48V battery monitor for a golf cart

I'm looking to get a battery monitor meter for our 48V Club Car golf cart at camp (to know how much charge the batteries have).
I've checked Amazon, and they have a ton of them. Trouble is, the reviews seem to be about 50/50 for most all of them.
Seems like a lot of them wont work with specific batteries, so it makes me hesitant on getting one that doesn't say if it does or doesn't work with all batteries.

Sooo.... does anyone here have any recommendations or suggestions on what I should get?
I'd like to stick with Amazon 'cause I have a $100 service award coming to me from work and it has to be something from there.

So as an electrical engineer, it's not easy to tell how full a battery is. You must know what chemistry the battery is, it's charge and discharge cycle, etc. The voltage isn't linear with like a gas tank. If the gas tank is 1/2 empty, the wiper on the sending unit is 1/2 way. For a battery, the voltage will only change a few volts from full to empty. Also, if you have multiple batteries inline (4 12V batteries?), you'll need to monitor each individual battery. I'm guessing these factors add the hit or miss factor of reviews.

https://www.golfnreview.com/top-5-be...for-sale-2017/

These are 36V meters but I'm sure they have 48V versions.

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Originally Posted by jslavic

So as an electrical engineer, it's not easy to tell how full a battery is. You must know what chemistry the battery is, it's charge and discharge cycle, etc. The voltage isn't linear with like a gas tank. If the gas tank is 1/2 empty, the wiper on the sending unit is 1/2 way. For a battery, the voltage will only change a few volts from full to empty. Also, if you have multiple batteries inline (4 12V batteries?), you'll need to monitor each individual battery. I'm guessing these factors add the hit or miss factor of reviews.

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I understand about voltage not dropping like a gas gauge would. Like when a AA battery is 1.5V but at 1.2 volts the device (such as a flashlight) is visibly dimmer.
It's not really voltage I want to monitor, but amount of charge remaining. Is there a difference in monitoring that compared to voltage?

You would have to program the battery's (each battery's) capacity into a smart system and monitor the discharge. This is the only true way to know what's left in them.
Using the voltage and a pre-determined discharge rate will give you a somewhat accurate measurement.
Systems can get pretty complex if you are trying to squeeze every electron out of the batteries. We do some crazy stuff in our hand held devices at work as runtime vs cost is a huge selling factor.
For a golf cart though, the voltage meters should work for what you want.