Drive battery issues

[tomtt2]

I guess I’m officially a Geezer. Just turned 65 and live in a community that allows us to run around the streets in our golf carts. I parked the second car and pretty much use my 2007 Yamaha Drive for most errands around the community. I use it every day—week end and week out.

The Drive came with big tires and a high speed motor that does about 24.9 MPH according to my Sigma BC 509 bicycle speedometer that is calibrated for my tire circumference.

The Drive came with a 48 volt system consisting of four twelve-volt batteries (US Battery) (okay, okay, I know the 4x12 battery pack is the least desirable, but it is what came with the cart).

Understanding that batteries are not cheap, I’ve gone to great lengths to take care of the four that I have. I have an automatic watering system and only use distilled water. I plug in the charger every time I pull into the driveway and try to keep the charge from dropping too low. I also regularly check cables for corrosion and us baking soda to clean it up and cover terminals with Vaseline to try to prevent (slow) corrosion.

The batteries are only about 2 ½ years old and I had expected to get about five years from them if I continued to take care. I was pretty surprised when shortly after the twelve-month mark, I started to notice a significant decrease in range on a charge. I had the selling dealer take a look and was told that two of the batteries were “bad” and were replaced with two Trojans at no charge. All was well for the next year or so, then I began to notice the drop in range again. Not a lot, maybe 15% but I do notice it and know where this train is heading.

Before rushing back to the dealer again (at 2 ½ years, I expect they will want to see my checkbook) I did a little basic testing. Here is what I’ve got.

Test 1: Individual battery voltage (after charging and waiting 1~2 hours):

Battery 1 (Trojan): 13.0 v
Battery 2 (US Bat): 12.5 v
Battery 3 (US Bat): 12.6 v
Battery 4 (Trojan): 13.0 v

Repeated the test several times to ensure consistency.

Test 2: 100 Amp load test (the Harbor Freight thing):

Battery 1 (Trojan): Well within the green “Good” range.
Battery 2 (US Bat): Just within the green “Good” range.
Battery 3 (US Bat): Just within the yellow “Weak” range.
Battery 4 (Trojan): Just within the green “Good” range.

I repeated the load test several times over two days to ensure consistency.

Test 3: Specific Gravity (after charging and waiting 1~2 hours):

Battery 1 (Trojan):
Battery 2 (US Bat): 1.265, 1.275, 1.260, 1.250, 1.260, 1.275
Battery 3 (US Bat): 1.265, 1.275, 1.265, 1.255, 1,265 1.265
Battery 4 (Trojan):

I used an automotive type battery hydrometer (the one with the pointer instead of floating balls). I realize it is not temp compensated, but it was right at 80 degrees today here down south. A temp compensated unit is on the way from Amazon.

So, here’s my question: since the load tests appear pretty good, the voltages look pretty good and the specific gravity readings are all reasonable with no great variances within a single battery, what is causing the loss of range?

I’ve kept an eye on tire pressures to ensure that they stay up to the recommended level. The charger appears to be functioning properly. Our weather is pretty mild down in Hilton Head, so I don’t think cold weather is the problem.

Could this just be the result of sulfation build up on the plates? If so, it’s pretty disappointing after all the TLC that the batteries have received.

I would appreciate any insights and/or suggestions you folks might have regarding these batteries (and yes, I know that six eight-volt Trojans would solve all my problems, but I’m not quite ready to pony up near a grand for lead).

Thanks.

[Great white north]

How many miles are you getting now for range as opposed to before
Put DVM on battery while driving see how low it gets then put clamp on amp meter on wires to motor to see how much amps the motor is drawing
Cheers !

[tomtt2]

Thanks GWN.

I typically got about 15 miles from a charge (4.5 ml to course, 5 miles on course, then home). Now I get about 12 miles. This is all based on keeping my foot out of the throttle and driving at about 12~15 mph to course.

I'll try the voltage / amp reading thing.

TT

[Volt_Ampere]

I think your 4 x 12V and 15 miles is pushing the range enough that you will not get very long battery life. Next time you go for new batteries you should change to 6 x 8V and you will get better battery life.

[tomtt2]

Thanks V_A.

I agree that 15 mls is the top of the range. The concern is if the batteries continue to decline in range. 15 is perfect, but if they drop to, say, 10 then I won't be able to get to the course and back.

I would love to go to 6 eight-volt Trojan T-890s. That would solve all of my range issues. It's just a matter of stepping up to the expense.

In the meantime, I'm still curious as to why my test specs are pretty good, but the range declined. Since there was no sign of a shorted cell (voltage test) or an open cell (specific gravity test) and the load test was good or right on the margin for the US batteries I wonder if range problem is due to accumulated sulfation on the plates of the US batteries. This would seem to be the only thing left.

Thanks again for weighing in.

TT

[Volt_Ampere]

If you are pushing your batteries below 50% by going 15 miles then they are going to degrade fairly rapidly. You will save $$ in the long run by getting some with larger amp hour capacity. You want to be above 50% charge after each use to get decent battery life.

[tomtt2]

Thanks V_A.

I didn't realize that taking them below 50% had such an immediate effect. I thought that getting the pack on the charger immediately (versus letting it get low and stay that way for a day or two) would tend to negate the sulfation/degradation.

Thanks for the insight and tip. It doesn't take the bight out the $$ for six T-890s, but it does support a move in that direction.

TT