1993 EZGO XT 500 Workhorse

[JohnnieB]

In general terms, it is best not to load a Deep-Cycle Lead-Acid Wet-Cell battery below 1.75 VPC (Volts Per Cell) and bad things may start happening when they are loaded beyond 1.50 VPC

Your 36V battery pack has 18 cells and the voltage sag under load was down to 34.8V, or 1.93 VPC, so they were doing okay.

I'd try the keep the voltage under load above 31.5V (1.75 VPC)for a 36V pack and never go below 27.0V (1.5 VPC), except in dire emergencies and even then, only for the absolute minimum length of time.

How much the pack voltage sags under load depends on how many amps are being drawn from it and the batteries' storage capacity, as well as the State of Charge at the time and the ambient temperature, plus some other factors.

When a battery discharges, the electrolyte in intimate contact with the plates is depleted and in order for more electrons to be produced, fresh electrolyte must get in contact with the plates. If the migration of the fresh electrolyte to the plates is less than the demand, a resistive barrier is formed and the output voltage from the cell is lowered by the voltage dropped across that barrier.

This is called stratification and it occurs whenever a battery is discharged. The heavier the discharge, the greater the stratification of the electrolyte.

When you stop your cart, you'll notice the battery voltage climb on the meter. That is from the depleted and fresh electrolyte mixing and forming a new concentration that has an overall lower Specific Gravity that it had before the discharge.

--------------
Stratification, and some other stuff, occur during charge as well as discharge, so to measure a battery's State of charge, you have to let the batteries rest a while before measuring their voltage to get meaningful State of Charge voltage reads.

The attached Voltage vs State of Charge chart is based on a 12 hour rest after charge and about a 15 minute rest after being used.

[cowboysclassics]

Originally Posted by JohnnieB

In general terms, it is best not to load a Deep-Cycle Lead-Acid Wet-Cell battery below 1.75 VPC (Volts Per Cell) and bad things may start happening when they are loaded beyond 1.50 VPC

Your 36V battery pack has 18 cells and the voltage sag under load was down to 34.8V, or 1.93 VPC, so they were doing okay.

I'd try the keep the voltage under load above 31.5V (1.75 VPC)for a 36V pack and never go below 27.0V (1.5 VPC), except in dire emergencies and even then, only for the absolute minimum length of time.

How much the pack voltage sags under load depends on how many amps are being drawn from it and the batteries' storage capacity, as well as the State of Charge at the time and the ambient temperature, plus some other factors.

When a battery discharges, the electrolyte in intimate contact with the plates is depleted and in order for more electrons to be produced, fresh electrolyte must get in contact with the plates. If the migration of the fresh electrolyte to the plates is less than the demand, a resistive barrier is formed and the output voltage from the cell is lowered by the voltage dropped across that barrier.

This is called stratification and it occurs whenever a battery is discharged. The heavier the discharge, the greater the stratification of the electrolyte.

When you stop your cart, you'll notice the battery voltage climb on the meter. That is from the depleted and fresh electrolyte mixing and forming a new concentration that has an overall lower Specific Gravity that it had before the discharge.

--------------
Stratification, and some other stuff, occur during charge as well as discharge, so to measure a battery's State of charge, you have to let the batteries rest a while before measuring their voltage to get meaningful State of Charge voltage reads.

The attached Voltage vs State of Charge chart is based on a 12 hour rest after charge and about a 15 minute rest after being used.

That is some great information JohnnieB, thank you for taking the time.

I have read so many posts about how batterys might have a short life due to how they were abused or not maintained properly by the previous owner. As bad as shape as the cables, connections and 2 of the 2 year old batterys I was afraid they might have been to far gone, but it is starting to sound like I might have gotten lucky with the 4 older ones.

[JohnnieB]

You might have gotten lucky.

One thing to remember, the two new batteries will quickly age and become about the same effective age as the old batteries, so when you replace the pack, you have to replace all six.

[cowboysclassics]

Originally Posted by JohnnieB

You might have gotten lucky.

One thing to remember, the two new batteries will quickly age and become about the same effective age as the old batteries, so when you replace the pack, you have to replace all six.

Well you could have went all day without saying that.

The part that really sucks is the reason I replaced the two other batterys, The posts that the cable connected to had came loose and the previous owner put JBweld on the terminals thinking it would make the connection tight.

No doubt he was wrong, and I noticed the first time I put the charger on it, the connections were smoking and the cables were getting real hot. After I removed them, I tested both batterys and they were fine after I charged them up, just the posts were fried making them useless to me.

[pggroves]

Originally Posted by cowboysclassics

Well you could have went all day without saying that.

The part that really sucks is the reason I replaced the two other batterys, The posts that the cable connected to had came loose and the previous owner put JBweld on the terminals thinking it would make the connection tight.

No doubt he was wrong, and I noticed the first time I put the charger on it, the connections were smoking and the cables were getting real hot. After I removed them, I tested both batterys and they were fine after I charged them up, just the posts were fried making them useless to me.

Not tyring to make ur day any worse...but did you know about this little trick?

http://www.buggiesgonewild.com/batte...nal-repair.php

You can also just drill a hole and use a 5/16" dia. ss hanger bolt and just screw that in. Do a search on terminal melted, or terminal repair. Lots of reading...

[cowboysclassics]

Originally Posted by pggroves

Not tyring to make ur day any worse...but did you know about this little trick?

http://www.buggiesgonewild.com/batte...nal-repair.php

You can also just drill a hole and use a 5/16" dia. ss hanger bolt and just screw that in. Do a search on terminal melted, or terminal repair. Lots of reading...

No Sir, I sure didn't know about or had even seen that thread, thank you for posting the link.

I did think about trying something like that if the terminal wouldnt have sunk down into the top of the case as bad as it did, but my wife said she would feel better about it if I just bought 2 new batterys. That was the end of that discussion.

[cowboysclassics]

Just posting some reference pics per members request.

[Slamminsam]

That bed is in great shape compared to mine. i had to have new sides made and made my own 1/4" treadplate aluminum floor.