Converting CC (Ahem) to Lithium Power

[ronncat]

First Off. YES… I know this is the EZGO Electric section. But have you done any searches on Lithium conversions in the CC section??? Three threads and nothing in about a year. On the other hand, in this section…

I digress. Since I completed my 84 Volt Lithium AC motor TXT, I realized how tired my everyday cart had become. I built this Mercedes bodied cart a dozen years ago, and at that time it was the Cat's meow. 550 amp Curtis controller with a 5.5 Horse GE motor, (no such thing as D&D and Plumquick in those days) Big 1/0 welding cables, and bypassed the OBC. Sucker did close to 30 MPH until I strapped on the custom fiberglass body, Beard seats, stereo, etc, etc.

Anyhow, it was the fastest and trickest cart at the club for a long time. Nowadays, it struggles to keep up with a few of the other members' carts. Enter the 84 Volt monster,

http://www.buggiesgonewild.com/elect...motor-txt.html

So I'm safe for the time being… Although my neighbor is talking about buying the special edition Garia which will definitely give me a run for the money.

Which brings me back to the conversion. I have located a local source for new Leaf Modules. I plan to put seven of those in which will give me a nominal voltage of 53.2 Volts and a fully charged voltage of 58.8 Volts which I will limit to somewhere between 56 and 57 volts through the BMS. In my 84 Volt conversion, I used a mini-bms along with an EV Display from Dimitri at Clean Power Auto. Since then I have stumbled onto the Orion jr BMS. Seems that the wiring would be easier, but the display shows only SOC as opposed to the EV Display which shows everything from SOC, Pack Voltage, Fuel Gauge, temperature, current, etc. There is also a 50% cost premium for the Orion…
Will have to puzzle this one out

Also, I want to try to keep my existing controller and motor. Seems as if the controller has a max voltage of 60 Volts, so I will be within its spec. The motor should be OK as well I hope. Maybe it's time for new brushes and some TLC, but I just want to get the conversion done first.

Then I am debating whether to use the existing DC/DC converter to supply the 12V to lights radio, clock, etc. It would certainly be easier, but don't know if I'd rather do a standalone 12 volt system as I did in the 84V cart.

Lastly, the charger… It's neat to have an onboard charger. Had Elcon (local to me) configure one for the other cart and I may do the same here. I know I can just have the bms cut off my current charger at a certain voltage, but it's programmed for LA and not Lithium batteries. Gotta think that over too

Just wanted to get this thread started while it's fresh on my mind. I'll try to document with pictures as I get into this as I think this is a worthwhile and more usable conversion than my other build. I'm thinking that the entire conversion should be somewhat south of $2K. Given the life expectancy of Lithiums vs Lead Acids, this thing will pay for itself over the next few years

[sportcoupe]

Ron,
If you are going to use a BMS, I believe you could keep your current 48v charger if it can hit 58.8v (doubtful). Elcon is good but consider Quick Charge also, they can be lithium programmed for any cut-off voltage you need. For my conversions that eliminated the BMS reducing costs.

[ronncat]

Originally Posted by sportcoupe

Ron,
If you are going to use a BMS, I believe you could keep your current 48v charger if it can hit 58.8v (doubtful). Elcon is good but consider Quick Charge also, they can be lithium programmed for any cut-off voltage you need. For my conversions that eliminated the BMS reducing costs.

Will do…

I measured my pack at 52.8V, so probably no go for this charger

Don't know too much about the Quick Charge so I'll have to check it out. The advantage of the Elcon is that I can have them program it so I can add cells if I ever decide to kick up the voltage. Then a simple push of the button and the charger is reconfigured for the new pack voltage. Hmmm… wonder how fast I could go with 16 Leaf cells at 121.6 volts nominal

Problem though is once I pass 8 Leaf modules, I would outgrow the Orion jr bms. Would be no problem with the mini-bms though, as I can add as many cell boards as I need. Let's see… 8 modules gives me 60.8V nominal and 67.2V at max charge. At that point I would need a new controller as well And who knows if the motor can take it. This could get expensive… I was gonna try to do this on a budget

[Revolution]

Lithium and budget don't often get used in the same sentence!

[sportcoupe]

The Quick Charge has an adjustable pot on the main board that can be used to increase voltage if cells are added. I don't know it's max range though, may involve shipping back for reprogramming once a certain range is exceeded.

Once you pass 80v alltrax is out of the question for controllers and you'll have to go full size EV controller. That's where the price is really going to jump.

[ronncat]

Was jus dreamin

I mean what am I gonna do if both of my carts are that fast??? Probably end up running one into a tree at some point. I think I'll try to pick up a little speed with this install. I mean, if I drop 300 lbs or so of lead, the cart should go faster Add a couple of Volts and the capability of moving max current through my existing controller…. who knows??? We'll just have to find out. Put a deposit on my Leaf cells and will pick them up when I get a chance.

[ronncat]

Leaning back to using the mini -bms instead of the Orion jr

Couple of reasons…
1) The mini-bms is a tried and true set up for me. I already have the cad files to mill out the cell board mount.
2) It allows more expansion than the Orion jr.
3) I like the SOC meter more than the one from Orion. It gives me all kinds of info that the Orion does not. Plus, since it is round, I can take out my old Curtis SOC meter and do a direct replacement. (P.S.- anyone need one?)

On the other hand, the orion has a Canbus option and is VERY programmable. Can also download all the battery info and give it the once over….
Then again, do I really care about that?

What are your opinions on this…It just a stinkin golf cart...

[ronncat]

plus… the mini-bms is only 2/3rds the cost

[benjylafond]

Originally Posted by ronncat

plus… the mini-bms is only 2/3rds the cost

Ronncat: I followed your TXT thread. That is one badass cart! I converted my TXT to lithium and initially installed the same mini-BMS you did along with a QuickCharge charger configured to cut off at 42.00 volts (I used 5 leaf modules). Had some issues with the BMS so I re-did everything and went with SportCoupe's bottom balancing method and got rid of the BMS. Haven't had any problems with the batteries and they still charge fully to 42.0 volts after approximately 100 rounds of golf (I installed digital voltmeter on dash so I can watch for low voltage issues).

[sportcoupe]

To me, Ron said it best. "…It just a stinkin golf cart.."

For that reason and I don't care to get absolute maximum range from a cart I see no need for a BMS. It's just more expense and complexity to what should be a simple transportation. I bottom balance each cell, then balance the pack and then charge to voltage cutoff. Done. For some sense of safety I add a simple balance alarm that will tell me is a cell goes higher or lower then the rest of the pack.

Is it wrong to use a BMS? Absolutely not. I look forward to the CC on lithium results.