RXV with 6 Trojan Batteries Rundown Quick

[wingnut2000]

would it be stupid to replace one or two batteries?

[wingnut2000]

Bump

[kernal]

Originally Posted by wingnut2000

would it be stupid to replace one or two batteries?

I don't think stupid is the right word. Ill-advised maybe better.

New batteries mixed with old or older batteries will have different capacities. In a golf cart they are hooked together in series. The charger doesn't see individual batteries, only the total voltage. Older batteries (or ones with lower capacity) will charge faster than new batteries. The charger just sees total pack voltage to shut off at it's predetermined point so for every charge cycle the newer batteries will be undercharged and the older batteries overcharged. The result is the newer batteries are very quickly aged to the same state as the older ones. The pack is only as strong as the weakest battery. You may get a temporary gain in range but the new batteries are being ruined at a very accelerated rate so you end up right back where you were or worse in a very short time. Depending on charge cycles maybe just weeks.

With 20 years of golf cart ownership and about 10 years of monitoring this board, this is what I have learned about flooded golf cart batteries:
To get the maximum range per charge and the longest service life of the batteries:
1. Get the highest rated capacity battery you can for a reasonable price.
2. Get batteries that have not been sitting on the shelf for very long. Get all of them from the same shipping pallet if possible. (easy for me but I realize this is a problem for most) The goal is a "matched" pack if possible. All produced in the same month at least.
3. Charge them before first use and keep them charged between uses.
4. Keep the connections and batteries clean. Stacking order of the connections should be big wires on first (bottom) and small wire on top (last) if applicable.
5. Loose connections generate heat and can melt the post. Conversely over tightening them can pull the post loose from its lead seat resulting in the same melted post.
6. Keep water level correct. Too low is bad and too high is almost as bad.
7. Everybody neglects the wires (high current cables). Just because they look ok doesn't mean they are. Don't assume the factory installed wires are adequate for the way you use the cart. Quality cables will pay back many times their cost. IMO
The biggest killer of batteries in general seems to be neglect and heat. Neglect includes a lot if sins including poor maintenance and poor charging routine including bad chargers. The climate in Ga. is hot enough in the summer to put extra stress on the batteries but not as bad as Arizona for example.

Reality: You only get a set amount of charge cycles before end of life. The deeper the battery is discharged before charging the fewer cycles you get. Mismatched batteries accelerate this process for the pack as a whole.

[JohnnieB]

Originally Posted by kernal

I don't think stupid is the right word. Ill-advised maybe better.

New batteries mixed with old or older batteries will have different capacities. In a golf cart they are hooked together in series. The charger doesn't see individual batteries, only the total voltage. Older batteries (or ones with lower capacity) will charge faster than new batteries. The charger just sees total pack voltage to shut off at it's predetermined point so for every charge cycle the newer batteries will be undercharged and the older batteries overcharged. The result is the newer batteries are very quickly aged to the same state as the older ones. The pack is only as strong as the weakest battery. You may get a temporary gain in range but the new batteries are being ruined at a very accelerated rate so you end up right back where you were or worse in a very short time. Depending on charge cycles maybe just weeks.

With 20 years of golf cart ownership and about 10 years of monitoring this board, this is what I have learned about flooded golf cart batteries:
To get the maximum range per charge and the longest service life of the batteries:
1. Get the highest rated capacity battery you can for a reasonable price.
2. Get batteries that have not been sitting on the shelf for very long. Get all of them from the same shipping pallet if possible. (easy for me but I realize this is a problem for most) The goal is a "matched" pack if possible. All produced in the same month at least.
3. Charge them before first use and keep them charged between uses.
4. Keep the connections and batteries clean. Stacking order of the connections should be big wires on first (bottom) and small wire on top (last) if applicable.
5. Loose connections generate heat and can melt the post. Conversely over tightening them can pull the post loose from its lead seat resulting in the same melted post.
6. Keep water level correct. Too low is bad and too high is almost as bad.
7. Everybody neglects the wires (high current cables). Just because they look ok doesn't mean they are. Don't assume the factory installed wires are adequate for the way you use the cart. Quality cables will pay back many times their cost. IMO
The biggest killer of batteries in general seems to be neglect and heat. Neglect includes a lot if sins including poor maintenance and poor charging routine including bad chargers. The climate in Ga. is hot enough in the summer to put extra stress on the batteries but not as bad as Arizona for example.

Reality: You only get a set amount of charge cycles before end of life. The deeper the battery is discharged before charging the fewer cycles you get. Mismatched batteries accelerate this process for the pack as a whole.

Just like to add some thoughts to #2 and #4.
I special ordered my batteries, so they all came out of the same production run. I didn't specify the terminal type, so I got the "Universal" type, a post with a bolt hole through it. (#7 on attached list.)

The stud terminal we usually get (#1) has some issues.
a. Easy to over-tighten and melt terminal.
b. Only one place to connect multiple wires and cables. (High current, Charger, battery meter and voltage reducer all go on the main +&- terminals)
c. Easy to stack wires and cables in wrong order.

Terminal types like #6 and #2 allow an automotive type clamps to add additional fastening points for the lower amperage cables and wires freeing the main attachment stud for the high current cable alone. With the #7 type terminal, I put the high current cable on one side of the bolt and the rest on the other.

I'm speculating, but you will likely have to special order to get something other than the type #1 terminal, which may improve the probability of getting closely matched batteries.

Like I said, just some thoughts.

[Cobra,1]

Kernel your last post should be in stickies
Pretty much summed up battery care in nutshell.
Good post👍

[wingnut2000]

IDK what to do with the current Batteries. They are not even two years old. Should I replace them? I have kept water in them but I did notice they were somewhat low one time but couldn't have been very long. I charge the cart after every ride and if it sits for more than a couple days I will reset the charger.

should I replace them already?

[kernal]

Originally Posted by wingnut2000

IDK what to do with the current Batteries. They are not even two years old. Should I replace them? I have kept water in them but I did notice they were somewhat low one time but couldn't have been very long. I charge the cart after every ride and if it sits for more than a couple days I will reset the charger.

should I replace them already?

I would advise against a knee jerk reaction. Battery range is down now for us (Ga.) because of cold weather. It is common for people to be surprised by the apparent loss of range this time of year (more so in sept and oct). Historically we see a jump in perceived battery problems in the fall on this board. I believe I swapped a good set of batteries some years ago due to this phenomena before I became aware of the science.

Assuming your batteries were brand new (all of them) when installed and are now about 18 months old they should be fine. If they are not then you have an issue somewhere. Batteries can be ruined in that amount of time but it would take a fair amount of neglect/abuse IMO.

As preached here for many years now battery health should be determined before an informed decision can be made about the basics: cart runs poorly or not at all---should upgrades be installed and what to expect---should batteries be replaced (end of life).

Battery health can be determined by a load test at a competent dealer or independent shop with the appropriate equipment-- or -- you can do it yourself with a volt meter and clips for the probes. There are many posts here on how to do it. This will also show if individual batteries are the problem or if they are all the same. Not uncommon for a single battery to fail early which will affect the whole pack.

If you have a battery meter (no matter who made it) installed assume it is lying to you until proven otherwise. Do the load test one way or the other.

End of life (EOL). I believe EOL is not a defined point but is different for everyone. For me EOL is when the batteries will no longer take me where I want to go with out range anxiety. That point is much different than someone who just uses their cart around the farm for example.

[R.Boyd]

Does the voltage sag heavily under a load, like when accelerating or going up a hill? I don't see 2 year old batteries being bad. Leave your volt meter on the batteries as you charge them also and see at what voltage they are at when the charger shuts off. I would want to know what the cutoff voltage when charging is and how they react under a load before making a decision of that magnitude. Does it run smoothly and quietly while running it. Also, unhook all accessories for a couple of cycles to rule that out. Got to be methodical while figuring this out.

[wingnut2000]

Originally Posted by R.Boyd

Does the voltage sag heavily under a load, like when accelerating or going up a hill? I don't see 2 year old batteries being bad. Leave your volt meter on the batteries as you charge them also and see at what voltage they are at when the charger shuts off. I would want to know what the cutoff voltage when charging is and how they react under a load before making a decision of that magnitude. Does it run smoothly and quietly while running it. Also, unhook all accessories for a couple of cycles to rule that out. Got to be methodical while figuring this out.

The meter installed on the cart shows 50.1 V when charged. I will try the load testing as Kernal suggested but first I am going to grab my dads charger that is the same as mine and rule out the charger. He has a txt so hopefully the profiles on the charger wont matter.

[JohnnieB]

In your post #12. you listed the voltages of individual batteries after 10 hours of rest and they add up to 51.59V while in your post #29 above you state the meter installed on cart shows 50.1V when charged, but do not state how long the batteries have rested. There is a 1.5V variance in the readings, so one or both of the two voltmeters isn't accurate, or the rest time is significantly different, or the SoC of the battery pack was truly different at the respective times of measurement, or the interconnecting cables are exceedingly bad.

Put new batteries in your handheld DVM and use it to measure both the pack voltage and the individual battery voltages about 12 hours after the charger shuts off to get a reasonably accurate SoC estimate. (At-Rest Voltage vs SoC chart for Trojan brand batteries attached)

If batteries are not charging to 100% SoC, do several back-to-back charges and they might recover a bit. (The 18 month old T-105 batteries that came with my cart would only charge to 85% SoC when I got it and after a couple weeks of 2 or 3 back-to-back charges almost every day, they were charging to 95% SoC.)