ad: elecraft

Side Post Battery

Discussion in 'On the Road' started by K5ATG, Dec 22, 2019.

ad: l-rl
ad: Left-2
ad: L-MFJ
ad: abrind-2
ad: Left-3
ad: l-BCInc
ad: Subscribe
  1. K5ATG

    K5ATG Ham Member QRZ Page

    Hello fellow amateur radio operators, hope all is well.
    I have a 1993 Chevrolet Silverado 1500 and I'm attempting to install a 2 meter / 70 cm mobile rig. Everything went pretty good considering this was my first install. I did run into a little snag. The battery in my truck is one of the batteries that have side posts like this one:

    I have tried to attach the wires to the battery using large ring terminals but that doesn't work because it interferes with the bolt that screws into the terminal. I'm pretty sure that I am not the only one who has run into this. So please let me know if you have a solution to this.
    Thank you
    Aaron K5ATG
  2. WL7PM

    WL7PM Ham Member QRZ Page

    Get your wires AWAY from that battery.....
    There's plenty of POWER available on the firewall, just above the heater hoses.
    All nicely , safely fused . Take your choice of the 8mm studs, all lined up there.
    Catch the BODY ground close to where your radio is mounted.
    K5ATG and K0UO like this.
  3. K5ATG

    K5ATG Ham Member QRZ Page

    Thank you for your reply. I'm not entirely sure of where you are talking about. My truck has a black cover right there. After asking Mr. Google, he told me it is a junction box. If we are thinking of the same thing then it will be pretty easy to hook up to that.
    Thank you
  4. KL7AJ

    KL7AJ Ham Member QRZ Page

  5. KF5FEI

    KF5FEI Ham Member QRZ Page

    K9ASE, K5ATG and K0UO like this.
  6. KB3WFV

    KB3WFV Premium Subscriber QRZ Page

    Good Morning Aaron,

    There are four (4) excellent ways to connect the radio's 12 volt power supply to your truck.

    Side post batteries terminals, when installed correctly are very good at preventing corrosion which can lead to bad connections, charging system problems and engine starting problems. The side post connections to the battery should be clean and tight. Side post connection are often installed incorrectly causing multiple problems.

    Option #1
    Install side terminal post extenders as mention in another reply to you. Then connect the radio to the extensions. This option works very well although it is often installed incorrectly. It also means that the connection to the radio will have to be removed when replacing the battery and any jump starting may cause a problem with the radio.

    Option #2
    Depending on how GM built your truck, there may be a connection point on the passenger side of the firewall of the truck. The firewall is the back panel of the engine compartment between the engine and the passenger compartment. When looking into the engine compartment from the front bumper looking toward s the rear of the truck, is a terminal block with studs sticking out. The hood light may be connected to this terminal block.

    You can connect the positive fused wire from the radio to this stud and the negative fused wire to a body ground bolt.

    This connection works ok, although I have found it difficult to get mechanically correct. It can also be hard to find a nearby good ground connection with out drilling a hole.

    Option #3

    Again depending on how GM built your truck... On the drivers side fender/wheel well housing should be an under hood fuse panel. In this fuse panel are TWO auxiliary circuit connection studs. on the fuse box cover label and in the the owners manual they are labeled either AUX or ACC A and B. These studs are used to connect trailer brake controllers and 12v battery charge to a trailer.

    Connect the fused positive wire from the radio to one of these studs, install a maxi fuse of adequate value into the fuse position for the stud you chose to use. Connect the negative fused wire from the radio to the negative body ground connection of the trucks wiring harness that is on a bolt near the under hood fuse box.

    This is a solid connection that will provide plenty of power for the radio. It is also the cheapest to install, all you will needs is a nut to go on to the stud and a fuse to power the stud. It is ABSOLUTLEY necessary to install/use the fuse in the radio wiring to protect the wiring, because the MAXI fuse for the auxiliary studs are rated at 40 amps.

    Option #4

    The side post battery can be purchased in a dual terminal style battery. The dual terminal battery have both the side post terminal and the top post in one battery. The Interstate Battery part number for your truck is a MTP-78DT or a MT-78DT.

    Install the dual terminal battery, connect the truck battery cables to the side post terminals as normally done. Connect the fused wires from the radio to the top post terminals of the battery. You will need to buy top post battery terminal cable ends to allow connection of the radio power wires.

    Aaron, option #3 and #4 are the best. I personally use option #4. I have used #3 and it is the cheapest to install, but I find that the radio is much happier with a solid top post direct connection to the battery.

    K9ASE and K5ATG like this.
  7. KF5FEI

    KF5FEI Ham Member QRZ Page

    Before going this route, make sure the hood (or anything else) is not going to hit the top battery terminals. Take a blob of PlayDoh taller than the battery post / terminal, and place if on the top of the existing battery where the top post should likely be. Fully close the hood, open it, and see if the PlayDoh is deformed or not. If it is, I would not go the dual-terminal route.

Share This Page