Will the Roadtrek E-trek solar panels keep the batteries “topped up?”
In our previous post from mid-June, Our 2015 Roadtrek E-trek (What we have learned) we promised to provide some follow-up testing regarding the charging for the Roadtrek E-trek batteries by the various methods: driving, idling, solar panels, and plugging in to shore power.
Roadtrek has clarified the following terms, which appear in the Roadtrek E-trek Owner’s manual:
- Full charge…..25.5 volts
- Moderately depleted…..24 volts
- Adequately charged…..23.5 volts and above
- Minimum charge ……21 volts
According to the E-trek Owner’s Manual, the Roadtrek E-trek solar panels are supposed to keep fully-charged batteries “topped up.” To do a fair test, we wanted to start with fully charged batteries. Also, anything that drains the battery (battery disconnect, Webasto, and inverter) needs to be turned off. During the test, we only turned on the inverter briefly to check the battery reading.
Before plugging in to shore power, the battery strength was 90%/25 VDC (VDC=Volts DC); according to Roadtrek, 25 Volts is considered “adequately charged.” On Tuesday, August 4th at 8:00 AM, we plugged into (20 AMP) shore power. Remember, in order to charge the batteries off of shore power, set the inverter to the “up” position, i.e, Power Saver Auto. You should see the “battery charger shore power on” light illuminated (see photos below). Also, note that when plugged in, the battery strength goes to 100%/27VDC.
After one hour, at 9:00 AM, we disconnected from shore power and checked the Roadtrek E-trek battery reading, which was at 98%/26VDC, which is considered “fully charged” by Roadtrek. We plugged in to shore power again and checked the readings hourly. (Each time we checked the reading, we first disconnected from shore power, because the battery will always read 100% when you are plugged in to shore power.) At 10:00 AM the E-trek battery strength was 98%/26 VDC, and at 11:00 AM, the E-trek battery strength was 100%/27 VDC.
At 11:00 AM we disconnected from shore power and continued to check the readings to test whether the solar panels maintained the battery strength. At 1:00 PM the battery strength was at 95%/26 VDC. At 2:00 PM the battery strength was at 94%/26 VDC. By 6:00 PM the battery strength was down to 90%/25 VDC.
Conclusion: According to our analysis, the solar panels do not keep the batteries “topped up” since 25 VDC is not considered fully charged.
Our next test will be to see to what level (in volts and percentage) the solar panels can recover the batteries after being run down to 23 volts (68%).