In this setup, you don't need a BCDC for engine room batts.
Option 1: Connect the two batts between their positive terminals (recommend 0/0 gauge and fused on both ends. MRBF's are the most compact solution), yet separated in-line by just a simple, normally-open (non-conductive) relay.
Such a relay is dash-switched and with monitoring you decide when to bind them based on the voltage state (via the monitoring) of the second batt.
In the same stroke this solution enables the second batt to be connected at-will to the main batt in the event of a dead main to start the vehicle.
AND/OR winch off 2 batts if you so choose.
There's is a wiring trick for the winch as well in this scenario.
Regardless ... this is a $60 solution, tho requires that you maintain the second batt charge level by switching the relay open or closed depending.

Option 2: Put your faith in an automatic solution called a VSR (voltage-sensing relay). This device is physically connected to both batts via the positive terminals but rests in an open state (non-conductive).
It tracks the voltage of the second batt (compared to the main) and when the second batt voltage drops to a preset limit, the relay closes (conductive) and binds with the primary batt to charge the second batt.
The cheaper VSR's ($20 -$50) do not provide at-will control over when the batts bind and are thus exclusively one-way - i.e. main to second only, unable to bind to start the vehicle from the second batt.

More expensive VSRs (~$90) provide a dash-mounted momentary switch that enables at-will binding for second batt start capability.
But you still have no control over when (or if) they bind for charging purposes.

I used a relay similar to this one, but w/o the VSR tech. Mine is just a dumb realy, dash-switched via monitoring.

The consumption rate and use frequency of the lights will determine either battery size or when you use them.
And given they will have to be wired to the second battery for power and presumably wired into the cabin for selective control dictates the size of the wiring required. But it's pretty straight forward.
You could:
Option 1: Mount a switch control panel in the cab capable of handling the current needed to run the lights and just wire the batts to a (stand-alone) fuse box, then to the panel, then to the lights.

Option 2: Mount a relay & fuse board/box (much smaller relays, ~30A or 40A each) at or near the battery (or on the firewall most practically). Wire light power from the batt to the relay box. (one wire, decent gauge (12/10), fused on batt end; again MRBF, ground can be local to the body)
Then run relay trigger power (far smaller wire as it's far less current) from the box (just picked off the light power connection) to the cabin switch control panel then back to the relay box.

If you want all the lights on one switch, then just need one switch and one relay (provided the current demand of all the lights together does not exceed the current capacity of the single relay used, nor the rating of the fuse in said circuit)
If you want to control which lights are powered then yeah, need a switch panel and requisite number of relays/fuses.
Usually 1:1, switch/fuse/relay/group of lights requisite to the current demand of the light group and relay/fuse current rating.
 
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IF the batteries are going to spend a significant amount of time connected in parallel then they should be as identical as you can get. Strongly suggest that such a battery system be grounded to the same bolt. Merely both to the frame or the engine is not good enough. BT, DT, got to buy new batteries when they kilt each other off prematurely.

If not, then it's not too important that they be the same. I still ground mine to the same bolt.

Lithium makes a lot of sense for almost every use. They're lighter, and they make your wallet lighter, so if speed is important that's a win-win!
Seriously though, I'm looking at LiFeO for the 'house' battery of my next build. I don't have a lot of room for a second battery in it, so lithium's smaller space claim is very attractive. If I do go down that path it will not see winching or self jump-starting loads. I typically carry an XP-10 for the latter need, and there's no absolute requirement that a winch has to have two batteries. Just that it's a good idea if feasible.
 
Slee second battery tray with Red arc isolator with merge switch when I use the air compressor or winch. Ran big old wires to the rear with a dedicated Anderson plug for future platform. Running a fridge 2 days without starting truck on the house battery with zero issues to date. Running this way for four years now.

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@ntsqd it’s a redarc. I believe it’s different than what documentation you linked but that is a great public service to provide. I’m going to look that up to be sure. I do hate it when a perfectly good rig gets crispy.
 
It may have been sold by Redarc, but I doubt that they made it. In general it looks like a Sure Power design, but that doesn't mean that SP made it. Both Sure Power and gigavac do private label some of their contactors. Kilovac used to, but since Tyco bought them their product seems to have disappeared from the general market. I would imagine that Rincon Power does private labeling too, but I don't know that for sure.
 
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Expanding a little on my post above, these: https://www.bluesea.com/products/category/20/77/Solenoids/L-Series are gigavac or kilovac contactors that are private labeled. Their size can be small because they switch inside a hermetically sealed chamber. They're rated at something like 10,000 cycles under load, but they typically are good for 10 times that. Note that these are only contactors, they do not have Low Voltage Disconnect, Battery Combining/Isolation or any other built-in functions.
 
LandLocked93 said:
Battery charge/use:
In this setup, you don't need a BCDC for engine room batts.
Option 1: Connect the two batts between their positive terminals (recommend 0/0 gauge and fused on both ends. MRBF's are the most compact solution), yet separated in-line by just a simple, normally-open (non-conductive) relay.

Option 2: Put your faith in an automatic solution called a VSR (voltage-sensing relay).
Click to expand...

Adding my two cents after installing and repairing a number of different variations of option 2. For my personal rigs I am 100% on the option 1 bandwagon.

I do this for three reasons. First is in the name of simplicity. There is very little to fail and when the relay/solenoid eventually does, I can buy a marine or automotive one anywhere. Second is in pursuit of flexibility. I can link or isolate the batteries, connect charging sources and loads any way I want. Third is for compatibility - it is quite annoying to have a voltage sensing relay paired with a solar charge controller each making different decisions about what constitutes under or over voltage.

Its also much cheaper.

I wire mine to a dual pole switch so I can manually link, manually unlink, or have the ignition trigger linking. It spends most of its time linked by the ignition.
 
On our pop-top camper the camper's batteries are connected to the solar charge controller. I have a dual sensing VSR next to it that will combine the starting and house batteries whenever one of them reaches float, whether from solar or from the alternator. Been that way for almost a decade and hasn't been a problem. What I really have come to like is that the solar keeps the camper batteries up, but it also keeps the starting batteries up as well. No need for a battery tender on the starting batteries even though the vehicle might occasionally sit for a couple of months.
 
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