For a Canadian battery management shunt, Walsin Technology (Walsin) lists 32 current sense part numbers at plus or minus 0.5 percent out of 11,616. All 32 are in one metal foil series, all are 5 milliohms or higher, and the best implies 20 A from its power rating. Below 5 milliohms the tightest tolerance is plus or minus 1 percent.
Venatech Limited, an authorised Walsin distributor in Hong Kong, wrote this for a design or sourcing engineer at a Canadian maker of battery packs, energy storage or vehicle battery management systems who is choosing a pack-current shunt. It uses the Walsin chip resistor export, re-measured on 10 November 2026 (234,815 rows, 234,401 distinct part numbers), and our stock list dated 23 September 2026. Every part number is real.
What did Statistics Canada report on zero-emission vehicle sales in June 2026?
It reported a fast-growing base of battery vehicles. Statistics Canada’s The Daily of 17 August 2026 said 21,876 new zero-emission vehicles were sold in June 2026, up 56.1 percent from June 2025, and 11.5 percent of all new motor vehicles sold, against 7.9 percent a year earlier.
Those are the agency’s figures, fetched 10 November 2026. They say nothing about what any pack maker buys. The engineering link is that every pack needs a current measurement for state of charge and protection, and the accuracy of that measurement starts with the shunt’s tolerance and temperature coefficient. We have no relationship with any Canadian vehicle or pack maker.
How many Walsin current sense resistors reach plus or minus 0.5 percent?
Thirty-two, from one series. We parsed the 11,616 current sense and power sensing part numbers in the Walsin export and found 32 at plus or minus 0.5 percent: all in Metal Foil Low Ohm Power Sensing, all rated 50 ppm, none on our shelf.
By case size they split into 21 at 1225, 6 at 0612, 2 at 1206, 2 at 2512 and 1 at 0805. Every other tolerance in the 10 series is plus or minus 1 percent (6,044 parts) or plus or minus 5 percent (5,540 parts). We have not seen this counted anywhere. A pack designer who needs half a percent has a short list and should check it before fixing the shunt value.
What happens to tolerance below 5 milliohms?
It stops at plus or minus 1 percent. We counted all 241 current sense part numbers below 5 milliohms: 134 are plus or minus 1 percent, 107 are plus or minus 5 percent, and none is plus or minus 0.5 percent; the lowest value among the 32 half-percent parts is 5 milliohms.
That matters because a high-current pack wants a small resistance to limit dissipation. The export implies, from rated power over resistance, at most 20.0 A for a half-percent part (a 5 milliohm 1225 at 2 W), against 77.5 A for the best plus or minus 1 percent part (a 0.5 milliohm 2512 at 3 W). The implied current is arithmetic from the power rating, not a datasheet current rating. If your pack current is higher, the choices are a looser tolerance, a trimmed or calibrated gain, or a different sensing method.
Which Walsin parts cross a 5 milliohm, 0.5 percent, 50 ppm BMS brief?
One meets every field; the rest differ. The brief is 5 milliohms, plus or minus 0.5 percent, 50 ppm and at least 20 A implied: exactly 1 of the 32 half-percent parts, WW25YR005DTL, meets every field, and 1 more matches the electrical fields at a lower power.
| Walsin part | Description | On shelf 23 Sep 2026 | Match / mismatch with the brief | Your incumbent |
|---|---|---|---|---|
WW25YR005DTL |
Metal foil, 1225, 5 milliohm, plus or minus 0.5 percent, 50 ppm, 2 W | No | Match on every field; implies 20.0 A | |
WW12YR005DTL |
Metal foil, 0612, 5 milliohm, plus or minus 0.5 percent, 50 ppm, 1 W | No | Match on electrical fields; mismatch: 1 W implies 14.1 A | |
WW25DR010DTL |
Metal foil, 2512, 10 milliohm, plus or minus 0.5 percent, 50 ppm, 2 W | No | Mismatch: value is 10 milliohms; implies 14.1 A | |
WW12DR010DTL |
Metal foil, 1206, 10 milliohm, plus or minus 0.5 percent, 50 ppm, 1 W | No | Mismatch: value and power; implies 10.0 A | |
WW25NR005FTL |
Metal plate power, 2512, 5 milliohm, plus or minus 1 percent, 50 ppm, 2 W | No | Mismatch: tolerance is plus or minus 1 percent, wider |
A match is a match on export fields only. Our post on low-ohm current sense, thick film against metal explains the family split, and the thin film against thick film post covers where precision resistors usually sit.
What is on the Hong Kong shelf?
No half-percent part. Of the 11,616 current sense part numbers, 3 appear on our stock list dated 23 September 2026, all thick film at 0805 between 0.27 and 0.47 ohm, and 0 of the 32 half-percent parts.
The list holds 1,125 distinct codes, 254 of them chip resistors. It is a snapshot, never live. The Walsin chip resistor range lists the families, and a to-order enquiry goes through the site with no promise on timing.
What do we hold on Stackpole for battery management?
No Stackpole data. Stackpole is a line Venatech supplies; Walsin is the only line we are authorised for. We tried stackpole.com on 10 November 2026 and every requested page redirected to the johnsonelectric.com homepage, which held no product data, so this post cites no Stackpole specification.
We hold no Stackpole export or datasheet. Send the part number and datasheet of the shunt you use today and we will read it against the Walsin fields above, stating each difference. We state nothing on Stackpole availability. Confirm against both datasheets and qualify in your own circuit. Qualification, including any automotive or functional safety work, stays with you.
How can Venatech help a Canadian BMS designer?
How Venatech helps starts with the free cross-reference tool (VenaMatch): it decodes 18 manufacturers’ part numbers across 800,000+ crossable parts, takes up to 500 part numbers or an Excel or CSV file, and marks each field match or mismatch. Paste a BOM to check every sense line. The ready-stock list is a Hong Kong snapshot dated 23 September 2026.
We serve from Hong Kong in small lots, and you request a quote through the site. We hold no office or stock in Canada. We give no customs or legal advice, so confirm with your compliance team.
The short version
For a Canadian BMS shunt, tolerance is the scarce field: 32 of 11,616 Walsin current sense parts reach plus or minus 0.5 percent, none below 5 milliohms, and none is on the shelf. Decide your tolerance before your resistance.
Send us one BMS shunt line with the resistance, tolerance, TCR and current you need, and we will return the Walsin parts with every difference stated. If your pack current needs 1 milliohm, are you prepared to calibrate at plus or minus 1 percent?
Related reading
- Low-ohm current sense: thick film against metal
- Thin film against thick film chip resistors
- Chip resistor power rating by case size
- Free cross-reference tool and the dated ready-stock list
Last reviewed 10 Nov 2026.
Sources
Fetched 10 November 2026.
- Statistics Canada, The Daily, New motor vehicle sales, June 2026, 17 August 2026: https://www150.statcan.gc.ca/n1/daily-quotidien/260817/dq260817c-eng.htm
- Venatech Walsin chip resistor export, re-measured 10 November 2026; Venatech stock list, as at 23 September 2026.
Frequently asked questions
How many new zero-emission vehicles were sold in Canada in June 2026?
Statistics Canada reported 21,876 new zero-emission vehicles sold in June 2026, up 56.1 percent on June 2025 and 11.5 percent of all new motor vehicles sold. The figures are the agency’s, in The Daily of 17 August 2026.
What is the tightest tolerance in Walsin current sense resistors?
Plus or minus 0.5 percent, on 32 of 11,616 part numbers, all in the Metal Foil Low Ohm Power Sensing series at 50 ppm. Every other current sense part is plus or minus 1 percent or plus or minus 5 percent.
Does a half-percent Walsin shunt exist below 5 milliohms?
Not in the export we parsed. All 241 part numbers below 5 milliohms are plus or minus 1 percent (134) or plus or minus 5 percent (107). The lowest half-percent value is 5 milliohms.
How much current can WW25YR005DTL carry?
The export implies 20.0 A from its 2 W rating at 5 milliohms. That is arithmetic, not a datasheet rating, and it ignores layout, copper and derating. Request the datasheet for your exact part number.
Does Venatech hold Stackpole current sense data?
No. Stackpole is a line we supply and Walsin is the only line we are authorised for. We hold no Stackpole export or datasheet, and stackpole.com redirected to the johnsonelectric.com homepage on 10 November 2026.
Are the half-percent Walsin shunts on the Hong Kong shelf?
No. As at 23 September 2026 none of the 32 is on our stock list. The snapshot is dated, not live, so ask through the site for a to-order enquiry. We hold no office or stock in Canada.