DIY Lithium Ion 56 Volt Golf Cart Battery Conversion

HarborCartGuy

New Member
I build “Warp Drive” conversion kits....14S lithium Leaf batteries. We install about one a day. Sophisticated BMS board, 4awg wires, and just a few other things. Yesterday we converted a totally stock 2004 36v Txt to a 12S (6 pk) unit, wires and “clean up” a few things. Fresh paint, 12” trailer tires 21” tall. Cart was a 13 mph start...finish was 23 mph. Cart weighs 720 pounds. Goes 20 miles on a charge.
 

Lloyd-ss

Active Member
Harbor Cart Guy, The Lithium Ion batteries have so many advantages over the lead acid. Its good to know that people are doing the conversions.
 

Lloyd-ss

Active Member
The cart only has 7 more miles on it since my last post. Had to catch up on stuff that went un-done during the cart conversion. Voltage is still good at 53.4 volts.

PARKING BRAKE

The brake pedal parking brake has always scared me with all the grand kids around. We have absolutely NO flat land and the cart will roll from just about anywhere you leave it. There is a piece of 2x2 in the cart that is always used as a safety chock, but you know how reliable that is. I'm afraid that brake pedal will get accidentally bumped and something seriously bad will happen.

This parking brake for $25 ppd off ebay did the trick. Used some 1/8" aircraft cable to connect it to the brake linkage. Now I just have to re-educate everyone on using the new parking brake. At least it will be harder to accidentally knock loose.


ParkingBrake.jpg
 

Lloyd-ss

Active Member
TOE-IN ADJUSTMENT

This cart has always been twitchy above 12 or 15mph, but nothing looked bad or felt loose. I finally got around to measuring the toe-in, and I was kind of shocked. I carefully placed boards along the centerline of the front tires and checked the gap between the steel wheels and the boards to make sure I wasn't just measuring a bulge on a tire.

As you can see in the picture, the measurement across the front of the tires is 41-3/16" and the rear of the front tires is 42-1/2". I haven't looked for any specs, but 1-5/16" toe-in seems WAY too much.

What say you guys???
Thanks in advance!


-Toe-In.jpg
 

HotRodCarts

Cartaholic
I usually set them at 1/16" toe in. With 1 and 15/16" it will definitely be twitchy. Make sure you roll the cart a few feet in between adjustments before measuring.
 

Lloyd-ss

Active Member
Thanks Hot Rod, I'll do that in the morning. And that was actually an inch and 5/16 toe in! The steering wheel seems pretty well centered up right now, so I guess I just adjust both rod-ends the same amount to keep things straight, while getting the 1/16" toe-in?
 

Lloyd-ss

Active Member
I usually set them at 1/16" toe in. With 1 and 15/16" it will definitely be twitchy. Make sure you roll the cart a few feet in between adjustments before measuring.
The adjustment has been done and it definitely steers better at speed. Also eliminated almost all of the tire scrubbing noise in tight turns.
 

Diode

Cartaholic - V.I.P.
Ok I hooked up one of my packs and have them on the charger
what voltage did you turn your charger up to ? 54.6
 

Lloyd-ss

Active Member
I charged my 7 module pack to a maximum of 57.0 volts. If you look at the graph in post 5 of this thread, there is a graph of the voltage as the pack is discharged. 54.6 volts might be plenty, but you can charge higher if you want to. But you want to stay away from the max and min voltage to achieve maximum battery life. For a 7 module pack, 58.8 volts is the absolute maximum, because higher than that and the batteries start to get permanent damage. The charger I have, which is probably similar to yours, had 3 trim pots in it. One changed max current. One changed cut off voltage, and I couldn't figure out what the third one did. I've got pics of those pots if you need them.
 

Lloyd-ss

Active Member
ANOTHER RE-CHARGE ON THE LI-ION BATTERY PACK

It had been quite a few days since the batteries were fully recharged (on Aug 11, I think) and I have not been recording the daily voltages. But yesterday in the afternoon I noticed that the batteries were sitting at 48.4 volts while idle and dipping down to about 44 volts under full load.
Time to recharge. At about 7:30 last night, I flipped the dash switch to charge (the charger instructions said that the output leads needed to be connected before the charger was plugged in), and plugged in the on-board charger and it showed a starting charge current of 5.5 Amps, just as it was supposed to be. Again, I forgot about it until the middle of the night, but didn't check on it.
This morning, the charger had shut off automatically, and the voltage was again reading 56.8 volts, just where it is supposed to be.
Still in good shape!!

The miles on the previous charge was only about eleven, but a few of those miles had been pulling a drag, made from half a length of railroad tie and some logging chain, on my woods trail. Just kinda wanted to see what it could do. That really sucks up the power but the battery and cable and electronics temps were cool when I checked them afterwards.
 

EzgoSun

New Member
Thank you Loyd-ss !!
I just found this posting and have been glued to my screen. I am 6 weeks into restoring 96 EZGO TXT. I fabricated a gas strut assisted dump bed for fun, & converted to 48v ezgo txt 2014 electrics. 6" lift, off road tires. It will be lithium powered, but charged with 435w solar panel. The ranch where it will be used doesn't have grid power. I may still be 3 weeks away from testing. Base on your information my results should be very successful.
I am days away from buying batteries, & your details have been extremely valuable.
 

Lloyd-ss

Active Member
Hey EZGoSun,
Sounds like a great project and the solar charger will be the icing on the cake. The records from my cart showed an average consumption of 135 watt hours per mile. If you can get 5 hours of sunshine a day ( don't know where you live so might be way off) that could be 1740 watt hours per-day (5 hrs x 435 watts x .80 efficiency) or almost 13 miles a day. Sounds darn good.
Does the solar panel feed into its own combo control box and battery charger? I am assuming that it will put out the correct voltage for the battery modules to charge the batteries directly? Monitor the first charging cycle carefully, but first verify that all cells start out at the same voltage. There are 4 cells in each module, set up as 2 in-series cells connected in parallel to 2 more cells in series. Recommended max charging voltage per cell is 4.05 vdc, or 8.1 vdc per module. If they are uneven, top them up (or discharge any that are overcharged). The reason it is such a big deal to keep the voltages even is because these batteries get permanently damaged if outside their operating range of 8.14 VDC max per module and 7.0 vdc minimum. Since your solar charger will be putting out up to 9 amps at 48v (maybe) it will need to be monitored by you, or a BMS. The charge and discharge curve of these batteries is very flat in the middle operating range (50 volts to 56 volts), so you need to closely monitor the first charge or 2, till you get confidence in the design.
Good deal!
Please keep us informed!
Lloyd
 

Lloyd-ss

Active Member
UPDATE ON THE LITHIUM ION BATTERY CONVERSION
Nov 3, 2019

It has been about 3 months since the Lithium Ion batteries were installed and running nicely. And they are still running nicely!
I did change out the throttle potentiometer from a rotary kind to a linear one. I couldn't get the linkage working smoothly on the rotary one, but the linear one is working nice and smooth.

I've been charging the batteries about once a week, which is normally less than 15 miles of driving. I charge them more as a habit, before the voltage gets low.
We are starting to get a few nights below freezing and I am curious as to how the batteries will do in cold weather. They are supposed to operate fine at all temperatures but you are not supposed to charge them if they (the batteries) are below freezing. I have a plan to warm them up if it becomes necessary, but we'll see how it goes. Most winter days around here usually get above freezing, except to a couple of weeks here and there.
Overall, I am still very happy with the conversion.
Lloyd
 
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