Alltrax DCX 400 Settings

[JohnnieB]

Originally Posted by chasenfish16

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Please answer a question for me Jonhnie in your last statement batteries should not be loaded down routinely lower then 5.25 volts. that shows up to me as 10% on the state of charge sheet. I keep reading that i should not discharge my batteries below 50% please clarify this for me. I am just trying to learn how to get the most out of my batteries but not kill my run time.

State of Charge voltage and Battery loading voltage are two different subjects.

The battery's open circuit terminal voltage At-Rest, tells you what percent of the battery's Amp-Hour capacity is in the battery.
When a battery is charged, it acquires a "Surface Charge", whose elevated voltage does not accurately reflect the battery's State of Charge, so the batteries have to "Rest" for a number of hours for the surface charge to deplete.
The voltages on the State of Charge charts are taken after the batteries have sit for about 12 hours without being charged or discharged (Resting)

The opposite of a surface charge occurs when batteries are used (discharged), however it only take a few minutes for the terminal voltage to recover after being discharged. 5-15 minutes is usually long enough.

To get an accurate voltage reading to determine the battery's State of Charge, you have to wait several hours after they have been charged, or several minutes after the have been used.

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There are a ton of variables, but in general terms the battery's voltage drops when it is being discharged. The higher the discharge rate (more amps being taken out), the more the voltage drops.

How far a battery's voltage drops when 100A is being drawn from it (or any other number of Amps) depends on the battery's Amp-Hour capacity, so the voltage of a 260AH battery does not drop as low when 100A is being drawn from it, as the voltage of a 180AH battery with 100A being drawn from it.

The battery's age as well as its State of Charge also influence how far the voltage drops.

Once the load is removed, (amps no longer being drawn from it) the voltage returns to the voltage that reflects the battery's State of Charge (as previously mentioned, this may take up to 15 minutes.)

This is normal operation for batteries and no harm is done as long as you stay above 1.75VPC.
Some minor damage may occur if the Under-Load voltage goes below 1.75VPC. (Possible shortening of lifespan, but probably not immediate failure.)
Major damage will occur if the batteries are taken below 1.5V under load.
(Definite shortening of the lifespan and may fail immediately - The surface of plates are literally being torn off)

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I'm speculating, but with new 232AH batteries, a 400A controller and 22" tires and 600 pounds of people on-board, you might see as much as a 4 or 5 volt drop on a steep incline.

The best way to protect those new batteries is install a digital voltmeter type battery meter and keep an eye on it while going up hills. If the voltage starts dropping below about 32V, just lift your foot off the throttle pedal a bit.

[chasenfish16]

So if I buy a digital voltmeter type battery meter what is a good voltage to consder while driving to be around the 50% mark seeing that you have to wait 5-15 minutes for the state of charge to be acurate. In the past I just drove the cart to the last segment on the stock meter.

[JohnnieB]

Originally Posted by chasenfish16

So if I buy a digital voltmeter type battery meter what is a good voltage to consder while driving to be around the 50% mark seeing that you have to wait 5-15 minutes for the state of charge to be acurate. In the past I just drove the cart to the last segment on the stock meter.

That is a gray area because you are reading the battery voltage under load while driving and you need the at-rest voltage to determine the State of Charge. But, you can make a ballpark estimate if you figure out how much your battery pack voltage drops while cruising on level ground and add that amount to the reading you get while cruising on near level ground.

Every cart and battery pack is different, so the number I use won't be valid for you cart set-up and battery pack. To find out what your number is Drive one level ground and note the battery voltage. Stop and wait 15 minutes (or until the battery meter stops rising) and note the voltage. The number is the difference between the two.

BTW - If you don't want to discharge below 50%, 37.3V (75% SoC) is the all the lower you want to get on the outbound leg. Of course, if the in-bound and out-bound legs aren't equal in distance, adjust the turn around voltage accordingly.

[chasenfish16]

JohnnieB

Thanks again for all the great info.