Reached out to Alta this monring. Here is their response:
Hi Tom,
Thanks for reaching out. I am sorry about the trouble you are having with your generator, below is everything you need to know to charge:
Our Rapid charger comes with a locking 4-pronged Nema L14-30P plug. This plug plugs into locking 240VAC L14-30R power receptacles. At 240VAC our Rapid charger can charge R-pack Redshift models from 15-90% SOC (State of Charge) in as little as 1hr. 30 minutes or 0-100% SOC 1hr. 45 minutes.
Our Rapid charger can also charge R-pack models at 120VAC using a step-down adapter utilizing a standard U.S. 3-pronged Nema 5-15P Plug. (After purchasing a Rapid charger, you can obtain a step-down adapter by emailing me your request and shipping address.) At 120VAC, our Rapid charger can charge from 15-90% SOC in as little as 2hr. 12 minutes or 0-100% SOC 2hr. 55 minutes.
Charge times will increase if the bikes systems are hot either from riding or ambient temperatures. When the bike is hot, you can cool off the battery and optimize charge times by spraying the battery pack with water before and during charging.
However, be sure to keep water out of the bikes charge port and remember to seal the charge port closed when not charging.
Alta Motors has not tested generators, however the specifications our bike and charger require are below:
To charge at 120VAC our systems require a minimum of 1,600 Watts (1.6 kW) be delivered to the bikes charge port at all times during charging. To achieve this amount of power at the bikes charge port (after transmission losses) we encourage the use of an inverter generator which has a steady state power rating no less than 2,000 Watts (2 kW).
To charge at 240VAC our systems require a minimum of 3,300 Watts (3.3 kW) be delivered to the bikes charge port at all times during charging. To achieve this amount of power at the bikes charge port (after transmission losses) we encourage the use of an inverter generator which has a steady state power rating no less than 4,000 Watts (4 kW).
In addition to achieving the necessary power outputs specified above, the generator you use must also be properly grounded to avoid tripping our chargers GFCI.
Please note that a power loss of about 3.5% per 1,000 feet of elevation gain is typical for gasoline, diesel, or propane-fueled generators; natural gas-fueled generators may suffer a power loss of about 5% per 1,000 feet.
Lastly, if possible, always test if a generator will charge your Redshift before purchasing. It is also a good idea to make sure you can return or exchange the generator for another model if you are not able to test a generator before purchasing.
I hope this information helps. For additional insights, please also consider consulting other Redshift owners by visiting the independently run and owner operated, Alta Owners Forum:
Alta Owners Forum
Otherwise, please let me know if you have any additional questions or concerns, I am happy to help.
Happy Riding and Stay Fast!
-Kevin