Battery Question

pearmanbryan

I just got a 1989 E-Z-GO 36V. First golf cart I've ever owned. I hadn't installed a dash volt gauge yet. I'm wanting to get the batteries back up to par before I start using this cart full time. The guy I got it from said the batteries were about 2 years old. I checked the batteries with a analog ohmmeter. One reads at 20V and other 5 read around 30V. Should I run the cart until the batteries are dead then do a full charge on the whole system? Or should I unhook the batteries and charge each one individual then hook them back up?

BGW

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JohnnieB

Welcome to BGW.

DO NOT run your cart until the batteries are dead.
In fact, never discharge your cart batteries more than 50%.
Flooded Lead-Acid cells have no memory and do not need to be deeply discharged before recharging.
For maximum battery life expectancy, you want to keep the average State of Charge as high as possible or practical.
Attached is a SoC chart.

An analog voltmeter is not suitable for measuring battery voltage and troubleshooting Golf Carts.
A inexpensive DMM (Digital Multimeter) obtainable from *-Mart, Radio Shack, or your local auto parts store will suffice.
Individual batteries are typically measured to the nearest Hundredth of a Volt (0.01V) and total pack voltage to the nearest Tenth (0.1V).


Did you get a 36V charger with your cart? If not you need to get one because charging ought to be done daily if cart is used daily and charging them individually or in pairs will quickly get tiresome.

No, you don't need to disconnect the batteries to charge them individually or in pairs. Just connect the charger leads across one battery if it is a 6V charger and two batteries if it is 12V.

Attached Images

batterytable1118242f71.jpg (43.1 KB, 25 views)

pearmanbryan

Yes I did get a charger with it. My daughter was riding it around the yard for about 20 min. and I had to push her back to garage because it didn't have enough power to move. Just plugged in charger, went to 30 then after a couple of minutes it's down to 20.

Also, I already have a set of 25" tires and rims I want to put on it. I'm going to build a 8" lift kit for it too. I don't have the $ to upgrade motor or anything right now but I am going to go ahead and upgrade the cables now. 4ga or 2ga? Will those batteries work for that set up? 25" tires and bigger cables?

simple man

You will have to do serious upgrades to run 25" tires! I would concentrate on electrical upgrades first. If your cart is a resistor cart, you will have to do even more upgrading. Some of our sponsors will be on in a bit and can help with the costs of the various upgrades. In answer to the cable question, yes, this should be the first upgrade no matter what kind of cart you have! I would go to 2ga cables to start. You'll need them in the long run.

JohnnieB

1. 30A dropping down to 20A in a couple minutes, that sounds about right. The charging Amps should continue to drop down to about 5-8 within a half hour or so, but with the batteries being that low, it'll probable charge 8-10 hours (or more).
Which 36V charger do you have? Hopefully it is an automatic type.

2. Which type of Marathon do you have. Resistor or Controller?
Plug your serial number in here and it should tell you.
http://www.shopezgo.com/customer-ser...ialNumber.html

Unless you are going to be installing controller over 500A, 4Ga will probably be okay, but I'm old school and think bigger is better.
Be sure to replace ALL the high current cables. I'm guessing, but I think you cart will have 13 or 14 of them.

I recommend upgrading the F/R switch when you replace cables. If the stationary contacts are in good shape, you might get away with just putting in a Heavy Duty Cam.
http://www.cartsunlimited.net/F_R_Switch_Upgrades.html
Scroll down to bottom of page for HD Cam info.

After the batteries have fully charged (Charger automatically shuts off) let them rest at least 6 hours (12-24 preferably) and measure voltages.
The two year old batteries might be okay, or they might be trash. It depends on how they were treated and maintained in those two years.

Those 25" tires are going to put a lot of stress on the drive system, so be aware that the rest of the stock components (Solenoid, controller and motor) won't take it forever.


Here's the SOC Chart I forgot to attach top my earlier post.

Attached Images

StateofChargeChart.jpg (53.8 KB, 12 views)

pearmanbryan

Serial # 541156. I put that in and all it said was 1989 Electric Marathon. Not sure if it's a Resistor or Controller. I'm new to this "electric" golf cart thing.

It's a "Lester Electrical" Model 8714

It's been on charge like 4 hrs now and down to 10.

I think the guy said that had been replaced. If it was, it was replaced with stock.

Also, how do I put a "signature" on my post?

JohnnieB

1. Does it look like the attached picture under the seat?
If so, you've got a "Resistor" cart. The resistors are coils of wire in the box with 4 heavy wires attached in center of picture.
If not describe what you see or post picture.

2. A Lester 8714 is a manual charger. You set the timer for how long it stays on.
It charges batteries okay, but you have to monitor the battery voltage while on-charge or you will be undercharging or overcharging them.
A dash mounted DVM type battery meter would be handy for this.

3. Only down to 10A after 4 hours of charging is a bit high, but the batteries were dead, so it might be okay.
Check the electrolyte level and make sure the plates are not expose to air. If so add just enough distilled water to cover them.
Electrolyte level should only be brought to full height when batteries are fully charged, use only distilled water.

Check the voltage, they should stay on charge until pack voltage reaches 44V to 46V. (Yes, that is the correct on-charge voltage termination point for a 36V battery pack)
Be sure to read correct scale if you use your analog voltmeter. The voltage you stated in your first post must have been read off the wrong scale.

4. A stock F/R switch won't last long with good cables and good batteries and 25" tires. Either be proactive or reactive, your choice.

5. Scroll up to the top of the page you are on now, find the second menu bar down and click on "User CP". You can edit your signature under "Settings & Options"

Let us know what the battery voltages are after resting.

Attached Images

Kernal's marathon battery comp.JPG (171.3 KB, 20 views)

Davemuzz

JohnnieB,

I've read a couple of post where you have mentioned not to discharge a cart's batteries below 50%.

Well, I have to ask this....as I have a 48-V EZ-GO that is modified for hunting, (a TXT) and usually when I go out for a day it's quite often that I will run the cart down below the 50% charge as indicated on the "fuel meter" bar. There have been only a few times where I have barely made it back to the truck\trailer as I am pretty cautious about that.

However, I am running 8-v excide batteries and I am on my fourth year with these. I do plan on upgrading this summer to 8 6-V Trojan's.....but I guess I am saying that for me, the discharge below 50% hasn't seem to harmed the life of my Excide's.

Dave

Coltf1991

Dave, start a new thread and post your readings on charge, right after charge then 8-12 hours after charge. (in the words of Scottyb "unmolested")

Then we can tell you if you are getting full potential of your batteries

JohnnieB

Good observation and question.

When a battery discharges, the Sulfuric Acid (H2SO4) electrolyte combines with the Lead (Pb) negative plate and Lead Oxide (PbO2) to form Lead Sulfate (PbSO4) and Water (H2O) plus a few electrons are released.
When batteries are recharged, electrons are added to the Lead Sulfate, which converts back to Lead and Lead Oxide and releases Sulfur Ions that combine with water to form Sulfuric Acid.
Only problem is that the process isn't 100% reversible, not all Lead Sulfate converts back to its original form and Lead Sulfate on the plates is what kills batteries.

The less a battery is discharged the better the reversible/irreversible ratio is.
Irreversible sulfation actually begins the moment discharge begins and is relatively insignificant down to around 70% SoC, but becomes relatively significant around 50% SoC.

Picture a battery as a bucket full of marbles, each marble is a recharge cycle and when the bucket is empty, your batteries are unusable. If you play nine holes of golf before recharging, only one marble is taken out of the bucket, but if you play eighteen holes, three marbles are taken out instead of two. At 50% and lower, you're removing marbles by the handful.

Will discharging your batteries blow 50% SoC kill them instantly? No, probably not, but doing it routinely it will definitely shorten their life expectancy.

Here is a chart showing average Soc vs life expectancy. The original chart was from Trojan, but was in % discharge instead of %Soc like we are used to using, so I flipped it and added some voltages.

You got over 4 years out of your 8V batteries, so you take good care of your batteries. However, with 8 x 6V you won't be discharging them quite as deeply due to the longer run time, so they'll last longer than the 6 X 8V set did, unless you start going further afield with them.

Attached Images

SoC vs Theoretical Charge cycles with Voltages.JPG (119.3 KB, 15 views)