Passive Components for German Battery Storage Builders: Walsin’s Chip Current-Sense Range Stops at 77 A, 17 of 11,616 Rows Reach 50 A, and None Reaches 100 A

A German home-storage design that needs a 100 A battery shunt will not find it in Walsin’s chip current-sense range. We computed the continuous current every row can carry at its rated power: the best is 77 A, 17 of 11,616 rows reach 50 A, 4 reach 70 A, and none reaches 100 A.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the Walsin Technology (Walsin) chip resistor exports: 137 files and 234,815 rows, of which 11,616 sit in the two low-ohm current-sense groups. This post is for an engineer or buyer in Germany who builds battery storage, a battery management system or a hybrid inverter and wants to know where a chip shunt runs out. Every part number is real, every count is ours, and where we quote a market figure we name the source, its date and the day we read it.

How big is the German battery storage market a component buyer is selling into?

Large, and shifting from home units towards bigger systems. Battery Charts, the RWTH Aachen ISEA project, counted about 530,000 new German storage systems in 2025, and Germany’s grid agency data reported by pv magazine put the installed base at about 2.2 million systems. We read both pages in full before writing this section.

pv magazine reported on 12 January 2026, citing Battery Charts, that Germany added an estimated 6.57 GWh of storage in 2025 and reached roughly 24 GWh in total, with home storage at 4.19 GWh, down 6.4% on the year before. Clean Energy Wire, in an article that cites pv magazine and the grid agency BNetzA, reported about 526,000 new batteries in 2025, down from 561,000 in 2024, about 25.5 GWh installed in total, and 460 projects above 1 MW in planning. The two sources differ slightly on totals because they use different data cuts, and we quote each as stated.

Those figures describe a market. They say nothing about any one maker, and we name none. What they do mean for a component buyer is that the current path of a pack, the shunt, is a part many designs need, and the number of designs pushing more current through one pack is growing. That is our view, not the sources’.

How much current can a Walsin chip current-sense resistor carry?

At rated power, 77 A at the very most, and 14 A for the thick film shelf. We parsed all 11,616 current-sense rows, converted each resistance and rated power to a number, and computed the current at which the part dissipates its full rated power, I equals the square root of P over R.

The method is arithmetic, not a datasheet value. It tells you the ceiling, not a design current, because real designs run well below it. The distribution is steep:

Continuous current at rated power	Rows reaching it, of 11,616	Series that supply them
10 A or more	685	Thick film and metal
20 A or more	192	Metal only (thick film stops at 14.1 A)
30 A or more	83	Metal
40 A or more	31	Metal plate and foil
50 A or more	17	Metal plate (16 rows) and metal foil (1 row)
70 A or more	4	Metal plate, one 0.5 mΩ value
100 A or more	0	none

We have not seen this counted anywhere: the thick film shelf of 10,428 rows tops out at 14.1 A, and the whole 11,616-row range stops at 77.5 A, because no row has a resistance below 0.5 mΩ or a rated power above 3 W. Sixteen of the 17 rows at 50 A or more are the 2512 case size, and one is a 1225. The 8 automotive-labelled series rows among them carry the same figures as their commercial twins. Walsin’s own series names are “Metal Plate Power Low Ohm Current Sense Chip-Resistor” and its automotive variant; we hold no datasheet for either, so we do not state what the automotive label covers.

Which Walsin parts come closest to a 100 A shunt?

The 0.5 mΩ metal plate part in a 2512 case. Our working target is 100 A continuous, which is about 104 A for a 5 kW pack at 48 V (our arithmetic, power divided by voltage, not a figure from any source). At 100 A, a 0.5 mΩ part dissipates 5 W against a 3 W rating, which is 167% of rating. Here is how the nearest parts line up.

Walsin part	Case	Resistance	Rated power	Current at rated power (our arithmetic)	Match / mismatch for a 100 A shunt
WW25AR0L5FTL	2512	0.5 mΩ, ±1%, TCR ≦±70	3 W	77.5 A	Mismatch: 5 W at 100 A against 3 W
WW25A0L75FTL	2512	0.75 mΩ, ±1%, TCR ≦±70	3 W	63.2 A	Mismatch: 7.5 W at 100 A
WW25AR001FTL	2512	1 mΩ, ±1%, TCR ≦±70	3 W	54.8 A	Mismatch: 10 W at 100 A
WW25YR0L5FTL	1225	0.5 mΩ, ±1%, TCR ≦±100 (metal foil)	2 W	63.2 A	Mismatch: 5 W at 100 A against 2 W
WW15WR005FTL	0815	5 mΩ, ±1%, TCR ≦±200 (thick film)	1 W	14.1 A	Mismatch: 50 W at 100 A

The first row is the closest, and it is 22.5 A short in the sense that matters. A 50 A design is another matter: WW25AR001FTL clears it on paper, by 4.8 A, with no margin for derating. Paralleling two parts is a design decision for your engineer. It halves the current each part carries and raises current-sharing and layout questions that we leave to you. Our posts on thick film against metal current-sense parts and on what a 1 milliohm sense resistor publishes go further on the fields.

What do we hold in stock for current sensing?

Three lines, and none of them is a battery shunt. In our stock list as at 23 September 2026, 1,125 part numbers, three lines are low-ohm current-sense parts: WW08WR270FTL, WW08WR390FTL and WW08WR470FTL, all 0805 thick film at 1/4 W, good for 0.96 A, 0.80 A and 0.73 A at rated power.

None of the 1,188 metal plate and metal foil rows is on the shelf. A pack-level shunt in Germany is therefore a factory order from Walsin, not a shelf pick, and we will say so before you design it in. The ready stock page shows what is held in Hong Kong now. The stock list is a dated snapshot and moves.

What do we not know about these parts?

Three things, and each matters for a shunt. We hold two Walsin chip resistor datasheets, the WR general purpose and the MR automotive sheets, and neither covers a metal plate, metal foil or low-ohm part. The export has no column for operating temperature, derating curve, pulse rating or inductance.

On our request list: the datasheets for the metal plate and metal foil series. We state no current rating, no pulse capability and no AEC-Q200 status for them. Qualification stays with you.

What can you do about a 100 A shunt today?

Cross your current incumbent and read the differences. Paste the shunt line, or a whole BOM, into the free cross-reference tool, which decodes 18 manufacturers’ part numbers across 800,000+ crossable parts. If the answer is a 0.5 mΩ 2512 part at 77 A against your 100 A, you have your answer in a minute instead of after a sample round. The chip resistor range lists the families.

We will not call any part suitable for your pack. We will show you where it differs, and you confirm against the Walsin datasheet and qualify it in your own circuit.

The short version

German storage is a growing market, and its biggest shunts outrun a chip resistor catalogue. Of 11,616 Walsin current-sense rows, 17 reach 50 A, 4 reach 70 A and none reaches 100 A on our arithmetic, with 3 W and 0.5 mΩ as the limits. We stock three current-sense lines as at 23 September 2026, all 0805 thick film below 1 A.

Send us your shunt line and the current you need to carry. If your design is at 100 A, which do you change first, the shunt, the pack topology or the supplier?

Sources

Fetched 20 October 2026. The market statements above are taken from these pages; the part data comes from our own Walsin exports and stock list.

• pv magazine, “Germany adds 6.57 GWh of battery storage in 2025, total hits 24 GWh”, 12 January 2026 (data credited to Battery Charts, ISEA RWTH Aachen): https://www.pv-magazine.com/2026/01/12/germany-adds-6-57-gwh-of-battery-storage-in-2025-total-hits-24-gwh/
• Clean Energy Wire, “Total number of Germany’s battery storage systems rises by a third in 2025”, January 2026 (citing pv magazine and BNetzA): https://www.cleanenergywire.org/news/total-number-germanys-battery-storage-systems-rises-third-2025

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Frequently asked questions

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