This guide follows Very Detailed Beginners Guide To Building A Custom DIY LiFePO4 Battery from Offgrid Power Solutions, a workshop walkthrough that has picked up around 158,000 views and a comment section unusually full of people who built the thing and reported back. The build is a 12V 280Ah pack from four prismatic cells, and the video's value is in the order of operations rather than any single clever trick. Get the order right and the pack works first time; get it wrong and you find out at the torque stage, when the cells are already clamped in a box.

Offgrid Power Solutions — "Very Detailed Beginners Guide To Building A Custom DIY LiFePO4 Battery"
Watch on YouTube →
About 158,000 views. A full workshop build of a 12V 280Ah pack from four prismatic cells.

One framing note before the steps: the pack in the video is roughly 3.58kWh nominal (3.2V × 4 cells × 280Ah). That is a real house-bank increment for a van or small cabin, and the parts cost is dominated by the cells, not the box. Everything below assumes you have already bought matched cells from one batch.

What This Build Actually Is

Four 280Ah prismatic cells in series make a 4S 12V pack. Each cell measures about 72mm thick, 175mm wide and 200mm tall, with terminals bringing the overall height to roughly 230mm. Stacked side by side, the four cells occupy about 288mm of width, which sets the internal dimension of the enclosure. The finished box in the video comes out around 210mm wide, 325mm long and 330mm tall — taller and narrower than a standard drop-in, which is typically about 250mm tall, 350–370mm long and 185mm wide.

That dimensional difference is the whole reason people build instead of buy. A drop-in has to fit a battery tray that was designed for a lead-acid group size. A custom box only has to fit your own space, and you can trade height for footprint.

The Cell Choice and the Math Behind 280Ah

280Ah is the most common prismatic capacity for DIY packs, and the reason is economic rather than technical: it is the size EV cell manufacturers produce in volume, so matched cells are available and the price per watt-hour is lower than for smaller cells. Four of them give you 280Ah at 12.8V nominal. Usable capacity depends on how far down you discharge and how well the cells are balanced, but a realistic planning figure is 90–95% of nameplate for a healthy pack.

The parts list that matters is short: four matched cells, a 4S smart BMS rated above your intended load, bus bars and hardware, ring terminals, adhesive heat shrink, a fuse or breaker, and the wood for the box. The video uses a Daly 200A 4S smart BMS with a temperature probe and balance leads. A 200A rating on a 280Ah pack is generous — the cells will deliver more than the BMS will pass — which is the right direction to err.

Why the Box Is Part of the Design, Not an Afterthought

The enclosure is not just a container. Four threaded rods run through the stack and clamp the cells together, and that clamping force is what keeps a prismatic pack mechanically stable as the cells expand and contract slightly over charge cycles. It also keeps the bus bars flat against the terminals instead of letting them lift under vibration.

The video builds the box from 36mm side panels with a base sized to the 288mm cell stack plus the panel thickness. Four 10mm through-holes take the threaded rods, and two 25mm holes cut with a Forstner bit become handles — positioned about 40mm down from the top edge and 60mm in from the side. The black water-based paint at the end is cosmetic; it has no electrical or thermal function.

Drill position is the one irreversible mistake in this build. A hole that lands inside the cell's footprint punctures the case. Before any drill touches the base or sides, mark the cell outline on the wood and keep every hole outside it.

Top Balancing: Two Ways, One Goal

Four cells from the same batch still arrive at slightly different states of charge, and a pack is only as good as its weakest cell at the top of the charge curve. Top balancing brings all four to the same full voltage before they are assembled, so the BMS has almost nothing to correct on day one.

The video shows the method it prefers: clamp the cells in the enclosure first, wire them however you need for balancing, and use ordinary 1.5–2.5mm household wire as the balancing links. Two configurations work. You can connect all four in parallel — all positives together, all negatives together — and charge the group with a bench supply until the current tapers to near zero. Or you can build them into a 4S string and use a 4S charger, with pigtail leads bolted to the pack terminals for the charger connection.

Either way, the finish line is the same: all four cells sit at the same voltage, checked with a meter at the terminals rather than trusting the charger's display. Doing this with the cells already in the box saves the awkward step of lifting a 20kg stack in and out, which is exactly why the video does it that way.

Bus Bars, Threaded Rods and Torque

The bus bar layout follows the 4S string: negative, positive, negative, positive down the row, so the pack's main negative is at one end and the main positive at the other, with the series links between adjacent cells. The video measures the main positive cable run at 110mm centre to centre when bringing it out of the box, which is the kind of number worth writing down before you cut cable.

Two details decide whether the pack stays reliable. First, the balance leads get cable-tied so they cannot vibrate against a terminal or chafe on the rod. Second, every terminal gets a washer and a flange nut, tightened to the cell maker's torque spec and re-checked after the pack has been through one full charge and discharge. Loose terminals are the most common cause of a "my BMS reads weird voltages" complaint, and they are the easiest thing to prevent.

Crimping Lugs and the Tug Test

The video uses an older manual crimper and adhesive-lined heat shrink. That combination is fine and cheap. What matters is the sequence: strip to the lug's barrel depth, crimp once at the barrel's centre and once near the end, then pull hard on the lug with the cable before you shrink anything. A crimp that moves under a firm tug will heat up in service; a crimp that survives the tug will not.

Adhesive heat shrink is not cosmetic either. It seals the strand ends against moisture wicking, which is what turns a good cable into a green corroded one two years later in a damp van. Use it on every lug, including the BMS sense leads if they terminate in ring lugs.

BMS Wiring, Temperature Probe and First Power-Up

Mount the BMS with enough clearance that your fingers can reach the balance-lead connector and the terminal screws — the video is explicit about this because a BMS jammed against a cell wall cannot be serviced. Connect the balance leads in order, starting from the most negative cell and working up, and check each lead's voltage against the meter before plugging the harness into the board.

Then fit the temperature probe against a cell body, not against the bus bar, so it reads cell temperature rather than terminal temperature. Before the first load, do a no-load check: BMS wakes, cell voltages read within a few millivolts of each other, and the pack voltage matches the sum. Only then connect the fuse or breaker and the load.

What It Costs and What It Weighs

A 280Ah prismatic cell weighs about 5.5kg, so four cells plus bus bars, BMS and a plywood box land somewhere near 27–30kg. That is heavier than most people expect and it matters for a van build, where the pack has to be bolted down and the mounting point has to carry the load through a crash.

Cost is dominated by cells and BMS. The enclosure, hardware and cable are comparatively cheap, which is why the video's box design is worth copying: it lets you spend the budget on the parts that determine capacity and safety instead of on a manufactured case.

Reviewed by Dajiu Energy Engineering Team — a Chinese LiFePO4 battery manufacturer building LiFePO4 batteries for RVs, homes, golf carts and portable applications since 2017, serving OEM/ODM projects with CE, UN38.3, MSDS and ISO9001 certified builds.

What Viewers Are Asking (Top Comments on the Video)

The comments below are the highest-value technical threads on the video, sorted by likes. Where the creator replied, his wording is quoted as posted; where he did not, the answer is ours.

@nathoilboy2053 · 27 likes
"One of the best demo's I have seen! 10/10 and cant thank you enough. Production, editing, lighting, sound and presentation is well beyond perfect! Love your workshop and attention to all the details. Time to bulid mine!"
@offgrid_power: "Thanks for the feedback, Nathan! Glad the video was helpful for you!!" Our take: The production quality is genuinely useful here because it lets you see the terminal hardware and the balance-lead routing clearly. Watch the bus bar section twice before you order hardware; the visual is better than any parts list.
@maarwopi · 12 likes
"all good but you should put yellow sheets to separate cells too"
Our take: This is the most repeated criticism of the build, and it deserves a straight answer. The cells arrive with a thin blue PET film, and the video relies on that film plus the clamping force. Adding a dielectric sheet between cells — fish paper, FR4 sheet or the yellow insulating paper the commenter means — costs a few dollars and removes a failure mode. On a pack you intend to keep for ten years, add the sheets.
@the_colour_of_your_mind · 12 likes
"Astonishingly good video. I've ordered my cells and BMS, and cannot wait to build my own battery. Thank you so much for providing this content. It's incredibly useful"
Our take: Ordering cells and BMS first is the right order, because cells from one matched batch are the constraint. While you wait, build the box and cut the bus bars — the woodwork takes longer than people plan for, and it is the step that has to be finished before the electrical work can start.
@PortablePowerSolutions · 5 likes
"Very nice video, will make it easy for people to build their own batteries. I would suggest mentioning that jewelry should be removed and using shrink tubing on metal tools to insulate. Experienced people know how to be careful and still have ..."
Our take: Correct, and it is the safety point the video underplays. A 280Ah pack will deliver a welding-grade arc through a ring or a wrench across terminals. Remove rings and watches, tape or sleeve the shank of the wrench you use on the terminals, and put an insulating mat under the pack before you tighten anything.
@gerykis · technical thread, no like count shown
""Aluminum Cases Touching" Risk While it is true that cells have a factory blue plastic wrap (PET film), this film is extremely thin (often only 0.1mm to 0.2mm). The Problem: The aluminum case itself is electrically live (connected to the positive ..."
Our take: This is the best technical comment on the video. The cell's aluminum case is electrically live, and the factory film is thin enough that a nick during assembly or a rub in service can expose metal. Two touching cases at different potentials in the string is a short waiting to happen. Dielectric spacers between cells plus a check of the film before assembly is cheap insurance, and it is standard practice in manufactured packs.
@KarlsruheNo1 · technical thread
"Just watched this video because I´m looking for ideas to build my own DIY Battery. Thanks for talking calm and using an easy understandable englisch. Nevertheless there is on critic. You using not isolated tools, when you tightened the nuts at the ..."
Our take: The comment is fair. A bare wrench bridging a terminal to the adjacent cell's case is exactly how beginners destroy a cell. A double-ended wrench with one end wrapped in tape, or a properly insulated socket, removes the risk. The video's technique is otherwise careful — the missing piece is tool insulation, not competence.
@remnl · 4 likes
"just wanted to thank you guys for this video. due to your videos i build my own battery for my camper conversion and i used this box design. i only used the JK smart bms instead. greetings from the netherlands"
Our take: The box design transferring to a different BMS is the useful signal: the enclosure and compression approach is BMS-agnostic. JK boards are common in camper builds because the app exposes per-cell data and balance settings, which is worth having when you are commissioning a pack for the first time.
@MT-cc2fz · 1 like
"I'm guessing you could build several of these and connect them in series to get more capacity? And build a separate box for distribution... Really good video, you explained things really well."
Our take: Series adds voltage, parallel adds capacity — so four of these in series gives 48V 280Ah, not more amp-hours. Multiple packs in parallel is the usual way to add capacity, and each pack needs its own BMS and its own fuse. Do not parallel packs of different age or capacity and expect them to share current evenly.
@CrusterfunkShenanigans · technical thread
"thank you very much for this video, I am currently using it to make a 36v battery for my cargo tricycle ! Greetings from the Netherlands!"
Our take: A 36V pack from 12S cells is a legitimate use of the same method, but the BMS changes to a 12S unit and the top-balancing step gets more important, not less. Twelve cells drift more than four, and a 36V cargo trike pulls hard. Balance at the top, then verify at the bottom of the first discharge too.
@NounXXX · 1 like
"Hello friend. Please write down the dimensions of all sides, or give me a link to the drawings if you have one. I will be very grateful to you"
Our take: The dimensions are in the video but scattered across the build. Write them down before you cut: cell stack 288mm, cell height about 200mm plus terminals, box around 210mm wide, 325mm long, 330mm tall, panel thickness 36mm, rod holes 10mm, handle holes 25mm. Scale from your own cells, not from the video's, because cell sizes vary by a few millimetres between batches.

If the build looks appealing but the certification paperwork does not, that is the other path: buy the finished pack. Dajiu Energy has been manufacturing LiFePO4 batteries since 2017 for RVs, homes, golf carts and portable applications, and the range covers drop-in replacement batteries, EV and golf cart packs, wall-mounted home storage, portable power stations, commercial energy storage and battery swap cabinets. A 12V 280Ah pack in a custom enclosure is a standard OEM request for us — see the lineup in our product center, or read more build and buying guides. Send the dimensions you have to work with and the load you expect, and we will spec the cells, BMS and enclosure to match.