Brand new batteries dying while just sitting

[gc7305]

Hi All,

I have a 1986 Electric Ezgo Marathon and I cannot figure out why the batteries will lose charge while just sitting there. The batteries are brand new and I have new wires to connect all the batteries. I am replacing all the connections but was hoping to get some answers on what might be wrong. Thanks for any and all help

[Swan]

batteries will drop voltage over time , how long of a time and how much voltage drop are you seeing ?

[ThreeCW]

Welcome to BGW!

All batteries naturally self-discharge during storage.

Note also that new batteries are not necessary at a full state of charge when you get them. Before use, all new batteries should be given a full charge cycle.

Accelerated self discharge can occur for the following reasons:
1) Parasite loads if the batteries are connected
2) Batteries self-discharge faster in high temperatures
3) Batteries should be stored and installed in a clean, cool and dry place, keeping water, oil, and dirt away from the batteries. If any of these materials are allowed to accumulate on the batteries, tracking and voltage leakage can occur, resulting in self-discharge and possible short-circuits.
4) Impurities in the water used in batteries (should always refill with distilled water)

What make and model of batteries do you have?

What indications are you seeing that the batteries have self-discharged?

Note - The above information was taken from the Trojan User Guide ... attached for your reference. This is a good guide to read (cover to cover) no matter what make of batteries you have.

[gc7305]

I have an 86 EZGO 36v. I am seeing my gauge drop every time I hit the gas pedal. Also, the gauge will drop power when just sitting right after a charge.

[gc7305]

I am seeing the voltage drop immediate from the start. It can say full charge and then jumps right to half charge. I have made sure all the wiring is done correctly and the thing flys when it goes for the first few minutes. After about 5-10 minutes you can feel the GC slowing down. The batteries are a week old.

[ThreeCW]

I'll start out by saying what many on BGW have already experienced ... those indicator light battery gauges are notoriously inaccurate ... almost useless in some cases.

The state of charge of a battery or battery pack is most accurately determined by using a hydrometer or a refractometer to determine the density of the acid in each cell of the battery. Although highly accurate, it is not a practical method to do a quick check or when driving down the road.

The voltage of the battery can also be use to "estimate" the state of charge of a battery. To determine the battery state of charge, the battery voltage should be stabilized prior to measuring the voltage. Stabilization can take 12 to 24 hours after disconnecting the charger or up to 30 minutes after being used. A battery can be considered stabilized if the battery voltage does not change with 3 successive readings spaced 5 minutes apart. The stabilized voltage is looked up in a chart to determine the state of charge (see attached).

Many members here have gone to digital battery voltage display gauges to replace their indicator light battery gauge. Here is a good source of gauges from a site sponsor: https://www.cartsunlimited.net/battery-meters.html

Originally Posted by gc7305

I have an 86 EZGO 36v. I am seeing my gauge drop every time I hit the gas pedal. Also, the gauge will drop power when just sitting right after a charge.

It is the nature of a battery to drop voltage when current is taken out of the battery ... so every time your "hit the gas pedal" (let's call it an accelerator pedal in an electric cart), yes, the voltage will drop.

It is also the nature of a battery for the voltage to drop after disconnecting the charger. The finish charge of a 48 volt pack is about 65 volts. When the charger turns off, the battery voltage will drop fairly quickly from the 65 volts to about 55 volts. It will continue to drop slowly over time (12 to 24 hours) until it stabilize at the fully charged 48 volt pack voltage of approximately 50.9 volts ... which is the 100% state of charge value. Different brands of batteries and different models may have slightly different fully charged voltage readings. My pack for instance stabilizes at about 52.0 volts.

Originally Posted by gc7305

I am seeing the voltage drop immediate from the start. It can say full charge and then jumps right to half charge. I have made sure all the wiring is done correctly and the thing flys when it goes for the first few minutes. After about 5-10 minutes you can feel the GC slowing down. The batteries are a week old.

As discussed above, the indicator light gauges are very inaccurate ... don't believe what they telling you.

You say "the thing flies" for the first few minutes. If that is right after charging, you "might" get some extra from the elevated charging voltage. On the other hand, driving your cart with the "pedal to the metal" is not the correct way to break in your new battery pack. A nice slow break in will give you a longer life with your battery pack.

You mention the cart slowing down after 5-10 minutes. You will want to measure the stabilized voltage of your battery pack after charging to determine the state of charge to ensure that your battery pack is being fully charged (i.e. you want to ensure that your charger is charging correctly).

Here is some good information to read on breaking your new battery pack:
https://www.cartsunlimited.net/battery-break-in-.html

I read an interesting quote the other day: "As someone in the industry once put it, few batteries die a natural death, most are murdered." That being said, following a proper break in process, regular charging and good maintenance, your new battery pack can live long and prosper.

[scottyb]

Fyi - If it hasn't been mentioned chargers take the battery pack way above the nominal voltage and then if you let the pack set it will settle down to what it can hold... and that number is significant in terms of a % of total capacity seen on the chart posted above.

[Cobra,1]

Assuming you are useing a golf cart battery charger.
What is the battery voltage after cart is charged , and voltage after charge but cart has not been used for 12 hours.
Measure with multi meter, not golf cart factory volt/level meter.
Batteries getting charge everyday after use?
What is each batteries voltage after charge?
Are batteries all the same brand and age?
Few things to check to have forum better help 😊