Where does Radio Constant for 8v (6 battery) cart hook up at?

the_freshmaker5

Im installing a radio in my "Ruff and Tuff" brand golf cart. The difficulty for me is that it has 6 batteries at 8v totaling 48v. It comes stock with a 48v to 12v converter. It only works when you turn the cart on which works perfectly to power the radio only when the ignition is on just like a car stereo. My question is where do i hook the constant (yellow wire) from the radio to? Normally you wire it to the positive of a 12v battery and this keeps your time and preset stations on your radio because it gets power constantly. I dont have 12v though since my batteries are 8v. I was thinking i would just hook the constant to the 8v positive terminal because the radios clock doesnt draw much power and most importantly its not more than 12v so it shouldnt damage the stereo. Is my thinking correct here or do you have some advice for me? Thanks.

BGW

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simple man

I've seen a 9V battery hold the memory in a stereo, while the battery in the vehicle is removed. I'd think 8V would probably work also, but I'm not sure if your radio can run on two separate sources for the input. Someone will pipe in I'm sure, who knows if this would work for you. I don't want to tell you it would and you burn out your radio!

the_freshmaker5

Thank you for your opinion. Im hoping for a few more before i take the plunge. I think it might work though because when driving a car, your voltage varies. This is especially true if you have let your car sit from not driving and your battery gets drained to the point of barely starting the car. If the battery is drained it could be anywhere from 12 all the way down to 0 volts (dead) per say. In theory, the constant is hooked to that battery the whole time and it doesnt damage the radio in that case so i think i would be ok. Im thinking the clock and preset stations will either work good or not work at all and not damage anything which is my biggest worry since its brand new. Although it may work and slowly damage it over time? You mentioned the radio running on 2 different sources (12v and 8v) but i wonder if when you turn the ignition on if the constant 8v turns off and the 12v takes over or if it would run on both sources like you said? Its not something we normally think about because usually both sources are 12v. That could be the tricky part but i still think if its only powering the memory of a clock that it should still work. I have researched this and everyone who has this problem is using (4) 12v batteries and the solution is easy. Someone must have a stereo in a cart with 8v batteries out there but i cant seem to locate the answer yet. I wonder if i could get another simple step down voltage converter that is always hot so i could pull my constant from it?

simple man

What I'm concerned with is that if you connect your memory to the 8V source, as soon as the radio is turned on is the 12V source ( your voltage converter ) going to flow current to the 8V source ( the cart battery ) in an attempt to charge it? I don't know if the radio memory is a totally separate circuit from the switched circuit. A feedback like I described would be a lot of current and would most likely fry the radio! I'd hang on for a bit and let someone familiar with radio circuitry pipe in! I'm sure not all radios are the same setup, either, so it would probably help to post up what radio and model you have.

the_freshmaker5

lol, im waiting patiently for someone to pipe in since im hooking it up soon! So based on what you said, im going to analyze it like this. My 48v batteries are getting stepped down to 12v and going "out" to 12v sources such as my radio. The 8 volt source goes out to it too but nothing charges the batteries such as an alternator in a car. I have to plug the cart in to charge it. So im thinking in a normal car situation the 12v based on the ignition and the 12v constant would either total 12v or 24v so in my situation it would total either 12v??? or 20v which would be less. Someone has to have ran into this before though. So i just signed up yesterday on this site and i put an album on my profile with pics of my cart. But i can figure out and was wondering how did you get the pic next to your name and also you have a pic below each post. thanks.

rfquiggle

I beleive it will hold memory on 8 volt. This should not be a problem other wise. IT will either work or it wont. It will not hurt anything.

simple man

I'm not sure how many posts you have to have before you can post pics. Your profile pic ( under your name ) and signature pic ( bottom of post ) have to be really small. All the setup is covered in the control panel ( User CP ) top of the page on the left. I just had to play around and crop my photos for my profile and signature to get the correct size.
As far as the radio installation, in an automotive setting, you have only one source for your input power. No matter what the voltage is ( vehicle off, running and charging, low battery, etc ) both inputs come from one source. There will be no cross current flow. Splitting the two inputs to different sources, I believe will cause problems. I'm also quite interested in finding this out myself! I plan to upgrade my cart from 36V to 48V and I want to use 8V batteries too. We have some very knowledgeable electronics engineers on the board, so I'd wait just a bit more for their input. I hate waiting too, but I'd rather wait than toast something.

DOOmsman

Connect the radio to the 12 volt keyed source then with a
dvometer check the yellow for back fed power, if none hook it up to a battery.

kgsc

I would be leery of doing this. You are assuming the radio just uses the constant wire for memory backup when it could be using it for main power. The switched wire in may be like a remote on for an amplifier. I could be 100% wrong but I think I would be too chicken to try it.

edit: just saw Dooms suggestion. That is a good idea. You may could also put a diode in there to prevent a backwards connection.

Another possibility would be to use a zener diode circuit. It basically is a very simple voltage regulator. Pick up 16 volts from 2 batteries and run through a simple resister and a zener diode to drop it to 12. It would not be enough power for the main but should be fine for memory backup.

Look here www.calculatoredge.com/electronics/zener.htm

the_freshmaker5

I looked up a dvometer and nothing comes up. Do you mean a voltmeter because i know what that is and i have one? Let me make sure i have what you are saying correct as well. My carts 48v to 12v stock converter your saying to hook the + of the radio to the + on that because that is operated by the ignition and that powers the radio with the key on. This is the part i want to be sure of.... From there you want me to go to the back of the radio and take a voltmeter and test the constant wire coming out of it with the radio on. If it reads 0L then im good to hook up to 8v and if it gives me a reading its a bad idea. Also, i have two prongs on my voltmeter so would one go onto the constant from the back of the radio and the other just go to a ground on some metal on my cart? Thanks so much guys!