A method for connecting two capacitors or supercapacitors, each of them comprising a sealed housing, each housing comprising a tubular element and at least one lid closing the tubular element at its end, this lid comprising a centring pin forming means for positioning the strip thereupon, this method comprising the steps consisting in: - on the two lids of two housings placed side by side, a connector strip is positioned sized to be in contact with the lid of each of the housings, this strip comprising two orifices allowing its positioning on the pins, this method being characterized in that it comprises the steps consisting in: - placing in contact with the lid and the strip, a friction stir welding device mobile in rotation, translating this device along a predetermined axis normal to said lid, so that it enters into the material of the lid and of the strip and displace it in order to weld the strip on the cover by friction stir welding, thus forming a first weld bead along the contour of one of the two centring pins, - withdrawing said friction stir welding device from the lid and from the strip after the formation of the first weld bead, - placing in contact with the lid and the strip, a friction stir welding device mobile in rotation, translating this device along a predetermined axis normal to said lid, so that it enters into the material of the lid and of the strip and displace it in order to weld the strip on the cover by friction stir welding, thus forming a second weld bead along the contour of the other of the two centring pins, - withdrawing said friction stir welding device from the lid and from the strip after the formation of the second weld bead, - and/or the steps consisting in: - placing in contact with the strip, the friction stir welding device mobile in rotation, translating this device along a predetermined axis normal to said lid, so that it enters into the material of the strip and of the lid and displace it in order to weld the strip on the cover by friction stir welding, thus forming a weld bead along the contour of the connector strip, and - withdrawing said friction stir welding device from the lid and from the strip after the formation of the weld bead along the contour of the connector strip. - on the two lids of two housings placed side by side, a connector strip is positioned sized to be in contact with the lid of each of the housings, this strip comprising two orifices allowing its positioning on the pins, - placing in contact with the lid and the strip, a friction stir welding device mobile in rotation, translating this device along a predetermined axis normal to said lid, so that it enters into the material of the lid and of the strip and displace it in order to weld the strip on the cover by friction stir welding, thus forming a first weld bead along the contour of one of the two centring pins, - withdrawing said friction stir welding device from the lid and from the strip after the formation of the first weld bead, - placing in contact with the lid and the strip, a friction stir welding device mobile in rotation, translating this device along a predetermined axis normal to said lid, so that it enters into the material of the lid and of the strip and displace it in order to weld the strip on the cover by friction stir welding, thus forming a second weld bead along the contour of the other of the two centring pins, - withdrawing said friction stir welding device from the lid and from the strip after the formation of the second weld bead, - and/or the steps consisting in: - placing in contact with the strip, the friction stir welding device mobile in rotation, translating this device along a predetermined axis normal to said lid, so that it enters into the material of the strip and of the lid and displace it in order to weld the strip on the cover by friction stir welding, thus forming a weld bead along the contour of the connector strip, and - withdrawing said friction stir welding device from the lid and from the strip after the formation of the weld bead along the contour of the connector strip. - placing in contact with the strip, the friction stir welding device mobile in rotation, translating this device along a predetermined axis normal to said lid, so that it enters into the material of the strip and of the lid and displace it in order to weld the strip on the cover by friction stir welding, thus forming a weld bead along the contour of the connector strip, and - withdrawing said friction stir welding device from the lid and from the strip after the formation of the weld bead along the contour of the connector strip.