Go on line and order 2 x 185650 with tags
https://r.search.yahoo.com/_ylt=Awr.QpIFCk1kn3Er4TZ3Bwx.;_ylu=Y29sbwMEcG9zAzIEdnRpZAMEc2VjA3Ny/RV=2/RE=1682799237/RO=10/RU=https://www.batteriesplus.co.uk/acatalog/Li-Ion-18650-battery-3-7-V-1800-mAh-1186.html/RK=2/RS=rxo64J3rC74LT9yt.vsfVJRl_DU-
tools needed a sharp thin blade ""mind fingers" or hold in a vise! and Good soldering iron , sharp small pair of cutters
1 Cut glue around the flat base and remove the cover.
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2 Remove battery assy a bit of wiggling as its been hot glued in place .TAKE NOTE OF BATTERY POLES BEFORE CUTTING AWAY OLD ONES OR TAKE A PICTURE
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3 De solder the wire from each end remembering what wire is what and location of -/+ . end of the battery and wires.
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4 Place the new batt's in place and trim tags once correct location is made and with a flux solder make the joint along with the wire each end use a glue to make them stay in place like a contact type evo stick .( a small pair of long nose will help hold them together )
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5 test unit with a tester .
place unit cover back on and place in charger after charging remove cover and test to see if your joints are holding up if the unit is holding a full charge replace the cover again and glue the two back together , I used a waterproof rubber sealer called Sikaflex 221 from the motor trade but any water proof glue sealant will do.
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It reads as if its a long job but its only around 15mins when you start and have everything to hand.
all pulsar seem to run on 18650 in some sort of config .
Done a fair few now none have failed and guys are still happily using them with the knowledge they have saved a fair few £ on a new unit lol.