Brazil’s first battery storage auctions, on 2 and 4 December 2026, drew 296.8 GW of registered projects. Each battery rack needs a current sense resistor. We paired all 384 Walsin Technology (Walsin) metal plate shunts with their automotive J twins: 42 pairs change TCR, and in one case the automotive part is looser.
Venatech Limited, an authorised Walsin distributor in Hong Kong, wrote this for a design or sourcing engineer at a Brazilian maker of battery management systems, power conversion systems or storage cabinets who is choosing a milliohm current sense resistor for a rack or string. On 11 November 2026 we re-read the two Walsin current sense exports, Thick_Film_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx (10,428 rows) and Metal_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx (1,188 rows), and our stock list as at 23 September 2026. Every part number is real. The auction facts are from eixos, fetched today.
What is happening with Brazil’s first battery storage auctions?
Two capacity reserve auctions, with a crowded field. According to eixos on 1 October 2026, Brazil’s battery reserve capacity auctions (LRCAPs) are set for 2 and 4 December 2026, EPE registered 6,091 projects totalling 296.8 GW, 71.1 percent of them in the Northeast, and qualified participants are to be announced on 17 November.
The same report said contracts cover operation from August 2028, and that a technical note from ONS, ANEEL and EPE dated 30 September flagged connection restrictions at substations in Rio Grande do Sul, Rondônia, Bahia, Ceará and Pernambuco, where breakers would exceed their capacity. These are the publication’s figures and the agencies’ findings, not ours, and only a fraction of the registered capacity will be contracted. We have no relationship with any bidder and say nothing about what any of them buys.
Where does a current sense resistor sit in a storage system?
In the current path of every string, where the BMS measures charge and fault current. A milliohm shunt turns rack current into a voltage the BMS can read, and Walsin lists 11,616 low-ohm current sense part numbers across the two exports: 10,428 thick film and 1,188 metal, of which 866 are metal plate and 322 metal foil.
At 1 milliohm and 100 A the shunt dissipates 10 W, so storage designs often use several 2512 shunts in parallel or move to a larger metal element. The two figures that decide accuracy are the tolerance and the temperature coefficient (TCR), because a shunt that heats by 50 °C drifts by its TCR times that rise. We have published before that none of the 10,428 thick film rows reaches 1 milliohm, so at that value the answer is metal. Our post on low-ohm current sense: thick film versus metal explains the trade.
Which Walsin parts answer a 1 milliohm, 2512 current sense brief, and what differs?
Twenty-eight part numbers, all metal plate. We filtered for 1 milliohm in 2512 and found 28 distinct part numbers in seven type letters: J and M at 1 W, K, N and R at 2 W, and A and B at 3 W, each at plus or minus 1 or 5 percent, half of them automotive; none is on our shelf.
The last column is for your incumbent.
| Walsin part | Series as exported | Power | TCR, ppm per °C | Match / mismatch with a 1 milliohm, 2512, 1%, 2 W or more, TCR 75 or better, automotive brief | Your incumbent |
|---|---|---|---|---|---|
WW25KR001FTLJ |
Metal Plate Power Low Ohm (Automotive) | 2 W | up to 70 | Match on every exported field | |
WW25NR001FTLJ |
Metal Plate Low Ohm (Automotive) | 2 W | up to 70 | Match on the fields; the series name drops “Power” | |
WW25BR001FTLJ |
Metal Plate Low Ohm (Automotive) | 3 W | up to 70 | Match; more power than asked | |
WW25AR001FTLJ |
Metal Plate Low Ohm (Automotive) | 3 W | up to 70 | Match; more power than asked | |
WW25RR001FTLJ |
Metal Plate Power Low Ohm (Automotive) | 2 W | up to 100 | Mismatch: TCR up to 100, looser than its commercial twin | |
WW25RR001FTL |
Metal Plate Power Low Ohm | 2 W | up to 75 | Mismatch: commercial, no automotive label | |
WW25JR001FTLJ |
Metal Plate Power Low Ohm (Automotive) | 1 W | up to 70 | Mismatch: 1 W, below the brief |
A match in the table is a match on export fields, no more. The export has no column for pulse rating, terminal construction or working voltage, so confirm against both datasheets and qualify in your own circuit; we hold no Walsin datasheet for the current sense series.
Does the automotive version of a Walsin shunt always have the same TCR?
No, and the direction varies. We paired 384 commercial metal plate part numbers with automotive twins made by adding J: 42 pairs differ in TCR, none differs in power, and 214 pairs change the word “Power” in the series name.
In the WW25RR family, the 1 milliohm automotive twin reads up to 100 ppm per °C against 75 for the commercial part, while the 2 to 10 milliohm automotive twins read up to 70, tighter than the commercial 75. In the WW25QR family, all eleven automotive twins from 2 to 15 milliohm read up to 70 against 100 commercial. We have not seen this counted anywhere. A Brazilian BMS buyer who swaps a commercial shunt for its automotive twin, or the reverse, should re-read the TCR field rather than assume it carries over; our cross-reference tool shows that field beside every candidate. The series-name flip matters for any filter written on the word “Power”: it returns half a family.
What does the Hong Kong shelf hold for current sense resistors?
Three thick film lines, none at milliohm level. Our stock list as at 23 September 2026 holds 3 of the 11,616 current sense part numbers, WW08WR270FTL, WW08WR390FTL and WW08WR470FTL, all 0805 thick film from 0.27 to 0.47 ohm, and 0 of the 866 metal plate parts.
The ready stock list is a dated snapshot, never live-synced, and it counts part numbers, not pieces. For a 1 milliohm metal plate shunt, ask for a to-order enquiry by exact part number; we make no lead-time or stock promise. We hold no office, entity or stock in Brazil; our locations are Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation. We give no customs, local-content or auction advice; confirm with your compliance team. The chip resistor range lists the families.
How can Venatech help a Brazilian storage electronics buyer?
How Venatech helps starts with a free paste box. The cross-reference tool, VenaMatch, decodes 18 manufacturers’ part numbers and covers 800,000+ crossable parts; paste up to 500 part numbers or drop an Excel or CSV file, filter by commercial or automotive grade, and every field comes back marked match or mismatch. Load a whole BOM for a check, and see the ready-stock list, a Hong Kong snapshot dated 23 September 2026.
Worked example from our own export: the 1 milliohm 2512 brief returned 28 metal plate part numbers, 4 automotive matches at 2 W or more with TCR up to 70, and none on the shelf. Venatech Limited is authorised for Walsin only; Stackpole and Viking are lines we supply. We serve from Hong Kong, welcome small lots, and you request a quote through the site. Qualification stays with you. Our post on passives for a battery management system walks the rest of the BMS board.
The short version
Brazil’s battery reserve capacity auctions on 2 and 4 December 2026 drew 296.8 GW of registered projects, per eixos. For the current sense resistor in each rack, a 1 milliohm 2512 brief returns 28 Walsin metal plate parts, and 42 of 384 commercial-to-automotive pairs change TCR, so re-read the field when you switch grade.
Send us your shunt lines with the current, TCR and grade you need, and we will return the Walsin parts with every difference stated. When your customer asked for the automotive version, did anyone re-check its TCR?
Sources
Fetched 11 November 2026.
- eixos, ONS indica restrições para conexão de baterias em cinco estados, 1 October 2026: https://eixos.com.br/energia-eletrica/ons-indica-restricoes-para-conexao-de-baterias-em-cinco-estados/
- Walsin current sense exports (Thick_Film_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx and Metal_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx) and the Venatech ready-stock workbook as at 23 September 2026, re-measured 11 November 2026 (internal files).
Related reading
- Low-ohm current sense: thick film versus metal
- Passives for a battery management system
- Chip resistor power rating by case size
- Free cross-reference tool (VenaMatch)
- Ready stock, Hong Kong snapshot dated 23 September 2026
Last reviewed 11 Nov 2026.
Frequently asked questions
When are Brazil’s first battery storage auctions?
eixos reported on 1 October 2026 that the battery reserve capacity auctions are set for 2 and 4 December 2026, with 6,091 projects totalling 296.8 GW registered and qualified participants due on 17 November. These are the publication’s figures, not Venatech’s.
Which Walsin current sense resistors reach 1 milliohm in 2512?
Twenty-eight metal plate part numbers in seven type letters: J and M at 1 W, K, N and R at 2 W, A and B at 3 W, each at 1 or 5 percent, half automotive. No thick film part reaches 1 milliohm.
Does adding J to a Walsin metal plate shunt keep the same TCR?
Not always. We paired 384 commercial and automotive metal plate parts; 42 differ in TCR. WW25RR001FTLJ reads up to 100 ppm per degree against 75 for WW25RR001FTL, while other twins read tighter. Re-read the field.
Which Walsin part matches a 1 milliohm, 2512, 1 percent, 2 W automotive shunt brief?
WW25KR001FTLJ matches every exported field, with TCR up to 70 ppm per degree; WW25NR001FTLJ matches the fields under a series name without “Power”. Confirm against both datasheets and qualify in your own circuit.
Does Venatech stock milliohm current sense resistors in Hong Kong?
Not in the snapshot dated 23 September 2026. It holds 3 of 11,616 current sense part numbers, all 0805 thick film from 0.27 to 0.47 ohm, and none of the 866 metal plate parts. Ask for a to-order enquiry through the site.
Do you have an office or stock in Brazil?
No. We hold no office, entity or stock in Brazil; our locations are Hong Kong, Shenzhen, Singapore and Jiangmen. We hold no ISO 9001 or IATF 16949 certificate and give no customs or legal advice. Confirm with your compliance team.