Wiring 36v golf cart

GotWood

GotWood

Sayer of Fact
Joined
Jan 12, 2007
Location
Maiden, NC
Working on a cart for my father in law. It's a mid 90s ezgo and it works fine but doesn't have a radio or lights.

I've never messed with carts or LED lights so let me know what to buy and not to buy.

From what I think I know I need:
36-12v converter
Fuse block
Stereo/speakers
LED for under body and under roof (color changing)
LED light bar (24"?) for front
LED rear lights/brake
USB/cigarette charger
 
I'd just pull a hot after the second battery from the ground.
 
shawn said:
I'd just pull a hot after the second battery from the ground.
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Radio must have 12v constant. If you hook directly to 2 batteries (6v each) the radio will die each time you mash the gas.
 
shawn said:
I'd just pull a hot after the second battery from the ground.
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That can cause problems if there is any significant amount of power draw. You've got 3 batteries wired in series, and you're discharging that center tapped battery in the string more than the others. If you're also charging in series, the charge current goes through the entire string, and the center tapped battery will not get charged fully compared to the others.

A DC-DC converter is the best option, unless the battery pack has a series/parallel charge monitoring system that can vary charge current across individual cells to compensate for individual cells needing more charge the the others in the string. I'm more familiar with electric cars and don't know if that exists for golf carts. It's very common with lithium batteries, and critical for charging big packs with strings combined in series and parallel.

Size the DC-DC converter carefully, because it it sounds like you may need some significant 12v current for all of that.
 
It it's actually 6 batteries wired in series.
IMG_20170704_100353552.jpg
 
GotWood said:
Radio must have 12v constant. If you hook directly to 2 batteries (6v each) the radio will die each time you mash the gas.
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Except that a 6V battery is 6V nominal, so it's more than 6V when charged, so 2 batteries in series is the same as a 12V battery. A standard 12V automotive battery is 6 smaller cells (2.1V each) internally connected in series to make a 12V nominal battery. Those 6V batteries are 3 cells internally connected in series.

Anyway, the radio is meant for a 12V nominal automotive system, and they're normally rated for operation at voltage range of 9-18VDC (varies slightly depending on brand/model).

You're probably looking a couple of hundred bucks for the DC-DC converter for what you're looking for. Forget about an external amp for that radio, you'll be burning a lot of money to upsize the DC-DC converter with the current involved.
Look for something good quality like a Sevcon or ElCon brand converter, and think carefully about isolation. If you have an isolated converter, you may lose that isolation with something like a radio and speakers that has a chassis-connected ground, etc. Not a big deal, but you may run into problems with ground loops and induced noise at that point, which can cause buzzing, etc., over the radio. You probably don't need an isolated converter, but I don't know enough about golf carts to say one way or another.
 
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GotWood said:
It it's actually 6 batteries wired in series. View attachment 250073
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That's the problem. When those 6 batteries are charged in series, the same amount of current goes through each battery. When you tap off between the 2nd battery and ground (per Shawn's suggestion) to make 12V, you're discharging those first two batteries more than the batteries in the rest of the series string. Then when the battery string is charged with a 36V charger, those first 2 batteries never get charged the same amount as the other 4 batteries because they've been discharged more but get the same amount of charge current as the other batteries.
 
Fabrik8 said:
That's the problem. When those 6 batteries are charged in series, the same amount of current goes through each battery. When you tap off between the 2nd battery and ground (per Shawn's suggestion) to make 12V, you're discharging those first two batteries more than the batteries in the rest of the series string. Then when the battery string is charged with a 36V charger, those first 2 batteries never get charged the same amount as the other 4 batteries because they've been discharged more but get the same amount of charge current as the other batteries.
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It's a car stereo and a 5V USB plug.

On a golf cart.

Who gives a shit?
 
shawn said:
It's a car stereo and a 5V USB plug.

On a golf cart.

Who gives a shit?
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And a light bar, and brake lights, and underbody lights...

I agree with you, but eventually those tapped batteries are going to get less and less charged compared to the other ones. It's better not to knowingly walk into battery charging problems if there is a proper solution. If the batteries are going to be charged individually (or in pairs on a 12V charger) instead of in a series string, that's another workaround.

To your point, it's not my golf cart, and it's not my money. I've outlined the problem with tapping batteries in a series string, and what is done with that information is up to the owner.
 
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Ive done it both ways, DC step down converter and extra battery. IMHO i like the extra battery the best, deep cycle battery on a tender. Will run a radio, light bar, etc for a long while. No stress on the main pack. Fabrik8 is right, the 2 batteries that the accessories draw off of will be weaker than the rest all the time. Just a radio would be fine but when you add the other stuff you will kill those faster.
 
Fabrik8 said:
And a light bar, and brake lights, and underbody lights...

I agree with you, but eventually those tapped batteries are going to get less and less charged compared to the other ones. It's better not to knowingly walk into battery charging problems if there is a proper solution. If the batteries are going to be charged individually (or in pairs on a 12V charger) instead of in a series string, that's another workaround.

To your point, it's not my golf cart, and it's not my money. I've outlined the problem with tapping batteries in a series string, and what is done with that information is up to the owner.
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Your converter costs more than the batteries do.

All the other stuff will take a 40V source. Radio is the only thing that won't.
 
LBZ_Duramax said:
Ive done it both ways, DC step down converter and extra battery. IMHO i like the extra battery the best, deep cycle battery on a tender. Will run a radio, light bar, etc for a long while. No stress on the main pack. Fabrik8 is right, the 2 batteries that the accessories draw off of will be weaker than the rest all the time. Just a radio would be fine but when you add the other stuff you will kill those faster.
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That's a good point, an extra 12V battery charged separately would work well too.
 
Go to the golf cart web sights.....it's simple and they offer a little device made just for external loads, balanced discharge, and balanced charging cycles.

36 Volt Golf Cart Electrical Accessories Installation

Installing electrical accessories into a 36 volt electric powered golf car provides a bit more of a challenge since the battery bank does not provide 12 volts already as in the gas installation above. Luckily, 36 volt systems generally use six deep cycle 6 volt batteries and six is a divisor of twelve. There are two options when attempting to provide a suitable 12VDC power source from a 36 volt battery bank – one is adequate, the other is correct and preferred.

The first option which is adequate, but not preferred, is to use two deep cycle 6 volt batteries in series to provide the 12 VDC. This method will work fairly well if you keep the accessories to a minimum such as just a set of headlights or a horn. However, if you are installing many accessories, this is not the route to pursue, even if you use a different set of two batteries from the battery bank for each accessory. It will eventually present problems and if a particular accessory is left ‘ON’ while the car is in storage or unattended, you may cause permanent damage to those batteries or greatly reduce their life. As in the gas example above, the negative or ground wire is wired directly to the negative battery terminal of the second battery in the series (series of two 6 volt deep cycle batteries). The positive wire runs from the accessory to an ‘ON/OFF’ or actuating switch, through a fuse block or inline fuse and then to the positive battery terminal on the first battery in the series. The negative terminal on the first battery in the series will lead to the positive terminal on the second battery without any additional wiring due to the power wiring circuit of the vehicle.



The second option is to use a voltage reducer to “reduce” the power from the entire 36 volt battery bank to a usable 12VDC. Voltage reducers draw power evenly from the entire battery bank rather than from just a few as in the first method. This method ensures that all batteries are used evenly to prevent the premature death of any single battery. It is also much simpler to wire this option. The voltage reducer is wired to the main negative terminal of the entire battery bank and the main positive terminal of the battery bank. Each accessory is wired to its respective actuation switch through a fuse block and directly into the voltage reducer for the 12VDC power source.

We carry 10 Amp and 25 Amp versions of these voltage reducers. The 10 amp version will power head lights, tail lights, and a horn, but doesn’t leave much amperage for future accessory expansion. The 25 amp version will handle a whole lot more accessories. You will have to research each accessory you are adding to the car in order to determine the amperage draw of each and ensure you buy the correct reducer for the application.
 
I for one prefer the correct way. Really good cart batteries are stupid expensive.
 
$_1.JPG

30 amp job....found on flea bay.
105 bucks still cheaper than 2 cart batteries getting cycled out of balanced and ruined.
 
I know I want to go with the converter as was the first part I listed in my original post.

As for the separate 12v battery, I considered that but this thing needs to be as easy as possible for him to use. 1 plug into the charger, check battery level the first of every month. They only want this to ride around the campground.

I've found 30A converters cheap if it will suffice. I still haven't checked load on the light system and accessories.
 
WARRIORWELDING said:
I for one prefer the correct way. Really good cart batteries are stupid expensive.
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The problem is there isn't a "right" way, there are compromises. One way involves buying questionable electronics from eBay, depending on them to last long-term, just so that you can have a radio on a golf cart. The other way involves just running the radio for free. I'm a fan of free and foolproof.

GotWood said:
I still haven't checked load on the light system and accessories.
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Check the lights. All the ones I have will take a 6-40VDC input.
 
Contact scottyb with any questions you have. He knows golf carts inside and out
 
Sorry Scotty B is the guy that runs carts unlimited. He has helped me a lot over the years with upgrading and repairing my wife's club car.
 
Depending on your current draw, you can potentially save some money and just use a buck converter. Amazon.com: DROK DC Car Power Supply Voltage Regulator Buck Converter 8A/100W 12A Max DC 5-40V to 1.2-36V Step Down Volt Convert Module: Industrial & Scientific

That will run a head unit and a set of speakers well enough to piss off the neighbors, and most decks these days have your USB charger built right in. As was stated earlier, look at your lights. Many of them may be rated to run right off the mains and not require a step-down at all. So all you'd really need to drop it down for would be the head unit. It probably won't be as reliable as a $100 step-down you get from a cart store, but it's also 1/10th the price. If this is just a weekend warrior/neighborhood cart, it might be worth it to try out the cheapo buck converter.

Edit: Quick digging on Amazon revealed very few 36-48v LED bar options. However, they all appear fine on 12-24v. So theoretically, you could wire two LED pods in series so they're both getting 18v. Maybe getting a little complicated, I know, but I'm always looking for the cheap way around things.
 
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How much tail do you think your FIL is going to pull if his stereo quits working because you cheaped out and bought a shitty internet DC voltage converter?

Zero.

Guys without working golf cart stereos get zero trailer park pussy.

Fact.
 
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