12v system thoughts

bpenn1980

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Hi all,

First off, I've never had any trouble running a single 27f flooded battery hooked up per factory. Life was simple. No accessories, no need for power.

All of that is changing now with my kids getting into the sweet spot for camping/hunting/exploring. With my kids in tow, I want more make life better/easier stuff, which requires power. With that in mind, below is an early draft of a system I am trying to get my head around. I think I'm 80% there, but maybe not. I'd appreciate any comments/suggestions.

A few comments/questions:

1) I don't really care about Redarc products, its just the reference material I used. If other stuff works, that's fine too.

2) I like the idea of having two basic/cheap flooded batteries up front in the engine bay. Partly for redundancy/get-home factor due to kids, but also partly because I've heard the fixed alternator on the 80 doesnt play well with AGM. On the upside, by keeping the chemistry the same I basically have an super robust starting battery for like ~$300 in battery cost plus the one-time isolator cost.

3) On the battery isolator, is there any reason the override switch has to be momentary? Could it just be a normal toggle switch so I could link the batteries for starting/winching without having to hold the button? I'm assuming there is a practical or safety issue involved, I just don't know what it is.

4) I don't think I can hook an unregulated/uncontrolled solar panel up to one of the 27F starting batteries without risk of damaging it, but would like confirmation. Ideally the solar would go to starting batteries, then to lithium battery, but I'm guessing I'll need a controller for the solar to do it that way.

5) I'm mixed on hard wiring/mounting the compressor in the rear quarter panel or just keeping it in the drawer and hooking it straight up to the starting battery when needed. I've read it should be fine to run the compressor off the lithium battery, but not sure.

My rough system outline for your critique. Thanks!
12v system upgrade v2.jpg
 

e9999

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4: yes, that's right, AFAIK you can't just connect a typical "12V" solar panel in the 90W range directly to the battery without a controller. You may get away with that with a 2 or 3W mini panel just for battery-maintainance because the battery will draw the panel down to a low enough voltage and the currents are small, but your typical "12V" 100W panel -which is likely something like 20V or so when open circuit- would likely cook the battery before too long, I would imagine.

Having said that, I have not tried that myself, and I'm sure some inquiring minds would be interested in somebody (else) trying this and telling us what happened...


And what kind of fridge is it that takes 288W?
 

spressomon

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You need a solar charge controller between the panel(s) and the battery/batteries; most panels will put out 17+volts; they're relatively cheap for basic PWM type anyway. I use Victron controllers, Blue with dongle has much stronger Bluetooth otherwise the Smart combo works fine; gives very useful programming and real time data via BT & a smart phone; but not totally necessary if you want to keep it cheap and simple.

Ideally, with two vastly different battery chemistries, FLA and LFP you will want a controller for each which kind of means two panels.

15+ years of using dual AGM in my UZJ100 has proven worthy; my preferred flavor is Odyssey. Yeah, I know the price of entry is relatively high but I've been getting 10-years out of them; your alternator and mine are basically the same.

Run the engine when using the compressor. Ditto for winching. Combining two batteries of similar chemistry with similar static charge won't be a problem winching. OTOH, I've had to do copious amount of winching with up to 6T load pulls using one battery with the engine running w/o issue.

Get a good dual output 120v charger to maintain (AGM or FLA) them properly at home and then couple with whatever solar you need to keep the aux battery happy for the current draw x time you want...

Battery isolators: Everyone has an argument for their preferred isolator. The two Perfect Switch isolators I use, the one in the LC is a dozen years old with the one in the '07 HD2500 being 4-years old...made me a believer. Small form factor, no contacts to maintain/wear out, etc. Did I mention small form factor?

Ditto e9999's question: Fridge/freeze draw of 288watts must be 24 or more likely a 48-hour rate.

Just my $.02 and maybe all its worth...
 
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bpenn1980

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@e9999 , @spressomon

The fridge wattage is for 24hr, but the fridge I'm considering is made by Indel, sold as Truck Fridge in US. Those numbers are for the 65L. I may do 49L. Not sure. Nothing bought yet. I was thinking it'd mount on top of my drawers and I'd weld a cage to keep it protected/ventilated. I want the kids to have relatively easy access and the other setup I was considering (Engel MT45 combi with Easy Slide) seemed heavy and complicated for a kid to operate (got fingers?), plus @Fisher23 pointed out the footprint of the Easy Slide really is massive, which doesn't appeal to me. I should also note that my drawers are 15" tall (just a hair above the tailgate), so drop slides still leave it 4" or so off the tailgate which means kids and maybe even wife(?) needing to get on tailgate to reach into the bottom of a traditional fridge.

Appreciate the comments and confirming the solar controller requirement.

@spressomon I'm not sure what to make on the AGM/alternator thing. I hear conflicting anecdotes about it working and not working. Obviously a 2x AGM setup is probably the same cost (maybe less) and maybe a touch less complicated than the 2x FLA + LiFePO4 setup I show above. Simple is good.

On the 120v charger, I thought a Noco Genius 10 would be fine hooked up to starting battery #1 since it puts out 14.5v and the isolator connects the batteries at 13.2v. That way starting battery #2 gets maintained as well as LiFePO4 battery once starting batteries are healthy.
 

spressomon

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Latest information: 3.6+v/LFP cell is too high for long term lifespan. If you impart a DC-DC charger with programmable profile, between the alternator and the LFP then you're golden. Or a BMS that can limit the current to what is best for LFP.

RE: AGM, all I can say is dual Odysseys have worked perfectly for me for over a dozen years. Yeah, I probably read all the same naysayer stuff you have/do, but proof's in the pudding. The key is to put them on a high quality/capable dual bank charger when at home. Curious: Using a multi-meter, what is the output voltage of your alternator at say idle & say 1500 rpm?

Depending upon how long you want to sit w/o adding current back to your aux battery, you may indeed need/want a suitably rated LFP to run the fridge.
 

bpenn1980

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Latest information: 3.6+v/LFP cell is too high for long term lifespan. If you impart a DC-DC charger with programmable profile, between the alternator and the LFP then you're golden.

Curious: Using a multi-meter, what is the output voltage of your alternator at say idle & say 1500 rpm?

Depending upon how long you want to sit w/o adding current back to your aux battery, you may indeed need/want a suitably rated LFP to run the fridge.
I'm planning to have a controller between starting batteries and LFP, so check that box.

I'll check alternator, but replacing with new shortly as PM. Will rebuild old for spare.

Probably 3 days parked is a good estimate at the moment.
 

spressomon

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Lastly, and your probably already know this but, LFP doesn't like getting charge current when the cells are below freezing. It may sound as if I am anti-LFP...quite the contrary as I have 200Ah and a 400Ah LFP arrays in two different vehicles. But w/o extra Ah capacity during the low sun angle months, its a little bit of a chore getting all the electrons replaced we use during sub-freeze overnight temps (it takes a while to get the LFP above 32F the next morning to accept a charge). Again, all this for maximum lifespan.
 

e9999

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I imagine you meant 288 *Watt-hours* used over 24 hours then. This seems low for a largish fridge working under normal conditions, I think.
 

bpenn1980

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Latest information: 3.6+v/LFP cell is too high for long term lifespan. If you impart a DC-DC charger with programmable profile, between the alternator and the LFP then you're golden. Or a BMS that can limit the current to what is best for LFP.

RE: AGM, all I can say is dual Odysseys have worked perfectly for me for over a dozen years. Yeah, I probably read all the same naysayer stuff you have/do, but proof's in the pudding. The key is to put them on a high quality/capable dual bank charger when at home. Curious: Using a multi-meter, what is the output voltage of your alternator at say idle & say 1500 rpm?

Depending upon how long you want to sit w/o adding current back to your aux battery, you may indeed need/want a suitably rated LFP to run the fridge.
Showed 14.6 volts at cold idle, so maybe 1,000rpm
 

bpenn1980

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Thank you for the recommendation on Victron. I think the bluetooth connectivity and displays will be useful.

I've revised the design slightly and updated the below items:

Redarc SBI212D to isolate starter batteries
Victron Smart Solar MPPT 75/15 to control the solar panel into the start batteries
Orion TR-Smart to control input into LiFePO4 battery

BattleBorn is also having a sale on a 100Ah LiFePO4 battery that includes a self heating feature for the cold weather trips. I think I'm going to pull the trigger and get this show on the road. 100Ah 12V LiFePO4 Heated Battery Kit - 1 Battery - https://battlebornbatteries.com/product/100ah-12v-lifepo4-heated-battery-kit/

Next I need to figure out how to size fuses/breakers and cable for this setup. Any tips on that front appreciated.

12v system upgrade v3.jpg
 
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Looks good. I have a similar setup in my 80. I would just suggest some sort of monitoring for the LiFePo4 via shunt and display of some sort. Dual voltmeter on the engine batteries for good measure too.
 
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Just FYI

The RedArc are great especially if you are going to put them exterior, like in the engine bay or even under the vehicle as they are water tight.
Battle born batteries are also great.

But if you want to to save a little you can get a nice 138AH Lithium used from $150 to $350 if you look around. Some companies replace ALL batteries once they hit 3 years old if used or not.
If you put the DC to DC charger inside your vehicle the renogy and similar dc 2 dc charges are just slightly over $100.

My setup is very similar to yours and in building it some of the folks above help me with my setup.

I have the dual AGM batteries in the engine bay, then a DC 2 DC for the lithium in the rear with 200 watt solar and a 2000w inverter.
My solar only charges the lithium (vs you have it charge the AGM 2nd) as I depend on the solar to run my fridge 24/7 when parked.
Charging a AGM with solar and then having the AGM charge your lithium with a DC 2 Dc I believe is slower than just charging the Lithium with the solar, but you may have some purpose not mentioned.
The 100w single panel was good enough for running the fridge 24/7, I add the other later due to invertor use.

All those parts you selected have manuals specifying the minimum wire gauges they require. You can always go a little bigger guage to save cost and use the same size wires.
I like the circuit breaks vs fuses, as they are easy to turn off if you want to work on something.
 

LandLocked93

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Just curious, why is the solar panel going to the engine room aux batt and not to the batt supporting all the load? This is unnecessary complexity and makes less efficient use of the fruits of solar regen. And $400 for a 90w panel??
+1 RedArc BCDC for efficiency. But I'm biased.
Are you running a smart alternator? If not, then the RedArc relay should be voltage sensing and will bind the engine room batts to equalize the charge. You asked if the momentary switch can be replaced with a static on/off. Confirm with RedArc, but I 'm pretty sure that relay can handle constant energizing (static sw) up to whatever it's rated for given that the momentary switch activates that relay when far more current than simple charging would pass through it (aux batt crank event).
++1 on current and voltage monitoring for each of your batts. This really ties it all together so you can see what's going on normally, and also see what's not right when it's not (fire/stranding prevention).

That Orion device...at what voltage does it function? Alternator voltage - >13.4v+?
At what voltage does it shutdown? Battery voltage - <12.8?
 
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bpenn1980

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Just curious, why is the solar panel going to the engine room aux batt and not to the batt supporting all the load? This is unnecessary complexity and makes less efficient use of the fruits of solar regen. And $400 for a 90w panel??
+1 RedArc BCDC for efficiency. But I'm biased.
Are you running a smart alternator? If not, then the RedArc relay should be voltage sensing and will bind the engine room batts to equalize the charge. You asked if the momentary switch can be replaced with a static on/off. Confirm with RedArc, but I 'm pretty sure that relay can handle constant energizing (static sw) up to whatever it's rated for given that the momentary switch activates that relay when far more current than simple charging would pass through it (aux batt crank event).
++1 on current and voltage monitoring for each of your batts. This really ties it all together so you can see what's going on normally, and also see what's not right when it's not (fire/stranding prevention).

That Orion device...at what voltage does it function? Alternator voltage - >13.4v+?
At what voltage does it shutdown? Battery voltage - <12.8?

Solar going to 2nd starting battery just to scratch the redundancy itch and prioritize starting vs cold beer. I can wire it the other way if it looks like the LFP is draining faster than expected. Panel is expensive, yes.

No smart alternator on the 80.

Monitoring the batteries will be new for me, but hopefully not too complicated/cumbersome.

The Victron unit can be configured to start/stop at different voltages, but those voltages are close to the default I believe.
 

LandLocked93

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Solar going to 2nd starting battery just to scratch the redundancy itch and prioritize starting vs cold beer.
Well as it is the 2nd batt - with the SBI relay - is the redundancy.
What is the device connecting the 2nd engine room batt to the LFP? That was the device I was referring to as "Orion device" (bad eyes/screen).
I can wire it the other way if it looks like the LFP is draining faster than expected.
It will. lol

All I'm trying to get at is if the "orion device" only functions at alternator voltage, then the wiring as displayed above will force you to run the truck (burn petrol) to recharge the batt supporting the majority of the load (LFP). Your solar regen will be marooned at the aux engine room batt with the engine off.
 

bpenn1980

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Well as it is the 2nd batt - with the SBI relay - is the redundancy.
What is the device connecting the 2nd engine room batt to the LFP? That was the device I was referring to as "Orion device" (bad eyes/screen).

It will. lol

All I'm trying to get at is if the "orion device" only functions at alternator voltage, then the wiring as displayed above will force you to run the truck (burn petrol) to recharge the batt supporting the majority of the load (LFP). Your solar regen will be marooned at the aux engine room batt with the engine off.
Got it. Yes, the orion device "opens" at alternator voltage. I thought the solar would hit that voltage and open the flow to the LFP (once starting batteries are full), but I might be thinking about it wrong.
 

e9999

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there are indeed some potential surprises with this type of equipment. For instance, I was surprised to read that my Victron battery controller will only start working if the solar panel gives 5V above the battery level, but then subsequently works with only 1 or 2V (IIRC) difference, which seems strange. Now in practice it's not a big deal because it does not take much light at all for a "12V" panel to give an actual 18+V but still unexpected (for layman me). So yea, designers may put in some subtleties in there.
 

LandLocked93

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Got it. Yes, the orion device "opens" at alternator voltage. I thought the solar would hit that voltage and open the flow to the LFP (once starting batteries are full), but I might be thinking about it wrong.
OK, I see you're hip to what's with it, so I'll just throw out what I've learned. Take what you find useful. 👍

1) Recommend the SBI12 instead of the SBI212. Keep current flow one-way only. There is no use-case to charge the crank batt from the aux batt, even when the crank batt is dead. Once bound by the SBI, the truck will start from the aux batt and the alternator will charge the crank batt double-quick. The 212's dual-sense feature opens your crank batt to potential drain keeping the beer cold. The 212 has a place, but that ain't it.
2) Voltage drop will be far less with the solar regen going straight to the LFP. Running it up front, then back to the rear (LFP in rear yeah?) should show 10% or more drop. (mentioned already)
3) The alternator is the bread winner for power gen/regen. The solar will only ever be a trickle in comparison.

Ideally, you want:
1) The alternator charging all 3 batts as necessary when the truck is running. (as you have it)
2) The solar going only to the batt expected to provide the majority of power to the loads - usually stationary/base-camp types of load - when the truck isn't running.
3) The BCDC (Orion) connecting only the front aux batt and rear 'load' batt. (as you have it)
4) Crank batt remains tied only to the OEM wiring (apart from the SBI) and always isolated from any and all add-on wiring being installed until you hit a manual switch to bind the crank to the aux.

And then of course the monitoring.
Generally this involves 1-display per 2 batts, 1-shunt per batt, , 4-wires per shunt (for wired versions), a few switches of differing types - 1, 2, 3, and 4-PDT, with the 4PDT enabling an indicator LED for charge/discharge and/or power on/off - easy to surmise from a distance (outside the truck) as to what's doing what.
And to really scratch that redundancy itch, don't forget to enable 'switching between' the 2 front batts to power the monitoring and SBI. Nothing worse than going to bind the batts only to find the batt powering the SBI happens to be the dead one.

I can help with wiring if need be. I've done all this to my truck. Pics prove it happened. lol
Happy Trails 👍
 

bpenn1980

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OK, I see you're hip to what's with it, so I'll just throw out what I've learned. Take what you find useful. 👍

1) Recommend the SBI12 instead of the SBI212. Keep current flow one-way only. There is no use-case to charge the crank batt from the aux batt, even when the crank batt is dead. Once bound by the SBI, the truck will start from the aux batt and the alternator will charge the crank batt double-quick. The 212's dual-sense feature opens your crank batt to potential drain keeping the beer cold. The 212 has a place, but that ain't it.
2) Voltage drop will be far less with the solar regen going straight to the LFP. Running it up front, then back to the rear (LFP in rear yeah?) should show 10% or more drop. (mentioned already)
3) The alternator is the bread winner for power gen/regen. The solar will only ever be a trickle in comparison.

Ideally, you want:
1) The alternator charging all 3 batts as necessary when the truck is running. (as you have it)
2) The solar going only to the batt expected to provide the majority of power to the loads - usually stationary/base-camp types of load - when the truck isn't running.
3) The BCDC (Orion) connecting only the front aux batt and rear 'load' batt. (as you have it)
4) Crank batt remains tied only to the OEM wiring (apart from the SBI) and always isolated from any and all add-on wiring being installed until you hit a manual switch to bind the crank to the aux.

And then of course the monitoring.
Generally this involves 1-display per 2 batts, 1-shunt per batt, , 4-wires per shunt (for wired versions), a few switches of differing types - 1, 2, 3, and 4-PDT, with the 4PDT enabling an indicator LED for charge/discharge and/or power on/off - easy to surmise from a distance (outside the truck) as to what's doing what.
And to really scratch that redundancy itch, don't forget to enable 'switching between' the 2 front batts to power the monitoring and SBI. Nothing worse than going to bind the batts only to find the batt powering the SBI happens to be the dead one.

I can help with wiring if need be. I've done all this to my truck. Pics prove it happened. lol
Happy Trails 👍
This is all super helpful. Thanks for typing it up.

Regarding the SBI212D, I figured since it has 200amp rating it would work better in high amp "jumping and winching" situations. I think it only opens at 13.2v+ and closes at 12.7v, so I thought the primary starting battery would be protected from dropping below 12.7v? Also, I thought about running the winch of the 2nd starting battery since the wire cable runs are shorter.

Honestly the monitoring stuff is over my head right now. I need to spend some time reading up on it. Same for figuring out switches/displays/LEDs that will fit the dash. Not my cup of tea and where s*** like the Delta shifter console with a bunch of cutouts for switches and displays starts seeming like a good waste of money.

Also dont like the idea of the SBI draining the starting battery! Guess I'll get religious about plugging in the NOCO at home.

Updated diagram with some fuses and wire gauges added.

PS- Do you know a good route to chassis ground in the PS rear cargo area? Dont really want to cut a hole if I dont have to.

PXL_20211019_015546452.jpg
 

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