This maybe what you are looking for and they are cheap - but I use this for testing the battery or alternator with/without a load

TESTER

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15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
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