Battery storage electronics for Italy meet a current ceiling in chip shunts: of 11,760 Walsin Technology (Walsin) low-ohm current-sense resistors, none reaches 100 A when we derive current from rated power and resistance. The best is 77.5 A, 17 parts reach 50 A, and our 3 shelf lines are all 0805 parts of 270 milliohm or more.
Venatech Limited, an authorised Walsin distributor in Hong Kong, wrote this from the Walsin chip resistor export (234,815 rows, 234,401 distinct part numbers) and our stock list as at 23 September 2026 (1,125 distinct part numbers). It is for a design or sourcing engineer at an Italian battery-storage, battery-management or power-conversion maker who is choosing a milliohm shunt. Every part number is real and every count is ours, re-measured on 10 November 2026. The market statement names its source and the day we fetched it.
What did Terna schedule for the second MACSE storage auction, and why does a component buyer care?
It scheduled a 16 GWh procurement for delivery in 2029. According to Review Energy on 29 May 2026, Terna confirmed that the second auction of Italy’s MACSE long-term storage mechanism takes place on 24 November 2026 at 10:00, for 16 GWh of capacity delivered in 2029, mainly lithium-ion, with regional ranges including 3 to 11.5 GWh for the South and Calabria and 1 to 6 GWh for Sicily.
Those are the report’s figures, not ours. The conclusion we draw is ours: storage racks in a procurement of that size carry battery-management boards, and each board measures current through a shunt. We have no relationship with Terna or any bidder, and we say nothing about what any of them buys. The auction is still ahead of the date we fetched the page, so nothing here describes its outcome.
How much current can a Walsin low-ohm chip resistor carry on its rated power?
Less than most storage racks need. We parsed the 11,760 low-ohm rows in the Walsin export and derived a ceiling of the square root of rated power divided by resistance: 685 parts reach 10 A, 192 reach 20 A, 83 reach 30 A, 17 reach 50 A, 4 reach 70 A and none reaches 100 A.
The highest is 77.5 A, on four 0.5 milliohm, 2512, 3 W parts: WW25AR0L5FTL, WW25AR0L5JTL and their automotive-series partners. Of the 17 parts at 50 A or more, 16 are 2512 and 1 is 1225, and 8 sit in an Automotive series. This is a ceiling from two export columns, not a current rating: the export gives no derating curve, no pulse energy and no board temperature, and a real continuous rating is lower. We have not seen this counted anywhere. A rack that carries 100 A or more through a chip shunt is outside the catalogue; a busbar shunt or a parallel arrangement is a design decision for you, not something we can recommend. Our post on low-ohm current-sense, thick film versus metal explains the construction difference.
Which Walsin parts cross a 60 A, plus or minus 1 percent, 2512 shunt brief, and what differs?
Five parts clear 60 A at plus or minus 1 percent, and four are 2512. For a brief of at least 60 A on the derived ceiling, plus or minus 1 percent, in 2512, we found 4 parts, WW25AR0L5FTL, WW25AR0L5FTLJ, WW25A0L75FTL and WW25A0L75FTLJ; a fifth, WW25YR0L5FTL, is a 1225 metal foil part.
The reader’s incumbent goes in the last column.
| Walsin part | Description | On shelf 23 Sep 2026 | Match / mismatch with the brief | Your incumbent |
|---|---|---|---|---|
WW25AR0L5FTL |
Metal Plate Power Low Ohm, 2512, 0.5 milliohm, plus or minus 1%, 3 W, up to 70 ppm per degree, ceiling 77.5 A | No | Match on size, tolerance and the 60 A ceiling | |
WW25A0L75FTL |
Metal Plate Power Low Ohm, 2512, 0.75 milliohm, plus or minus 1%, 3 W, up to 70 ppm, ceiling 63.2 A | No | Match on the electrical fields; thinner margin over 60 A | |
WW25YR0L5FTL |
Metal Foil Power Sensing, 1225, 0.5 milliohm, plus or minus 1%, 2 W, up to 100 ppm, ceiling 63.2 A | No | Mismatch: 1225 body, foil technology and 100 ppm | |
WW25BR001FTL |
Metal Plate Low Ohm, 2512, 1 milliohm, plus or minus 1%, 3 W, up to 70 ppm, ceiling 54.8 A | No | Mismatch: ceiling 54.8 A, below the brief | |
WW08WR270FTL |
Thick Film Low Ohm, 0805, 270 milliohm, plus or minus 1%, 1/4 W, ceiling 0.96 A | Yes | Mismatch: about 540 times the resistance; the only shelf family |
A match in the table is a match on the export fields, no more. Confirm against both datasheets and qualify in your own circuit. The chip resistor power rating by case size post shows why the 2512 body carries 3 W.
What does the Hong Kong shelf hold in low-ohm current-sense resistors?
Three part numbers, none below 270 milliohm. Of the 11,760 low-ohm parts, our stock list as at 23 September 2026 holds 3: WW08WR270FTL, WW08WR390FTL and WW08WR470FTL, all 0805 thick film at plus or minus 1 percent, 0.27, 0.39 and 0.47 ohm.
So any storage-rack shunt in the milliohm range is a to-order enquiry from us today. That is a fact about our shelf, not about Walsin’s availability, and we make no lead-time promise. The ready stock list is a dated snapshot, never live-synced, and the chip resistor range lists the families.
What will we not tell you about battery storage systems?
Anything about your rack architecture, your safety case or your grid-connection approval. Of the 28 Walsin datasheets we hold, 2 cover chip resistors and neither is a low-ohm current-sense family, so every figure here comes from export columns, not a datasheet.
We make no claim that any part suits a storage rack, a battery module or any pulse profile. We hold no ISO 9001 or IATF 16949 certificate. We hold no office, entity or stock in Italy; our locations are Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation. We give no legal, customs or conformity advice; confirm with your compliance team. Qualification stays with you.
How can Venatech help an Italian storage and BMS buyer?
How Venatech helps starts with a free paste box. The cross-reference tool, called VenaMatch, decodes 18 manufacturers’ part numbers and covers 800,000+ crossable parts; paste up to 500 part numbers or an Excel or CSV file and every Walsin candidate returns with each field marked match or mismatch. Load a whole BOM for a review. The ready-stock list is a Hong Kong snapshot dated 23 September 2026.
Worked example from our own export: the 60 A, plus or minus 1 percent, 2512 brief returned 4 parts that match, none stocked. Venatech Limited is an authorised Walsin Technology distributor in Hong Kong; Stackpole and Viking are lines we supply. We serve from Hong Kong, welcome small lots, and you request a quote through the site.
The short version
For an Italian storage designer, a chip shunt is a ceiling question: 11,760 low-ohm parts, 17 that reach 50 A on rated power, none that reach 100 A, and a shelf of three 0805 parts. State the current, the body size and the tolerance, then check the margin yourself.
Send us one shunt line from your BOM, with the resistance, current, body size and TCR you can accept, and we will return the Walsin parts with every difference stated. If your rack current is above 77 A, where does the shunt sit?
Sources
Fetched 10 November 2026.
- Review Energy, “Italy’s MACSE mechanism takes next step as Terna confirms 24 November 2026 auction date”, 29 May 2026: https://www.review-energy.com/almacenamiento/italy-s-macse-mechanism-takes-next-step-as-terna-confirms-24-november-2026-auction-date
- Walsin chip resistor export (Low Ohm Current Sense groups) and Venatech ready-stock workbook as at 23 September 2026, re-measured 10 November 2026 (internal files).
Related reading
- Low-ohm current-sense: thick film versus metal
- Chip resistor power rating by case size
- Anti-surge chip resistors
- Free cross-reference tool (VenaMatch)
- Ready stock, Hong Kong snapshot dated 23 September 2026
Last reviewed 10 Nov 2026.
Frequently asked questions
What did Terna schedule for the second MACSE auction?
According to Review Energy on 29 May 2026, an auction on 24 November 2026 for 16 GWh of storage delivered in 2029, mainly lithium-ion. These are the report’s figures, not ours, and the outcome was not known when we fetched the page.
What is the highest current a Walsin low-ohm chip resistor can carry?
On our derivation from rated power and resistance, 77.5 A, on four 0.5 milliohm 2512 parts rated 3 W. None of 11,760 reaches 100 A. This is a ceiling, not a rating; confirm against the datasheet for your exact part number.
How many Walsin shunts reach 50 A?
17 of 11,760: 16 in 2512 and 1 in 1225, of which 8 are in an Automotive series. Ask for the qualification report for the exact part number if you need AEC-Q200 documentation.
Which Walsin low-ohm resistors are on the Hong Kong shelf?
Three, as at 23 September 2026: WW08WR270FTL, WW08WR390FTL and WW08WR470FTL, all 0805 thick film. The snapshot is dated, not live, so ask us through the site for current availability.
Is the 1225 foil part a drop-in for a 2512 shunt?
No. WW25YR0L5FTL matches the 0.5 milliohm value and plus or minus 1 percent, but the body, technology, power and TCR differ. Confirm against both datasheets and qualify in your own circuit.
Do you hold stock or an office in Italy?
No. We hold no office, entity or stock in Italy; our locations are Hong Kong, Shenzhen, Singapore and Jiangmen. We hold no ISO 9001 or IATF 16949 certificate and give no legal, customs or conformity advice. Confirm with your compliance team.