Current Status

We are successfully using a single 170w panel and a MPPT boost controller to charge our three 48v e-bike batteries. With this extremely simple set-up, we logged 2500+ miles of solar-powered bike riding from March-July 2020.

It is working well and keeping up with our current needs, but we have some planned upgrades:

Intelligent Charging
Monitoring
Switches/distribution panel
Large Cheap 48v (maybe DIY) battery for storage and
- at home charging while riding
- DC-DC Charging
- better storage while touring the Friendmaker

Technical Specifications

Sunpower SPR-E-Flex-170 6×8 Solar Panel
- 170w
- 24v
- 6×8 cell
- Outer dimensions 45.4 x 31.9 x 0.8 in
- flexible
Genasun GVB8-WP MPPT Boost Solar Charge Controller
Batteries
- Two no-name 12.5Ah 48v hailong-style down-tube lithium batteries
- One UPP 17Ah 48v hailong-style down-tube lithium battery

Voltage Reading	Percent Charged	Notes
54.6 V	100%	Nominal max voltage of the battery
54 V	97.5%	Maximum charge boosted by the Genasun (24v panel, Genasun boosts to 54v)
51.48 V	80%	Max charge for storage
48.36 V	60%	Minimum charge for storage
39 V	0%	39v is cutoff voltage for motor to operate; can still charge cell phones/run computer