I’ve been reading this forum for days and just get more confused. Thought I had it figured out a few months ago, but just getting to the conversion now and my memory sucks. So at the risk of getting yelled at for asking the same question, here goes. I have a 2008 e2. Going to install the Elefast 72v battery kit from amazon. Comes with a charger. My car has a dq charger with separate dc-dc converter. Just leave the current charger alone? Do I have to mess with the interlock or any other wiring? Just hook up the big orange cables to the pack? Just hook the charging wires directly to the battery? Or do they have to hook up where the current charger does? Anything else required? Thanks.
Been dealing with one of those on someone elses cart.
Those are 23 cell lfp4 packs. The bms is set to let them charge up to 76v. The important bms settings are locked as far as i can tell. So, if lead acid level performance at 3x the price of lead is your jam, then hop on that pony and ride.
Overall it’s not a bad pack. But it’s for a golf cart not a gem.
So at the risk of getting yelled at
You need to be doing some serious badness to actually get yelled at around here. If that actually happens, it is only to get you to pay attention, not to make you feel small or inferior.
Some of us are not beyond a bit of ridicule, rude comment, or good natured jab at (what looks like) your expense. Don’t take it personal. This is to lighten up a sometimes dull thread and in comedy- timing is everything.
Speaking of timing - (directed at you as well as future readers that wander into this topic later)
When you have any questions on a build, It is always better to ask questions BEFORE YOU BUY your components. We might have an opinion that may affect the direction of your build and to make it better/easier.
→ Do you already have your battery?
→ How are you going to use this car? (what are your expectations?)
There is actually a lot to consider when building/buying a proper battery pack for use in a Gem car. As J^3 pointed out, this battery may not be an ideal performer. Being only 23s the operating range is going to be 69~76v. (the lower end of the operating range).
Usually when dropping in a new lithium battery all you need to do is hook it up to the B+ and B- cables. The trick is getting the SOC/Battery Bars on the dash to register correctly.
To be continued…
I have not bought the battery yet. If I could buy lead acid for 1/3 I sure would. Seems 6 12v golf cart batteries are about the same price as this one. I’m not looking for any increased performance. It’ll mostly just be for my grandkids to drive around the property when they’re here. If there is a better battery for a reasonable price let me know. But this is one of the few I found that will fit. The height of this one is the max that will fit and most are taller. Still might need a little modding to get it in there. Since this one comes with it’s own display, I don’t care about the dash SOC bars.
I’m not looking for any increased performance. It’ll mostly just be for my grandkids to drive around the property when they’re here.
This is why I always ask. Sometimes we forget others have a different concept/intended use for these things. That’s ok.
Our concerns become highlighted when the needs/potential expand outside the box. Our group experience shows that these cars can be a lot of fun. In basic form, they are fun for a while, but being limited they quickly become → “meh”. Once you see the higher potential, I bet you will be using it more too. Beyond being a fun toy, they can be incredibly useful as long as the grand kids don’t beat it all to cr@p. If you are worried about the grand kids going all “Dukes of Hazzard” when you are not looking, there are easy ways to hobble the car with a hidden secret “adult” switch. (until they find it).
(secondary thought)
You might also include them in on the build. Don’t just give it to them - have them build it alongside you with a side dose of responsibility. These things are highly customizable. Wheels/tires, paint, lights, streamers, stickers. It is a great platform to show the younger generation how to change a tire, check/change the brakes (and how hydraulic systems work), basic electrical, etc. All of these are lacking in schools these days, (at least out here in commiefornia). Most of all, they should learn if they abuse the car and it breaks, there is consequence of losing the fun. They should know how to fix it.
I suggest is that you do a bit more research, see if you can find a battery with 24s as a base. It is still within stock voltage range, but more on the higher end. You will appreciate this later.
But you are not wrong. If you are not careful, they can become quite a money pit.
I for one used my Gem e825 quite differently and “out of the box”.. and a “money pit” was a great way to describe it.. but damn it was fun. ha ha.. Still run it in night parades.
I’m building my own LifePO4 battery pack for my Club Car golf cart. In doing so I have read a great deal and watched a lot of YouTube videos. Most recommend a different product each, but those that deconstruct some of the store-bought packs really give some insight in them. Be very careful of what you buy on Amazon. You could do as well on Alibaba. It can be a crap shoot. I’d recommend buying from a reputable dealer. Do your home work before you buy. There are several very good brands out there the best I can see, but many times more Junk. The BMS is very critical. A cheap BMS in a battery pack can cause you a lot of issues, even more than the actual battery cells. That’s one reason I’m building my own is to be sure the BMS is big enough to take the amperage without cutting out. I have a lot of hills where I live. I’d watch some videos on the batteries you are considering and just some general videos on premade battery packs. As to the charger. I don’t know that the GEM charger won’t handle Lithium. I installed a Lester Summit II charger on my cart and it will charge lithium as well. My GEM came with a separate Delta Q charger. I haven’t had a chance to figure out if the onboard charger works, but I have to assume it doesn’t. And, it looks like taking the GEM charger out and replacing it with an other onboard charger may be a huge task. These are questions I’ll probably be asking as soon as I get into my 2002 GEM.
Not necessarily. A builder just needs to understand how it is integrated into your car and why.
In your car (2002) it is even easier. Watch out for that green wire coming out of the DQ. It may not be compatible with your car.
Try the dq first. It may be fine.
Use 24s lfp or 22s lith-ion for full voltage.
I WAS going to post about the new tail light I put on the back of my car. I was fairly proud of it and thought it was cool, then you posted your train/conversion project.
#nevermind..
What do you guys think of this set of batteries? Will they work? Enjoybot 72V 65Ah LiFePO4 Lithium Golf Cart Battery Set - 2 Batteries – Enjoybot Official Store Gets me 76.8v, only 65ah but again, it’s just for the grandkids. And they are rated for 2s4p so could add 2 more if I wanted more range. And they are drop in replacement. Finding something that fits really limits the options.
ha ha.. OOPs.. sorry ole’ man..
Wow.. those look cool.. you could put two in series and then another two in parallel.. 72v at 130AH. Those two are about the same price I paid for my 100AH AGM 12v batteries but you can take these deeper, charge more cycles and last longer.. much longer..
They should work. Easiest is put them in front over the motor, and for the connections where the other 4 batteries used to be in back, use 1/4" bolts & nuts to lug them together where each battery used to be and then wrap with lots of electrical tape.
Your design gem needs weight over the front wheels for traction and steering, so if you put the batteries in back, then you may need to put some concrete blocks up front.
With a 2002 gem (in theory: 5hp short GE motor, 1 9b0:35:1 gears, T2 controller) 65 Ah will get you about 10 miles range IIRC on mostly flat ground, Hills, lots of start-stop, dragging brakes, lots of weight in the vehicle, teaching the grandkids how to make donuts, etc will cut that down, like down to 7 or 8 miles.
Can’t comment much on the charging without knowing more, being “drop in” for golf carts with lead acid probably can use your existing charger. If you get those batteries, then post photos of your charger and someone here can give you some help with changing the settings to be a bit more gentle as these batteries don’t need as much wallop as some of the older chargers were set to in stock config.
My Gem is a 2008 E2 and all batteries are in back. 4 under the seat and 2 behind them under the cargo box. I’m guessing by “drop in”, they just mean they are the same size as the lead acid batteries. But if my charger would work that would be great. Hard to get great pics with it hanging under the controller. Part number is 912-7200-01. Don’t see any lithium profiles in the chart for this charger. https://support.delta-q.com/hc/en-us/article_attachments/360012712932
One good thing about the LiFePO4 is that they have a deeper discharge bottom.. like almost to zero where the LA batteries should not really go below about 50%.
Usable energy (real life, not brochure math)
72V 65Ah LiFePO₄
- Nominal: 4.68 kWh
- Safe usable: 90–95%
- ≈ 4.2–4.5 kWh usable
72V 100Ah Lead-acid (6×12V)
- Nominal: 7.2 kWh
- Safe usable: ~50% (to avoid killing them fast)
- ≈ 3.6 kWh usable
- And under decent load? Often less due to Peukert losses Usable energy (real life, not brochure math)
What that means in practice
- LiFePO₄ gives you ~20–25% more usable energy
- Holds voltage better → equipment runs stronger for longer
- Lead-acid feels empty early because voltage sags
- LA weight is usually 3–4× heavier
- LA lifespan: ~300–500 cycles
- LiFePO₄ lifespan: 3,000–6,000 cycles
My bad - I thought you had a 2002 for some reason, I probably switched tabs by accident and skimmed the first post in a different thread from a different person.
Drop in replacement typically means they are about the same size, usually have terminals you can connect your existing wires to without too much extra work.
Of course they want to sell you their charger too, but if you look on page 7 of the instructions for the batteries, they list 4 methods to charge, one is their charger, they may have a solar controller too, but they also list 2 other methods that sound like connecting in to existing systems. I’ve never worked with this brand, nor do I know how their BMS is set up - specific settings would have to come from them. The manual lists some cut off voltages, there probably is more in the BMS.
Some DeltaQ chargers can have new profiles added and sometimes even new firmware, some can’t. It’s not just the part number as I recall, there is more info on the sticker or another sticker. There are quite a few lithium profiles on their website for download, they have to be matched up just like the lead profiles - manufacturer and battery model, when you can’t find an exact, get as close as possible. The BMS should have the ability to cut the charge off at a pre-set max voltage.
“Not necessarily. A builder just needs to understand how it is integrated into your car” But, that is my problem . . . understanding just that! I really haven’t looked into closely. But, at first glance there seems to be a lot going on in the integration. Just connecting the DQ is not difficult, but removing the old one scares me that I might disable something else. I’m sure I’ll be calling out for help when I get there. Thanks for theencouragement.
@kj2 - since your car is a 2008 (Gen2 car), you will be interested in the following:
There are two features in a Gen 2 gem that needs to be addressed.
- The interlock
- The SOC Battery display.
The interlock actually does two things. It locks the car when it is plugged in so you don’t drive away and yank the cord out. This is easy to defeat, but you need to manually trigger it if your charger does not have an interlock contact built into it.
Search the archives using the key words → green wire, interlock
When active, it also puts the car in Charge mode, and resets the SOC Battery display after a full charge cycle.
The SOC Battery display uses a shunt (built into the PSDM). The charger needs to be installed on the correct side of the shunt so it can see the current flow going into the battery.
Search the archives using key words → SOC, Dash Display, battery bars, etc.
Make sure that when you disconnect it, everything is turned on and powered up. Makes you feel alive especially when you get that first loud crack sound from one of the wires. At that point i like to yell loudly “I am Thor! Fatass god of lightning” but you do you.