Posted by on 3/5/2026 to
Alternators
These instructions are for programming a Wakespeed alternator regulator to charge a Victron lithium battery directly, using the Cerbo GX as the mediator between the two. When set up correctly the Cerbo can tell the Wakespeed to stop the alternator from charging when necessary. You need to make sure the networking between the various devices is set up correctly and that both the batteries and the Wakespeed show up on the Cerbo. The Wakespeed needs to have an Alternator Temperature Sensor fitted and it also needs a shunt to measure the alternator output. Unless the alternator is isolated ground the shunt will have to be on the positive side of the Alternator output and the shunt will need a cover. Certain other brands of lithium batteries also have the ability to communicate with the Cerbo GX in the same way.
Programming is done on your phone using the Wakespeed app. Start by entering the alternator capacity, turning on the "sense rpm via stator wire" and adjusting the max field drive down. It is normal to reduce the max field allowed because lithium batteries would otherwise put too much of a load on the alternator causing it to overheat. We suggest you reduce the field by at least 20% to start, but maybe more. The aim is to keep the alternator approximately within its allowed temperature limit and then let the automatic temperature sensor just do the fine tuning. You can consult your alternator manufacturer to see their recommended limit but typically it will be between 90 and 110 Deg C.
Next we need to tell the Wakespeed what BMS we are using and also tell it that we have a current shunt on the alternator. This is shown in the screenshot below.
Next we need to program DVCC. This stands for Distributed Voltage and Current Control. This is the feature that allow the Cerbo to control external devices over their network connection. You can read more about it in the Cerbo manual. Check that DVCC is turned on in the Cerbo, in most cases this happens automatically when the BMS is connected to the Cerbo. Then you also need to turn it on in the Wakespeed as shown below.
One of the nice things about the Wakespeed is you can control alternator output based on engine RPM. This way the alternator isn't taking too much power at (or just above) idle or at wide open. They call this white space load shaping. You can turn it on and change the settings as you wish. The feature is particularly useful if your engine is relatively small and your alternator is relatively large and prevents the alternator from taking too much power at idle or at high speed.
This is just a basic introduction to programming the Wakespeed, there are lots of other options for fine tuning but the above will help to get you started.
Peter Kennedy has been in business since 1991 designing, installing and servicing marine electrical systems. The purpose of this blog is to offer support to both professional installers and do-it-yourself boat owners who wish to undertake this work themselves.
SEARCH
You can subscribe to get automatic notifications of new blog posts, this is separate from a newsletter subscription.
