If your Onewheel suddenly pushes the nose up even though the app still shows 50% battery or more, the battery may not be delivering the power the board expects. One possible cause is an imbalanced or weak cell in the battery pack.
The battery percentage shown in the Onewheel app represents the battery pack as a whole. The BMS also monitors the individual cells, and a weak cell can reach its low-voltage limit before the rest of the pack is empty. The result can be an early low-battery pushback, often called Captain Morgan.
An Onewheel can push the nose up with battery remaining if an individual battery cell reaches a low-voltage limit before the rest of the pack. An imbalanced or weak cell is one possible cause.
The first thing to do is check the individual cell voltages and see if one cell is dropping below the others. A balance charge can sometimes correct an imbalance, but if the same cell keeps falling behind, the battery may need to be replaced.
A weak cell often discharges itself during storage, this results in the board working fine if it’s ridden and charged daily but after a couple of weeks of storage, the cell will lose capacity and drop in Voltage. The Onewheel is programmed to stop the board when the weakest cell reaches 3V, independently of the total voltage of the pack.
How to check for a weak Onewheel battery cell
The easiest way to investigate an early Captain Morgan event is to look at the individual battery cell voltages. You can use the Onewheel Community Edition (OWCE) app to view the individual cells on supported boards.
1. Fully charge the Onewheel
Charge the board fully and allow the BMS time to balance the battery cells.
If the cell voltages are already close to each other, this is a good starting point.
For more information about charging and balancing, see my guide to Onewheel charging recommendations.
2. Check the cell voltages
Open OWCE and look at the individual cell voltages.
You are looking for one cell that is noticeably lower than the others, rather than focusing only on the exact voltage of the entire pack.
A healthy battery will normally have cells that remain relatively close to each other.
3. Ride the board carefully
If you need to reproduce the problem, do not deliberately push the board beyond its limits.
Monitor the battery and stop riding if the board starts giving strong pushback or another battery warning.
If Captain Morgan happens while the app still shows a substantial amount of battery remaining, check the individual cell voltages again.
4. Charge and repeat the test
A battery that is simply out of balance can sometimes improve after a long charge.
After charging, check the cells again. Then leave the board unused for a few days and check them once more.
If one cell repeatedly drops lower than the others, the problem is more likely to be a failing or degraded cell rather than a temporary imbalance.
5. Consider battery replacement
If the same cell repeatedly falls behind after balancing, the battery pack may need to be replaced.
If the board is still under warranty, contact Future Motion before opening the battery or installing third-party hardware.
Can storage cause Captain Morgan?
Long periods of storage can contribute to battery problems, especially if the battery is stored at a very high or very low state of charge. Future Motion In.c, we and the community currently recommends storing the Onewheel at around 40-50% battery and checking the charge level monthly. It also recommends avoiding long-term storage at 0% or 100%.
If your Onewheel has been stored for several weeks or months and suddenly starts doing Captain Morgan with battery remaining, give the battery a full charge and allow the BMS to balance the cells before assuming that the battery has failed.
If the problem returns after the cells have been balanced, check the individual cell voltages again.
How to live with a weak battery cell.
Sometimes battery cells get imbalanced and a 72-hour charge is enough to resolve it, at least for a while. The key is not letting the cell discharge before riding the board. Therefore don’t let it go more than a few days between charging the board.
The only fix is to get a new battery, there are off-market options from JW batteries and ChiBatterySystems.
It’s important to check what hardware version you have to see what battery options are available to you.
Why it is called Captain Morgan
Riding nose up, or Captain Morgan comes from the Rom bottle Captain Morgan. There you can see the Captain having his foot standing on the barrel to mimic the riding position the board gives you when it pushes the nose up.
