Making a 4 wire Voltage Reducer "keyed"?

AussieInSeattle

I purchased a Tecscan VOLTSeasy which converts 48V to 12V (15Amp). There are only 2 in and 2 out wires though (no switched yellow). Is there an "easy" way to wire it to my keyed switch on a 2011 Precedent?

Doing a search I came across this thread, but that doesnt fit into the "easy" category for me :-) :
http://www.buggiesgonewild.com/elect...y-reducer.html

BGW

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Sergio

That is the easiest way since You should not power the DC converter directly from the key switch.

Maybe the diagram below helps.

48v Relay:

http://www.mouser.com/ProductDetail/...HO3CeSfQ%3D%3D

1N4007 Diode:

http://www.mouser.com/search/Product...alkey1N4007-TP

Attached Images

48v_relay_for_DC_converter.jpg (118.3 KB, 0 views)

AWandKW

Excuse my ignorance- but why the diode?
Thanks!

Volt_Ampere

When using relays with DC, you almost always want a diode to reduce the BEMF generated when the coil is deactivated. If you don't, a very high voltage is generated while current in the coil (inductor) collapses.

AWandKW

Got it. Thanks!!

notnilc

what is the issue with wiring a reducer power from the key switch? i am currently in the midst of wiring the same scenario and don't have any 48v relays readily/locally available.. other idea was from the batteries to a rocker switch and to the reducer.. problem being most rockers are rated for 12v.

teecro

Amperage draw... You do not want the heavy amp draw of the reducer being pulled through the rather light weight key switch.

While I'm no fan of some of the plastic-fantastic toggle switches sold at auto-parts stores there is absolutely no problem with pulling 48 volts through a toggle switch. The 12VDC rating is there merely as a guide to help you select the appropriate size, that same switch also has a rating for 120VAC too.

"Amp or Load Rating—You need to know how much electrical current will flow through the switch at the voltage of your circuit. You can compute this current if you know the amount of power required by the device you want to control.
For example, you have a 60 watt bulb powered by a 120 volt AC power supply. Use the formula Current (amps) = Power (watts) ÷ Voltage (volts) to calculate that the light bulb will draw 0.5 amps of current. You must select a switch with an amp rating higher than 0.5 amps at 120 volts AC. Remember, the required amp rating may change when there is a change in voltage.
Control Voltage—Some switches are activated by pressing a button (physical force), while other switches, such as relays, are activated by applying a voltage (electrical force). Relays need a control voltage (also known as an input or coil voltage) to operate. If your switch requires electrical activation, make sure your system can supply the appropriate voltage. If you need to use multiple relays, you may also want to look at power consumption (the amps or volt-amps drawn by the coil of the relay) to ensure your system can supply the required amount."

yawood

The following is what I ended up with after putting in a two wire converter. Note that this diagram does not have Sergio's diode (which should really be added). In this circuit, the converter operates through a separate switch which itself is operated by the key switch. This means that you can have the converter off while the key switch is on - i.e. use the cart but save battery if you don't need to run any 12V. However if the key switch is off, everything is off - even if you've forgotten to turn the 12v off.

This is a quote from the thread DC-DC Converter

yawood

Here's the diagram again with the diode shown (between terminals 85 & 86 on the relay). If you didn't want the separate switch then just take the connection from the cold side of the key switch straight to terminal 86 (preferably through the 3A fuse).

SF_Wood

I am sure that is a very detailed solution that many people understand. Me, not so much since my electrician skills are limited... I installed a 48V to 12V voltage reducer last night to power underbody LED's. This is the only accessory that will be used. The cart is mainly for golf so the only time the LED's will be running is for night cruises. This morning I checked the voltage reducer to see if it was hot and it was semi warm. I have been trying to figure out a way to add a switch that would allow power to the voltage reducer just when I want to use it. I was thinking of a toggle switch that could be added on the wire from the positive of the battery going into the reducer. It doesn't have to be anything pretty, just functional. Am I after something feasible?