16-18 GEM 500W DC Converter Recall

Polaris has issued a service bulletin recalling all 500W DC/DC converters in 2016-18 GEM’s. Intriguingly, they’re replacing it with a 300W unit. Does anyone know why the discrepancy? Anyone have a wiring diagram that might help us evaluate the connected load? I’m hesitant to decrease our power output by 40% without knowing at least what the load is…

Where is the DC/DC converter located on the 16-17

Mine is under the controller. 2018

I don’t know reason for the recall, but I can guess, as I’ve been studying the Sevcon converters.
Some are rated for battery charging, some are not. It may be that adding an aux. battery requires a dc-dc rated for battery charging.

Dimensions Standard
7.5(L w/ base) x 2.98(W) x 1.70(H) inches
5.6(L) x 2.87(W) x 1.69(H) inches
190(L) x 75.8(W) x 43.3(H) mm

Input Voltage nominal:
48V (28.8V Min. – 60V Max.)

Output Current
The converter will deliver a load current of:
48V to 12V @ 300W, 20.4 amps
Light load 13.5 Volts

Can be used to charge a battery

Operating Temperature -25C to +55C

The Sevcon DC/DC Converters are suitable for all electric powered vehicles and are designed to be fitted on-board the vehicle and connected permanently to the battery.

These converters deliver a stable isolated high power, low voltage DC supply for such accessories as lights, horns, and wipers. This eliminates inefficient battery taps and fragile, expensive high voltage accessories.

According to the GEM Parts Finder, the 4015999 500W DC/DC converter is replaced by the 4013453 300W DC/DC converter. The 300W converter on my 2018 e4 is mounted on the rear battery tray next to the Brammo BMC. I am taking measurements to install an Interstate GEL0100 and Samlex 600W inverter to power an Inogen O2 concentrator (the converter and BMC will be relocated nearby). Cart Mart is installing an EPS which includes a front-mounted auxiliary battery. The e4 already had the DC/DC relay installed. I didn’t notice an auxiliary battery anywhere.

Just to clarify: the Interstate battery and Samlex inverter are completely separate from the GEM electrical system. The battery will be recharged by a NOCO 10amp charger with a separate 110VAC port next to the J1772 port (there will be a safety interlock to prevent movement until the cord is unplugged). I’ve briefed Cart Mart on this design and they don’t see any safety, operating or warranty issues.

why didn’t you just install a 48v inverter ?

I considered the 48V option and it had many advantages especially simplicity. But for safety, operating and warranty reasons I chose a separate and independent power system for the O2 concentrator. I’ll post a top-level drawing as a new topic (so I don’t hijack this one) later this week.

BTW in the battery tray photo, the 300W 48V-to-12V DC/DC converter is top left; the white dingus is a standard SPST relay; the blue dingus is a fuse holder; and the BMC is bottom right.