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Solid State battery isolator with circuit breaker?

PDM Installation & Configuration

Relevant Module: PDM Practical Discussion > Isolation

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I'm building a replacement electrical system for a street/club level Lotus Esprit LS3 conversion that will manage power distribution with an ECUmaster PMU-24-DL, used together with ECUmaster's mosfet-based battery isolator controlled by CANbus and analog switches. Question is whether there is any advantage or disadvantage in combining an intelligent battery isolator like this with a circuit breaker.

The ECUmaster manual recommends wiring the alternator output to the load side of their battery isolator. To prevent a potentially damaging load dump from the alternator, the activated isolator instructs the PMU to cut engine power prior to cutting B+ between the battery and alternator.

Their battery isolator appears to have some of the characteristics of a circuit breaker. The manual suggests that it will shut down in an over-current situation. Not sure in this instance if it is acting like a circuit breaker, and as it shuts down, if it will do so in an orderly way so as to prevent that alternator load dump...

Would there be any protection advantage in adding a circuit breaker either between the isolator and the alternator, or between the battery and the isolator? Another (more old-school) option would be to connect the alternator output between the battery and the isolator.



While the Ecumaster battery isolator does have an adjustable over current trip setting, I have found it to not be overly useful honestly. More often then not I have to increase the setting way beyond safe just to prevent the starters inrush from tripping it during every start.

It is however great at preventing and detecting Load dump. The output from the isolator can be wired to control the PMU24's turn on, or to an analog input on it or the ecu. When the kill switch is switched (power save or emergency kill, both are independently set in software) the output triggers the PMU/ECU to turn off the engine, and after a set time the battery is disconnected. You can also kill via a CAN message.

See the attached screenshot for an over view of the settings in Light Client.

I do think this is a great unit, but there needs to be a software feature added for a start event to ignore or raise the over current trip...

Attached Files

Tyson provided great info, so I'll just chime in to say I wouldn't add a circuit breaker.

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