Testing Batteries & Charger

We live in a beach community and use the cart mostly to run down to the beach (~1 mile) - going down hill. The cart will make it to the beach and back no problem, but if we want to race around I can probably only go a total of 3 - 5 miles before I need to get home (and going up hill as the battery is lower I can only go 9-10 mph).

My questions are:

  1. What is a typical range on a good battery pack ?
  2. How can I test the condition of my batteries (I am sure they are at least 3 yr old)?
  3. How can I test my charger?
  4. Rather than just swap the batteries $1500+, are there any other options for increased range and reliability?

Thanks in advance!

quick answers based on my experience:

  1. You should be getting 20-30 miles fairly confidently.
  2. You can use a volt meter to test each of the 6 batteries, but you really need a load tester. They’re not too expensive on Amazon. I had 6 batteries test good with a volt meter, but 2 were bad with a load tester. Think of the batteries like steel cups full of milk - a volt meter will show you how full the battery is, sort of looking down into the steel cup and seeing if it’s full of milk or not. (Note, nearly every word of this sentence is incorrect but it’s also useful as an analogy). But, in this case, you can’t tell if the cup is full of sand and there’s just a layer of milk on the top - not much milk. A load tester will stress the battery even if it seems full when charged - very useful.
  3. as above, suggest starting with a volt tester on each battery, and if they are all showing as good then get a load tester and try it.
  4. Not really, if the batteries are bad they’re not things you can fix. But, it may be that you can swap one and that’s all you need - even one bad battery can jack up your power system. Get the Deka Gel batteries if you have to replace them all, or match what you have if you’re only replacing one.

Thanks for the information.

Using the voltmeter, what should each battery be at after a full charge (-13v?) ?

Generally, how long do the batteries last? Is it number of cycles (charges), miles, father time or a combination? Thanks in advance


So I tested the batteries and “fully charged” they all appear to be ~12.6-12.7v.

Try driving the cart a few miles until you’re at <50% and retest with the volt meter. If they’re still testing good, and your mileage sucks, then consider getting a load tester - your auto part store may have one to lend or else they’re pretty cheap on Amazon. If they test good under load (again, drive it to 50% then load test), I’d start to consider a problem with the cluster as maybe charging/measuring electronics in there are showing you bad data. But, most likely would be the batteries.

Very helpful, thank you. Lately, I have been hearing an odd buzz / humming noise (new noise). Sounds like it could be coming from the front of the car, which I believe really only is the charger. Is this a common noise when the charger is going bad?

LOL, the noise I was hearing was the wiper motor :rofl:…I did not notice the switch was on…

There’s quite a bit of information out there, some good, some not so good.

The only batteries that are made for this application id Deka 8G31, and NOT the 8G31-DT (dual terminal). They can be repeatedly be discharged down to 20%, and as long as you don’t wait a long time to recharge them, they typically last 5 - 7 years. Don’t ever let them fully discharge.

I think that 15 - 20 miles of range is what you should expect. This depends on the motor, controller, battery pack, age condition, tire pressure, tire rubber and size, 2 seater, 4-seater, or pickup truck model, number of passengers, type and flatness of driving terrain and surfaces, speed, controller programming, and environmental conditions.

Ford’s Service Manual echoes the view of the battery industry that if you have a battery fail after 30 days, you must replace the pack as a whole. Testing batteries is good, but load testers don’t do a good job. The battery to be tested must be fully charged, and you only get 1 shot at testing… you need to recharge the battery again before retesting to get a meaningful reading. Conductance charging is what I use, but they are not inexpensive. A simpler and less expensive way to test the batteries is as follows:

1)Make sure your batteries are fresh from being charged. Just because the charger has been plugged in for hours (or days) does not mean they are. Ford chargers are NOT trickle chargers, and trickel chargers don’t fully and properly charge the batteries; they are for preventing the batteries from fully discharging over a period of (unattended) time.
2) Draw a quick diagram of their layout.
3) Hook up a digital multimeter to 1 battery at a time. Write down that voltage
4) Block the wheels securely, turn on the key, and gently step on the accelerator pedal… NOT too hard as it stresses the drivetrain and axles.
5) Write down what the voltage drops to, with the same amount of pedal depressing. You’ll need to repeat this for the other 5 batteries, so take note of how far you’re depressing the pedal, so as to repeat it when testing the other5 batteries.
6) Repeat for the other batteries, writing the before test voltage, and what it drops to.

It’s usually 1 battery that will be weaker than the others.

‘Matching’ a battery is pretty much impossible, You can get load tester readings, conductance readings, but what prevents an accurate interpretation isn’t possible, as NO tester can tell you the number of charge cycles, discharge cycle, depth of discharge of each cycle, interval between charging events, and differences in the manufacturing cycle.

If you replace 1 weak battery with a new one, the 0ther 5 batteries are weaker (lower capacity) so they will take the charge and be overcharged before the new battery gets fully charged. Same thibng when discharging. Think of the 5 older weaker batteries as being like a small motorcycle battery versus the new one being the bigger new battery, and you can see why the weaker batteries would be overcharged and the betteer battery would be prevented from being full charged.

AGM (Absorbed Glass Mat) and flooded batteries are mnot made to be discharged to less than 50%, or thet suffer a little bit of damage each time. I’ve sold / deliver more than 2800 Deka 8G31’s and my experience with all of the brands of AGM batteries id that they work amazing well when first installed, but all six fail completely in 6 - 9 months.

I have more information, but need to get back on clusters and xhargers.

Scott Taylor
Electrons In Motion LLC

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Super helpful Scott! Thank you