Barrus Shire 90 Amp Narrowboat Alternator Upgrade replacing the original Barrus 80 Amp unit.

The most popular alternator upgrade job that I do – I’ve fitted this kit to ~ 200 Barrus Shire engines all over the canal network.

barrus80A

It replaces the original factory fitted 80 amp alternator which is expensive, unreliable and has poor performance providing nowhere the rated 80 amps. The kit I fit is far better in every respect. Charging performance is transformed with tickover output significantly improved.

Barrus90

The shims and a high speed pulley have been made for this specific job and this marine alternator fits perfectly. I use a longer Gates Quadpower belt which increases wrap around the pulley and brings the alternator further away from the exhaust manifold.

Cable sizes should suit the 90 amp output. Notice in the photo with the original alternator the cable size is 10mm. I upgraded the charge circuit to 35mm including the battery link leads and earth.

Have to be careful with the fixings for the terminals – with heat the insulating washer on the B+ terminal shrinks and can cause the nuts to loosen off which can destroy the alternator. I fit spring washers and locking nuts to prevent this. Also the insulated return negative terminal is only M5 and with the original nuts sustained high current can be too much for the contact – fitting good quality copper tube terminals and extra nuts helps this.

Charging has been totally transformed and customer very happy with the job.