wi_taco 12V house power v1.0

Project Overview

Wanted to add a 12V house power system. Added a fridge to start and in the future it will expand to include lights, charging for phone/drone batteries, and many more things.

Update 10/28/23: I have now evolved to version 1.1 of my setup, separate write-up can be found here.

Goals For This Project

• I want a 12V system for off-grid power for a new fridge + future lights & power additions that would otherwise drain my starter battery.
• I want to be able to monitor power status for the system preferably using an app on my phone.
• Most importantly I want cold beer (and fresh fruit/vegetables that won't spoil as quickly) without having to worry about constantly putting ice in a cooler or worrying if I have enough battery power.

Table Of Contents

1. Design Process
2. Parts & Costs
3. Unexpected Rear Seat Delete
4. Wiring and Installation
5. Final Thoughts and Future Improvements

 

Chapter 1: Design Process

Inspiration for this project came from a trip in the Gila Wilderness of New Mexico during an elk hunt. My father was commenting how most hunt guides say people usually only last like 3 days offgrid before wanting a shower, hot food, and other comforts of the modern world. I agree that after several days of hard hiking and sweating there is nothing better than a shower and clean clothes to boost morale. Furthermore there is also an issue of keeping food fresh when the weather outside is incredibly hot, and there is nothing worse than having to drive 2 hours just to get ice for the cooler.

From there I saw the TW thread for dual battery setups and dove down the rabbit hole of research. I never liked the idea of running dual batteries under the hood as space is already scarce, and now that lithium-iron-phosphate (LiFePO4, or LFP from here on) offerings have better costs, availability, and capacity it seemed the better choice. Watched lots and lots of YouTube videos, especially from Will Prowse who has some good info and entertaining battery teardowns. Then I started posting in the DIY Solar Power forums and from there it was just a matter of doing the build. Here's the relevant thread that resulted in this V1 build:

https://diysolarforum.com/threads/n...ron-orion-tr-smart-shunt-wiring-please.46720/

And here's a diagram of my system for reference so you don't have to read the above thread. In a nutshell, here are the main parts and reason why they exist:

1. Victron 30A DC-DC charger to charge the house battery
2. Victron shunt to monitor current draw and battery capacity
3. Fuse block to easily wire up the fridge
4. SOK battery because they are readily available and reputation for quality & reliability

I blame ICECO for making me actually start the project - they had a sale that I couldn't pass up and naturally I did the smart thing and impulsively bought a fridge. Then thinking it would take a while to arrive expecting it to come from China, I was surprised when it arrived in less than a week. And then I had to rush and get everything else to make it work. This was not a smart thing to do but it worked out in the end. Hooray for bad/good decisions!

Alright, moving on...I had to test the current draw from the fridge first to make sure the specs match reality. They did, and even on the highest "fridge" mode it only draws about 3.75A as confirmed with a Kill-a-watt meter (converted AC to DC).



Here are the settings I used for the initial testing which is nearly what I ran in the field. 34°F, battery monitor (i.e. low voltage cutoff) set to high, and the cooling mode set to MAX. Basically the least efficient setting just to see the draw while I have AC power still readily available. I have to say it cools off much quicker than I expected and when it runs is very very quiet.



Now that power draw is confirmed, I can roughly calculate how well this should work. Taking the battery capacity of 206Ah fully charged, and then setting a very conservative depth-of-discharge at 80%, that means I have roughly 165Ah usable capacity. Dividing that by 3.75A tells me I can run the fridge for 44 hours continuously. Keeping in mind the fridge won't be running 100% of the time especially in the cool temperatures of Wisconsin's north woods in September/October, it's safe to say I can go a minimum of 2 days without charging and likely much longer.

Future me says this: Original build date was 09/26 and I'm doing this write-up now on 10/29. I can confirm the fridge only draws ~20-30Ah per day in autumn temperatures. This means if I decided to go off-grid and be stationary it should be able to run 5+ days without charging. Success!

"That looks over-complicated and over-priced! Why didn't you do it using [insert some other method here]?"

In the future I plan to add more loads to the system. This is just the beginning. The Victron DC-DC is one of the few where you can change specific granular charging parameters based on your battery type which helps ensure my LFP battery doesn't get damaged. I've done lots of thinking on different arrangements, and for now this seems like the best idea for my specific needs. It is not the end-all-be-all solution for everyone. All systems have pros, cons, and compromises and this one is no different. This is a great setup but I already have plans to change this for V2 - scroll down to the summary section to read why.

 

Chapter 2: Parts & Costs

I'm not going to have exact costs because the small things like connectors, heat shrink, etc. were purchased in bulk and I'm too lazy to calculate fractional stuff. Going to round most things to nearest dollar and estimate small items best I can. This does not factor in shipping or taxes because I could have done that more efficiently with more time & better planning; and also because this varies by location. Specialty tools like the cable crimper also are not included as I expect they will last me a lifetime and should pay for themselves eventually.



EST. GRAND TOTAL FOR MY BUILD = $2,299
% OF GRAND TOTAL FOR FRIDGE + BATTERY = 71%

Quick reaction is this: Impulse buys are expensive, but long-term this will add some killer functionality. LFP batteries last a heckin' long time. Don't panic looking at the bank statement, don't panic looking at the bank statement...

 

Chapter 3: Unexpected Rear Seat Delete

My initial plan based on measurements of the fridge and components (pre-arrival) was to only "seat delete" the 40% behind the driver side. Credit to this post which is where I got the idea while researching Dometic vs ICECO. Also credit to this other post with great photos & dimensions of the rear seat area that helped during the planning stage so I didn't have to remove my own seats at the time. Mocking up the fridge first, it fits but less room on the back cab wall than expected...



I tried doing it this way, but that Victron Orion-TR takes up more space than expected, and fitting it to the wedge-shaped area / storage bin behind rear seat backs didn't work like I wanted it to. That SOK battery wasn't my first choice either and is too big for my initial plan. Did some mockups with cardboard and it just wouldn't all play nice together.



By the time I found this out I was down to 3 days before the trip and had to abandon the 40% option. Instead I bought a sheet of pre-finished birch 3/4" plywood from the local big box hardware store and did a very basic rear seat delete. Not many photos during this stage, was busy rushing to get it all together. Caused me to start my vacation a day late which sucked. Lots of trips to my local hardware store for small nuts & bolts but lucky for me that's only 7 blocks away.

Seat back I believe is using M6x1.0x30mm bolts and 1/4" fender washers (don't quote me on that though). Seat bottom area is using some old 5/16" T-nuts I had leftover from my sleeping platform build, washers, a lock washer, and I think 5/16" x 3/4" bolts. Not pictured here, but seat bottom is fastened to the seat back using some 90-degree brackets, and a few 2x4 cutoff scraps under the rear seat bottom for structure and to level the platform. Overall it's less than $20 in miscellaneous hardware. Also not shown here: I drilled out spot welds and removed all the OEM child safety seat hooks/loops/restraints on the cross-brace behind the seat back because I don't have kids and never will.



I removed all the seat brackets and reinstalled the bolts because those holes go all the way through to open air below the body. I used one of the smaller bolts on the driver side as my grounding point and used a small wire drill brush to expose raw metal. Used a multi-meter back to the starter battery and confirmed this is a very low resistance route making an excellent ground.



Lots of adjusting and mocking things up along the way. Here's what the 45L fridge looks like on the platform before it was fully bolted together. Notice the driver seat position and keep in mind I'm only 5'6" so if you are taller there will be even less room. Also keep in mind the lower part of my rear seat platform isn't raised up, meaning it sits right on the original lower seat brackets and is as low as you can go. It's a game of inches back here. This photo alone shows me I had no chance on the 40% delete from the start. Oh well, full seat delete worked and I'm moving on.

 

Chapter 4: Wiring and Installation

Here's most of the wiring parts: charger, shunt, bulk wire and fittings, bus bars, and fuse panel. Also shown are kit assortments of adhesive shrink tubing and small wire crimp ends, fuses, some non-conductive ratchets from HazardFraught, and Husky d-rings and cam straps to hold down the fridge. Pictured but not used: a Daystar firewall boot and hole saw (I just poked a hole in driver side firewall boot and pulled the new wire).



I was most concerned about the SOK battery itself. This is the non-Bluetooth model because they've had problems with the other BMS causing some problems. This one arrived already at 13.13v which is better than I expected even based on the specs. Could have been a show-stopper but we are good to go!



I have a pretty good assortment of tools, but one I was lacking was a cable crimper. Ordered the

$150 TEMCo TH0006 Hydraulic Electrical Cable Lug/Terminal Crimper Kit with 18 Die Sets 12 AWG - 00 (2/0) (5 US TON)

TEMCo TH0006 to do heavy gauge cables and I'm ecstatic with how well it worked. Crimps are excellent, and pairing the UL cable lugs with high-quality wire and adhesive-lined heat shrink means these should be bomb proof. For me it was non-negotiable to have anything of lower quality because I want to have zero problems with it when out on the trail. I'm using all 6 AWG because it's within spec for this system: max output from DC-DC is 30A, wiring should be good up to at least 50A or more, and I have no appliances that will total that high anyways.



Custom wiring mounted to the battery. Using a 60A MEGA fuse as specified by Victron's documentation. I also installed an Anderson SB50 disconnect plug on the end so I can remove it / cut off the battery quickly without wiring up a much larger battery disconnect switch. Current Connected even gave me free stickers so I'll give them some free publicity.



Due to my fitment issues I chose to put the SOK battery on the driver side rear floor. It's a sealed marine battery and it fits quite well in that spot without taking away usable space anywhere else in the back seat. Not pictured here but there are some rubber boots to cover those terminal bolts. I could have secured this a little more, but it really doesn't move around much and those RC neoprene seat covers kind of give it a cushion anyways.



After I had the entire house system wired minus the fridge, it was time to connect source power at the starter battery. I already have SDHQ billet terminals so this was quite easy. Fuse protection was accomplished by adding a Blue Sea 2151 dual post block and a Blue Sea 5178 60A terminal fuse, and the 6 AWG cable was connected. No immediate smoke or explosions, and power back to the DC-DC charger was confirmed with a multimeter.



First "boot" at key-on required me to update the firmware through the iOS app for both the DC-DC and the SmartShunt. I almost had a problem with the shunt but after a couple attempts it went through. Be patient during this step if you use these same parts.



After updates it's time to set the shunt parameters to match the LFP battery manufacturer specs. Discharge floor is set very conservatively to 20% because this is the maiden voyage and I want margin for error. This is one place where the Victron unit shines over alternative products on the market - Bluetooth access via a stable phone app, and ability to tweak nearly everything.



Wiring up the rest was straight-forward but also extremely time-consuming to get it all fitted how I liked it. I cut a slot in the plywood back wall to run the in & out wires through, and mounted all the components so they don't interfere with the fridge. The shunt requires a small 18 AWG wire run to the house battery for power and I crimped it right into the big 6 AWG lug to be as clean as possible. I added a small block of plywood cutoff scraps down below as a stopper so the cooler can't move and accidentally contact the wiring. The fridge basically hides all of this except the DC-DC charger because it's too large.



Final steps were to add the small 6-spot fuse block and wire up the fridge. I cut the cigarette-plug connector and hardwired directly using heat shrink ring terminals and installed a 5A fuse. Remaining fuse block isn't wired but populated the slots with spare 5A and 7.5A fuses as spares. D-rings and cam straps were bolted down to that spacer block in back, then wrapped around the handle and cinched down. Fridge control panel was mounted towards the front so I can fold down the front seat and access them once installed. Operation worked flawlessly on the first try - looks like my planning payed off! And it's fairly simple so that's nice.



Here are a couple screenshots from the Victron app to monitor & make sure it's all working properly. Orion DC-DC is pretty basic but shows the voltages and which stage of charging it is running at - interesting but nothing super important. More critical is the data from the SmartShunt where (after the initial charge cycle) you can see State of Charge (SoC), live current draw, and consumed Ah. The history feature is also very powerful to help see trends. I didn't play much with the other "TRENDS" setting yet so I won't speak on that but you can find more online if interested. I can see why the SmartShunt is such a popular product for all 12V systems like this.

 

Chapter 5: Final Thoughts and Future Improvements

Immediately after finishing the install, I started a 2+ week roadtrip covering nearly 2,300 miles and 3 states (some trip photos here if you like that sort of thing). Outdoor temperatures ranges from highs up to 80°F and lows down around 20°F. I didn't have anything setup to measure ambient temperature inside the truck cab but typically it stays a bit warmer than outside.

Some thoughts based on this trip:

• I feel immediately validated for worring so much that my LFP battery has low temperature charging protection. Some forum trolls and even one vendor (located in California) told me "nah bro, don't sweat it!". WRONG. Do your research and choose products that work for your region. Lots of solar power vendors that sell this stuff are located in CA/NV/AZ and just don't understand the kind of cold we get. It was probably down in the high teens one night in Minnesota - not unusual for October/November.
• For this type of trip the 206Ah battery was overkill and my SoC never dropped below 90%. This is because I was driving for a long time. With 30A output from the DC-DC I could basically drive 1 hour a day for full charge. This will change in the future when more loads are added.
• It was AMAZING to not worry about ice in a cooler. The fridge just works. In this regard the ICECO is an incredible value for the luxury it gives.

Some thoughts for the future:

• Everyone who said doing a rear seat delete vastly increases road noise wasn't lying. Make sure your stereo & speakers work well so you don't hear it as much. I was already thinking of doing sound treatment for audio upgrades later and it's definitely higher on the list now.
• My biggest problem is the physical size of the Victron Orion DC-DC charger. It requires space around it for passive cooling on the large heatsink and can't really be mounted in an enclosed space. Functionality? Great. Mounting pains? Not ideal for tight spaces like this application.
• Way way back when I started considering this project I wanted to go with a Redarc BCDC 1225. Relatively inexpensive all-in-one unit that I can mount in the engine bay AND it has the option for solar later on. The Redarc has no ability to monitor via Bluetooth, and although it has different charge profiles you can't fine-tune quite like the Orion. In that regard the Victron is superior...
• HOWEVER, I am now reconsidering the Redarc (possibly the 40 or 50 Amp offerings this time) as a future replacement for the Victron Orion. For my specific truck configuration this may allow for more optimal use of the interior cabin. If I go that route I'll do a V2 write-up and link to it here. The downside is it definitely requires a "Big 3" wiring upgrade first, and probably also should have an alternator upgrade too. More costs and I don't have a money tree yet.

Would I Build This Again?

• Victron charging system? Maybe. It works great, but as previously mentioned the physical size/cooling needs of the Orion may not be for you.
• Victron SmartShunt? YES. That thing is a rockstar. Buy one.
• SOK Battery? Yes, but with a caution. The SOK itself is great and I have no complaints. The size isn't what I wanted and I might do something else later down the road. If I sell the SOK later I'm sure I'll take a hit. LFP batteries ain't cheap. Try to be 100% sure you pick the right battery for your application so you don't have to get another one later.
• Fridge? ABSOLUTELY. I've been living like a caveman all these years with just a cooler. Though I wish I bought a dual-zone so I can have cubed ice for cocktails at camp, and for longer expeditions having the ability to pre-cook and freeze meals then thawing later seems like a good option. So that might change later as well.

Thanks for reading, hopefully someone finds use for this so I can give back to the community for all the help I have received.

 

Reserved for future updates and stuff and things.

2/17/23: Sold the Victron Orion DC-DC charger for $150, oddly enough to a guy on craigslist in Baltimore. Great charger but you almost can't give it away on the secondary market because it is a very niche item. Keep that in mind if you buy one.

 

Damn bro, you spent over 2k and a fridge and a battery

I'm just talking poop. I can't talk, I run my VL45 off of a Jackery 1500. I use a 100w solar panel while parked and a 12v outlet in my bed to charge while driving. It kinda sucks. I also have a Jackery 240 & 300. I honestly think they are more efficient than the 1500. You can look at the 1500 wrong and the loud ass fan turns on and takes a toll on the battery. I just sold my shell and will be getting a pop up camper soon. The plan is to build a system like yours. After watching will rip open a few Chins batteries, that's what I am going with. I'm in the CA desert, I don't have to worry about low temps like you. We do drop below freezing at night, but once the sun comes up, it warms up. I'm just going to install a few kill switches, to isolate the solar from the charger and the charger from both batteries. That way I have protection for those nights it gets below freezing and isolate it all when the truck is just sitting between trips. I'm also going to make it so the LFP and charger are easy to take out, kinda like Will's milk crate builds. You guys deal with actual cold weather, I get crazy heat. I don't want it sitting back there when it's 115 outside with the truck just sitting there.

Anyway, good write up!

 

Thanks for the feedback and thanks for reading! Talk all the poop you want LOL, that's why we share these things. But as I'm sure you already see there is no single way to solve this type of puzzle and everyone puts their own flavor on it. Yes I did it the expensive way for just a fridge + battery but like I said this is just the beginning. Future will include adding solar, a 12v shower/water pump, lights, ports for USB and 12v power to charge and run heated blankets, maybe an electric heater or fans depending on the season, a medium-ish inverter for 110V stuff, etc. The possibilities are really endless once you have the foundation in place. I now have room to build & grow.

You are right that you potentially have more concern over high temps than low temps, but it does still get hot up here too. Plus I've been in Death Valley and Joshua Tree where temps were below freezing and that's no joke. My SOK specs say high storage temperature limit is 140°F (60°C) and I think all LFP batteries are about the same. Online searches show it can get that hot inside a vehicle after an hour at 95°F. I do visit New Mexico to see family and/or hunt elk about once a year so heat is still a big thing on my mind. All it takes is even once and those LFP batteries won't be happy. Anyone running LFP should be concerned with temperatures avoid expensive problems/failures. Protecting against low temps is relatively easy - insulate around the battery and if not enough add heat pads that are cheap & easy to find. High temps? That's going to take more trial and error to solve.

Prowse's milk crate builds are very cool. I'm still toying with ideas how to build my own into a smaller package but that's way down the road now. I do like the fact that my battery is easily removable using the Anderson plugs, but I prefer being able to leave the charging stuff mounted up. Just fits my build better to have it tucked away and leave it in the truck. And it's nice hard-mounting so you have peace of mind when going offroad that nothing is going to move where it shouldn't. At the moment my plan for V2 is to move all the bus bars, shunt, and fuse panel to the storage bin under the rear driver seat. The fridge will be on top anyways blocking access so it's already wasted space. But of course that may change as my design ideas evolve.

Fun stuff to think about!!

 

Yeah dude, it was pure shit talk. I completely understand dumping money into the truck, in my case, just to do it all over again lol. My wife is giving me grief about my talk of building a setup like yours. It's a good thing we have separate accounts and she never asks how much any of this stuff cost. I've been determined to get the right setup with my reg cab. There are many times that I tell myself that I should have gotten an AC, but I really like the short WB of the RC. I'm on my third sleeping setup. First it was bed bars and a soft RTT. Then I got a dog and wanted to get a 12v fridge. So then I bought a new shell and hard RTT. Took one trip in it and decided that I didn't like all that weight up top. So I sold the hard RTT and got the Topper EZ Lift Nomad and just slept in the back of the truck, with the dog. After over a year of that, around 40-50 nights, I got tired of having to unload and load EVERYTHING! I just sold my shell the other day and will have the Topo Badlander installed on Friday. For power I have been using a combination of a Jackery 240, 300 and 1500. I wired up an always hot 12v outlet in the bed and use that to charge while on the move, then switch to solar while at camp. The problem is, I normally run trails and explore all day and camp in a new spot every night, so I really don't get much out of the solar. I run the VL45 in the back and a cheap little 10q fridge up front for waters and snacks while driving. A 12v outlet just doesn't cut it. I want a system that I don't have to manually switch between power sources. I'd also like to get away from using the Jackery's. They are capable if pass through charging, but Jackery says that it's not good for them. LFP's have gotten cheap, compared to a Jackery, and they can handle pass through charging without a problem.

I'm looking forward to what your V2 looks like. Nothing wrong with changing stuff up. This is a hobby, and hobbies don't involve good financial decisions lol.

 

What are your ideas for heat? I've been thinking about an electric blanket and a 500w ceramic heater.

I highly recommend a couple of fans like this:

LEMOISTAR Portable Osillating Standing and Wall Mounted Fan with Remote Control, 8" Foldable Table Fan, 10000mAh Rechargebale Battery Operated, 4 Speed, Timer Desk Fan for Camping Travel Office

https://www.amazon.com/dp/B088TLJNCW?th=1
They kick out some serious air! You can run them all night and charge them by day. They can also handle pass through charging.

 

Heating will likely be a combination of something to insulate the battery + flat heater pads. Lots of people use small 12v silicone heat pads that are sometimes sold as water tank or beehive warmers. Good thread and examples here:

https://diysolarforum.com/threads/lifepo4-heating-pad-for-cold-temperatures.5/post-436240

Cooling is much trickier and I don't have many good ideas yet. My first task is going to be monitoring temperature inside the cab during hot days using temperature probes and data logging. Then I'll test various things like a windshield sun shade, vent fan, etc. and see what works best. I'm already tinkering with a 5V/USB vent fan for my camper shell that mounts into the sliding glass window and figure I can apply the same for the cab side. The thought is if I can get fans working well enough so cab temperature matches more closely to ambient temperature then it won't be a problem. Beyond that some people have done liquid cooling or building a small cooler/freezer enclosure to cool the battery but I really really don't want to mess with that.

 

I'm almost done with the planning and ordering of everything I'm going to need for my power system. Dude, it got out of control and added up quickly! I still need to order a battery and a shunt. After watching many reviews, I've decided on the Chins 100ah battery. Still don't know what shunt I would like. I was out in the Mojave Preserve weekend before last and the temps dropped into the low 20's. That's about as cold as I'm willing to go out in. The good news is, it didn't drop below freezing inside my topper. I'll be putting my battery inside of a Kickass battery box and using some foam to insulate it. That should get me the protection I need without having to worry about heating the battery. I'm not going to worry too much about keeping it cool. I've never had a problem with a Jackery in the back getting too hot. On warm days I just crack the windows on the topper while I'm driving. Living in a desert, the summer is pretty much my off season, unless I take a trip up into the mountains. When I do that, I just don't let the truck sit too long and heat up at lower elevations. Everything will be setup with SB50's and when the truck is sitting between trips I'll take the battery out. I'm getting excited and can't wait for everything to show up and slap it all together!

 

100% agree the costs can get out of control quickly on a setup like this. The upside though is it should last quite a long time giving a good return on investment.

I think you're in a better geographical location than I am to use the Chins battery, and your plan for the box + insulation sounds great. You shouldn't have a problem but might be worth finding a small thermometer to put inside the box so you can test how well it works since the battery is the single most expensive piece.

Lots of good shunts and I will 100% stand by the Victron 500A SmartShunt. Has worked flawlessly for me so far and with the bluetooth + mobile app I can see what's going on in terms of current in/out. Would buy it again.

Good luck with your setup and be sure to post it to the dual battery megathread when you get it running!

 

Planning version 2 of my setup and decided I'm selling the Orion-TR DC-DC charger if anyone is interested. Link to the B/S/T thread:
https://www.tacomaworld.com/threads...p-360-watt-dc-dc-charger-non-isolated.786406/

Edit 2/17/23: Charger is sold.

 

I seriously looked into all that but I want heat and maybe someday a/c. I bought a Honda EU2200i. While it is pretty quiet already, I plan to build a sound insulated box for it to get closer to total quiet.

 

Don't tease lol. What direction are you thinking about going?

 

If I wasn't dealing with the space constrictions of a reg cab, I would totally figure out some sort of AC solution. I absolutely hate the cold, but camping in temps above 100 are just no fun. I have a little 500W ceramic heater that I run off a Jackery 1500. I'll run it for like 30 minutes before I go to bed, to heat up the topper. Then I'll run it again in the morning to take the chill out of the air. Nothing wrong with being comfortable. The more comfortable your setup is, the more likely you are to head out on an adventure.

 

Current plan for v2 (subject to change) is a Redarc BCDC mounted under the hood using an Offgrid Engineering battery tray mount. Victron shunt, bus bars, and wiring for the fridge will be in the underseat cubby on driver rear seat (underneath the 40% seat). Still lots of planning left before it happens though.

 

Sounds pretty good. Are you going with the dual input Redarc, that will give you the option of adding solar in the future? I was going to go with the Redarc dual input, but decided to try out the Wagan Tech DCDC. They just introduced it a few months ago. The specs and features are really close to the Redarc. The deciding factor was I got it on sale for $200. It's normally $300. If it doesn't work out for me, I'll just get the Redarc. Wasting $200 would suck, but I'll get some of it back by selling it and it won't be the end of the world. When I decided on the Kickass Battery box, they have a model with a DCDC charger already mounted on it, but its max solar voltage was 23V, and my panel has a VOC of 24.3V. The Redarc and the Wagan both have a Max of 32V, so that leaves a good amount of head room. I considered the Renogy, but that thing is way bigger than the others I was looking at and its max solar input was 25V. I wouldn't feel comfortable always pushing so close to the max.

It has been fun researching all this stuff, and talking to others about their setups.