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Pics of the compression fixture. I made the end plates from some 1/2", 9 ply Birch plywood from Home Depot. This is the experimental version, once I am convinced I have everything figured out I will rebuild it using 1/2" Baltic Birch plywood I have. The end plates are 12" high, because I didn't...

If you notice, almost 100% of my posts have been edited. I immediately go back and reread them. I don't know why typos only show up after I click the Post Reply button. I think it is the site software. Yah, that's my story.

Got results from my research to report. I found a stackup of McMaster Carr spring washers that will do what I think is needed. My criteria is to limit force at 100% SOC to 15 PSI. I have read that these cells expand between 0.7mm to 0.8mm from 0% to 100% SOC. I am working with 4 cell stacks in...

You will be amazed how easy it is going back as an adult. Old enough to not be afraid to do the work. No day job to have to work around. No wife and kids. I had all 3 of those when I got my BSEE. https://www.unlv.edu/degree/bse-electrical-engineering When I went to school, I was surrounded by...

I have been looking for a tiny inverter based microwave for my Van RV build and Panasonic has this 0.8 CuFt, 950W beauty. Rotating glass turntable for even heating and only requires 1200W to operate. https://shop.panasonic.com/support-only/NN-SD372S.html $140 from Staples...

60 Hz transformers have some high frequency filtering capability. Not enough to fix what is wrong with modified sine wave inverters, but some. Pretty much all modern inverters are high frequency as in they use high frequency PWM modulation to turn DC into AC. The cheapskates do it by stepping...

I like to keep an open mind, but not so open my brains fall out.

A power supply comes in 3 flavors. No current limiting, you overload it and it burns up. Current limiting by turning off the output until the load is removed. Constant voltage output up to max current, then constant current from then on. As you lower the load impedance the output voltage...

I got an idea. How about a catapult held down by a very flammable rope. Battery pack catches fire, launches them in an arc aimed at the backyard pool. This sounds like a product we should be able to buy from Acme. http://www.jamesfuqua.com/lawyers/jokes/coyote-acme.shtml

Now we are getting into the fun part. Research, collecting data, being scientific. I will even wear a lab coat and carry a clipboard while I am doing this. Who's with me?

On the subject of grounding. Victron has this statement on their MPPT FAQ page. https://www.victronenergy.com/live/drafts:mppt_faq I agree with the reasoning behind connecting DC negative to chassis ground at a single point. Avoiding ground currents (ground loops?) makes sense. You don't want...

The smell is unmistakable if parts got burnt.

An architect, artist and an engineer were discussing if it is better to spend time with a wife or a mistress. The architect said he enjoyed time with his wife, building a solid foundation for an enduring relationship. The artist said he enjoyed time with his mistress, because of the passion...

USA power is center tapped 230VAC. The center tap is the neutral wire which is connected to earth and safety ground at the point it enters a building (main circuit breaker). The 120VAC in our wall outlets is from either of the two hot wires to neutral. 230 (for dryers and air conditioners) is...

This is what I am using for my 12V control panel. The safety toggle switch is used as the On/Off control and you have to press the start button to latch in the power relay to the 24V to 12V DC-DC converter. I am using a 24V automotive relay instead of the 12V relay that came with the control...

If you want a more accurate method. Get a piece of unistrut and mount a socket extension in the middle. Mount an eye bolt at each end of the unistrut (the same distance from the middle to each end). Mount the socket wrench in the vise and plug the socket extension into the wrench. Hang weight...

Agreed and to make a long story even longer. In general we don't want to use the vehicle chassis to carry current. Doing so leads to corrosion and weird electrical behavior. To ensure this can't happen we use a negative bus system and only connect that negative bus to chassis ground at a single...

Serves double duty as a fire detector too.

Here is what my battery pack will look like including the compression frames. The two 4 cell sets are completely independent except for cabling between them. Each cell pack will mounted on a set of these rubber shock mounts to keep them from bouncing around inside the battery compartment...

How dare you interrupt our digression into a bit of Tesla worship by discussing the original thread subject! ?

Looks might mean nothing. When the Chinese knock off a product they often make a visual duplicate. I once sent a thermal label printer to a contract manufacture to give us a cost estimate on what it cost our competitor to make. They misunderstood what I wanted and made a visually perfect...

I am putting 7.2 kWh of batteries in my Ford E350 van conversion. They are going to be in a 2 x 4 orientation (24V) when done, just sitting on the bench right now. Building the cell compression frame this weekend. hey

OK, new figures. Assuming 0.9mm is the travel I need to handle from 0 to 100% SOC. I am using 5/16" x 18 TPI threads. 18 TPI is 0.056" per turn. Convert that to mm and I get 1.4224mm per turn or 1 mm = 70% of a turn. I am going to call this 2/3 of a turn since I am not a human protractor. I...

Borrowed a 2000 Newton load washer from work today. 2000 N = 449 lb. Now I have to build the test fixture. And get a lab coat.

The point of the ground wire is to provide a fault clearing path in the event the metal enclosure of an AC powered device gets energized. This can only work if the neutral and ground are electrically connected (bonded) together. This way the circuit breaker will trip. In residential wiring the...

Older low frequency inverters used a square wave generator that was fed into a ferroresonant transformer to filter out harmonic noise and convert the square wave into a sine wave. Ferroresonant transformers have the ability to regulate the line voltage by storing energy in magnetic form within...

And to be clear. The isolated version just means you can leave the output floating (no need to tie ground to the vehicle ground). The positive output is in fact isolated at least as far as protecting your starter battery and alternator are concerned with either version. That is the entire point...

Or just buy an upgrade, continuous duty rated alternator and use a 12V to 24V boost battery charger. Like a Victron Orion TR 12/24-15 Smart Charger. That will draw 30A from the alternator and charge a 24V battery at 15A. It will also protect both your alternator from overload and your battery...

You did the right thing.

Everybody has the Chinese hydraulic crimp tools with changable dies for around $60. Color me skeptical, but I wonder how well these actually work. I was reseaching crimpers and found this Temco crimp tool. No dies, you dial in the desired amount of crimp to suit your particular crimp lug and...

I had a Sharp Microwave when they first became a thing. Had a rotary knob like an egg timer and a sliding lever to set the power level. That thing lasted forever.

Agreed. Victron seems to have a lot of unnecessary features. At least they seem unnecessary until you actually start implementing the system and realize the truth is that lower cost vendors leave out important features that you really wish they supported. How many threads have we seen from...

Update: One of the reasons why I am particularly interested in using Belleville Disc Springs is it makes it easy to create a progressive spring (lighter compression in the first part the of the travel, heavier further in). Next step was to try to do so. Same 12 larger springs combined with 6...

After months of pontificating, I have finally pulled together the electrical design for my RV conversion. Let me know what you think. This is my first version and I would much rather fix as many problems at the pixels on a screen stage as I can.

The cheap manufactures may have given up on serious transformers, but high quality inverters continue to use them. This is the inside of my Victron Multiplus 24/2000-50. LF vs HF is not really the thing it used to be. Back in the dawn of time, saber-tooth cave inverters consisted of...

Definitely not safe to lick. Ask me how I know???

And that is why it can make sense to just buy drop in batteries if you don't have the technical expertise to deal with something like using a Tesla battery. Buying equipment when you don't know if it will work is an expensive way to get an education.

In my opinion, Victron does a fantastic job of specifying their products. They rate things in both watts and VA and shows proper temperature derating data for their equipment. Every electronic device has a temperature derating curve. To simply ignore that this when specifying max power rating of...

The Victron battery balancer would be needed if you wired the two 12V batteries in series to form a 24V system. In parallel, they will balance themselves.

If you are shopping price to the point you are looking at modified sine inverters, then don't worry about it. Whatever you end up buying will be very unlikely to be able to start the AC compressor motor in the first place. A soft-start circuit for your air conditioner will cost ~$300. I...

The Xantrex Freedom X (Inverter) or XC (Inverter/Charger) is one I was looking at very hard before I decided to go with a Victron Multiplus. The low voltage disconnect on these is programmable (0.1V granularity) which lets you set this to the appropriate voltage for LiFePO4 batteries). Cheaper...

Love the description of that noise filter. That is precisely what I want to do. Eliminate the car inside the car and keep my water ripple from being interfered with. Item description "12V Car Vehicle Stereo Radio Audio Power Wire Engine Noise Filter Suppressor. Eliminate the car inside the car...

Replace it with a 10A or bigger diode and add a heat sink. 5A with 0.5 V drop is 2W of heat. You want a big enough diode to dissipate that heat. I never operate a diode above 50% of its current rating. And more thermal headroom is often desirable.

I am an EE also, that doesn't mean I understood the concerns initially either. Low Frequence vs High Frequency inverters refers to if the inverter uses a 60 HZ power transformer or not. What it really is, is a short hand way of distinguishing between products designed to meet a price point and...

That is why companies like Eco Flow and Goal Zero are thriving. Don't sweat it, we are doing this ourselves because we want to. If all you want is a solar powered AC outlet then buy an all in one and hook it up to a few solar panels.

Sorry, I noticed that after I made my post (and I corrected this in an edit). Your modified image is correct. To make things more explicit, the DC system is not supposed to be isolated from chassis ground, but the negative to ground connection is only supposed to happen at a single point. What...

Deliberately using the chassis for high current? That reminds me of the guy from "Down Periscope." I prefer to use a separate conductor to carry return current. I am not responsible for what Ford did in the engine compartment, but in my RV's house DC wiring, the negative bus only connects to...

No idea. I don't have one. Just saw it and thought wow I know some cheapskates who would love to know about it. This place reminds me of my riding buddies. Half of them doing DIY luggage on their KLR650. And the other half mounting a set of Touratech panniers on their adventure bikes...

To be fair surge should only need to last long enough to get a motor moving. If you are in surge for more than a minute you are doing something wrong.

Typically you wear a conductive mesh suit, while hanging out the side of a helicopter to boot. The voltage is not the hazard these guys face.

You make excellent points. Seems pretty misguided to spend $$$$ on batteries then balk at spending $$$ on the rest of the system. That couple of hundred you save buying a marginal inverter/charger could end up costing you thousands due to premature battery failure. Seems like a bad place to try...

Just started the first charging cycle on the first cell using the Mean Well HRPG-150-3.3. Resting cell voltage was at 3.3V (so no idea what SOC these cells were when shipped to me). Voltage adjust topped out at 4.05V so plenty of range (spec is max = 3.8V). I am using a 30A current shunt...

I hate cigarette lighter plugs with a passion. Useless connect with almost no retention force.

A cursory examination of the 3 phase waveforms shows that when any phase is at max voltage, the other two phases are at 50% of max voltage. This indicates to me that the correct answer is that 3 phase power is capable of delivering double the max power of any single phase. Going to take calculus...

Not going to get a lot of use. The power efficiency and reduced surge requirements are what attracted me to the Panasonic.

P.S. In my opinion, Victron's pricing is very competitive for equipment I am actually be willing to use. Forget what the cheap crap costs. That is like comparing a harbor freight table saw with an old Rockwell or a SawStop. You really do get what you pay for and you don't get what you don't pay...

I hope Will is socking away as much as he can. It could all go away in a moment. Meanwhile the unemployement rate for people who do what I do has been zero for 50 years. I make my living with my brain and getting my EE has the best investment I have ever made in my life. But beyond the job...

"Fire Sale"?

Possible is not the same thing as wise. Based on Dzl's chart, -20 Degree C charging should be limited to 0.1C rates. You are off the scale (0.0C) at anything -30 and below. With my 120AH battery pack I plan on a max of 0.5C charge rate. If I use the 280 AH battery pack, the max charge rate...

Turns out there are HF inverters that aren't lying. They just start at $700. I have about decided to get one of these. Xantrex 24V, 2000W inverter. 4000 W surge rated for 2 seconds (not 40 mS like the crap inverters). Fully configurable low voltage cutoff voltage and recovery so it won't hurt...

Considering how unlikely these cheap 280 AH cells are to be matched, I am using an 8S Deligreen 5A Active balancer in addition to my BMS. Hopefully this will maintain the cells in a fairly top balanced condition. I am curious to see how the capacity changes over time and if the change is...

Advantage to being single. I can spend ridiculous amounts on my van's electrical system without having to justify it to anyone.

I use the small Hesse. Bought mine from Ace Hardware for $150. https://www.acehardware.com/departments/heating-and-cooling/air-conditioners-and-coolers/evaporative-coolers/8015782 You have to be in the airpath, but if you are it works, even in a Phoenix summer.

That would definitely be safer than trying to spray or pour water on to a burning battery. Thought I would mention this since that is something I would have tried. I really like the Acme battery ejection catapult idea. Make the trigger out of cannon fuse so there is no question about it...

Very interesting video (almost said cool). I was surprised how similar power consumption is. I have the little guy Iceco GO20. It works and is very quiet. And I hate cigarette plugs with a passion.

A data point on the DIY battery. A 7160 WH battery made from eight of the EVE 280 AH cells would cost approximately $1000 to build here in the USA including a BMS, fuse and terminals. This is 20% of the cost of a comparable battery pack made from commercially built "drop-in replacement"...

In the thread about new regulations making DIY illegal, I recall reading a comment about systems that are located in an out-building being regulated differently from systems installed into residence. Might want to look into what regulatory issues installing something like this inside your house...

Thanks for the analysis. My electric machines classes where back in the 80's and I haven't had much to do with 3 phase power since. Most of my practice is involved with signal processing and embedded systems. And every time I do think about it, I am just impressed as hell by Tesla. He truly was...

What I really want is one that puts out more power than I put in. I bet there is a Chinese product that claims that.

Electrical system is together. Working on the van it is going in. Insulation, plumbing, wall panels. I hope to get done before summer gets here.

The first method is in series. It increases travel. The second one increases clamping force. I am thinking about doing the first one with a pair of face to face washers on each nut (on each side of the battery pack). That way I will have plenty of travel before completely flattening the washer...

Glad to hear you are being financially prudent. You have to treat this like being a professional athlete or a movie star. You can be hot for a while, but you have to be prepared for it to all go away.

That is a great list of resources. Thanks.

I have a blacksmith friend. As he once told me, "Outbuildings are the secret to keeping mama happy!" Not burning down her house would certainly count as a plus.

I don't see the BMV712 shunt wired in the house battery negative nor do I see the BMV-712 positive connected to the house battery positive. Rather than trying to show the negative return wires which really complicates the drawing, you might try to focus on showing how power flows from one...

These require hardwired electrical outlets, circuit breakers etc. Like wiring a house. The vendors assumption is you either you or the person doing the install knows what they are doing. When techies are talking to other techies we tend to assume comparable experience and skill sets. Simple to...

What are your DC loads? It is possible to buy dual voltage (12V or 24V) devices. I made a point of buying dual 12V/24V fridge and fans. My LED lights are all 24V. The main 12V load I have is my CPAP. That lets me use a much smaller 24V to 12V DC-DC converter. Generally, the more heavily...

This is a D.I.Y. forum after all. Knowing what to do is more than half the battle.

That has excellent range of voltage settings. At the highest settings you could use it for a lithium house battery. That is still going to limit you to essentially a 350W load. If that is enough, well great find!

Glad I didn't dawdle buying my Iceco GO20.

F.Y.I. I am posting updates to my system diagram here if you are interested. https://diysolarforum.com/threads/24v-van-system-drawing-get-your-overripe-tomatoes-ready.11669/ I have updated my drawing to add battery temperature sensing to the BMV-712. The BMV-712 has a charging disable function...

One of these on the ends of each extrusion. Mounted to the bottom the extrusion, then mounted with bolts to the bottoms of the crossbars on my ladder rack. The idea is the solar panels will ride in the windbreak formed by the crossbars. Nothing sticks out above the crossbars so I can still carry...

F.Y.I. I have read several comments about setting the CV higher than 3.65V in order to speed up charging. I have my power supply set precisely to 3.65V and after an hour it was still delivering 26A to the battery. I monitored charging current while the first cell was charging and the current...

I wouldn't make that assumption. Battery life is typically defined as the point where the battery has 80% of the rated remaining charge capacity. 3kWh for a 5kWh rated battery is only 60% of original capacity. If batteries were still reliable when this heavily used, then why would industry...

The Victron is a high frequency inverter. It chops the battery voltage using PWM into approximately 8 VAC, then uses a step up transformer to boost the voltage to 120 VAC. What you refer to as a low frequency inverter is a simple square or modified sine wave inverter cleaned up by passing the...

Depends on the BMS. The Daly BMS are essentially a hybrid. My understanding is they are all separate port, but they can internally connect the charge and discharge port in parallel. So if the discharge port is disabled due to low battery voltage, the charge port is still conducting, and...

The current rating is max output. That is why the SCC will deliver double the power to a 24V battery than it will to a 12 V battery. A Victron SCC should protect itself if over paneled, but it will run hotter which will further reduce the power it will deliver to your battery. The SCC has a...

This guy has the right idea. https://www.realpatriotic.com/homes-for-sale-details/8541-S-ALMOSTA-RANCH-ROAD-HEREFORD-AZ-85615/6218380/123/?q=true&fbclid=IwAR35Ox6v5u6jp5Nz38v1hligoMFFJf2owkJXOx_iYwNQK5XXCKcDQE1NMJg

I have a whole thread on this subject here. Essentially it comes down to money. Big AC power transformers are expensive. Anybody willing to put a $300 transformer into a 2000W inverter is not going to cheap out on the circuitry to drive it. What most people call HF inverters are inverters...

Are these all in series? I am not sure what you are doing. If talking load, then as long as each load is wired to independently then it doesn't matter. The reasons to use a busbar are to make the wiring neater and more logical. Plus it helps remove the temptation to wire power in a daisy chain...

Indeed. That is why I always want to leave margin when specifying parts. There seems to always be something that you either didn't know about or forgot to take into account. When specifying the power ratings of resistors I just automatically tripple the calculated wattage, except for high power...

I have been thinking about this and shopping for months. Now I am finally able to start making it happen. This is the bed I am installing in the van, perfect for a single man. I received it last week. It came on a 6' long pallet, still on the pallet in the back of the van...

So basically you are running it continuously at maximum rated power for hours. I'll bet that thing is cooking. Be glad it hasn't let the smoke out. I would add a fan and be grateful to be getting this level of performance from it. I will be using a couple of Orion 24/12-5 converters to power...

I haven't seen that. Tesla's life reads like a blockbuster movie. Self assured young genius makes his way to the top, overturning the establishment in the process. Wins huge only to end up loosing it all pursuing a doomed dream. Ends up dying in obscurity a broken man virtually forgotten by the...

Thanks that answered my questions. No surprises there. F.Y.I. There are essentially 3 kinds of inverter outputs. Square wave. This is the cheapest and is the noisiest electrically . Switching happens at line frequency (60 Hz). There is some kind of low pass filtering on the output, but...

Impossible? No. Just unwise. I would not modify the internals of your inverter. If you already have that particular inverter then you could plug an extension cord or outlet strip into one of the outlets on the inverter.

You could use this for shore power charging or on the bench. Looks like a "smoking" deal. Hope its not smoking, that would be bad. https://www.goldmine-elec-products.com/prodinfo.asp?number=G25029

I decided, why am I messing around and put all 8 cells in parallel. Charging current is holding steady at almost exactly 30A. It is like the specs for that power supply actually mean something. Who knew? Should finish up early Sunday morning.

Got to work fast. After about an hour, the edit function on a post is removed. I guess so we can't hide the evidence of our stupidity after we get called on it.