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When I purchased my van back in 2017, it already had lithium which I knew I wanted for my van. The debate could go back and forth about if lithium is worth it or not, but for me, it’s what I wanted and bonus, it was in my van when I purchased. However, I’ve always been a little bit disappointed with the BMS as I felt it was lacking in several areas. In this post, I’ll talk about how I addressed those and how someone looking to build their own lithium bank can go about it today. I’m also going to talk about some utterly useless addons that no sane person actually needs. I just like to tinker….

The lithium in my van is built with raw large prismatic cells with an external BMS that was pieced together at AM solar from different suppliers. The BMS was a Power House Auto Mini BMS v7(sadly it’s no longer in production, but there is a GREAT replacement that I’ll talk about later in this post). It’s a very basic BMS with hard limits (you can’t program it yourself) but it does the job. It has the ability to turn off chargers when the voltage gets too high (HVC at 3.6v per cell) and turn off loads when the voltage gets too low (LVC at 2.9v per cell). When the voltage recovers (3.1v or 3.5v) the chargers or loads turn back on on its own. Each of these have a 10 seconds warning phase in case of sag or low voltage drop, so if they aren’t addressed (IE there is a problem with the BMS or a relay), it also have a main contactor (500amp Tyco EV200) for emergencies in the event the BMS does not shut off the charger or loads (3.65v or 2.6v). When this happens, there is a momentary switch used to signal the alarm and requires you to hit a button to “reset” the battery. This is there to prevent automatic restart and further deplete or overcharge the battery.

As shipped from AM solar, it only had the main contactor to shut off the battery for either a HVC or LVC condition. While I’ve never had either happen, it always bugged me that if there is ever a problem with the balance of the battery or it was over discharged, it will shut off the battery entirely (including chargers). Since I travel with my wife who has asthma, she doesn’t go with me on very strenuous or high-altitude hikes. We also take my mother in law sometimes (I get booted to a tent). I’ve always worried about the battery shutting off and one of them not knowing how to reset it.

Since the BMS has the ability to add high and low voltage disconnects, I looked into the BMS more to figure out how to achieve this. I found that the BMS will pull to ground on the low and high voltage ports on the board. This is inverted compared to a typical BMS which will remove the high or low when there is an alarm. It would also make it difficult to find Normally closed relays that could handle a decent amount of current for my chargers. I ended up building out a few relays on top of the BMS to invert the signals. To do this, I used standard automotive relays that have a Normally Open pin and a Normally closed pin. So the common wire is a 12v signal and the output to the disconnect is on the Normally closed pin so when the BMS if fine, it’s passing through the 12v signal. Because I’m using the same power to power the relay as the COM, this is no longer an isolated circuit. I found a 4 channel optocoupler which will isolate the circuit for up to 4 signals (this will prove to perfect for my application). Now I have taken the output of the NC relay for the low voltage condition to a splitter (wago connector) to two of the optocouplers and the output of the NC relay for the high voltage condition to another splitter and now I have two outputs for each condition (low voltage and high voltage).

Old BMS in it’s small box:



New BMS I wired together with those green phoenix connectors to make install easier:



4 Channel Optoisolator in the old BMS box (recycling and saving money):





So now that I have the outputs on the BMS, I needed to find a solution for turning off my chargers (Charger on the inverter, my charge relay linking the starting battery for charging from the alternator and the MPPT charger) and loads (DC loads and inverter). My inverter was a Magnum MS2000. This inverter has been rock solid since the day I got the van (and I assume the previous owner had no problems with it). The issue with it was the ability to remotely turn off the charger. Magnum has an accessory to turn off the inverter, but did not make one for the charger. I very rarely use shore power at all since I mostly camp at BLM spots, but if I wanted to make a full proof solution, I needed to come up with something. Of all the 12v inverter/chargers on the market, only one has a remote switch to shut off the charger fuction: Victron Multiplus series of inverter/chargers. I ended up getting a great deal on a gently used Multiplus 3000. It’s a bigger unit that I needed, but at the cost, I couldn’t pass it up. This would give me to 1 signal from the HVC out to turn off the charger and 1 signal from the LVC output to turn off the inverter.

I’ll be using the two AUX inputs to disabled the charger and inverter with the software assistant:





I also wanted to protect my new inverter. Hooking up an inverter through a contactor will subject both to high inrush currents. Thankfully REC-BMS makes such a device in a small package. It also is time adjustable from 1 second to 11 seconds. The pre-charge unit is a device that charges the input capacitors of the system components before the main contactor switches on. Pre-charge device eliminates high inrush currents at the switch-on of the contactor and prolongs the contactor lifespan dramatically. I tested it on my bench setup before installing:



With the timer switch:



And it fit perfectly where the old BMS box went right next to the contactor:



Next up I wanted to address the charge relay for linking the starting battery to the house battery. It was a Blue Sea ACR. The selling feature of the ACR (other than the 500amp rating) is that auto sensing voltage reading. Basically, when it senses a battery above 13.2v, it thinks one of them is charging so it will link the batteries. The problem with lithium is they have a high resting voltage than lead acid so the ACR will always want to connect the batteries. I never really used the ACR as solar has always kept up with my loads, but it’s always nice to have the option. I also wanted to regulate the charge current to my batteries so I opted to go with a DC-DC charger. I ended up with an Australian version of the Kisae DMT-1250. When researching dc-dc chargers, for some reason google didn’t show me the Kisae but did point me to an Enerdrive version of the same thing. A quick email to my friend in Sydney and a quick PP gift payment, I had a new one on it’s way. When it arrived a few weeks later, I learned of the Kisae model. I paid around the price but paid for shipping from Austraila. Oh well live and learn. This unit is pretty slick as it does 50 amps either from solar or alternator/starting battery. You can have both hooked up so for a smaller install, this could be an all in one DC charger. However since I have a 400ah bank, if I ever was in a jam and need to recharge quickly, I can charge from whatever solar gives me, plus the 50 amps from the alternator.

So now all that’s left are relatively low current items. Victron makes battery protects that can be used as switches. They aren’t contactors, but mosfets. The downside to this is current can only flow in one direction plus they can’t handle high inrush currents from large inverters (but I already handled the inverter above). What I ended up doing is to have the output of my DC-DC charger and the MPPT charger controller to a battery protect. This effectively shut off the chargers by disconnecting the battery. This presented a problem for my MPPT charger controller. It didn’t like having the charger disconnect from the battery (which I knew from a previous change I made to my system a year or so ago). When the battery was present again, in certain circumstances it wouldn’t reconnect the charge properly. It also had my battery monitor on the remote panel so if I ever had the BMS disconnect the chargers, it would disconnect the remote panel and the SOC of my battery would reset. I decided it would be best to just replace the MPPT charger AND the battery monitor with two separate units. Since I already had a Victron inverter, I decided to go with a Victron MPPT 100-50 and a BMV-712 battery monitor. The battery monitor is a great unit as you can set charge efficiency and Peukert ratio. This better handles the calculation of state of charge for lithium batteries. I highly recommend the BMV700 series if you want a battery monitor. With the BMV-712, there is also temp probe that you can add and a programable relay (which I’ll get to later in this already super long post).

DC-DC charger along with the new MPPT I also used this time to add some breakers as the old system didn’t have any. I also added a two way switch so that if I end up with a dead battery, I could switch to position two and link the starter battery and house battery manually (blurry photo, but it’s there):









So now that I had a new mppt that won’t have issues if I remove the battery, I ended up getting a BP100 that can handle 100 amps. My DC-DC charger for my alternator charging is 50 amps and I currently only have 300w of solar on the roof and that max I’ve ever seen from the mppt is 17.8amps so a total of 67.8amps. I took output of each charger to the input of the Battery Protect. Then the output of the battery protect went to my busbar to the battery. I then took the remaining HVC signal and wired that to the Battery Protect. Since the Battery protect is programable, I can program it in Lithium Mode which will take the signal and act as a switch. It also has a 30 second cool up period after the BMS wants to turn the battery back on so the voltage can recover. As for the remain loads, it’s just my DC circuits. I took the remaining LVC signal and wired it to a BP65 battery protect. This will disconnect my DC loads in the same way as the BP100 will disconnect my chargers.

Some photos before the BMS hookups. I also remade all my DC cables as they were poorly crimped and undersized in some areas. I’ve also included a screen grab from the BP showing when the BMS disconnects the loads:








So the BMS is almost perfect. The last item to address is low temps and disconnecting the charge sources. I had previously used another Tyco200 (overkill but I had an extra one) and an external 12v thermostat to disconnect the panels from the charge controller. This worked and would have continued to work, but now that I had a Victron Battery Monitor with temp probe and programable relay, what I did was take the HVC signal that disconnect the BP100 and before it went to the BP100, I took it to the BMV712 relay com port, then ran the normally closed output of the BMV to the BP100. This way, if the BMV seems a high or low temp that I can set, it will open the relay and disconnect the chargers. Now because this is only going to the BP100, it won’t turn off the charger on the inverter charger. I almost never use shore power, but if I do I’ll be using the van and keep it heated. Plus I’ve since moved to Nevada, so I don’t think I’ll ever be traveling in the van to a place where it will get that cold that quickly where the van wouldn’t have heat on. Though now that I’m writing this out, the Multiplus does have extra aux inputs so I could possibly find a way to use one of those input and the normally open port on the BMV to disconnect the charger as well….hmmmmm An edit may be coming.



Everything is installed and working great. Now that I have pretty much all Victron components, I had thought about adding a Color Control GX (Venus OS) to network all the chargers together. The benefit of this is you can enable a feature called Distributed Voltage and Current Control. This allows you set a max charge current as well as share the temp and voltage of the battery with your other chargers. This basically negates the need for the relay in the BMV as the venus will control the chargers that are networked (Victron chargers). However I still have it setup through the relay of the BMV as the Dc-DC charger isn’t Victron. So if you want to max your charge to .5c for the best health of the battery, you can set the limit. If you have a 200ah battery, you can set the max charge to 100 amps. So if you have a multiplus 3000 with a 120 amp charger and you are bringing in 20 amps from solar, it can lower the charge rate or the multiplus to 80amp plus 20 amps from solar (it will always prioritize solar). Solar charge goes down to 10 amps, multiplus goes to 90 amps. That’s just one of many features it can do. It can log all your production data, send alarms to your email, and much much more. The color control is an expensive product, but Victron software is open source. Someone at Victron ported the OS of the color control to a Rapsberry Pi ($35 all in one computer). I had one laying around and added a $50 touch screen and a $100 mount, a few serial to USB cables and I have a touch screen version of the color control GX. I’ve added a GPS module to the Venus so you can set a geofence. If the van leaves my neighborhood, I’ll get an email about it. I also purchased a cheap 4G/LTE modem and a $50 a year data plan with 1GB of data per month so the van is always sending info from the van. This was the part of the build that was TOTALLY unnecessary. I work in IT, so this was a fun little project that didn’t add much to the cost of the upgrades. I also purchased and Analog to Digital converter board for the Pi to take the resistive signal from my auxiliary diesel tank for my heater and input that into the Venus as well so my tank gauge was no longer needed as it’s on the Venus OS.















 

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Discussion Starter · #2 ·
PART 2:

I also needed to remake my control panel piece since I switched out a lot remote panels. This was probably the hardest part for me as I don’t many tools anymore (they didn’t make the move from PA). I have a facilities department at work borrow some tools so I took some ½ MDF along with a ¼ black panel board and glued them together. I went with black to break up the wood look of the cabinets in the van. I think it turned out pretty nice.

Old Panel:



New Panel:



I had extra panel board so I remade a storage panel to add USB chargers for headlamps, phones, ect.



And the mess of a backyard:



This has been installed for a few weeks now and we did a couple of weekend trips already. It’s been working pretty good. The only items left to install is the external antenna for the GPS and LTE modem as signal inside the van is pretty bad. I’m going to use the existing hole in the roof as the previous own had a cell booster antenna that was torn off on one of our recent trips (I don’t remember any low hanging items, but we weren’t using it anyway). I’ll use the torn off wire as a pull string and purchased an external box to mount the antennas.


One last item to add to this list is a BMS…. While I have a pretty solid setup now, the BMS is no longer being sold. The point of this post is to help people that want to do a DIY lifepo4 battery. The creator of the BMS closed up show and went to work for Lithionics (they sell lifepo4 batteries). This left a void for a cheap, high quality BMS for 12v applications for camper van. Enter Electrodacus. This guy did a kickstarter a few years back for a BMS and solar charger in one unit. He has now released an SBMS0 which is a bare bones model that doesn’t have the solar charger built in. What’s great about this unit is it is programable and has 4 optocouplers built in for remote disconnect, and has an input for a shunt so it can be a battery monitor as well. There is a lot more info on his website about it.

I did draw up a pretty detailed diagram with where everything plugs in with the Electrodacus SBMS0 and the components I used. I may have gone too far with the details (those QR codes if you zoom in actually work), but there should be no question about where you plug things in at. The only thing that’s not in the diagram which is my setup now is the contactor, precharge and my BMS. But none of those would be needed with his BMS.



And a high resolution version to zoom in for details:

https://i.imgur.com/LmM7frj.png
 

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Thanks for posting this.

Although I and most of the members here have no idea of what you are talking about, much less doing (have done) several will find it very helpful, I’m sure.

This illustrates what one can achieve with the proper knowledge (and finances). It also serves as a warning to others, not as knowledgeable, to what they may be getting themselves into and cause them to further evaluate their needs and power requirements other than just thinking they will have "bragging rights " when they go for this type of technology.

For me and most others here, however, the down to earth reality is a pair of 6v golf cart batteries, 200w of solar and a manually switchable connection to the alternator is more than sufficient for our needs. As usual, there is always a huge disparity between what people want and what they actually need and wants typically win out in life.

I commend you for knowing both your wants and needs and being able to forfill them both to your satisfaction and sharing how you did it. ;)
 

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" I’m also going to talk about some utterly useless addons that no sane person actually needs. I just like to tinker…."

I feel you brother.
 

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WOW !!

That is Totally Impressive- Congratulations!!

I have some of the components you have used (but very few). I considered Lithium batteries, but at the end of the day I went with AGM (inside under my bed). I will probably go lithium on my motorbikes

Im very interested in following this thread & understanding what must be the leading edge here for camper vans

Great Job !!
 

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Discussion Starter · #8 ·
Thanks for the kind words. It was a lot of work and planning to get everything right. I'm just glad everything worked out as well as it did.

It's for sure a huge undertaking. My setup is rather excessive. A normal person could put together a 100ah lithium pack for cheaper than a battleborn drop in, but not my much. It really starts to pay off when you have 200ah, 300ah, 400ah as you aren't buying a BMS for each battery. The electrodacus BMS is around $130 I think, the victron BPs are I think 100 for both if you don't get the bluetooth versions, so for 230 for the "brains" of the battery, then it's just the raw cells which can be had pretty cheap. These are my favorites at the moment as they come with mounting hardware:

https://www.electriccarpartscompany.com/Fortune-100Ah-Aluminum-Encased-Battery

So for 120*4, that's 480 plus the "brains" 230 for a total of 710. Much cheaper than bbb, but can't beat BBB's simplicity for light use. However when you step up to wanting more, it's only an extra $480 for an additional 100ah and you don't need an additional BMS. So for 1190 for 200ah, 1670 for 300ah, and 2150 for 400ah. So for a little over the cost of 2 BB batteries you are getting 400ah.

But KOV is 100% right! There is a lot that goes into a system like this and the beginner needs to do a TON of research before they can just start throwing a system like this together.
 

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Discussion Starter · #9 ·
Alright, more info on the (almost) useless part of the upgrade...

Mounted my GPS and 4G LTE antenna today. Removed the existing antenna and used the same entry point (through the solar combiner box). I used a project box to mount both antennas to and also ran a DC cable to the box for future add-ons (I'm thinking about doing an LED strip on the awning for a permanent outdoor light instead of using headlamps). I used heat wrap for the cables then did an extra covering with electrical tape (I don't think the extra part was necessary but the old cable I pulled out was pretty dry and not brittle, but felt like it could eventually get there.

The benefit of having the 4G is due to the Venus device from Victron. It sends data to an online portal I can access from anywhere. I can set different alarms based on any metric the device logs. For example, I have high and low temp alarms setup. If the battery goes above or below a set limit, I'll get an email. I also have a SOC alarm in case the battery chargers aren't working properly.

I also setup GPS so Venus knows where the van is. I've setup a GeoFence so if the van goes out of a set area, I'll get an email. I don't think the van should ever get stolen, but if it does I'll know where its at.








 

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Really nice setup.
I have been scouring the internet for someone who has done the Enerdrive DC2DC with a Victron inverter/charger.
Can you give me more detail as to why you use the Victron Battery Protect? Is it to keep the DC2DC and MPPT isolator from the inverter? So only one source can supply power to the battery?
Cheers
 

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Very nice, detailed writeup with great descriptions of what you did and why. That is typically glossed over on most writeups, and you did a great job. Before I did the electrical system in my van, I did a TON of research. I am not an Electrical Engineer, so I decided to go with drop in battery and a far simpler system. I drew up a simple schematic and had my Electrical Engineer son-in-law check it out. After getting the thumbs up, I installed it and everything is working great, just as intended. It was a tremendous relief to me.

Thanks for sharing and for putting together such a great writeup! Wish it was available when I was designing my simple system.
 

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Great job.

Nice to see battery prices coming down. Thanks for information. The bare battery cost works out to just over $330 per kWh when purchased in volume. A complete 150Ah 48V battery pack (7.2 kWh for around $4,000, or $550/kWh) is getting close to cost of built-in generators for air conditioning overnight.

Makes sense that mainstream RV manufacturers like Winnebago, Coachmen, and Thor are offering camping vans with lithium options in lieu of Onan generators.
 

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Discussion Starter · #13 ·
Really nice setup.
I have been scouring the internet for someone who has done the Enerdrive DC2DC with a Victron inverter/charger.
Can you give me more detail as to why you use the Victron Battery Protect? Is it to keep the DC2DC and MPPT isolator from the inverter? So only one source can supply power to the battery?
Cheers
The victron Battery protect is basically used as a switch to turn off the MPPT and the DC2DC. Since the DC2DC has no on-off port and neither does the MPPT, I run the current through the battery protect to disconnect the chargers from the battery since that has the remote on/off. This is not the best way of doing it (it would be better if the DC2DC and MPPT had a remote port) as I've been told the chargers don't like to be disconnected from the battery, however it's what I have to work with at the moment. And since installing, I've never had the BMS shut off the chargers as my cells are well balanced. It's basically there from protection. I could have used two battery protects and installed them BEFORE the chargers but that would have added to the cost, complexity, and SPACE (it's getting cramped up the bed).

Very nice, detailed writeup with great descriptions of what you did and why. That is typically glossed over on most writeups, and you did a great job. Before I did the electrical system in my van, I did a TON of research. I am not an Electrical Engineer, so I decided to go with drop in battery and a far simpler system. I drew up a simple schematic and had my Electrical Engineer son-in-law check it out. After getting the thumbs up, I installed it and everything is working great, just as intended. It was a tremendous relief to me.

Thanks for sharing and for putting together such a great writeup! Wish it was available when I was designing my simple system.
Thanks!

Great job.

Nice to see battery prices coming down. Thanks for information. The bare battery cost works out to just over $330 per kWh when purchased in volume. A complete 150Ah 48V battery pack (7.2 kWh for around $4,000, or $550/kWh) is getting close to cost of built-in generators for air conditioning overnight.

Makes sense that mainstream RV manufacturers like Winnebago, Coachmen, and Thor are offering camping vans with lithium options in lieu of Onan generators.
You have to get a large volume to get that low of a price per kWh (or buy direct from China). But yes, lithium is dropping. You can get a 100ah lifepo4 in raw cells for $476. Quantity discounts start at 16, so 400ah for $1840.

And 12V vs 48V in a van just becomes complicated. Winnebago does 48V and the entire system has to be changed (second alternator, DC-DC for 12v devices, ect.). Keep it simple and stick with 12v. Wire runs in a van aren't that long so the smaller wire with 48V doesn't really matter all that much.
 

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Coachmen and Thor are doing 12V systems, but I think Winnebago has the right idea with 48V as a replacement for generator.

There’s really not much middle ground in my opinion. If you are not going to air condition using batteries, there isn’t the need for 600 Ah like on some of these mass-produced systems. Like others have said, 100 ~ 200 Ah at 12V should be enough for most buyers/owners.

When they power A/C with batteries, all of these systems have a second dedicated alternator anyway, so why go with 12-Volts? Granted, it saves a small DC-DC converter to keep a 12V house battery charged, but that’s a minor cost.

A 3,000-Watt inverter (with 6,000- to 9,000-Watt surge) is a lot of current at 12V. Even their 280A X 12V second alternator doesn’t make much sense to me.
 

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Since this thread was replied to recently I may provide you with an update. Let me start out by saying this was my fault as I was tinkering with settings and mistakenly left one one.

I've found another benefit of having the monitoring system online...I was tweaking some settings and playing with the beta software and firmware from the mppt controller. I mistakenly turned on a setting that conflicted with another setting that put the MPPT in fault (I enabled DVCC AND Ve.Smart Networking at the same time). DVCC shared voltage and temperature information between all victron products (the voltage/temp comes from the battery monitor and sends to the mppt and inverter/charger) and so does the Ve.Smart networking ut it works over bluetooth without the need of a Venus device. Starting with the the new firmware, it will put the MPPT into fault because it's getting the information twice and it shouldn't conflict. I didn't notice so I didn't think about it.

My van has been sitting for 2 months now while my free weekends are dedicated to remodeling our kitchen, I got an email on Saturday that the SOC was low (I have an alarm set to 40% soc to send me an email). That's when I logged into the portal and found out that the solar charger wasn't enabled. I figured out what it was and disabled VE.Smart and the charger started right back up:

58361


My BMS would have kicked and and shut off the discharge had it gotten low enough, but the early warning alarm I set up prevented that.
 
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Discussion Starter · #16 ·
Another cool feature of Victron Products: They are always upgrading their software. This can be done with the bluetooth app but since I have the van online 24/7, I can remotely upgrade from anywhere:

59952


FYI here are the changes:

v1.47 – 10 December 2019
Released for all HW versions.

Change:
  • Improve PV Short Protection for 250V models (safety improvement)
  • Reduce maximum charger output voltage to 65V on the 250V models
  • Add error 40 to detect when PV short functionality does not work (safety improvement) for 250V models
  • Add delay on error 2 (battery voltage too high) to be less likely to be triggered
  • Add synchronized charging via Bluetooth (for SmartSolar models only)
  • Tail current mechanism improved: it can now use the real battery current. The current can be received via VE.Smart Networking (Bluetooth) as well as from a GX Device. Included for all SmartSolars and the following BlueSolars: 100/20, 100/20 48V, 100/30 rev2, 150/35 rev2, 100/50 rev2, 150/45, 150/60, 150/70, 150/85 and 150/100)
  • Error 68 (network misconfiguration) now only does not allow same data to be sent on two different interfaces
  • Update way of dealing with out of range Vsense data.
Bug-fix:
  • Fix Vsense bug for BlueSolars (did not compensate negative offset)
  • Auto equalisation max time was configured per charge cycle, not per day. The setting will be used per day now.
  • Fix mistreat of non-supported VREGs that could lead to unexpected behaviors as, i.e., Load output becoming permanently OFF.
These upgrades are great as they allow for better absorption charging that can be set by the user.

The battery monitor had minor improvements:

v4.03 – September 2019
  • Change buzzer frequency from 8kHz to 4kHz. This is how it should have been from the beginning: equal to the BMV-700 & BMV-702.
 
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That squishy sound you just heard was the newbie's brain exploding...

But seriously, impressive stuff! It'll take me years to understand it, but impressive.
 
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