Most alternator charging setups are not designed to charge Lithium batteries. To take full advantage of Lithium’s fast recharge property it’s often necessary to upgrade the alternator system. I’ve developed some standard upgrades for specific engines and with the move towards Lithium it’s quickly become a big and exciting part of my work.

This page ties in with my work fitting External Alternator Regulators – The Wakespeed WS500 and Mastervolt Alpha Pro have some brilliant features to optimise charging and realise the full potential of a big alternator setup.


Isuzu 200 Amp Bosch Alternator Upgrade.

The excellent Isuzu Canaline engines are let down by a particularly poor factory domestic charging setup. I have a 200 amp alternator upgrade running a freewheeling clutch pulley & custom 6PK poly-v crank pulley conversion. This series of Bosch alternator is used in the £2500+ Mastervolt 14/200 package. Available for most of the 4 cylinder engines. Custom stainless steel adjusting arm and mounting bracket. Options on alternator pulley sizes giving upto 4.2:1 pulley ratio. This upgrade transforms charging performance. For charging lithium it requires an external alternator regulator to limit alternator load at low engine speeds. Please call for details.

Isuzu Canaline 42 200 Amp Bosch Upgrade


Beta Marine Engines

For charging lithium the factory 175A Iskra fitted to Beta 43/50 engines is good – it just requires an external regulator fitting. It’s possible to upgrade this to a 200A Bosch for the performance and quality of the latest Mastervolt 14/200 system. For the earlier (pre 2011) Beta 43/50 it’s possible to upgrade the 95 Amp Iskra to the current 175 amp Iskra, 200A Bosch, or 24V 150A Bosch. The poor performing 12 & 24 volt Delco Remy alternators can be swapped out for these too.

These engines can suffer crank pulley problems potentially destroying the crank shaft. This is a particular problem when charging big lead-acid banks and lithium with the large alternator loads they create. An external regulator works so well here limiting loads at low engine speeds and increasing the load at the 1200rpm (that Beta specify for charging) & looking after the expensive battery bank with it’s adjustable voltage and max charge rate.

For early Beta bv1505, Beta 35, Beta 38 I’ve a 90 amp alternator with custom 65mm pulley, wider XPA belt upgrade and cable sizes uprated to 35mm. Transforms charging performance from the standard original setup:

For the later Beta 38 with 6PK poly V pulley there’s a 200 amp Bosch upgrade available. An external regulator must be installed to de-rate the alternator loads to suit engine power at low speeds.


Vetus Engines

Vetus engines only offer disappointing V pulley drive systems. This gives limited charge options unable to take advantage of a high power poly-v drive setup with large alternators and good pulley ratios. It means it’s relatively expensive to get modest continuous charge currents for charging Lithium. On the job below I squeeze in a high quality 150A Bosch alternator + Mastervolt Alpha Pro. A custom XPA pulley is fitted and a Gates Quadpower belt used – this belt sits higher in waterpump and crank pulleys (slight increase in crank pulley diameter) and the XPA (12.5mm) alternator pulley can transfer more power than the factory 10mm setup. The Mastervolt controller is setup to limit current to belt limitations and manages and controls alternator temperatures to below 100 deg C. Fitting such a large alternator means that it can run at a continuous high current without overheating. Max current is set at 110 amps and a very impressive 70amp continuous output is available just off tickover.

This setup gets the very best out of the poor V pulley setup and takes full advantage of the Mastervolt controller’s clever features allowing a large alternator to be run right on the edge of belt limitations.


Barrus Shire Engines
**New** 200 amp Bosch alternator setup for some Barrus Shire 40 & 45’s. 6PK poly-v crank pulley conversion with freewheeling alternator pulley. Can replace the discontinued 110 amp Prestolite RDG5725. Custom folded stainless steel mounting bracket & adjusting arm. Unstrained & powerful, transforming the original setup. This kit isn’t suitable for all of the Barrus 40/45’s – call me for more details.

If you have a Barrus Shire 45/50 with the 240 amp Prestolite alternator you may experience poor charging performance due to the extremely low 14.0 to 14.20 voltage regulator set point. There’s problems with squealing and chirping belts due to the 6PK drive setup unable to transfer anywhere near the 240 amp current through the small solid alternator pulley. This job shows a 200A Bosch upgrade on the 240A Prestolite achieving a reliable 180A continuous. https://www.instagram.com/p/CausPpxD41m/?utm_source=ig_web_copy_link


Engines Plus Canaline 42 12V 200amp Bosch Alternator Conversion.

For the 42HP engine with 6pk multi v crank pulley. Replaces the discontinued 110A Prestolite 35214420. Massive increase in performance throughout rev range. I use a custom alternator mounting bracket and adjusting arm, and fit a freewheeling alternator pulley which improves power transmission, helps stop belt squeal/chirping and makes for a smoother running engine. Can go down to a 50mm freewheeling pulley giving an excellent 4.2:1 pulley ratio. The photo shows a 175amp Mahle alternator and I’m now using a 200amp Bosch unit..