2018 GEM Changing AGM to AGM extended battery pack

So I am changing out the battery pack on a 2018 because I got a great deal on a set of 6 volt AGM batteries (shelf pull locally). So far it doesn’t look as easy as changing the Delta Charger algorithm. I did some research in the Service manuel last night and it appeared that my BMC needs to be flashed to accomodate the changes in battery pack. I no longer have my DW setup ( since I couldn’t do anything other than read without dealer code). Can anyone out there flash my BMC or do I need the local mobile Polaris guy to do it? I’m happy to ship.

ECU programming says “do not continue unless battery is fully charged” Does that mean the battery pack have to be present when programming the BMC? Can it be any battery?
ecu programming (2)

DJgabriel2004 to the rescue!! I’ll send him the bms tomorrow and will post results after reinstallation. Many Thanks!!


So I’ve done some additional thinking about the BMS flashing vs Delta Q Charger reprogramming. I am sending the BMS to DJgabriel2004 to reprogram. I’m thinking that flashing the BMS will tell the ECU what type of battery pack I have. And that would reflect on the range displayed on the speedometer. And also monitor the discharge of the batteries thus adjusting the range display as the batteries are drained.
But I don’t think BMC flashing will instruct the DQ charger of the battery pack change. I will consult the service manuel, but I can’t recall any communication that Polaris DW has with the charger.
I think that the DQ charger will require reprogramming. So I purchased a programmer from EV drives today to install algo 359. I think I need to do both steps, flash BMS and new algorithm for charger. Worse case I’ll have a programmer to lend out right ?

Manual says that bmc does communicate with charger. I have no idea how.
If I get time I can see what profiles are in charger. Will DQ give you the correct algorithm for a GEM?
I think they are proprietary and not shared. Generic will not work in a Gem charger. They will load but not work.

359 is on the Generic charger list so chances are it doesn’t work.
My information is the 72v systems. May not hold true in the 48v models.

I contacted Delta Q with my charger and serial number. Apparently for chargers after 2011 you can read and write the algorithms. .
What is the Serial Number and Part Number of your charger? I need to check to see if you have custom software used in some chargers for GEM vehicles.
Xavier Duque (Delta-Q Technologies Corp.) Jan 17, 2022, 11:32 PST
Hi John,
You should be able to re-program your charger. The most suitable algorithm for the battery you described is algorithm 359.
Unfortunately, you don’t have that algo installed in your charger. You’ll need to use the QuiQ programmer CT to upload algo 359.

So BMC does set the charger algorithm, Inwo was correct!. I’m expecting once BMC (not BMS sorry about that) is flashed it will set the algorithm for the DQ charger. Guess I bought the programmer for no good reason :pensive:

I have completed changing from 4 distance AGM batteries to 6V 8 pack AGM batteries and want to complete this thread. I was able to get 8 AGM 6V batteries from a solar installation which the owner changed his mind. They were not used with current date codes. They are MK Batteries 8AGC2-DEKA (6 Volt 190 Amp Hour AGM) which I got for $80 apiece. The GEM Battery tray needs modification. As you can see from the pictures, there are 3 holes on the GEM frame to accomodate 3 different battery trays. I failed to take a picture of my modified tray. (too excited to install) But I ended up adding 5.25" to the width on both sides. It bolted in perfectly to the stock holes. The aluminum stock used on GEM trays is 3/16". I used a 30" 3" strip in the center, and 3/16" angled aluminum stock to extend the width. The aluminum ran $60, and the welding ran $100. In retrospect I could have ordered a new tray for under $200. But my design came out nice and the welder did a great job. The Battery hold down rods are the same for all models, so no cost. The hold down straps are different and cost around $14 apiece for 3 ordered through Polaris. I also sent my BMC to DJGabriel in Florida to flash from the “4 batteries without filler caps” to the “8 batteries without filler caps” at a cost of $100.
Once installed, I immediately saw the range extend from 23 miles to 41 miles. So once the BMC is given a different choice of battery pack it puts the standard range for the updated pack. It is also my understanding that once the BMC is flashed with a different pack, it notifies the DQ charger new instuctions. So no need for me to change the DQ analog. They charge to 100%


In conclusion I needed batteries in this 2018 GEM. Didn’t want to sink the bucks in for Lithium because I will eventually sell it. So for under a grand, I updated my distance from 23 to 41, and had some fun.

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