About this replacement
Simrad WR20 Remote Commander — 3.7V Li-Polymer Replacement Battery (CP-WR20)
This is a 3.7V 1800mAh Li-Polymer battery for the Simrad WR20 and WR20 Remote Commander. The WR20 is a marine wireless remote that controls Simrad navigation and fishfinding systems from a distance. When the original battery loses charge capacity, this replacement restores full wireless transmission range.
- WR20 and WR20 Remote Commander fit: Both units use the same CP-WR20 cell with a matching connector, voltage rail, and Li-Polymer charge profile. Either model accepts this battery without modification.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge passes on the WR20 platform. The protection circuit responded correctly to low-voltage cutoff and charge termination at 4.2V.
- Marine storage tip: If the remote sits unused for an extended season aboard a vessel, discharge it to around 50% before storing. A fully charged Li-Polymer cell held in a hot engine bay or cabin accelerates electrolyte breakdown faster than a mid-state cell would.
Why the WR20 loses transmission range before the battery is fully flat
The WR20's radio transmitter needs a steady voltage to drive the RF output at rated power. As the Li-Polymer cell ages, internal resistance rises. Under transmit load, voltage sags below the threshold needed for full-power RF output — even if the remote still powers on and the display stays active. The result is shorter effective range well before the battery reads empty. A fresh cell with low internal resistance eliminates the sag.
WR20 shows no response at all after a new battery is installed
The most common cause is reversed polarity on installation. The CP-WR20 connector is keyed, but it is still possible to force it in the wrong orientation. Check that the positive terminal on the battery aligns with the positive marking in the battery compartment. If the polarity is correct and the remote still does not respond, the cell may have shipped in a deeply discharged state — connect it to the charging dock for at least 15 minutes to allow the BMS to wake the cell before testing again.