During our difficulties is May and June, we were trying to clarify the charging times for the Roadtrek E-trek battery. According to Roadtrek, “while driving, the under hood generator will be providing 3300 watts at 24 volts with 2000 RPM.” (This is slightly different than the Roadtrek E-trek Owner’s Manual which states 3500 watts.)
In addition, we wanted to clarify some terminology from the manual, so we asked Roadtrek to define as a percentage what the E-trek manual (p. 85 FAQ: Electrical) means by “moderately depleted,” “adequately charged,” and “minimum battery charge.”
- Full charge…..25.5 volts
- Moderately depleted…..24 volts
- Adequately charged…..23.5 volts and above
- Minimum charge ……21 volts
Roadtrek could not provide the information in percentages; however, we are keeping a log so we can eventually create a table to show what battery percentages map to what battery volts.
Since the service at Mercedes-Benz in May and the dealer service in June, we had not driven more than 10-20 miles at a time, so we decided it was time to take a short trip to test the charging capabilities of the Roadtrek E-trek Battery and verify the information we received from Roadtrek. Our son was working as a camp counselor for the summer about 50 miles away, so we decided to visit him and do the charging test..
The battery reading before we departed was 89%/25 VDC (Volts DC). While we were driving the display on the inverter was 100%/28 VDC. After the 1-hour/50-mile trip, the reading was 94%/26 VDC. After the drive home, we took another reading and 95%/26 VDC. According to Roadtrek, Volts 25.5+ indicate fully charged; however, we were surprised it had only moved up 1% during the second hour of driving.
For a full hour of driving at highway speeds we would have expected the battery to be 100% charged. Our next test will be to charge the battery by idling.