Lithium Battery Conversion

GEM Forum
1

I have a 2009 GEM eS with AGM batteries. One of the things I’ve enjoyed about the eS is its total hands-off reliability. I can park it for a month, hop in, turn the key and drive away. It’s been trouble free for over five years and I’d like that to continue. But I believe this is the year the batteries are scheduled to go South and I’d like to replace them with Lithium.

I have followed several conversions online (including bgeery’s, but he hasn’t posted in several months). All were done by someone much more conversant in things electrical than yours truly.

So I’d like a turn-key solution. While I’m an electrical Luddite, I am an experienced ICE wrench. I believe I could do the installation from a “kit” that contained ALL the necessary parts and step-by-step instructions. I might not mind paying someone to do the conversion. I’ve spoken with several vendors over the past few years and they are, without exception, selling batteries and have zero experience with a late-model GEM. I would like a proven solution – one that has worked for an extended period in other GEMs.

Any recommendations would be most appreciated.

2

I have NOT done this conversion due to cost BUT I believe you’ll purchase the batteries along with a BMS (Battery Management System) intended for your new LI batteries.

Mechanically you’ll obviously need to get the batteries and the BMS to fit into the battery bay and under the dash but that shouldn’t be too difficult. The only dilemma will probably be getting the total voltage to be in the range of the existing batteries. I think you’ll find that each LI battery cell isn’t the same voltage as your existing technology so the supplier will need to “tweak” the number of LI batteries to get to a nominal 72V or slightly more when fully charged. The old charger will need to come out to be replaced with the supplied BMS. Electrically don’t think you’ll have much to do once you get it physically installed. I THINK the BMS will have a separate lead for each LI pack but that just means running more leads instead of just the two for the lead acid technology.

Good luck! Let us know how it goes.

Al

3

[quote=ARandall;23821]The only dilemma will probably be getting the total voltage to be in the range of the existing batteries. . . . The old charger will need to come out to be replaced with the supplied BMS.
Al[/quote]

Al,
Thanks. You have identified my dilemma. I have no idea how to do that. Nor what BMS is required. Hence my search for someone who’s already been there, done that. I’m not in an “experimental” mood with this vehicle.
Don

4

Hmmm

Did some searching on Yahoo. Looks like a $5,000 plus item. Whan you do this we are very interested and would like a detailed story on the process with lot’s of pictures.
Can’t wait.

5

I think the battery OEM is responsible for that portion.

6

Based on my research, appropriate batteries are available from China for around $3000 plus shipping. One can also spend $7000 for batteries that look just like the AGMs being replaced.

Appropriate BMS and install is on top of that.

I’d still like to find someone with experience to talk about this.
Don

7

[quote=Laslonimne;23818]I have followed several conversions online (including bgeery’s, but he hasn’t posted in several months). All were done by someone much more conversant in things electrical than yours truly.

So I’d like a turn-key solution. While I’m an electrical Luddite, I am an experienced ICE wrench. I believe I could do the installation from a “kit” that contained ALL the necessary parts and step-by-step instructions. I might not mind paying someone to do the conversion. I’ve spoken with several vendors over the past few years and they are, without exception, selling batteries and have zero experience with a late-model GEM. I would like a proven solution – one that has worked for an extended period in other GEMs.[/quote]

Hey, I’m not dead! :eek: I get notifications if someone replies to my GEM conversion thread.

There are some kits out there for GEMs now, but most of what I’ve seen are overpriced part kits. You still have to do all the hard work of installing all the parts and making it all fit. You might as well put your own parts list together and get a better overall price.

Conversion is easier on the older GEMs, because the Zivan charger can be (somewhat) reprogrammed. With a newer GEM you will have to replace the changer.

You will find a lot of debate over BMS, and the need for one. In my research, they are worse than waste of money. If you bottom balance and set the charging voltage correctly, it avoids the need for a BMS. Most anti-BMS people (bottom balancers) used to be pro-BMS, until it let them down and destroyed batteries. I’m not aware of a single pro-BMS person that has any experience running no-BMS bottom balance. They just insist you must to run a BMS.

Anyway, my thread has most of the info on converting, and the journey I took for my '02. You would have to add a charger (offboard or onboard) and maybe a BMS (if that’s the way you roll.) Also thundersky is no longer around, so you would be looking at probably CALB in California for the cells nowadays.

If you do have questions, let me know.

8

[quote=bgeery;23865]
Anyway, my thread has most of the info on converting, and the journey I took for my '02. You would have to add a charger (offboard or onboard) and maybe a BMS (if that’s the way you roll.)
If you do have questions, let me know.[/quote]

Thanks for the reply Brent. My attitude seems identical to [I]nakedwaterskier Jeffrey - “I am a gearhead not a chiphead ie I am fairly mechanically inclined but not electrically inclined. I am afraid to start tinkering/upgrading unless I can find a reliable source of knowledge.”[/I]

I’ve read your thread multiple times, including the updates yesterday. I’ve looked at the photos you posted yesterday also. I know you couldn’t fit the Lithium batteries in the same place as the original and had to build custom hold-downs and relocate the two batteries under the bed to the motor compartment. My '09 is different in may ways from your '02, but I could probably figure out how to install and wire the batteries. I confess I’m not excited about relocating the two batteries - surely there’s room under there to make them fit??

You correctly say I’ll need to add a charger. As I said earlier - I want the same conveniences I currently enjoy so an onboard charger is the way I would go. I understand from your posts that you still have to monitor your charger to prevent overcharging. That doesn’t appeal to me. If I opt for no BMS, this is probably the biggest stumbling point right now. Is there not a charger that can be set and forgotten?

I appreciate your experience and help.
Don

9

I think you’re going to find that a Lithium Ion conversion is NOT yet “mainstream” and you will be a technology pioneer at least in the GEM community.

If you live in a big city, you might get lucky and find a shop somewhere that would be willing to do this for you on a turnkey basis but they are going to charge you for it I’m sure. Other than that I suspect you’ll have to wrench you own. As far as I can tell, there’s nothing “turnkey” about it.

My real question is why anyone would spend this kind of money on a LiFePO4battery system when you can buy a LOT of lead acid technology for the same amount of money. Assuming costs eventually come down significantly AND/OR the advantages go WAY up, I’d consider it but given the current cost/benefit, it really doesn’t seem to make sense at least to me. I think you’d need to commit to keeping the converted GEM for at least 8 to 10 years to make any sense and that assumes the Lithium batteries won’t need replacing in the interim.

I suspect that those who made this conversion like Brent enjoyed the engineering and tinkering for it’s own sake rather than any practical reason.

Good luck and if you do the conversion, please let us know how it goes.

Al

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[quote=ARandall;23889]
My real question is why anyone would spend this kind of money on a LiFePO4battery system when you can buy a LOT of lead acid technology for the same amount of money.
Al[/quote]

I can answer your question in one word Al - range.

A couple of years ago I replaced my 12.44:1 gear with a 6:1. While I can now easily cruise at 40 mph, my range has dropped to 12 or so miles. I would like to see 30 or more miles per charge. I understand that is easy with LiFePO4.

I suspect you’re correct that I’ll not find a turnkey solution. But I won’t know unless I try.

Don

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[quote=Laslonimne;23890]I can answer your question in one word Al - range.

A couple of years ago I replaced my 12.44:1 gear with a 6:1. While I can now easily cruise at 40 mph, my range has dropped to 12 or so miles. [/quote]

I upgraded my motor and reprogrammed the controller to achieve more top end. If I don’t push the pedal too hard and keep the speed down the range isn’t awfull. More range [U]would[/U] be nice of course but at what cost?

Al

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[quote=Laslonimne;23886]I know you couldn’t fit the Lithium batteries in the same place as the original and had to build custom hold-downs and relocate the two batteries under the bed to the motor compartment. My '09 is different in may ways from your '02, but I could probably figure out how to install and wire the batteries. I confess I’m not excited about relocating the two batteries - surely there’s room under there to make them fit??[/quote]No, in my conversion, the batteries are placed exactly where the old ones were placed, I just had to modify the front battery tray (the one under the hood) by removing the front half if it. The taper at the tray bottom was just a bit too small. The existing aluminum angle was enough by itself, without the tray.

I was trying to fit the largest LiFePO4 cells I could easily fit. If I would have used smaller, say 100Ah cells, I probably would have been able to fit them all under the seat, and none under the front hood.

Find out how big the cell are you plan to use, mock up some batteries in cardboard, and see if they will fit your existing battery trays on your '09. Then you just have to figure out how you want to tie them down. You can find extra long battery tie down “J” bolts that work great in most cases. These are both mechanical tasks, that even I managed to pull off easily enough.

Wiring the batteries together in series is the easy (electrical part).

[quote=Laslonimne;23886]You correctly say I’ll need to add a charger. As I said earlier - I want the same conveniences I currently enjoy so an onboard charger is the way I would go. I understand from your posts that you still have to monitor your charger to prevent overcharging. That doesn’t appeal to me. If I opt for no BMS, this is probably the biggest stumbling point right now. Is there not a charger that can be set and forgotten?[/quote]Yes I still monitor the charge manually, but it’s second nature to me after a few times. I only charge once or twice a month, so I’ve never bothered to improve the system. I plug it in, and come back 8-12 hours later and unplug it.

I could wire in a JLD404 (or here) on the pack, and when it hits 85 volts, a relay cuts AC power to the charger. No need for a BMS for that function (uh, that might qualify as a simple BMS, of sorts). eBay sells these things too. Hmm, here is a guy that used a JLD404 (as Ah gauge) in a lithium golf cart conversion.

With lithium, the OEM fuel gauge will no longer be accurate. If you want a fuel gauge with the the new cells, the Cycle Analyst is the best choice today. But, if using a JLD404 anyway as a poor-man’s BMS, might as well also use it as a Ah meter (fuel gauge).

You can certainly have equivalent functionally to your current lead setup.

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[quote=ARandall;23889]I think you’re going to find that a Lithium Ion conversion is NOT yet “mainstream” and you will be a technology pioneer at least in the GEM community.
…

My real question is why anyone would spend this kind of money on a LiFePO4battery system when you can buy a LOT of lead acid technology for the same amount of money.
…

I suspect that those who made this conversion like Brent enjoyed the engineering and tinkering for it’s own sake rather than any practical reason.[/quote]Hey Al,
Lead is dead. Lead never worked right in EV use, but it was all we had back in the day.

I can assure you I did the conversion for the most practical of reasons. Having an 80 mile range means a GEM becomes a practical main transportation means, vs a cute toy to run down the street with.

The cost of a set of lithium cells is the cost of about three sets of lead batteries. The lithium cells have the life cycles to meet or exceed to life-cycle cost of lead, today. With lead just going up in price, and lithium either flat or going down, the economics only get better with time.

But you are right about holding on to your GEM. You will never make back the cost of the lithium conversion when you go to sell, so get your money’s worth out of them while you are the owner.

But on the subject of money, it’s not as much as people seem to think. If you want equivalent range to the lead pack, a lithium conversion on an '02 GEM can be under $2K, and you can expect 2-3k cycles out of the LiFePO4 pack.

I think many people over-think the conversion process with these GEMs. There really isn’t much more to think about, beyond what someone might have to think about when replacing flooded cells with AGM batteries, for example. It’s not really a conversion; it’s more just an adaption. Do the cells fit? How do I hold them down? How to charge them? Is the fuel gauge still accurate? That’s about it.

14

Brent

Extended range would be nice! I suffer from range anxiety like most of us. Unfortunately my wife is an accountant and I’m an engineer so we do cost/benefit analysis on almost everything! I bought my GEM without cost justification and I’m still hearing about that three years later so a lithium conversion isn’t in my future sadly.
Al

15

Probably what would really bust open the market would be if Polaris offered a factory option for lithium batteries. Though I suspect it would be expensive and add significant $$$ to what is already a pricey “toy” for most of us. Lead may be dead but it’s still good enough for the average owner.

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REALITY: Over 92.34% of us don’t have range problems. We plug them in and drive them.

This is one of the reasons so many of us get away with using MDC31 (Marine Deep Cycle) batteries. We putz around the neighbor hood, run to the store, run uptown, take short joy rides etc. A typical trip for me is +/- 6 miles.

In almost all cases the GEM is a descretionary toy and is not our primary mode of transportation. I believe that the majority of us don’t even Golf.

Hmmmm Do you use yours to Golf?

17

I agree with your observation that most GEM owners don’t have range problems (though “Over 92.34%” seems a bit exact - :)).

I wonder what new markets would open up for Polaris IF they offered an LI option for a range of “up to 75 miles”. Sounds like there are other advantages of LI (extended range, little to no self-discharge, no need to recharge whenever possible, reduced weight, life of battery pack) to offset the rather large cost disadvantage. In certain applications (i.e. traffic patrol, package delivery services) I can see that having extended range MIGHT cost-justify the purchase of LI technology.

Al

18

I’m sure that in the future LI batteries will become common. However I’m 75 and probably won’t be here to see it. My good friend is a GEM sales manager. He sells only a very few carts with 9 8 volt gel setups which is the current state available state of the art.

For what it’s worth I like your 75 mile figure. At that capability you have a vehicle that is useful as a primary mode of transportation. Think Nissan LEAF.

Let’s face it. GEM’s are a toy and are not cheap.

19

[B]IF[/B] I lived in a warm weather state where I could drive year round, I might consider using my GEM as a primary mode of transportation rather than just a seasonal toy like a boat or a snowmobile though I’d still need to consider rain and night driving.

GEMs are certainly expensive to buy and own but I love running around on mine in the summer. Here in OH that’s far too short - maybe 5 months of fun!!

1 Like
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Al

As being a transplanted Michigander I can attest that doing everything you possibly can to move south IS WORTH IT!!!

Rodney