50v=60%?????

[deerhunter88]

Does this sound about right?

Thie evening i unplugged the charger(showing complete and on float stage at 52V).I went ride for maybe 3 miles and the SOC meter was showing one bar over 50%. When i get home i put the volt meter on the pack and it read 50.4V. After looking at the charts im thinking this is wrong but are these SOC bar graphs that far off?

[scottyb]

Yes. That is exactly what I was going through a couple of years ago. That is exactly why I searched out a good digital unit. Not only are the bars dropping off at milestone markers (one = time to recharge, 2 bars down = you will be pushing soon) but to add insult to injury they reset each time the charger turns off or the power is cut and that reset voltage is your new full.
So today's full mark can be different than yesterdays full mark

[mauimark]

The problem is not the meter, the problem is that voltage in lead acid batteries is a very rough aproximation of remaining power subject to many variables.

Unconveniently, the only true way to get an accurate reading on these type of batteries is with specific gravity of the electrolyte. Obviously voltage is a lot ,ore user-friendly, but if you want to be more accurate, you are better off with a numerical voltage meter combined with your own personal experience with your own cart, the numbers you read depending on load and state of life of your batteries can give you a fairly good indication.

[scottyb]

Originally Posted by mauimark

The problem is not the meter, the problem is that voltage in lead acid batteries is a very rough aproximation of remaining power subject to many variables.

Unconveniently, the only true way to get an accurate reading on these type of batteries is with specific gravity of the electrolyte. Obviously voltage is a lot ,ore user-friendly, but if you want to be more accurate, you are better off with a numerical voltage meter combined with your own personal experience with your own cart, the numbers you read depending on load and state of life of your batteries can give you a fairly good indication.

Or you can stop and pull out your refractometer, paper towels, and rubber gloves .

[JohnnieB]

Originally Posted by mauimark

The problem is not the meter, the problem is that voltage in lead acid batteries is a very rough aproximation of remaining power subject to many variables.....................

Deerhunter88's problem is the meter.

In general terms, the LED Bar Graph SoC meters are notoriously inaccurate, but not because they cannot measure voltage accurately.
The issue is that some, but not all, of them reset the 100% point when they are turned on and/or the battery is recharged.
An analogy would be having the fuel gauge on your car resetting to "Full" every time you started your car, without regard to how much fuel was actually in the tank.

The old analog type SoC meters may be low tech, but they are consistent.
The DVM type SoC meters are accurate and consistent, but the battery voltage fluctuates considerably while in use, so they take some getting used to.

As for measuring the energy remaining in a lead-acid battery, the only way to determine how much energy was in a battery is to measure what comes out as you drain it.
Fortunately, when done properly, both open circuit voltage and Specific Gravity will tell you the State of Charge fairly accurately.
However, neither will tell you how much energy is remains in the cells since they are both indicators of the State of Charge, rather than energy stored.