Westerbeke — Residual Voltage Measurement
Testing & diagnosis · alternator
From a Westerbeke service manual covering: WTA 15, WTA 20, WTA 25, WTA12KW, WTA15KW, WTA16KW, WTAl5KW. Check it applies to your exact model before use.
Before you start
- Generator must have no load; breakers and ship-to-shore switch must be open.
Procedure
- Stop generator, unplug regulator board and expose output lines T1 and T4.
- Start generator and measure AC voltage between T1-T2 and T3-T4; should be 25-35 VAC no load.
- Measure DC voltage between Pin #2 and ground; should be 5-6 VDC.
- If accessible, measure AC voltage across diodes A1 and A2; should be 10-12 VAC.
Tools required
- volt-ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 25-35 FridayParts $25.27 VAC T1-T2 Amazon eBay/T3-T4
- 5-6 VDC Pin #2 to ground
- 10-12 Amazon eBay FridayParts $169.30 VAC across A1-A2
Source: Westerbeke service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.