DIY Lithium Ion 56 Volt Golf Cart Battery Conversion

Lloyd-ss

Active Member
Hmm, looks like we've got another build about to happen. Cool!
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Day 13 (8-9-2019) of the Lithium Ion 2002 Club Car DS
DAY SEVEN OF THE FIRST FULL CHARGE
PERFORMANCE AND RUN-TIME RECORDING

The Li Ion batteries were fully charged on 8-2-2019, with a final voltage of 57.0 volts. Data is being recorded each day to see how the batteries perform until they are discharged to about 48.3 volts, which is the sensible lower limit for good battery life.

Data for Day 1 (Aug 3)

Start today at 57.0 volts (full charge), ended today at 55.5 volts, 3.14 miles traveled today.
7.43 Amp Hours used today. 411 watt hours used today. 131 watt hrs per mile.
Avg speed 6.81 mph, max speed 16.3 mph, max amps 126, run time today 28 minutes.

Data for Day 2 (Aug 4)

Start today at 55.5 volts, ended today at 55.3 volts, 1.16 miles traveled today, 4.30 miles total on this charge.
10.4 Amp Hours used on this charge. 573 watt hours used on this charge. 133 watt hrs per mile.
Total run time on this charge 38 minutes.

Data for Day 3 (Aug 5)

Start today at 55.3 volts, ended today at 55.0 volts, 1.21 miles traveled today, 5.51 miles total on this charge.
13.7 Amp Hours used on this charge. 755 watt hours used on this charge. 136 watt hrs per mile.
Total run time on this charge 51 minutes.

Data for Day 4 (Aug 6)

Start today at 55.0 volts, ended today at 54.5 volts, 2.02 miles traveled today, 7.53 miles total on this charge.
18.3 Amp Hours used on this charge. 999 watt hours used on this charge. 134 watt hrs per mile.
Total run time on this charge 64 minutes. Max speed today 18.9mph.

Data for Day 5 (Aug 7)

Start today at 54.5 volts, ended today at 53.0 volts, 3.52 miles traveled today, 11.05 miles total on this charge.
26.8 Amp Hours used on this charge. 1,448 watt hours used on this charge. 131 watt hrs per mile.
Total run time on this charge 1 hour and 28 minutes. Max speed today 26.7 mph (going down hill way too fast).

Data for Day 6 (Aug 8)

Start today at 53.0 volts, ended today at 52.1 volts, 1.95 miles traveled today, 13.00 miles total on this charge.
32.22 Amp Hours used on this charge. 1,731 watt hours used on this charge. 134 watt hrs per mile.
Total run time on this charge 1 hour and 48 minutes.

Data for Day 7 (Aug 9) FINAL DAY OF TEST
Start today at 52.1 volts, ended today at 46.3 volts, 3.27 miles traveled today, 16.27 miles total on this charge.
40.38 Amp Hours used on this charge. 2,134 watt hours used on this charge. 131 watt hrs per mile.
Total run time on this charge 2 hour and 21 minutes.
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I missed the minimum voltage target of 48.3 volts, and instead went 2 volts lower to 46.3 volts. I will analyze the data tomorrow when I am fresher and try and present some thingp useful data. I think the voltage fell off a cliff at the end of the test
Still more to come!
 

Lloyd-ss

Active Member
I woke up this morning and looked at the data from yesterday, and then made an excel chart for the battery discharge. I was actually pretty annoyed with myself that I went 2 volts below my intended stopping point. Problems with a human BMS, ha ha. But seeing that I don't plan on getting close to that low of a voltage during normal use, it should be ok.
Here are 2 pics of the CA when the cart went to sleep last night. The display toggles between miles and AHrs, so you can see the final miles and amp hours used from the first full charge.
FinalAHr.jpg

FinalMiles.jpg


But I do want to find the voltage where the battery pack kinda fell off the cliff, voltage wise. So i recharged the battery pack a little this morning. Here is a pic of how the on board charger plugs in, and a second pic of how the "charge" toggle switch is turned on and the yellow "charging" light is on. that pic also shows how the CA displays the amps as a minus 5.5 amps as the charger is putting amps back into the battery pack. The "amp hours used" display also counts backwards as the battery is re-charged.
After being plugged in for exactly 30 minutes, the AHr went from 40.38 to 37.44, and the volts went from 46.3 to 50.3. Now, I should be able to drive the cart and more closely monitor the CA and find the voltage where the volts fell off the cliff. I will avoid letting the volts get that low again.

FinalPlugged.jpg

FinalReChg.jpg
 

Lloyd-ss

Active Member
Thanks, HotRod. I don't have much experience with golf carts, so your feedback is much appreciated. Glad to hear that the run time looks ok to you, and is similar to the usual LA batts.

I'd like to come up with an honest list of pluses and minuses for the conversion, but actual battery life will be unknown for a while. Right now, the 300 pound weight savings is the biggest plus that comes to mind. All thoughts and comments are welcome.
Lloyd
 

Lloyd-ss

Active Member
I "reenacted" the last part of the run time test to be able to look at the data more closely.
It looks as if, on my property and terrain, the Lithium Ion battery pack, made up of 7 Nissan Leaf battery modules, can safely deliver about 15 miles of driving time on one charge, on steep terrain. In the chart, you can see that starting at 56.5 volts and ending at 51 volts is preferred by this particular battery pack.
The terrain that this test was done on is all steep up and down, with almost no flat areas. It is about one half paved, and one half rough trails through the woods. Slopes are as steep as 17%.

FINAL RESULTS
Looking at the chart, it is clear to see that running the cart under 51 volts will yield very few extra miles, and could possibly damage the batteries.
The new battery pack is almost exactly 300 pounds lighter than the Lead Acid batteries they replaced.
The new pack also boosted the battery voltage from 36 volts nominal to about 54 volts nominal, with a tremendous increase in acceleration performance.
14 miles of driving is a reasonable expectation for this Lithium Ion battery pack.
I am happy with the results.:)

FullDischarge-1.png

Stay between 56.5 volts and 51 volts and the batteries will perform well and probably last a very long time. :D

Lloyd
 

Lloyd-ss

Active Member
Late yesterday afternoon, with the Li Batt pack voltage at 47.2 volts, I plugged the on-board charger in to recharge the batteries in what I anticipate to be the "normal" manner. I checked the progress a few times and it was progressing just fine, but then I went to bed and forgot about it. This morning, the charge cycle was finished and the charger had automatically shut off and the voltage is 56.6 volts. The target cut-off point was 56.5 volts, so I won't mess with it. Just for peace of mind I checked the voltage on the 14 cells (2 cells per module) and all read between 4.046 and 4.057 volts. So, a variation of 11 milli volts, or 3 tenths of a percent. Very good!

The Cycle Analyst has been reset so that data can be collected for this charge. But this time, I will only let the voltage go down to 51 volts. I am anxious to see how many miles that is.

This is a pic of the battery pack with the charger plugged in. No need to take anything apart. Just flip one of the toggle switches on the dash to "Charge", plug it in, and then unplug after it shuts off automatically several hours later.

FinalPlugged.jpg
 

Diode

Cartaholic - V.I.P.
My battery’s should be here Tuesday already have my charger I purchased two packs Probably won’t start working on it for a couple weeks I will clean out the shop first and then go for it
 

Lloyd-ss

Active Member
Gentleman, This has been a fun project, and the results are better than I was expecting. It was difficult enough to be challenging, without being overwhelming. Sharing it makes it more fun. I am looking forward to see how yours goes, Diode. Two packs of modules should really put out some power. For my situation, the single pack of 7 modules is perfect.
 

just_me

New Member
My batteries arrived yesterday. No hardware or case that I had ordered. kinda messed up my plans for the day.
What charger is recommended for these cells? TDC sells a 15/30 amp charger no bells or whistles for 135.00. Lloyd-ss reported owning a 6 amp.
I found a simular 10amp for 108.00. What would be considered to be a good charger?
 

just_me

New Member
Thank you, I missed that even tho I've read this thread what seems like a million times.
The one I was looking at was the only 54.6v 10 amp charger that poped up on amazon. Same unit different price. It has been ordered.
Lloyd-ss thank you for the great writeup and for all the help.
 

Lloyd-ss

Active Member
My batteries arrived yesterday. No hardware or case that I had ordered. kinda messed up my plans for the day.
What charger is recommended for these cells? TDC sells a 15/30 amp charger no bells or whistles for 135.00. Lloyd-ss reported owning a 6 amp.
I found a simular 10amp for 108.00. What would be considered to be a good charger?
My stuff arrived in separate packages, too. The Li batts ship under special instructions and aren't mixed with anything else.
Have you had a chance to check the voltages on the individual modules and cells? Mine were all within a few milli volts of each other, and consecutive in serial numbers.
 

just_me

New Member
No I did not measure any cells yet. I pulled one cell out it was wrapped up nicely. I figured keep them safely in their boxes until I have all of the parts.
 

Lloyd-ss

Active Member
Feel free to start a new thread with the details on your Lithium Ion conversion @just_me . :thumbsup:
That sounds like a good idea. I know your cart (just_me) is quite a bit different from mine so it will be fun to see how you approach the conversion.:)
And Diode has his coming too!:)

I kinda wish I had another cart, a newish one that only needed new batteries to see if it could be a simple drop-in change to Li Ion. And it is definitely cool that these Nissan Leaf Li Ion battery modules are all from wrecked or junked cars and can be recycled as-is.:)
 
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