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[GLTHFJ60]

The fridge will cycle less when packed full of food/beer. I'm not sure how much less, but it'll extend your run time by quite a bit I'd imagine.

Nice work

 

[J Mack]

That’s exactly what I was thinking, I wanted to do worst case scenario start with a hot cooler and run it empty to see what that would do to a battery.

Based on what I think I know that 12 hour test would have ran a single group 34/78 AMG battery down into the danger zone and the 18+ hours I plan to run this system without charging the battery I would need to also use my start battery the keep my beer cold if I didn't have this new battery.



Some info for those that would like to look into battery options.

How To Maintain Batteries - Deep Cycle Battery Store

How to Calculate Battery Amp Hours - Deep Cycle Battery Store

Often we get asked how to calculate a how many amp hours the customer needs to run a device or multiple devices. So we prepared some notes on various topics like “How to Calculate Battery Amp Hours” and others Watts = Volts multiplied times Amps Step 1.Take

deepcyclebatterystore.com

 

[J Mack]

Thought I would sneak out to the shop and put some weather strip I've had for my doors since 2014 in-between prepping my house for paint.
I got the drivers door wrapped up and shut the door to check things out and the lower window channel fell out, my body guy was supposed to weld some cracking on the new door I bought and he decided spot putty was better than welding.
One more thing I need to do before the pig party now.

 

[riderjgs]

Thought I would sneak out to the shop and put some weather strip I've had for my doors since 2014 in-between prepping my house for paint.
I got the drivers door wrapped up and shut the door to check things out and the lower window channel fell out, my body guy was supposed to weld some cracking on the new door I bought and he decided spot putty was better than welding.
One more thing I need to do before the pig party now.

Brothers from different mothers!
I bought weatherstripping for all four doors about the same time you did. Did the driver door install a couple of years ago. The other three doors are still sporting patched together pieces from the three parts pigs that have passed through here. The replacements are still in plastic waiting to see if I finally get around to finishing up. We can compare progress (or lack thereof) at your place next week.

 

[PabloCruise]

I swear I did some reading before showing up with questions, so against my better judgement I am trying to multi-quote what I think are relevant points.
In the spirit of "knowing just enough to be dangerous", I come bearing questions and very little in the way of contributions...

I was able to test the LiFePO4 battery box I made a little yesterday and came up with a plan on how to interface it with my current wiring and hopefully keep the electrical fires to a minimum...

Wondering more about how to interface the battery box w/ your current wiring. I don't remember, but I think you were running an AGM as your primary battery. My limited understanding is that trying blend different types of batteries sets up quite a challenge in terms of charging and battery management. I am curious what logic you will arrive at for charging when the engine is running and isolating the batteries...

LiFePO4 batteries are the answer to this problem but they need some special considerations on the front side to get all they have to offer, I’m learning as I go so this is an ever changing plan so I first bought a Renogy DCC12 series battery charger (generic 20 amp DC/DC charger) thinking it would help me limit the current to my existing system to something around 20AMPS, in theory I suppose this would have worked but in practice it doesn’t. With the total length of 10gauge wire I tied into I was getting a voltage drop and I was seeing amperage spikes up around 40 AMPS, the DC/DC charger tries to maintain 14.3 volts at 20 AMPS output and will spike the input AMPS when the input voltage drops. My only option if I wanted to keep potential trail issues to a minimum was upgrade the wire size to #8. This is my fifth or sixth attempt to lower the voltage drop and I’m a little pressed for time now and needed to just get something usable for the upcoming camping trip so this is where I’m at now.

Sorry for all the rambling about nothing but I know a few of you guys are in the planning stage of your builds still and I would strongly encourage you to upsize a circuit running to your rear compartment even if you don’t think you’ll ever need it today, I thought 10 gauge was more than enough 4 year ago.

Is the Renogy just for charging the LiFePO4 battery pack? Or is it a "gate" that manages input and output?
When you talk about limiting the current to your existing system to 20A, are you talking about output from the Li pack?

I don't think anyone will regret running fatter cable around the truck to limit voltage drops. I remember a few years ago, I think it was GM was talking about running cars on something like a 48V system. You sure could run smaller wires w/ higher voltage. I guess that concept never took off...

Yeah I'm going to have to put some thought into a permanent solution, sitting around a camp fire with a few smart guys like you having adult beverages is going to go a long way to speeding up my learning curve.

Wish I was going to be there for this next round of camp fires, I am sure it will be great!

Put your batteries in the center of the truck and all your wire runs are shorter

This makes perfect sense! And w/ heavy batteries = better weight distribution.

Actually considering doing this - perfect place to put a battery box under the back seat.
But anyways... very interested in what you come up with here Mack. BTW, were you thinking about using a solar panel at all while the engine is not running?

Perfect place for them!
Are you thinking of inside the people compartment? I saw @J Mack mention battery packs that were 1.5" tall, that should fit under the factory seat, and I think even work if you fold the seat down. Not sure if the LiFePO4 packs need any cooling when they charge. Cool that there is no hydrogen gas discharge to worry about!

I was also thinking about solar panels! They are getting cheaper and flexible, I bet @J Mack has enough clearance under his rack he could affix a panel to the roof. Then just find the best place to route the wiring down from the panel. Back to my earlier questions about managing the charging system for different types of batteries...

LiFePO4 batteries the way I’m buying them are almost perfect for mounting them in available spaces in the cab of a 55 or a 60 in Johnny’s case, you need 4 cells (Nominal Voltage: 3.2v per cell) and can configure them to lay flat @ about 1.5” tall if you were mounting them under a seat.

This is the specifications for the 100ah cell that Johnny used:
Minimum Capacity: 100ah
Nominal Voltage: 3.2v per cell
End-of-charge Voltage: 3.65v per cell
End-of-discharge Voltage: 2.2v per cell
Max Continuous Discharge current: 200A (2C)
Max Discharge Surge: 500A under 5 seconds
Standard Charge current: 50A (0.5C)
Max Charge current surge: 100A (1C) under 10 seconds
Charging Temperature: 0 to 50℃
Discharging Temperature: -10 to 50℃

Dimensions: Height 11.5″, Width 5.25″, Thickness 1.5″
Weight: 5.85lb per cell



So as you can see a small lightweight battery with a true 100ah capacity that easily tucks into an available space is going to be about perfect for a second battery in a camping rig.

Solar would also be cool if you plan on base camping for a day or two at a time with your rig, like I keep saying about our hobby there really isn’t a wrong answer if we are all out here in our garage having fun building our vision of the perfect pig.

1.5" is pretty sweet! Do they need to be in the hard case system you built? Or was that to integrate the charger? Being able to organize an array under the rear seat would be pretty nice...

As for solar, back to my questions of logic for the isolator and charging the different batteries...

First thing to remember here Bob “I’m a janitor” I get paid to clean up other people’s messes not design battery systems so take all of my opinions with a grain of salt.

My ideal system would keep the “start” battery in the factory location and let it continue in its role as the “start” battery and add a LiFePO4 battery second battery to run everything else, these two batteries can be combined with something like the power gate battery isolator like Scraps and I use if needed when one runs too low to do what you need. This would not only be easier offering more mounting options but offer 4X the capacity (the only reason to add a second battery in the first place) at ¼ the weight of our standard Pig sized batteries. (About 30 usable amp hour)

It’s my understanding most of the LiFePO4 batteries “lithium” over promise on capacities when new and start to level into advertised capacities as they age.

Looking forward to watching as you learn more about isolating the different types of batteries, and if a separate isolator is needed to add for solar charging when engine is off/alternator not spinning.

Thanks for humoring me with my questions! This could really change the way we prepare for future Pig Parties.

 

[J Mack]

I come bearing questions

Pablo,
You are mostly correct with most of you assumptions unfortunately I do not have the time to type out the reply you deserve, painting my house right now ontop of all the other junk I'm in the middle of trying to get ready for PP20.
If you were going to make the party then yes this would make for some great campfire conversation, I will do my best to remember to give you a proper reply with links sometime after I get back

 

[PabloCruise]

Pablo,
You are mostly correct with most of you assumptions unfortunately I do not have the time to type out the reply you deserve, painting my house right now ontop of all the other junk I'm in the middle of trying to get ready for PP20.
If you were going to make the party then yes this would make for some great campfire conversation, I will do my best to remember to give you a proper reply with links sometime after I get back

Hey man, it sounds like you need to cram 10 lbs of stuff into a 5 lbs sack, and you don't have much time to do so.

No worries, no hurry on this conversation.

It looks like you are really putting together a solid knowledge base, and I would like to learn more. When we were up in the Black Hills it was pretty toasty and we had a couple of days where we did not have to drive the LX. The fridge was definitely putting a draw on the battery. Having a small accessory power source that could be charged by the alternator or solar panel would be pretty cool.

Have a great Pig Party!

I will just work and scheme on my 30% mo betta AC system...

 

[GLTHFJ60]

I swear I did some reading before showing up with questions, so against my better judgement I am trying to multi-quote what I think are relevant points.
In the spirit of "knowing just enough to be dangerous", I come bearing questions and very little in the way of contributions...

I can try.

Wondering more about how to interface the battery box w/ your current wiring. I don't remember, but I think you were running an AGM as your primary battery. My limited understanding is that trying blend different types of batteries sets up quite a challenge in terms of charging and battery management. I am curious what logic you will arrive at for charging when the engine is running and isolating the batteries...

The limitation with a hybrid battery bank within the vehicle (AGM+LiFePO4 in this case) is only that they reach maximum charge at slightly different voltages. The alternator is designed to charge lead acid battery chemistries (which include agm/flooded/spiral cell) and as such, cuts voltage at ~14.2 volts. Lead acid batteries are designed to top up their charge at this voltage. The LiFePO4 batteries top up at ~14.6v.

This voltage difference is why vehicle based lithium cells have a dc-dc charger, to reach 100% charge off of an alternator. The dc-dc charger bumps the voltage up to ~14.6v from the alternator-provided 14.2v, and monitors the SoC (state of charge) of the lithium pack.

The "battery management system", if you can call it that, for the lead acid batteries is the alternator. That's it, nothing else is required. For the lithium cells, it's a BMS (battery management system) that monitors the individual cell charge/discharge rates, SoC, and balance, but also overall charge/discharge voltage+amperage for the whole lithium battery array. Remember that a LiFePO4 array (in our context) is four 3.2v cells in series to get ~12v for use in the trucks. The lithium BMS interrupts the ground circuit to manage the array, meaning nothing extra connects to the charge side.

Basic idea. The 1.2.3.4 black boxes are the lifepo4 cells if that wasn't clear.

Is the Renogy just for charging the LiFePO4 battery pack? Or is it a "gate" that manages input and output?
When you talk about limiting the current to your existing system to 20A, are you talking about output from the Li pack?

More of a Jim specific question, but he's limiting 20a charging because of the wire gauge he ran through the truck. The cells and BMS are rated for closer to 100a charge/discharge.

The renogy model he's using is just to charge the lifepo4 cells. It's a DC-DC charger that bumps up the voltage to ~14.6v so that the lithium cells can top up.

Perfect place for them!
Are you thinking of inside the people compartment? I saw @J Mack mention battery packs that were 1.5" tall, that should fit under the factory seat, and I think even work if you fold the seat down. Not sure if the LiFePO4 packs need any cooling when they charge. Cool that there is no hydrogen gas discharge to worry about!

Yes, the batteries can be put inside the people compartment. That's what my setup is.

I was also thinking about solar panels! They are getting cheaper and flexible, I bet @J Mack has enough clearance under his rack he could affix a panel to the roof. Then just find the best place to route the wiring down from the panel. Back to my earlier questions about managing the charging system for different types of batteries...

With the type of system Jim and I have, your solar connection needs only connect to the lithium bank. That being said, you could connect the solar charge controller to the battery isolator and the rest of the system would behave as if it was just charging off the alternator. Just have to make sure the solar charge controller doesn't output more than ~14.2v (charging both banks at the same time) because more than that would cook the lead acid batteries.

1.5" is pretty sweet! Do they need to be in the hard case system you built? Or was that to integrate the charger? Being able to organize an array under the rear seat would be pretty nice...

The LiFePO4 cells we selected have an aluminum case. You can put them in another case if you wish, or put them straight in a tray like I did. Jim put his in that pelican style case so that he can easily transport them to where he needs power. Think portable power-pack or jump-pack, that's essentially what he made.

As for solar, back to my questions of logic for the isolator and charging the different batteries...

This gets into the weeds a bit as far as 12v systems go. In short, your alternator will operate as normal, and while running, the alternator needs to be connected to both battery banks. If you want to be able to reach ~100% charge with the lithium array, you need a dc-dc charger, but Jim and I believe you can hit between 90-95% SoC off just the alternator. Unlike lead-acid batteries, maintaining a 90-95% SoC is perfectly fine for lithium arrays like these.

We're both using a special isolator called a Perfectswitch Power-Gate. This type of isolator is a little more intelligent than the typical ACR style isolator, but does essentially the same thing. It allows charging voltage to pass to the batteries while the engine is running, and when the engine is off, the two battery banks are isolated. In both of our scenarios, all loads other than the starter, winch and jump point are connected to the lithium batteries. Solar charging would be hooked up to the LiFePO4 array, as the AGM batteries are never discharged unless winching or starting the truck. Should the AGMs go flat due to say lots of engine off winching, you can manually join the lifepo4 and AGM battery banks together using the power-gate.

Again, I'm not running a DC-DC charger as we should be able to hit 90-95% SoC with the lithium array straight off the alternator. If you decided to use one, it would go inbetween the power-gate and the lithium array.

Last picture. This is what the above basic diagrams look like fleshed out in my truck. Pretty dense, but I've labeled the major components and connections to help make sense of it.

Also, while this system is 100% functional and tested in the pic, it's not been wire-managed yet. Be kind

@J Mack sorry for the hijack @PabloCruise, hope that helps.

 

[roadstr6]

Holy cow! Johnny C. tech FTW!

 

[GLTHFJ60]

Holy cow! Johnny C. tech FTW!

I am Jim's student, lol!

 

[J Mack]

I can try.

And hit a home run, thank you Johnny!

 

[Pigeaten]

And hit a home run, thank you Johnny!

Camp fires are for BS where I come from, tech talk for sober days

 

[PabloCruise]

That was awesome @GLTHFJ60 - thank you!

How do LiFePO4 cells like the cold weather?

 

[GLTHFJ60]

That was awesome @GLTHFJ60 - thank you!

How do LiFePO4 cells like the cold weather?

They typically don't like below 32*f but the bms protects from charging/discharging at low temps. Insulating the battery array can help prevent the temp from getting low. In super cold temps, you can have a heating pad warm the array so that it can charge and discharge safely.

 

[PabloCruise]

I could run the heating pad off the main battery...

Oh wait, cancel that!

 

[GLTHFJ60]

No, in that situation the 10 or 15w heating pad would run off the lithium battery array, and keep the cell temp just above 32*. It wouldn't deplete the capacity by much. Once the array is being used, it would generate a bit of heat on its own.

All electric cars, Tesla's included, have a system that heats their battery arrays in cold climates.

 

[RUSH55]

Great little write-up there @GLTHFJ60 , thanks for taking the time to roll that up into something we can chew on. There’s another point I for one would appreciate you expanding on -

That sweet ammo-can center console!

 

[GLTHFJ60]

Great little write-up there @GLTHFJ60 , thanks for taking the time to roll that up into something we can chew on. There’s another point I for one would appreciate you expanding on -

That sweet ammo-can center console!

Thanks! Don't need to clog up Jim's thread any further. More detail in my Moonshine build thread.

 

[J Mack]

Don't need to clog up Jim's thread any further

Clog away!!

I'm a house painter now so reading your post in my build thread is the most interesting part of my day.....

 

[J Mack]

That was awesome @GLTHFJ60 - thank you!

How do LiFePO4 cells like the cold weather?

Not a big deal.

They are a little more sensitive to extreme cold charging and have a slight better discharge rate at extreme heat but all and all about the same for the way we will be using them.

The biggest difference is we have a BMS attached to our lithium battery that protects it from damage so not only do we get the extra capacity but we should see a much greater life expectancy over a lead acid battery everything else being equal.

Charging at High and Low Temperatures

Learn how extreme cold and high heat reduce charge acceptance, and the battery must be brought into moderate temperature conditions before charging.

batteryuniversity.com