EZGo 36v Interpret Battery Test Results

[drosen]

JohnnieB - re: your post on charging a few times a day for a few days, I finally had a block of days where I could do it. Looks like batteries took a better charge but after sitting overnight they were at the usual (Post #2) 37.6. What does it look like to you? Here were the results:

Day 1 - initial recharge 38.6, wait 1 hour recharge also 38.6, wait 2 hours recharge - 39.0, wait 5 minutes recharge 39.8

Day 2 - from sitting overnight was down to 37.7, recharge 39.2, no wait recharge 38.9, no wait recharge 39.5, no wait recharge 40.0

Day 3 - from sitting overnight down to 37.7, recharge 39.5, no wait recharge 38.5, wait 1 hour recharge 38.1

Day 4 - from sitting overnight down to 37.6, recharge 38.7, no wait recharge 39.3, no wait recharge 38.4

Day 5 morning (12 hrs after yesterday's last recharge) 37.7
Day 5 evening (24 hrs after yesterday's last recharge) 37.6

[JohnnieB]

Originally Posted by drosen

JohnnieB - re: your post on charging a few times a day for a few days, I finally had a block of days where I could do it. Looks like batteries took a better charge but after sitting overnight they were at the usual (Post #2) 37.6. What does it look like to you? Here were the results:

Day 1 - initial recharge 38.6, wait 1 hour recharge also 38.6, wait 2 hours recharge - 39.0, wait 5 minutes recharge 39.8

Day 2 - from sitting overnight was down to 37.7, recharge 39.2, no wait recharge 38.9, no wait recharge 39.5, no wait recharge 40.0

Day 3 - from sitting overnight down to 37.7, recharge 39.5, no wait recharge 38.5, wait 1 hour recharge 38.1

Day 4 - from sitting overnight down to 37.6, recharge 38.7, no wait recharge 39.3, no wait recharge 38.4

Day 5 morning (12 hrs after yesterday's last recharge) 37.7
Day 5 evening (24 hrs after yesterday's last recharge) 37.6

Looks like you need some new batteries.

[drosen]

Again, many thanks for your expert help.

From the test results of this multiple daily recharges for several days, this confirms hopelessly bad batteries? Prior tests hinted at it but didn't confirm it for sure, now it's for sure?

I don't drive the cart hardly at all, it mostly sits awaiting the next visit and use by the granddaughters who only come and drive it every couple months. I was just charging it up overnight every 2 weeks.

What is the best way to preserve what's left of the batteries with this limited pattern of use?

[JohnnieB]

Originally Posted by drosen

What is the best way to preserve what's left of the batteries with this limited pattern of use?

Get a charger, such as a DPI Accusense, that goes into float charge after the regular charge cycle ends and let it float charge the batteries between granddaughter visits.

[ThreeCW]

Originally Posted by drosen

The cart gets limited use, but it gets fully charged every 2 weeks.
I noticed the car runs out of charge much faster than it did last summer.
Full charges still produce 37.6 volts like last year.

Compared to your first post, your "fully charged" stabilized voltage has remained at 37.6 volts even after multiple attempts to recharge / top off your batteries.

Funny thing is that when your cart was running better, you still had a stabilized charged voltage of 37.6 volts.

Have you tested the cart for any change in "run time" since your multiple top off charges?

If it was me (for the sake of science), I would still perform the load test on the individual batteries "just to be sure" that a weak battery (under load), is not contributing to the short run time. If you are not into science experiments, that is OK too ... time for new batteries then.

By the way, what do you consider a short run time?

A few notes below for your consideration.

Regards, 3CW

The following comes from an Alltrax Publication: Technical Note 010: Lessons Learned (attached for your reference).

"Common failure mode is battery neglect. We are really dealing with a “chemical engine”; charging causes the chemicals to separate into acid and positive and negative plates. Discharging the battery basically turns the acid into water. Undercharging a battery is the #1 killer of the battery plate material as the plates become sulfated and water causes plate corrosion. In a charged state the batteries are returned back into the chemical (acid) state preventing plate sulfation.

Charge the batteries after heavy use, do not let them sit overnight in a discharged state."

[drosen]

JohnnieB: Thanks for the idea. A float charger would be good, but I have to admit that with the limited use of granddaughters only coming to use it every few months, the thought of buying a fairly expensive charger (or even worse buying new batteries!) is not too appealing.

Unless you tell me otherwise, I guess I should just continue to leave it parked and charge the batteries every 2 weeks so they don't run down too much in between the visits when it gets used and hope they don't become totally unusable too soon.

Where do the smart guys get a new set of batteries when they need them to get good quality at a decent price?
---------------------------
3CW - Thank you for the attachment and your comments.
When a friend first gave me the cart, the girls would ride around the house (big yard) a number of times throughout the day and night and it would last for about 3 days. Now they'll ride around for about 3/4 of one day and the motor is not strong enough to make it up a small hill (about 8 feet ) without the batteries being recharged.

I haven't forgotten your suggestion of a load test, just negligent. Also read even if it's only one bad battery you shouldn't replace just one and I'm not anxious to spend all the money on a new full set.
I'm with you on the value of science (retired college professor) so after the current visitor leaves I will get back to work on following your advice and doing the load

(Ever hear of using epsom salt to clean out battery sulfating?)

[yurtle]

Forget about any battery rejuvenation, like epson salts. Decide what you want out of the cart. Most batteries will last about the same time, as long as you never run them down too low, and promptly recharge after use. Batteries aren't good for shipping, so look at how many amp-hours you need, and shop around local shops. Many will special order, if you need. Given your limited use, I'd go for the cheapest batteries with suitable amp-hours for a daily use.

[cgtech]

If you just need limited use to work, I would suggest using a automotive battery load tester on each individual battery, and doing the test after some use (not fully charged, since that type of tester is not a really good one for golf batteries). Then trying the local shops for a good used battery to use in your set to replace the worst one. It's a crummy solution, but we are trying to make a loaf of bread out of bread crumbs. Yeah, skip the "secret tricks" like salts, they aren't gonna get you anywhere.

[Golf cart guy]

If it was my set of batteries, I would have charged, ran the cart a couple of miles and then recharged, and repeated this process a few times. Your on charge battery voltages near the end of the charge cycle are off, that's why I would try the charge, run, charge, run...etc. I see this issue quite a bit.

[JohnnieB]

Originally Posted by drosen

JohnnieB: Thanks for the idea.
1. A float charger would be good, but I have to admit that with the limited use of granddaughters only coming to use it every few months, the thought of buying a fairly expensive charger (or even worse buying new batteries!) is not too appealing.

2. Unless you tell me otherwise, I guess I should just continue to leave it parked and charge the batteries every 2 weeks so they don't run down too much in between the visits when it gets used and hope they don't become totally unusable too soon.

3. Where do the smart guys get a new set of batteries when they need them to get good quality at a decent price?

4. (Ever hear of using epsom salt to clean out battery sulfating?)

1. Expensive is a relative term.

Since the cart isn't used daily, charge time most likely isn't an issue, so a low power charger/maintainer will probably serve your purposes.

Something akin to this may be the answer: http://www.granitedigital.com/36volt.aspx

Costs about $100 and you just leave it connected to cart between the granddaughters' visits.

2. If you continue to use the existing charger, initiate a charge cycle at least once a week and put on charge the night preceding the granddaughters' visits.

3. Batteries are heavy and hazardous, so buying batteries anyplace except locally is usually not cost effective.

The most cost effective batteries to buy are the highest amp hour batteries at the lowest price for a local vendor.

4. The various snake oil battery additives cause the sulfated surface of the plates to slough off and hopefully the conductive debris settles the the bottom of the cells. If it doesn't, or the battery is agitated enough to mix the conductive sludge in the electrolyte, it can create shorts between plates, ruining the cell. At best, it is a temporary gain and at worst it is an instant failure.