Golf Cart Batteries - Gotta Love 'em

[BigE_]

BigE: I looked at the 48v BatteryMinder and it seems okay, but a bit expensive at $179. They said in their website that you could use your regular charger and then hook up the BatteryMinder. My question is why won't the BatteryMinder just replace the charger? It's probably a really good product, but if it is advertised as a charger/maintainer, then I want it to replace the golf cart charger completely. Too much stuff is too inconvenient for technology challenged people like my brother to deal with.

Here's the one I ordered: Amazon.com: BatteryMINDer Battery Charger / Maintainer with Desulphator - 12 Volt 2/4/8 Amp, Model# 12248: Everything Else
The price has gone up to $117, and it looks like free shipping is no longer there, so you are looking at $125 total.

It is both a charger and a desulphator, and it actually charges faster than my old standard 10A charger, because it charges at a constant current instead of constant voltage. It does, in fact, replace the charger.

It will charge up to 6 batteries at the same time, but they all need to be in parallel. Your golf cart batteries are in series, I believe.

Hmmm. Just looked at the one you must have been looking at. Amazon.com: BatteryMINDer Charger/Maintainer/Desulfater - 2 Amps for 48V Systems, Model# 48021: Home Improvement
This one also acts as a charger, but it is slower (2A charge rate). Honestly, when trying to revive one battery, I think you are better off with the 12V charger. I don't think the 48V charger will revive a battery. The 48V charger will keep them from becoming sulphated, but it won't bring them back from the dead like the 12V charger will.

If you don't mind delving into electronics a little, you can build your own desulfator for cheap. W5USJ Couper 1kHz Desulfator is one example. There are tons, now.

If you can get 12V across the battery terminals, then the battery isn't too far gone.

-Steve

 

[jinman]

If you can get 12V across the battery terminals, then the battery isn't too far gone.

-Steve

I would say that's right in many/most cases, but my battery read fine and even worked with a small load, but dropped like an anchor when loaded to about 5 amps. Removing the load made no difference for about a minute and then it instantly jumped back up to 12.5 volts. One time I had a 12 volt light attached and it would get dim for a few seconds and then come back on full bright followed by cycling dim and bright at odd intervals. With a voltmeter attached, I could see the voltage drop as low as 8.5 volts and then cycle back up to 12.5. Something was happening inside the cell that had nothing to do with sulfation. However, with no load and reading with a voltmeter, the battery produced a happy 12.5 volts or more. As Tim said earlier, the only way to truly measure a battery is to load it and measure voltage under load as well as measure its capacity in amp hours by how long it can maintain a load and not drop voltage. Sulfation will limit the useful amp-hours, but physical problems like shorts and opens in the battery cells will show up right away when the battery is loaded.

 

[jinman]

How about a DP4ST switch such as Rotary Switch 2 Pole 2-6 Positions - Adjustable Stops : Amazon.com : Automotive. Then you can switch both ground and hot at the same time.

Aaron Z

Yep, that would work, but I want to watch all four batteries at the same time while driving. The rotary switch would be good because I could make the first position OFF, then Bat 1, Bat 2, Bat 3, Bat 4. Depending on how this works out, I may do exactly as you suggest.

 

[BigE_]

I would say that's right in many/most cases, but my battery read fine and even worked with a small load, but dropped like an anchor when loaded to about 5 amps. Removing the load made no difference for about a minute and then it instantly jumped back up to 12.5 volts. One time I had a 12 volt light attached and it would get dim for a few seconds and then come back on full bright followed by cycling dim and bright at odd intervals. With a voltmeter attached, I could see the voltage drop as low as 8.5 volts and then cycle back up to 12.5. Something was happening inside the cell that had nothing to do with sulfation. However, with no load and reading with a voltmeter, the battery produced a happy 12.5 volts or more. As Tim said earlier, the only way to truly measure a battery is to load it and measure voltage under load as well as measure its capacity in amp hours by how long it can maintain a load and not drop voltage. Sulfation will limit the useful amp-hours, but physical problems like shorts and opens in the battery cells will show up right away when the battery is loaded.

Oh, it could be not charging correctly, like you are experiencing. What I'm saying is that it isn't too far gone for a desulphator to bring it back. If the voltage drops much below 12V, the desulphator likely won't be able to bring it back (although I've rescued one such battery).

 

[kevin37b]

Jinman , it's time to go shopping . New batteries , $ 600.00 , your brother priceless .

 

[jinman]

Jinman , it's time to go shopping . New batteries , $ 600.00 , your brother priceless .

Kevin, I think that's a bit of a stretch in comparison, but I agree with the sentiment in many regards. I would say it's something more like: New batteries - $600. Wasting money on something I don't need - senseless. So, I went to Walmart and bought their largest marine battery the Everstart Maxx Group 29 deep cycle. While it is not the original cart battery, it has about 3/4 the amp-hour rating and is only $99 with a 2-year guarantee. I don't have to search and dig through golf cart specialty stores or other remote locations if I need a warranty replacement or another similar battery. I can buy these batteries at any Walmart. Frankly, I was tempted to replace all four batteries with four of these and tell my brother he'll have to charge a little more often. With a working battery monitor, it will tell him when he needs to charge. Everything I read about these marine batteries was good with rare exception.

So, I bought and installed the Everstart Maxx battery with the three remaining US batteries. The only problem was the battery clamp since this battery is about 1-1/2" shorter than the US Battery. I just trimmed a piece of wood and slid it under the hold-down. It worked perfectly. I didn't take photos of the batteries, but I will and post them later. With the batteries installed, the battery monitor showed full power and I set off see how the cart performed.

I guess it seems a lot shorter time when you are on the golf course or using your cart for chores, but running these batteries down enough to recharge took me three days of riding trails and running up and down my county road. The battery monitor came one division off of maximum and then sat there like a rock as I drove and drove. The controller won't let you go faster than about 14 mph, but when you come to a steep hill, it just 'opens the floodgates' of power and the cart has power to spare. I tried some very steep hills that I thought I could not climb without 4WD and this little lightweight cart zipped up them without a hitch. Finally, after three days of riding in circles, the power monitor dropped to one mark above half-scale.

I put my voltmeter on the batteries and they all read between 11.6 to 11.8 vdc. The new Everstart Maxx was the 11.8 with two US batteries at 11.7 and one at 11.6. I got the 48 volt charger and plugged it in. I let it run for about 6 hours and the battery charger monitor showed 90% charged. While charging I read the voltage on each battery. This would tell me if the batteries were charging evenly. In a series battery arrangement. If one battery charges before the others, it will drop most of the battery voltage and reduce the amount of overall charging current. This was a critical thing to me because if the new Walmart battery charged much quicker than the US batteries, it would slow charging to a snail's pace and probably boil off acid to boot. As it turned out, the Walmart battery was up around 14.2 volts and the US batteries all showed 13.7 to 13.8 volts. The Walmart battery was obviously charging quicker than the larger AH rated US Battery cells.

I continued to let the batteries charge for another two hours. As I walked up to the cart, there was little difference in the charger's indication. I put my voltmeter on the batteries to find the US batteries at 14.7 to 14.8 volts and the Walmart battery at 15.8 volts. It was doing exactly as I suspected. As if by magic, the battery charger clicked and the fully charged light illuminated while the charger shut down. So now I had my data. The US batteries are probably only receiving about 95% charge while the Walmart battery is being overcharged for a short period of time. I saw no evidence of liquid at the battery caps and the body of the battery didn't seem to be warm to the touch. The next time I charge, I'll do it with the caps removed and watch for bubbling. I'm thinking that my brother will have to check the cells after every 6th charge or about once every 6 months. That's good practice anyhow on any battery. I'm calling this battery substitution a success for now. We'll see. . . .

In the meantime, I also built my battery monitor. I bought four of these potted and sealed digital voltmeters and four waterproof switches with boots. The real issue was whether I wanted to go all out with mounting the switches or build a prototype level assembly. I decided to apply the 'KISS principle' and make something I can install and remove without leaving a trace. I looked on my scrap pile and a piece of roof drip edge molding just jumped out at me as being perfect for mounting the meters and switches. The pictures below show the results. The only thing I wish is that the meters had more visible displays. The blue numbers are a bit hard to read in the sun. Shading them with your hand works pretty good.

Here's the back of my finished meter assembly.



Here's the front.



Here's the meters all working. Left to right they read: 12.2, 12.0, 12.3, 12.2
It's really not a good photo because my cell phone couldn't find the right focus.



Here is the overall charge state meter for the batteries. The cart didn't come with this meter. I added it before I gave it to my brother.



Finally, here's the cargo bed and SMV sign I rigged. I got the bed from BuggyWorx.com They are great people and very responsive. When I reported that two bolts in their kit were too short, they called to say I was correct and they were changing their kit. The bed was ordered off of their eBay store and arrived within a about 5 days.

 

[TheGoose]

Good on ya, glad to hear you found a better solution.

 

[jinman]

Thanks Goose. I realize this solution is not for everybody and would not have done it at all if the original batteries did not have some age. In a couple of more years, I may have to put in four new Walmart batteries. That will keep the circuit balanced and still provide plenty of juice for cruising. I promise if things don't work or this turns out to be a big mistake, I'll come back here and award myself the TBN dummie award. Time will tell. . . .

 

[jinman]

I ordered some rubber matting to put into the cargo bed on the cart and it took FOREVER to arrive. I think Amazon screwed up when they made this Super Saver free shipping. I paid $57 for a 47 lb roll and that came with free shipping. I priced shipping if I'd have paid for it and it was $32. Amazon must get great deals from shipping companies. This came to me all the way from South Carolina on Pilot Freight. It sat in their warehouse until I called to ask them about it. The next day, they brought it to me. Now, Amazon has the mat for $61.30 with $29 shipping. Maybe my order made them catch their mistake. I cut a 41" x 27" piece off the roll and put it into the cargo bed. Except for needing to flatten out completely, it is the perfect bed liner.

I showed photos of my voltmeters in my last post and finally took my better camera out and took pictures of my battery monitor wiring. In this first photo, you can see my battery monitor wiring with the yellow terminal lugs and the fuse bundle.



Here is some more detailed wiring and you can also see the difference in size of the Walmart Everlast Maxx Marine battery to the original golf cart batteries. I've discharged and charged the batteries twice and am convinced this battery will work perfectly. The Walmart battery is actually the strongest of the four batteries.



Here is a closeup of my fuse bundle. I wanted each wire leaving the battery compartment to be fuse protected. I had several 5-amp and 7.5 amp fuses laying around and just used them although they are overkill. They will provide catastrophic protection and that's what I want. I just used insulated female spade connectors taped together as fuse sockets. Then, I taped and bundled them all into a row of fuses as shown in the photo.



Finally, after the fuses, I wanted to mount a headlight on the cart for my brother. He needs a light when he hauls his garbage 1/4 mile down to the county road pickup point early in the morning before daylight. I found this 18W light at the LEDstore on eBay and the light is just perfect. I drilled the canopy and mounted the light up high and out of the way. It tilts down at the perfect angle and illuminates the ground perfectly.

 

[kevin37b]

Good job you must be an electrical engineer . Not senseless , you need your brother , he needs you and the cart . There is not much of that left these days . Have a good day .