# The High-Voltage system / circuit



## racunniff (Jan 14, 2009)

RoughRider said:


> Hello
> 
> 
> Are there any other good picture of the HV-circuits for EVs on the net?
> ...


Don't know that it is a good one, but the Electrojeep's diagram is here.

There are two main safety interlocks that people commonly put in EVs. The first is a neutral start interlock - it prevents the controller from powering up if the gas pedal is depressed (or, in some systems, if the control is put in "drive"). The second is a charger interlock. It prevents the controller from starting up when the charger is plugged into the wall (i.e. keeps you from trying to drive away while attached).

Regarding where to find components - there are many vendors and I don't want to single them out here, but you can start with the Parts Vendors forum on this site, or you can peek at the Vendor List on my blogs or other EV conversion blogs.


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## EV-propulsion.com (Jun 1, 2009)

Alot could be added to this basic circuit, but in this diagram the precharge resistor circuit is not shown. It depends on the controller you are using, but the type that appears to be shown in this diagram would need one.
Mike
www.EV-propulsion.com


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## racunniff (Jan 14, 2009)

EV-propulsion.com said:


> Alot could be added to this basic circuit, but in this diagram the precharge resistor circuit is not shown. It depends on the controller you are using, but the type that appears to be shown in this diagram would need one.
> Mike
> www.EV-propulsion.com


Good point. If your controller does not have internal contactors (the Azure / Solectria one in the ElectroJeep *does*) you need a precharge resistor. Your controller manual should have the ratings required. Here is a diagram of a very simple layout for a 24V Kelly system that includes a precharge resistor and diode across the contactor.


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## RoughRider (Aug 14, 2008)

thanks for the repleys...

where can i buy such a "safety interlock"...i looked through the homepages, but didnt find a vendor, that has such things on the online shop...

what about charging, i need disconnect the controller while i am charging, right?

and do i need such a "precharge" for the charger,too? i am not gonna use a onboard charger...so before charging, i have to connect the battery and charger through anderson connectors...


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## racunniff (Jan 14, 2009)

RoughRider said:


> thanks for the repleys...
> 
> where can i buy such a "safety interlock"...i looked through the homepages, but didnt find a vendor, that has such things on the online shop...
> 
> ...


A "safety interlock" is just a relay (if you're switching the 12V) or contactor (if you're switching the HV). For the charger, use an AC relay that can switch your 12V keyswitch signal to the controller. For example, I've used the Potter & Bumfield KUHP-11A51-240 for a 240V AC relay.

For the "neutral start" it is a little more complicated. Some controllers have it built-in - you should check your manual.


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## EV-propulsion.com (Jun 1, 2009)

your safety interlock is not a specific part, but a design option. It could be something like: 
controller will not have power (control side) with the brake pushed (so you cant power brake and burn things up),
electrical cord interlock so you can't drive off with the charging cord attached (on some cars the plug is obvious so may not be needed- or you could use an auto-eject that we have that would shoot the cord out)
you could even design one for the seatbelt-if its not fastened there is no power to the controller 
In other words the skys the limit on interlock ideas, but are generally safety related or for component protection. As far as what parts are needed for an interlock, usually some type of switch and relay for basic interlock, or electronic if you are so inclined.
Basically think about what you don't want to operate unless something else is done/not done....

The controller does not have to be disconnected while charging, but see above about the cord/controller power

There are many threads about precharge systems here, you wouldn't use it on a charge circuit. Do a search for "precharge" and if your questions aren't answered, we will do it on this thread.....

Mike
www.EV-propulsion.com


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## yashdwc (Sep 24, 2012)

can you tell what more can be added to the given basic circuit...


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## mk4gti (May 6, 2011)

Woah, blast from the past 

An inertia switch is an absolute must if you ask me. It will kill the contactor in case of accident.

A manual/safety switch for the charger is also recommended.

You may also need to account for the BMS wiring.


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