I'm Elmer-less: Two simple questions

[fremont]

1. I'm convering a TK-880 to a temporary base station with power from a 12V 28AH battery.  Do the wires need fuses?

 

2. I'd prefer to use alligator clamps vs. spade terminals on connection in #1.  I'm struggling to find insulated clamps for wire that small.  (At least on Amazon.)  Any tips?

 

Thank you.

[BoxCar]

Fusing the leads gives you protection against a failure that could result in fire.

[Lscott]

1. I'm convering a TK-880 to a temporary base station with power from a 12V 28AH battery.  Do the wires need fuses?

 

2. I'd prefer to use alligator clamps vs. spade terminals on connection in #1.  I'm struggling to find insulated clamps for wire that small.  (At least on Amazon.)  Any tips?

 

Thank you.

1. Yes you need fuses of the proper type and amp rating. Too low in amp rating the fuse will fail during transmit, which draws the most power. Look at the radio's manual. The recommended fuse and rating is typically specified there.

 

2. You can try some automotive trailer power connectors. You can get something like the below cable and plug.

 

https://www.amazon.com/807-Extension-Disconnect-Harness-Connector/dp/B07SQ1G56V

(You most likely can find something like this at your local auto supply shop)

 

Just cut the cable in half. Connect the wire end to the power supply, or battery, observing the proper colors, red is positive and black is negative. Then use the other half of the cut cable for the radio doing the same thing matching the red for red and black for black. The bonus is if you get two cables and cut them in half the second one can be wired into the automotive electrical system. Now you can freely move the radio between the vehicle and the house, for example, without having to worry about screwing up the wiring and wrecking the radio.

 

I highly recommend you permanently attach the wires to the power supply/battery and radio then use just the plug. Sooner or later you'll screw up and connect the radio up backwards. When the "magic smoke" comes out of the radio it quits working and there is noway to put it back in either. 8-(

[fremont]

Thank you for all of the help.  A couple follow-on equally naive questions:

 

1. I've set up PP connections between transceiver and battery (12AMG wire).  If my peak Tx drain is 8A, what fuse should I use?  I was assuming 15A.

2. Is a fuse only necessary on + wire?  (I'm studying for the Technician exam; electricity is not a strong suit but I'm learning.)

 

Thanks again.

[SteveC7010]

15 amp should be fine.

 

Fuse the + line within a few inches of the battery.

 

If you wire a car, the ground wire should go to a factory grounding point in the vehicle, not the battery negative post.

[WRAK968]

Thank you for all of the help.  A couple follow-on equally naive questions:

 

1. I've set up PP connections between transceiver and battery (12AMG wire).  If my peak Tx drain is 8A, what fuse should I use?  I was assuming 15A.

2. Is a fuse only necessary on + wire?  (I'm studying for the Technician exam; electricity is not a strong suit but I'm learning.)

 

Thanks again.

If your max amp draw is 8A then you should likely use a 10A fuse. The rule of thumb we used at the shop was the next highest fuse rating at 125% of the load. This rule was made this way to provide the quickest protection to both the battery and the device being run off it. And the fuse can be on either + or - (In fact Kenwood and most other radio manufacturers fuse BOTH + and -) The chief reason most people fuse the + lead is that a majority of vehicles are - ground. This means that a break anywhere in the + cable has a chance of contacting ground anywhere in the vehicle and causing a short.

 

In your case, the fuse will act as over-current protection for the radio. Likewise, (But don't test this without researching) if you plug the radio in backwards it should blow the fuse to save the radio, however not all radios do this.

[axorlov]

Alligator clamps:

these will do: https://www.amazon.com/URBEST-Spring-Battery-Insulated-Alligator/dp/B01M1BW0TC/ref=sr_1_4?dchild=1&keywords=alligator+clamps&qid=1602793484&sr=8-4

although, I dislike alligator clamps, they are not as reliable as other connectors. You'd need to solder the wires to the clamps. Same or similar clams are available at auto stores, O'Reilly, Autozone...

 

Inside the car bot (+) and (-) wires are with fuses to prevent a situation when common ground connection from the battery rusts, falling off completely or developing high resistance, and all the 12V devices now are looking for an available ground, that goes through your radio. When not in the car, one wire to have a fuse is enough. If you plan to add some other device (another radio, sound amp, usb charger, etc...) to the same battery, it make sense to have every consumer with it's own fuse on its own (+) wire.

[kteas]

What i would do. Use at least 12awg wire. And get lt fused. 10amp, but initial surge may draw close to that. So I would buy both 10 and 15amp fuses. Start with 10 if it doesn't blow, stick with it. If you surge (surge is when you key up, initially starting some circuits can cause a surge of higher amps then settle to avg). I would use a permanent connector to the battery, not clamps unless I was using the battery for other things. Clamps can come off, touch each other. They move around to much.