ebike solar charge question

[DiANA R]

Hello out there,
I was wondering how I am going to charge my ebike when I get to living in a van.
I got one of the first bikes that Lectric put out and I love it. Plus supporting this company is supporting some very community wise guys. They have given a lot back to nomads.
But I am wondering about how people who also have this bike charge up the battery in the boondocks.
It has a 500 watt engine and while I am trying to learn about amps and watts and volts I have never been to good with math. So I would like to learn about some of the ways people have chosen or figured out how much or how big of a setup you have to use with this bike. If it is down around the middle or below of the total charge it can take 4, 5 or 6 hours to charge plugged into my wall socket. It will definitely be the most power I will have to charge up. The others are the basics-phone-computer-lights and those I understand. It is that big bike engine that worries me. Thanks for anybody's help. Diana

 

[hugemoth]

The key question is how many miles per day or week will you ride?

 

[DLTooley]

Yeah, it takes a lot of power, and you will likely need an inverter too.

What you need to check is the size of the battery, not the size of the engine. Do be aware that even in the best of circumstances you’ll never get the full watt rating of a panel.

I would design my system, and use, to charge the battery when you have extra solar above that of your house battery.

Do be aware that while most of the available power stations offer inverters many do not allow pass through use while the battery is charging.

You’ll need to do the math, but I’d think you’d need at least 400 watts of panel. You won’t need as much battery, a major cost savings, unless you want to be riding every day during peak solar.

 

[tx2sturgis]

Yep it depends on how much you ride every day...that energy pulled from the battery has to be replaced. I've done this too so the following is based on actual use, rather than guessing. This assumes you will be pedaling about half the time...and riding on mostly flat ground, at more or less normal ebike speeds:

You will need at least a 300-500 watt sine-wave inverter, and at least 100ah to 200ah of house battery storage, and at least 200-300 watts of solar. This should be dedicated to the e-bike recharging if you normally ride about 2-5 miles or about that, every other day or so. (average use for me) 

If you ride a lot more, and/or pedal less, you will need more charging capabilities. You will need to do most of your ebike charging on bright sunny days. On overcast or rainy days, the system above may not be able to keep up, so you will either need to curtail your riding/charging and wait for sunny days, or you will need a small inverter generator to keep that ebike charged along with replenishing the house battery bank. If you have a spare ebike battery, you can charge that on sunny days, while riding with the other battery.

Of course, on cold/rainy/overcast days, you probably won't be riding much anyway...so that kinda works itself out.

 

[JohnnyM]

If you have a power station (like a Jackery) you can just plug your ebike directly into its 110v outlet to charge it and then keep the power station charged by the usual methods (like hooked up to your vehicle's cigarette lighter while driving or your portable solar panels when parked.)

The ebike charger does take a lot of watts (like 175 to 190) from the power station, but it will definitely work. Then all you have to pay attention to is keeping your power station charged.

Johnny

 

[Trebor English]

For about $20 you can get a device called Kill A Watt.  It plugs into the wall outlet then your device plugs into it.  It tells you how much power your device, the bike charger, takes and it keeps track of how long it takes it.  It can display the watts, how fast the energy is going, and the watt hours, how much energy was transferred.  To set up a mobile electric system you need to know the maximum watts and the watt hours.  If you want a microwave it's huge in watts but since it only runs for a minute or two the total energy isn't so bad,  A slow cooker runs all day at a lower wattage.  A food processor or vegetable juicer can be high wattage but shorter time.  Your bike charger probably has the watts required on the label. 

The normal order is to start with adding up all the watts and all the watt hours.  The watt hours sets the size of battery and solar panel you need.  The number of watts sets the size of the inverter you need.  Usually a battery that is big enough for the watt hours you want can also handle the watts you want but sometimes you need a bigger battery just for the watts, particularly with a microwave.  Then you see the price.  Sometimes the next step is to go back to the beginning and cut stuff out. 

How much power does the bike charger need?  What's the watts requirement on the label? 

With the commercial power electric utility you can take as much energy you want any day.  With a mobile, solar, battery, inverter system you can only take what the sun will put back tomorrow.

 

[MrAlvinDude]

When looking at the Lectric website,
https://lectricebikes.com/collections/accesories

I discover the following info about their batteries and the charger:


Batteries are (nominal) 48V and 10.4Ah 

This makes it a 500W(h) battery
(as 48V x 10.4Ah = 499.2Wh)

A 12V, 80Ah lead acid battery has about the same usable energy stored.


The charger data says:
Input: AC100-240V 50/60Hz~2.0A
Output: 54.6Vdc 2.0A

So the output from the charger is 109.2 Watt

With a 70-85% efficiency, the charger needs  between 156W to 136W from the inverter to function. 
So a small 200 to 300 Watt inverter will be the recommended minimum size inverter, to use with this charger.

Like it has been mentioned, using a Kill-a-watt unit,  at the 110V plug, is an easy way to get a more precise reading, of how much energy the charger actually is using. 



At 109.2W  output from the charger it takes (nominally - ideally) 500Wh / 109W = 4.6 hours  to do a charge from completely empty, to completely full. 

The official number is that it charges in 4-6 hours.  And this is because the charge process it not an ideal mathematical process.


Did these numbers help any? 


The battery is a 500W(h) battery. 

The charger is a  54.6Vdc, 2.0A output charger. It charges at a rate of about 110W,
and the charger needs a 110V input, and uses about 136-154W to operate.

 

[DiANA R]

Hey MrAlvinDude,
Yes your numbers make sense. I got to the 109.2W for the charger after looking up the figures from Lectric. That was my first number.
Where I got stopped was when I was trying to figure the size of the battery set up in the van and for the panels and well I didn't even factor in an inverter. I know what they do but I didn't know you could just use them by themselves. Are you saying that I just need a 200-300 watt inverter to plug into the 12v car input and that is all I would need?
Then while looking at some solar setups on AMZ and asking questions there people kept telling me I had to have way over 500 watts and that it would take anywhere from 9-16 hours to charge the bike. That was when I got confused. And figured I would never be able to afford that much pwr just starting out.
Someone also suggested getting an extra battery for the bike. Which is another possible option.

Now the next thing is to figure out how many panels and the battery set up. But it sure sounds more doable than before.

I also found this company called Ecoflow on kickstarter that has a solar generator called the River 600. It is 288 watts but you can by an extra battery that you actually combine together in the unit to make it 576 watts. It has a newer version of a battery they developed. It is about the size of a big toaster. It is pretty expensive but it charges about 80% in about 2 hrs with a 110wtt panel and about 3 or so hrs from the 12v car. So I believe it has an inverter and power surge protection and a lcd and app to go to a phone. That might take the place of the Kill-a-watt tool? And you can also plug more than one thing into it as long as the volts and watts are matched up. They have their own panels that can be linked easily together too. They are suitcase panels with kickstands.
Thank you for your help. Please let me know about the inverter and if I am thinking about this right as far as the set up goes. I would appreciate it.
Diana

 

[DiANA R]

If you have a power station (like a Jackery) you can just plug your ebike directly into its 110v outlet to charge it and then keep the power station charged by the usual methods (like hooked up to your vehicle's cigarette lighter while driving or your portable solar panels when parked.)

The ebike charger does take a lot of watts (like 175 to 190) from the power station, but it will definitely work. Then all you have to pay attention to is keeping your power station charged.

Johnny

Hi Johnny, that is a better number than what I was thinking I had to have also got some info from MrAlvinDude about figuring out the watts-I thought I needed over 500 watts. I like the solar generator idea-then it is all one unit. My build will be very minimal so something that is already figured out is easier for me I think.

 

[DiANA R]

For about $20 you can get a device called Kill A Watt.  It plugs into the wall outlet then your device plugs into it.  It tells you how much power your device, the bike charger, takes and it keeps track of how long it takes it.  It can display the watts, how fast the energy is going, and the watt hours, how much energy was transferred.  To set up a mobile electric system you need to know the maximum watts and the watt hours.  If you want a microwave it's huge in watts but since it only runs for a minute or two the total energy isn't so bad,  A slow cooker runs all day at a lower wattage.  A food processor or vegetable juicer can be high wattage but shorter time.  Your bike charger probably has the watts required on the label. 

The normal order is to start with adding up all the watts and all the watt hours.  The watt hours sets the size of battery and solar panel you need.  The number of watts sets the size of the inverter you need.  Usually a battery that is big enough for the watt hours you want can also handle the watts you want but sometimes you need a bigger battery just for the watts, particularly with a microwave.  Then you see the price.  Sometimes the next step is to go back to the beginning and cut stuff out. 

How much power does the bike charger need?  What's the watts requirement on the label? 

With the commercial power electric utility you can take as much energy you want any day.  With a mobile, solar, battery, inverter system you can only take what the sun will put back tomorrow.

The charger figures out to 136-156 watts to work. These are not my figures, MrAlvinDude figured them out. So he also came up with about 4.6 hrs to charge to full. The idea of buying an extra battery for the bike makes sense too. Love the Kill-a-watt tool too! Diana

 

[DiANA R]

Yeah, it takes a lot of power, and you will likely need an inverter too. 

What you need to check is the size of the battery, not the size of the engine.  Do be aware that even in the best of circumstances you’ll never get the full watt rating of a panel. 

I would design my system, and use, to charge the battery when you have extra solar above that of your house battery. 

Do be aware that while most of the available power stations offer inverters many do not allow pass through use while the battery is charging. 

You’ll need to do the math, but I’d think you’d need at least 400 watts of panel.  You won’t need as much battery, a major cost savings, unless you want to be riding every day during peak solar.

Hi Doug I got some good figures for the charger for the battery from MrAlvinDude. I had the charger for the bike figured out but he went ahead and found the rest of the equation. The charger needs about 136-154 watts to operate so for the 500 watt bike battery / 109.2 watt output for the charger figured = 4.6 hrs to charge. So there I see that the battery does not have to be big. And that I need more panels and an inverter of about 200-300 watts. Thanks for the reply Diana

 

[DiANA R]

The key question is how many miles per day or week will you ride?

It is so fun to ride, so from my miles in the city I ride about 15-20 miles a week and that uses about 1/2 the battery. This bike can go up to 30 or more miles depending how you use the pedal assist and the throttle. I'll start keeping better track of miles and the battery. So I know more. I just get on it and go w/o much thought. That is why you guys are so great here. You really have to think of the energy you expend and how it is going to affect what you can do. Thanks, Diana

 

[Trebor English]

In this thread there are several posts where the words "watt" and "watt hour" are used as if they are the same.  Think of a five gallon bucket with one gallon in it.  Think of a full one gallon milk jug.  They both contain one gallon.  The bucket can be tipped over and emptied very quickly but the one gallon jug will go glug glug glug and empty slowly.  In the end, they both give one gallon.  The amount is the same, the speed is different.

Watts are the speed of the energy flow.  A 109 watt charger running for 1 hour is 109 watts.  After 6 hours it is still 109 watts.  After 6 hours it is 109 x 6 = 654 watt hours. 

Power stations and power banks like Jackery have two ratings, watts and watt hours.  For example, the $77.00 Jackery 240 has an output of 110 volts 200 watts pure sine wave.  That should be fine for your 109, 136, or 156 watt bike charger.  However, it only has a battery capacity of 240 watt hours.  You need 654 or so watt hours.  The 240 watt hour Jackery probably won't fill your bike battery unless you only took a very short ride. 

"something that is already figured out is easier for me I think"  like a Jackery.  It may not do what you need to have done.  

Lead acid batteries are usually rated in amp hours.  The voltage is presumed to be to be 12 so multiply amp hours by 12 to get watt hours.  My battery is 75 amp hours.  It is lead acid so only figure half for long life, so 35 amp hours times 12 volts is 420 watt hours, not enough for charging your bike.  Lead batteries are more difficult to work with than lithium but cheaper. 

Inverters have loss.  You only get out about 80% of what goes in.  Batteries also have a similar loss.  Battery chargers have similar losses.  If you start at the solar panel, you need to account for loss of 20% in the battery, 20% in the inverter, 20% in the charger.  If you can charge the bike battery while the sun is shining, you save the battery 20% loss and maybe need less battery.  Mobile electric power systems are expensive.  Conservation is necessary to keep the price reasonable.