Which split charge relay is for me?

Here at Rayne Automotive, and in the world of charging in general, there are three main split charge types; ignition triggered, voltage sensing and smart alternator DC-DC charger.


Today we are looking to clear up the much-asked question, “which type do I need?” we are going to go through the merits of each one and provide a few rules of thumb for which one is for you.





Voltage sensing (VSR)

More modern technology

More expensive than ignition triggered relays of a similar amperage

Easier to fit


Covers more eventualities


CAN-BUS friendly



 Ignition Triggered

More versatile and can have manual override functions

Has to be connected to an ignition live feed

Cheaper than VSR


Available in more variants to suit individual needs


Very easy to mount with it’s traditional screw hole bracket


Can go up to 200A capacity




Smart Alternator

DC-DC Charger

Highly intelligent, variable charging capacity

More expensive than the other types

Can be used as a solar controller also

Has to be connected to an ignition live feed (CTEK only) Orion Smart does not require an ignition connection. 

Compatible with brand new vehicles, fitted with smart alternators


Provides a smooth charge with temperature adjustable voltage




So now we have seen the merits of each relay, you’re probably thinking; “that’s great, but which one is best for me?” well below is a list of situations and the best relay for them and the reason why.



Relay type


Pre 1990 vehicle

Ignition triggered

The main advantage of the VSR is it’s ease of fitting, this is somewhat negated on early vehicles due to how easy it is to find an ignition live and generally how simple the electrical systems are.

Heavy usage, such as winching or large inverters

Ignition triggered

Our range of relays is far larger in the ignition triggered range, meaning we can supply ultra-heavy usage kits of up to 200A continuous.

Modern vehicles (post 1990)

Voltage sensing

In modern vehicles, the ease of fitting of the VSR really comes into it’s own. In addition to this the VSR is CAN-BUS friendly so won’t interfere with your vehicles electrical systems.

Euro 5/6 vehicles (approx. 2015 on)

Smart Alternator DC DC charger

Vehicles fitted with a smart (or variable voltage) alternator need a different charging system all together due to the changes in their voltage output.

See here to find out if you need this type of unit. 


If you have any more questions, or aren’t sure which system you need, please don’t hesitate to contact us and a member of our technical team will walk you through it. Thanks for looking!