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An 8S DIY battery kit for pack builders: steel case in flat or 4×2 layout, smart BMS and the full accessory set for 280Ah-class prismatic LiFePO4 cells — supplied as a kit, assembled by you, branded by you.
A Kit, Specified Like a Component — Not a Finished Battery
This page is for assemblers, marine and material-handling outfitters, and distributors who build their own 25.6V packs: you source the cells, we coordinate the case, BMS and hardware around them. Eight 3.2V prismatic cells in series give a nominal 25.6V pack; with 280Ah cells that is about 7.2 kWh — the format behind 24V marine house systems, warehouse equipment conversions and mid-size off-grid plants. What this kit is not is a finished battery: no cells are inside unless you order the tier that includes them, and nothing on this page should be read as a ready-to-install product.
The kit is supplied in three tiers. The market uses loose words like “complete kit” for all three, so we define each tier by what is physically in the box:
| Tier | What is in the box | What you supply |
|---|---|---|
| 1 — Case-only kit | Steel case plus accessory set: series busbars, sampling boards or balance harness, insulation set, main terminals, protection hardware, fasteners | Your cells and your own BMS |
| 2 — Case + BMS kit (standard offer) | Everything in Tier 1, plus a fitted 8S smart BMS. This is the configuration meant when a listing says “Battery Case + BMS + Accessories (Cells Not Included)” | Your cells |
| 3 — Complete kit with cells | Everything in Tier 2, plus 8 matched Grade A cells of the model confirmed in your order | Assembly only |
If you only need the protection board itself, see our standalone smart BMS boards. If you would rather not assemble at all, finished units are in our 24V LiFePO4 battery range and surveyed in the 24V LiFePO4 battery series guide.
Reference Standard Configuration
The table below is the reference build most buyers start from. One feature of this size needs stating up front: 8S kits exist in two physical layouts — a flat case with all 8 cells in one row, and a 4×2 double-row case — and the published dimensions belong to one layout or the other. Any dimension quoted without its layout is meaningless, so we keep them attached.
| Item | Reference configuration | Basis |
|---|---|---|
| Pack format | 8S (8 × 3.2V cells), 25.6V nominal; ≈7.2 kWh with 280Ah cells | Fixed by the kit design |
| Case format | Steel case, 4×2 double-row layout as the reference; flat single-row layout as the option | Option — see matrix below |
| Case size, reference range | Double-row ≈ 395–435 × 402–450 × 246–273 mm (footprint × height varies by maker); flat layout ≈ 395 × 220 × 250 mm class | Reference range across mainstream market cases — exact drawing and layout confirmed per order |
| Cell layout | 4 × 2 double-row with compression plates (reference), or 8 in a single flat row | Confirmed per order |
| BMS (Tier 2/3) | 8S smart BMS, 200A continuous class for 280Ah builds, Bluetooth monitoring; CAN / RS485 where the system needs it | Brand family and model confirmed per order |
| Main protection | Fuse or breaker sized to the BMS class | Rating and type per kit — confirmed per configuration |
| Display | LCD on some with-BMS configurations; not included in the case-only tier | Per kit — confirmed per order |
| Main terminals | P+ / P− terminal pair sized to the current class | Confirmed per configuration |
An honest note on published sizes at this format: one established maker’s own shop lists its 24V case at 396 × 410 × 246 mm while its own manual for the same case says 420 × 396 × 250 mm. Both numbers are “official”; they simply measure differently (bare body against a drawing that includes fittings). That is why we quote a range, name the layout with every size, and fix the exact case drawing — with its measurement basis — in your order confirmation.
Configuration Options — Nothing Is Locked
| Dimension | Options | Notes |
|---|---|---|
| Supply tier | Case-only / Case + BMS / Case + BMS + cells | See tier table above |
| Case layout | 4×2 double-row (compact footprint, taller harness runs) / flat single-row (long, low profile for under-bench and vehicle floors) | Choose by the space the pack must occupy — state the installation space in the enquiry |
| Cells fitted (Tier 3) | EVE LF280K / LF280K V3, CATL 280Ah, Hithium 280Ah, REPT 280Ah | Terminal form confirmed against the physical batch |
| 314Ah upgrade path | The same case family also accepts 314Ah-class cells | See the dedicated 25.6V 314Ah kit page and the compatibility section |
| BMS family | JK (3–8S platform, active balancing, Bluetooth built in) / JBD (8–24S platform, passive balancing, UART / RS485 / CAN options) / Daly (classic passive 7–17S lines, or the active-balance line) | Category options — the brand and model in your kit are confirmed in writing per order, never assumed |
| BMS continuous current | 100A / 150A / 200A class | Size from your inverter, motor controller and load profile, not from the cell label |
| Balancing | Active 1A or 2A, or passive balancing depending on BMS family | Active balancing earns its cost on large 280Ah cells |
| Communication | Bluetooth app monitoring; RS485 and CAN as BMS-platform options | Name any inverter or controller that must talk to the pack, so the protocol match is confirmed, not hoped for |
| Display | LCD / none | “None” applies to the case-only tier |
| Heating pads | Optional add-on | Not standard fit. Add them if the pack will charge below 0 °C; this is separate from BMS low-temperature charge protection |
| OEM appearance | Case colour, your logo and labels, rating plate, manual and packaging | See the OEM / ODM section |
Cell Compatibility: The 280Ah-Class Footprint
The kit is built around one cell footprint family. 280Ah and 314Ah prismatic cells from the major makers share it — roughly 174 mm long, up to 72 mm thick, and up to about 207.5 mm tall including terminals:
| Cell | Capacity | Size (L × T × H, mm) | Terminals |
|---|---|---|---|
| EVE LF280K / LF280K V3 | 280Ah | 173.7 × 72.0 × 207.5 (incl. terminals) | Welded M6 stud, single or double-hole versions |
| CATL 280Ah | 280Ah | 173.9 × 71.7 × 207.2 | M6 laser-welded stud |
| Hithium 280Ah | 280Ah | 174.7 × 71.65 × 207.11 | M6 stud (DIY-market version) |
| REPT 280Ah | 280Ah | 173.93 × 71.55 × 207.23 | Published sources conflict (M4 vs M6) — confirmed against the physical batch before busbars are drilled |
| EVE MB31 / CATL 314Ah / Hithium 314Ah | 314Ah | Same footprint family (173.7–174.3 × ≈71.7 × ≈207.2) | M6 stud versions |
The compatibility rule is mechanical, not commercial: a cell fits if its footprint falls inside the family above and its terminal form matches the busbar drilling. Capacity class alone is not a mechanical standard — cells sold as “280Ah” can differ by several millimetres between makers. Send the exact cell model with your enquiry and the match is confirmed in writing. If you are still choosing cells, our guide on choosing LiFePO4 cells for pack assembly and the 280Ah / 314Ah prismatic cell range are the right starting points; cells are also listed on our cell wholesale page.
What Is in the Accessory Set
- 7 copper series busbars — an 8S pack needs one link per cell junction, i.e. series count minus one; in the 4×2 layout one link runs between the rows, and its form is part of the layout confirmation
- BMS connection busbar set — the main-path links between cell block, BMS and terminals (a separate set from the series links)
- Sampling boards, or a balance-wire harness — the two market forms of the same job: routing the 9 sense taps (B0–B8) to the BMS in order
- P+ / P− main terminals, sized to the current class
- Fuse or breaker for the main path, rating per kit configuration
- Display where the confirmed kit includes one
- Insulation set — epoxy / fibre sheets between cells and case, EVA pads between cells
- Fastener pack — terminal bolts, case and lid screws
Exact counts of insulation pieces and fasteners follow the bill of materials of the case in your order and are listed in the order confirmation — makers vary these counts widely, and we would rather confirm ours in writing than copy a competitor’s packing list.
Assembly: Eight Cells Into a Working 25.6V Pack
- Check the cells before anything is bolted. Compare resting voltage and internal resistance across all 8 cells, and bring them to a common state of charge. A spread you ignore here becomes the imbalance you chase for the life of the pack.
- Insulate first. Epoxy or fibre sheets between the cell block and the steel case, separators between cells. Steel cases and prismatic cell cans must never rely on the cell’s own film alone.
- Set the layout under even compression. In the 4×2 layout, build each row of four as a compressed unit first, then join the rows; in the flat layout, one row of eight. Prismatic LFP cells want moderate, uniform compression, not maximum force. Torque values come from the cell maker’s manual for your exact cell model and are stated in the kit documentation; there is no universal number.
- Land the sampling connections before the power path. Fit the sampling boards or balance harness from B0 upward and verify every tap reads in sequence — in the double-row layout, double-check the taps that cross between rows before any busbar carries current.
- Bolt the series busbars in order — 7 links, polarity checked twice. Work cell 1 negative to cell 2 positive and onward, checking polarity at every step with a meter, not by eye. The inter-row link is the step where polarity mistakes happen; meter it twice.
- Wire the BMS main path and protection. B− to the first cell’s negative, P− out to the load terminal, fuse or breaker in the main line, then the P+ terminal. Confirm the BMS wakes and reads all 8 cell voltages before the lid goes on.
- Supervise the first full cycle. Watch per-cell voltages on the app or display through the first charge. A cell that runs away on cycle one is cheap to fix on the bench and expensive to find inside a customer’s boat or warehouse truck.
- Close up and record the build. Note the cell batch, BMS model, settings and the layout on the build sheet. That record is what makes warranty discussions and repeat orders simple.
A necessary word on who should do this: a 25.6V 280Ah pack stores about 7 kWh and can deliver very high fault currents. Assembly belongs with trained technicians using insulated tools. If your operation does not have them, buy the finished battery instead — it is the honest recommendation.
Where a 7.2 kWh DIY Pack Earns Its Keep
- Marine 24V systems — house banks and auxiliary power on workboats and larger sailing vessels, where 24V halves the current of a 12V plant at the same power; see our marine power page
- Material handling conversions — 24V is a classic traction voltage for pallet trucks, stackers and cleaning machines being converted from lead-acid; see material handling
- Larger RV and expedition vehicles — truck-based campers whose inverter and air-conditioning loads outgrow a 12V plant
- Mid-size off-grid — workshops, farms and telecom-adjacent sites running 24V inverter systems; see off-grid power
OEM / ODM: Your Brand, Your Specification
The kit format exists for buyers who sell under their own name. OEM options cover case colour, logo and rating labels, manuals and packaging; configuration options cover the case layout, BMS family and current class, terminal arrangement, display, and — on Tier 3 — the cell model the kit is built around. For volume programmes, case dimensions can be produced to a project specification rather than taken from the standard range.
Our role in that process is coordination: requirements are confirmed in a written specification, matched against manufacturing partners’ production, and the agreed checkpoints and documents are handled on the export side. The specification confirmed in your order document is what binds the shipment — not this web page, which is why every variable item above is marked “confirmed per order”. Start from our OEM & ODM coordination page or the OEM / ODM RFQ checklist if you want the full document list.
What to Send Us for a Quotation
- Tier — case-only, case + BMS, or complete with cells
- Cell model — the exact cells you will fit (or ask us to supply them under Tier 3)
- Layout and installation space — double-row or flat, with the length × width × height the pack must fit
- BMS current class and system partners — inverter or motor-controller model, so current class and any CAN / RS485 protocol are confirmed against your actual equipment
- Quantity and destination — a sample kit for evaluation, or your expected regular volume, plus the destination port
One logistics advantage worth planning around: Tiers 1 and 2 contain no cells, so they ship as general cargo — no lithium-battery dangerous-goods freight. Many buyers ship kits by standard freight and source cells on a separate, optimised route; Tier 3 ships as regulated lithium cargo like any cell shipment. Exact packing dimensions and weights for your configuration are stated in the quotation.
Related reading before you enquire: the BMS selection guide for sizing the board, and the rest of this series below.
Frequently Asked Questions
Flat or 4×2 double-row — which layout should I choose?
By the space, not by preference. The flat layout is long and low (about 395 × 220 × 250 mm class) and suits under-bench, under-seat and vehicle-floor installations. The double-row case has a squarer footprint (roughly 400 × 410–450 mm) and suits equipment compartments, marine engine-room corners and rack-adjacent mounting. Both hold the same 8 cells; the harness routing and the inter-row busbar differ, which is why the layout is fixed in the order specification, not swapped at assembly time.
Why do published sizes for the same 24V case disagree?
Because makers measure differently — and sometimes publish both. One established 24V kit case is listed at 396 × 410 × 246 mm in its maker’s shop and 420 × 396 × 250 mm in its own manual. Bare body versus fittings-included explains most of it. Our response is procedural: sizes on this page are ranges with the layout attached, and the drawing that binds your order states its measurement basis in writing.
Can this case also take 314Ah cells?
Yes — 314Ah cells share this footprint family, and cases in this class are commonly rated across 280–314Ah. That is what the dedicated 25.6V 314Ah kit page covers. Confirm the exact 314Ah model when you enquire, because terminal form, not capacity, is what the busbars are drilled for.
Should I build 24V natively or series two 12V packs?
A native 8S pack has one BMS watching all eight cells, one protection path and one set of balance decisions. Two 12V packs in series have two BMS units that cannot see each other’s cells, and any state-of-charge drift between them is invisible until it is a problem. For a product you sell and support, the native 24V build is the defensible engineering choice; series 12V units are a field-expedient, not a product platform.
Do I have to buy the BMS from you?
No. Tier 1 is case-only precisely for buyers with their own BMS platform. What we would ask is which board you plan to fit: the case’s BMS mounting position and display cut-out are arranged around a board class, and it is cheaper to confirm that fit on paper than to discover it on the bench.
Is a heating pad included?
No — heating pads are an optional add-on, confirmed per order, and we say so plainly because some listings imply otherwise. Add them if the finished pack will be charged below 0 °C — unheated boats and unheated warehouses are exactly that case. They are a different thing from the BMS’s low-temperature charge cut-off, which is a protection setting on the board itself.
The DIY Kit Series
This page is the 25.6V 280Ah model in an eight-model DIY kit series: 12.8V 100Ah / 280Ah / 314Ah (4S), 25.6V 280Ah / 314Ah (8S), and 51.2V 100Ah / 280Ah / 314Ah (16S). Each model gets its own page because the cases, cell families and assembly details genuinely differ. The other seven models in the series: the 25.6V 314Ah DIY kit, the 12.8V 280Ah DIY kit, the 12.8V 314Ah DIY kit, the 12.8V 100Ah DIY kit, the 51.2V 280Ah DIY kit, the 51.2V 314Ah DIY kit and the 51.2V 100Ah DIY kit. The full product range is on Products.
Request a quotation for this kit: Start a DIY-Kit-24V280 inquiry · WhatsApp: +86 159 8945 0735
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