Costco Jupiter Discovery X5 E-bike Battery Replacement

We bought two of these e-bikes from Costco in April of 2021 to take with us when we went camping in our truck camper. The bikes are 36 volts with a 350 watt motor, so no speed demons, but they would fold in half and fit in the back seat area of our F350 crew cab without too much trouble. One little hiccup, when the pandemic hit in 2020, everyone and their brother went out and bought an RV, so by 2022 all the campgrounds got overcrowded and difficult to get reservations. We ended up selling our camper in May of 2023 but kept the bikes.

For whatever reason, we didn't end up riding the bikes much for a year after selling the camper, and when I went to charge my bike in 2024, the battery pack wouldn't take a charge. A new replacement GNS6 36-volt Lithium-Ion battery pack off the internet was in the neighborhood of $300. I think we only paid $600 or $700 each for the bikes.

Fast-forward another year or so and I decided to try and get a new battery for the bike. I did some searching on Amazon and found a generic battery pack for $76 shipped to my house. It's the same 36 volts but is 8 amp-hours versus the original battery's 5.2 a-h rating. The new battery is larger than the original one and will obviously have to live on the exterior of the bike's frame but I can live with that for the 75% cost savings and 54% greater capacity. Of course it remains to be seen how long this new battery lasts.

By the way, the wires coming out of the new battery pack don't appear to have any type of strain relief so I taped the wires to the battery pack to help alleviate any strain on them.

I did try to revive the old battery last year but didn't get anywhere.

This next photo shows where the original battery resided inside the frame. It's pretty small in there and takes a very specific size and power connector envelope.

Below shows the old battery power plug on the left (yellow one) and the plug on the right that came on the new battery (red one). The top black plug is the new battery's charging cable.

The old battery was actually hard-wired to a 5-spade female connector that mates to the connector shown below. Inside the frame of the bike I found the yellow connector seen above (it was soldered to the connector below) and removed it so I could solder it in place of the red connector seen above. By the way, the 5-spade connector and the mating one on the battery look intimidating wiring-wise but they're not. They basically have four wire connections. The two end ones are "+" and "-" from the battery that connect to the motor controller to power the bike and the other two are for charging the battery.

On the battery side, all the red and black wires terminate at "+" and "-" lugs on the battery. When I first saw this maze of wires I figured they went to different places on the BMS (battery monitoring system) but after a bit of study, it became clear that they all just terminate at the battery. The old wiring for this bike seemed to be overly complicated. The new battery and wiring is very simple.

The new battery's charging cable just hangs off the battery. I could have wired the charge cable into the charging jack on the side of the frame but decided to not cut and splice any more wires than necessary.

The new battery location and fastening system (electrical tape) isn't elegant at all but it is functional. Someday I hope to sew together a nylon strap with hook and loop (Velcro) fasteners to hold the battery in place. Someday....

The new battery is installed and connected up to the bike's controller. It actually works and I took the bike for a short spin. It was dark and the bike's tires were low on air so I didn't go far. It'll be fun to try it out in the daylight.

It's the next day and I took the "new" bike out for a test ride. It works just as it should. There's an uphill incline that I used just the bike's throttle (no pedaling) and was able to maintain 14.7 MPH, which doesn't seem bad for a 350 watt motor lugging around my 220 pounds. I then took out the second bike with the original battery and it only went 13.4 MPH up the incline. I guess someday it will need a new battery.

It's still the next day ("someday" has arrived apparently) and I didn't like the tape holding the battery to the bike so I went to the basement and dug out some 1-inch nylon webbing and Velcro. I fired up the industrial strength 1957 Singer 111W155 walking foot sewing machine and went to work making a webbed strap hanger to hold the battery onto the bike.

It's still not elegant by any means but is a whole lot better than the previous electrical tape. I also put the battery inside a plastic bag so as to keep most of the moisture off the battery. It was raining earlier today when I went for a spin and the battery got a bit wet, and it doesn't look at all waterproof.