Thought I’d start an updated thread around 2016+ GEMs and how to get better performance out of them. I did a high voltage conversion over a year ago and know we’ve learned a ton about these cars since then; batteries have changed, BMSes, controller programming, etc. Was hoping to get a discussion going as a reference guide for someone with a stock 2016 that’s looking to break the 25mph barrier.
Maybe we break this out between 48v and 72v+? Or Value to Performance?
What motors are available? (5kw stock, 6.5kw stock, 8kw, 10kw, PMAC?)
Controller options? (s4 72v, s6 72v, s6 48v, stock 48v controller)
Gears? (9:1, 12:1, 17:1)
Chargers? (Delta Q DCI)
Batteries? (So many options… what are folks stocking?)
BMS (chargery, JK, ANT)
Ideally, where’s the best place to source parts, and which forum members should we reach out to?
Swapping gears with accompanying proportional loss of torque. Not a huge issue as they have plenty torque to begin with.
Contrary to big name Gem builder’s opinion, high speed will lower range.
Reprogramming is available now at a price competitive with gear change. No torque loss but limited to 35mph @ 9,000rpm. We can push it to 10,000 rpm if you ask at your own peril.
Requires that parts be removed and sent in to be programmed.
All oem functions and dealer access unchanged.
Controller swap can be done economically, but only with battery swap to over 50v. 14s +.
Speed is still limited to 35mph. Works with gear swap for more speed.
Working speedometer, but somewhat buggy at this time.
Added wire harness is needed, but is getting easier to do.
I have two battery packages available for 2016+. Both come with Bluetooth BMS and custom battery cover. Both are available in:
14s = 56v use stock charger settings
15s = 60v use stock charger setting with one of our spoofs.
16s = 64v reprogram factory charger, may work with stock dc converter, testing happening now
#1 234ah, 60-70 mile range. $3195 (same capacity as Polaris’s largest lithium pack that costs $12,500) #2 312ah, 90-100 mile range. $3950. Biggest battery available for a Gem.
#1 Also available in a 24s, 96v configuration. This is the voltage, Ah that @grantwest is running.
eM’s are a bit of a different animal than any other Gem, ever. RWD, 4-wheel independent suspension, 4-wheel vented disc brakes, anti-sway bars, adjustable rate suspension. 7.5hp motor stock w/ 17:1 gears. 2" hitch receiver standard. They are work trucks. Mules. Tugs. Drag a 2000lb trailer around no problem. Not really built for speed, but 25mph sucks.
My 2015 is pretty much stock still, save some reprograming that Dave performed on it before he shipped it out. Raised the speed limit / RPM limit in the controller and and at my request, upped the regen. On paper, this should give 35 mph with the stock tires. I hit 33 with the worn out OE AGMs. Yeah, it’s that simple. Talk to @Inwo about a reprogram. No issues with buggy dashes (cab electronics and displays are unlike all other GEMs) everything worked great. The extra regen I requested in preparation for a Li-Ion pack blew the old azz #1 AGM battery apart, but that’s a different story.
Derrek converted his to lithium, I have all the parts to do something similar, just haven’t had time yet.
I did talk to Rodney about gear swaps, he confirmed he could put a 12:1 set in the TRIM gearbox that mine has, YMMV.
Having run Emmy at 33 a few times, I don’t know if I’d want to go faster than 35 though. They sit high and have very short wheel bases. With a full cab option and a steel bed with sides that’s a lot of weight up high. Stability at speeds concerns me. Emmy is basically like driving a real-live Tonka truck.
Without the cab and the bed sides, just a bare bed and the roll cage, might be a different story, they use a lot of Polaris Ranger parts as they are built on Ranger 300 steel frames, so a RWD go-fast GEM eM1400 might be a possibility for someone some day.
I have a 2017 em1400 with 2p14s lithium battery pack and I had @Inwo reprogram my controller to get more speed. I haven’t done anything with the charger, it should be set for agm batteries and it works great. It’s a bit buggy with a full charge when pulling out of my driveway, the regen causes the BMS to cut out (set at 3.95v/ cell). I can tell the difference in performance between full charge (~54v) and partly depleted (~48v), full charge it will quickly accelerate up to 35 mph and when it’s run down a bit the acceleration is a bit slower up to about 30 (but still quick enough) and then creeps up to 35. I have been thinking about adding 2 more batteries to make a 2p15s pack which will allow the batteries to charge more and not rely on the BMS to stop them from over charging and to keep the voltage up for a longer period of time ( it should keep the the batteries in the flat section of the voltage/capacity curve).
