EZ-GO Golf Cart Battery Died in About an Hour

Originally Posted by jlabs

They are 3 12 Volt Trojan batteries.

Originally Posted by JohnnieB

For starters, an RXV has a 48V battery pack, which means it would have four 12V batteries instead of the three you mentioned.

please confirm you have 3 or 4 12v batteries
if you are running 3x12v (36v)batteries in a 48v cart its not going to go very far
or you have the wrong cart info
use this link to see what cart you have ---> http://www.shopezgo.com/customer-ser...ialNumber.html

[yurtle]

48 volts is easy:
51 - 100%
50.5 - 90%
50 - 80%
49.5 - 70%
49 - 60%
48.5 - 50%

I took a little liberty with rounding, but if you remember 51 volts is 100%, you lose 10% for every .5 volt drop from there.

[rib33024]

You should never run a 48 volt pack below 48 volts

Originally Posted by eflyguy

.. and you need to note the pack voltage at-rest, after you stop. I put a small label under my volt-meter that says DO NOT OPERATE BELOW 42V, so my wife and daughter won't damage the batteries.
..a

[Sir Nuke]

Originally Posted by rib33024

You should never run a 48 volt pack below 48 volts

RIB......he wasn't talking about the AT REST voltage.....but the voltage displayed on the meter ON THE FLY......this came from another thread he was talking about the sticker.....but it doesn't sound right, when taken out of context of the original thread.

[rib33024]

I didn't want some members to read this a while down the road and think 42 volt was ok

[Sir Nuke]

Originally Posted by rib33024

I didn't want some members to read this a while down the road and think 42 volt was ok

you're right ........ point well taken

[JohnnieB]

Originally Posted by jlabs

1. How would I know if I actually discharged the battereis below 50% while on the road?
2. As in inaccurate, do you mean that it's actually higher, or do you mean it's lower then the exact?
3. Do you think one time incident of "E" will be fine if I manage my batteries well?

1. The battery pack's voltage fluctuates while driving, so you have to stop and let the batteries stabilize before you can determine their SoC. It takes an hour or more for the battery chemistry to reach an equilibrium after being used, but a voltage reading take five to ten minutes after stopping is sufficient for a reasonable accurate estimate of the SoC.

There are three different sets of battery voltages that exist and each has meaning, but you have to be aware of which voltage set you are measuring to understand what it means.

A. On-Charge Voltage: This voltage set only exists while the battery is actively being charged.
B. Under-Load Voltage: This voltage set only exists while the battery is actively being discharged.
C. At-Rest Voltage: This voltage set only exists when the battery chemistry is evenly distributed throughout the cell and that occurs about 12 hours after the battery has been on charge or about an hour after the battery has been used. This is the only one of the three that will provide a good estimate of the SoC.

While driving the cart, you are measuring the Under-Load voltage. The more Amps being drawn from the battery, the lower this voltage will be.
You do not want the pack voltage to routinely drop below 1.75 VPC (Volts per Cell), which is 42.0V for a 48V pack and you never what to drop it below 1.5VPC (36.0V for a 48V pack) or irreversible physical damage may occur inside the battery cells.

2. I mean it's accuracy and repeatability is unknown. It might read high, it might read low or it might be spot on, and it may change how it reads the next time it is used.

Your specific meter may be accurate and repeatable, but until those attributes are verified with a DVM, it is an unknown.

3. That is also an unknown since what the voltage is when the "E" comes on isn't known.

However, Lead-Acid Wet-Cell Deep-Cycle batteries are very forgiving, so all that probably happened was that the remaining useful lifespan was shortened a little.

[yurtle]

Not sure I'm adding value to this thread. Just food for thought.

Non digital volt meters may do a lot of averaging, to avoid some of the normal fluctuations, which might just confuse the average golfer. Car gas gauges are subject to acceleration and hard cornering, where gasoline sloshes around, but quickly correct for that. I'm bettin' a "bargraph" LED type SOC meter buffers a lot, unlike an analog SOC meter, which does no averaging. A digital readout type SOC meter is the best, once you get used to the changes due to driving conditions.

I often see buggies on our lake trail that are sittin' on empty, where the driver gave up and walked home. They are hurting their battery pack.

Originally Posted by JohnnieB

Lead-Acid Wet-Cell Deep-Cycle batteries are very forgiving, so all that probably happened was that the remaining useful lifespan was shortened a little.

Forgiving in that you might be able to drive home. Given the cost of new batteries, "forgiving" is a relative term. Due to the fact that lead-acid batteries "recover" when rested, you may be able to drive home, once it leaves you stranded, if you just wait. Car battery folks are familiar with this, in that when your car refuses to start, you simply wait a little while, then try again.

[sportcoupe]

Originally Posted by crash test dummy

please confirm you have 3 or 4 12v batteries
if you are running 3x12v (36v)batteries in a 48v cart its not going to go very far
or you have the wrong cart info
use this link to see what cart you have ---> http://www.shopezgo.com/customer-ser...ialNumber.html

He said it's an rxv and runs 20 mph. Can't do that if he only had 3 12v batts at 36v. Must be 48v.

[JohnnieB]

Good Grief, I missed the second page.

Like I said in my last post, you have to know what voltage you are reading.

The At-Rest voltage is a static voltage and is read when cart is stopped.
It is used to estimate SoC, and the SoC should not be allowed to drop below 50% before recharging. If you do, the battery's useful lifespan will be reduced.

Batteries are named for their approximate voltage based on how many 2V cells they contain. Only problem is that "2V" cells have about 6% more than 2V and when you place several in series, the battery voltage exceeds the named voltage by a significant amount.

Fortunately, 2.000V just happens to be pretty close to 50% SoC for a 2V cell and whatever the named voltage for a pack is (IE: 36V, 42V, 48V etc) is also about 50% SoC, and an easy number to remember.

On the other hand, the voltage measured while the cart is moving (Under-Load) is dynamic and fluctuates as driving conditions makes the motor draw more amps or fewer amps. This voltage will drop below the named voltage of the battery, but recovers quickly when the load is lessened or removed.

The more the battery is discharged, the greater the voltage drop per Amp drawn, so it is easier to drop the voltage too low on the return leg of a trip than it is on the outbound leg.

When doing non-destructive testing, batteries manufacturers only take their products to 1.75VPC under load, so that should be a safe voltage to stay above.

When the batteries are taken below 1.50VPC, bad things happen. Things like active material being sucked off the plates and becoming conductive sludge at the bottom of the jug, if it doesn't short between the closely spaced plates on the way to the bottom.

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Hope this clarifies rather than confuses.