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Charging electric bicycle battery
We are looking at purchasing 2 electric bicycles to carry on the back of our MB.  The e-bikes we are looking at have the Bosch Powerpack 400 lithium-ion battery with the following specs <https://www.bosch-ebike.com/us-en/products/batteries/>:   voltage = 36V, capacity = 11.0 Ah, and energy content = 400Wh.  Our MB has the 2 factory 100W solar panels but no built-in inverter.  When we are not hooked up to shore power, will we be able to recharge the e-bike batteries using a portable inverter hooked up to a 12V outlet in the MB?  If so what size inverter would be needed and would it need to be any special type?  The Bosch batteries are detachable from the e-bikes and could easily be taken into the MB for charging.
Paul H.
Paul
2010 MB (2011-present)                                                                                        
1994 Multiplan (1997-2010)
 
Re: Charging electric bicycle battery
Reply #1 –
To size the inverter, we need to know how many watts the charger draws.

If the 36-volt battery has an 11-amp/hour rating, that is equal to 33-amp/hours at 12-volts.
2 X 33 = 66-amp hours. That's a lot of power to generate with solar.

Your existing panels will charge the batteries very slowly, it could take several days, assuming you other needs for the battery power.
You will need a significantly upgraded solar charging system to make this practical, I would start with 600-800 watts of solar if you plan on using the bikes regularly, for long rides. 
This will require an entirely new charging system, including all the wiring and fusing.
Unless you do the install yourself, figure $2000-3000 or much more. You might also want to add coach batteries at the same time. Bigger inverters can be very expensive.
Free power isn't cheap.

While this may be doable during the long summer days, in the winter, the generator will probably be needed to supplement the panels.
You might want to consult with AM Solar.
Solar Panel Kits for RV - Solar Panels RV - DIY RV Solar

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Charging electric bicycle battery
Reply #2 –
Hello Paul.  Perhaps you've seen this post in the classified section?

Electric dirt and trail bike

I don't know if this electric bike is still for sale.  But it certainly seems like it would be blast as I use to ride motorcycles for many years to until a Honda VFR750f. 
Re: Charging electric bicycle battery
Reply #3 –
Quote from: Larry W  - 
To size the inverter, we need to know how many watts the charger draws.

I suspect the charger may be a fast-charger, designed to accomplish its task in the shortest possible amount of time, and thus at a very high wattage. Our lawn mower has a 56V, 5.0 A-hr battery, and a charger that can fully recharge in a half hour from 110V. That is about 600W for a half hour, and no slow-charge setting. What makes the most sense would be to recharge the batteries when you can run the generator for an hour or so. First you need to find the charger power rating and time-to-recharge.

Steve
2004 FL
2013 Honda Fit
Re: Charging electric bicycle battery
Reply #4 –
The charger that comes with the bike we are looking at (Electra Townie Commute) is 2 Amp and the charge time is 3.5 hours.
Paul H.
Paul
2010 MB (2011-present)                                                                                        
1994 Multiplan (1997-2010)
Re: Charging electric bicycle battery
Reply #5 –
Quote from: Paul H.  - 
The charger that comes with the bike we are looking at (Electra Townie Commute) is 2 Amp and the charge time is 3.5 hours.
Paul H.
To get a full 11-amp/hour charge requires more than 3.5 hours, at 2-amps
A partial charge, maybe.
Looking at the charger's specification plate, what is the  charger's voltage and wattage rating?

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Charging electric bicycle battery
Reply #6 –
Is this it?

Townie Go! 8i | Electra Bikes
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Charging electric bicycle battery
Reply #7 –
The charger looks to be 4 amps at 36 volts (144 Watts) with the battery holding 400Wh.  On a 12 volt system the charger would draw 12 amps without any losses in the inverter.  So you could charge both bikes if running the coach using the alternator or running the generator as you're most likely only averaging 150Wh from the solar panels throughout the day which is only enough for one bike.
1997 TK
Re: Charging electric bicycle battery
Reply #8 –
While I appreciate Ed providing the link for my HPC Typhoon Trail bike, for most folks, this would not be a good choice.  My bike is designed for off-road use and weighs 120 lbs.  I am listing it for $3995, and new, it is about $8500.  My friend has a Luna 750W fat tire bike.  He leaves me in the dust on pavement or mild hills.  His bike weighs about 75 lbs and costs $3000 new.  It is a great choice for pavement.  However... on a rough steep uphill climb, I will ride to the top, dismount, and wait for him to walk his bike up to the top.

For off-road use, my bike is a great choice but for riding on pavement or on good bike paths, something else makes a lot more sense.

Ken F in WY
'08 MB