Reverse Contactor wiring diagram and discussion

awb

So i asked for some advice from Scottyb in a pm about wiring diagram's involving a reverse contactor and he advised me to make a topic for it. So will get some good discussion and ill hopefully get my answer before my contactor gets here


So my current build is (8-6v)---48v, Alltrax AXE 4865 650 amp controller, D&D High Torque motor, 2g welders wire with copper terminals, Albright SW202
Contactor(48V-400A)


And now for the question. Ive seen alot of discussion about wiring diagrams but the topics are only ever 2 pages long and they arnt clear how well one way works vs the other.

in diagram one; aka scottyb's way, he uses a main solenoid inline where it would normally be and also use the reverse contactor.



in diagram two: theres no main solenoid,just a reverse contactor.





When i asked why he likes to use a main solenoid he responded with "Safety". i dont see any added benefit from using the main solenoid. I see it as just more points of failure imo and another spot were power will be burnt off and loss as heat. So what do u think? I think im going the simple route and just using the reverse contactor.

BGW

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Andy4639

awb

ahhh i see. this makes sense now. its a cutoff switch, but you wouldnt normally have these on a cart so i guess the conversion makes your cart that much safer. although im not one for safety, but i must admit the reverse buzzed on a electric cart makes sense. dont ask how i know.

scottyb

Every cart I can think of has a main contactor which is the main safety cutoff switch.

awb

maybe i said that wrong. you wouldnt normally see a reverse contactor on a golf cart. Adding a reverse contactor inline with a main soleniod creates redundancy. so a standard unmodified cart has about as much fail safe as a cart using a reverse contactor without a main solenoid.

scottyb

Leaving the main contactor in place when installing a reversing contactor leaves the fail-safe system in tact. Golf carts are full of redundant safety devices. A good example is the 5 switches needed to make some of them go.
There is more than one way to skin this cat. If you want to run without the main contactor you can. It's just not the most widely utilized schematic.

Andy4639

Revolution

I hate to step on toes around here, but for the sake of the discussion I'll give my opinion. I know it may not be the popular opinion.

Most carts have one contactor, not two. They are considered safe. My current cart and my bad boy rebuild in progress will use the reversing contactor and no main contactor. I don't feel this is dangerous in any way, as long as you use a quality reversing contactor, rated for the task at hand.

I am using sw202's for my carts, they are rated for 400 amps continuous duty. My 72 volt cart only pulls 340 amps for the first few seconds of EXTREME use. ( that's at least 32 hp, 72x340/764=32.something) So I am not really worried about welding the contactor shut.

Even if the contactor welds it's self, the controller would have to fail in full output mode to cause me any real problem. So two parts of the cart would have to fail in unusual ways to cause a problem, I am ok with that.

I fully expect to get a lesson in safety, so don't hold back. Maybe you can convince me to add another contactor to both my carts.

awb

yea revolution, i agree with you. ill let u guys know how it goes after i get it wired

branson

I seem to remember in another thread about the forward reverse contactor. it was recommended to close the reversing contactor before the main contactor in order to extend the life of the reversing contactor.