Solar powered electric trike project - what batteries?

[encore8899]

I've been reading and reading for the past week and can't really find solid answers for my project.
I'm sure someone has some suggestions or answers to my questions.

What I'm planning to do is build an E-trike and solar charging it. I'm planning to do some distance touring on it, maybe 50-80miles per day. I could just ride it, but I doubt I could do that many miles every day, or would want to. In any case this is what I've narrowed it down to:

* 48V 750watt bafang bbs02 - I plan to use the most efficient minimal level of assist to maximize battery life and solar recharge, and just use more throttle uphill if needed. I could go 500watts, but I still want to have fun, or outrun a rabid dog if needed.
* 300 watts of lightweight solar panels - I want as much solar as I don't want to rely on wall charging at all, if I can help it
* Genasun MPPT 48V controller - This is only 48V I found that sells locally, which fits my application. Unfortunately it's $$. Any cheaper suggestions?
* The charge controller charges at 8amps at 48V, so 384W at peak charge theoretical.
* Trike weighs 39 lbs with a rack, and fully loaded with batteries, solar panels, solar mounting frame, charge controller should add about 15lbs. I do a lot of backpacking and know how to pack light and efficient, so maybe 80 total max.

What I have trouble deciding is the battery.
* What chemistry of battery I need? I'm leaning toward LIPO (LICO) hobbyking since it's the cheapest. But I dont really want to deal with adding a BMS. I can get the Genasun programmed to 50V so I could use a 12 s pack, which runs at 4.16V per cell. So do I need a BMS if I monitor battery discharge? Is LICO okay for charge and discharge at the same time?
* If I go Lifepo4, Genasun charge spec is 56.8V. The math says I need a 15s pack. Is that what most vendors sell? This would be more $ but less headache I think, since I can buy with BMS. I just can't wrap my head around spending $600 for a battery pack. Is this chemistry good for charge and discharge at same time?
* What size pack do I need? I'm thinking 10ah, maybe 15 for cloudy conditions.

 

[JayTea]

My friends decided to try the solar charging bit on their trip last summer. It rained every single day for the first three weeks so they gave it up. If you end up out in the middle of nowhere and need to plug in because of cloud cover etc, ouch.

Someone else here can give a better technical breakdown but I believe immediate solar powered recharge is years away, no matter how well balanced the battery chemistry may be.

Have a nice trip though

 

[wb9k]

You might consider these:

http://endless-sphere.com/forums/viewtopic.php?f=9&t=58426

Trike should have lots of room for them and these are great cells at a really good price. Two modules in series is 16S, which works well with a 48V controller (nominal 52.8V). Capacity is 20 Ah or more, tested and guaranteed.

I'm skeptical that you will be happy with solar charging while riding. The wind loading would probably consume as much power as the solar panels could produce. You can charge while stopped, but how often will that be happening while the sun is out? Maybe you don't plan to charge while riding, sorry if I misunderstand. Solar charging of an EV can work if you have a fixed installation charging another battery that can be used to charge your vehicle's battery at the end of the day. I would expect mobile approaches to be frustrating/borderline useless except as maybe a very modest range extender. I'd be thrilled to be proven wrong, though.

Good luck!

 

[encore8899]

Wb9k,

thanks for the link, but those batteries are way too big for what I was thinking... for a stand alone house system yes, but not for a bike. I'm thinking small enough to put in a rack bag like this...
http://em3ev.com/store/index.php?route=product/category&path=35
Apparently great batteries, except pretty pricey.
I wonder if anyone makes LIPO battery packs WITH BMS? I haven't seen any posts on ES...
Maybe this pack, except I have to wait 8 weeks. =(
http://www.ebay.com/sch/Rechargeable-Batteries-/48619/m.html?_ipg=50&_ssn=sun-thing28&_sop=16

I'm here to prove everyone wrong. =)

 

[JayTea]

encore8899

I like your spirit!

Do let us know how you get on.

 

[dogman dan]

I think Wb9k is on the right track thinking the wind load of 300w of panel could be a problem. Tilting the panel to get max gain might be needed, and if you are riding west in the morning, that's going to be tilting it the worst possible way for riding.

Climate, I don't know yours, but where I live, 325 days a year you'd have no problems. But even here, a three day trip could be three of those days you wouldn't get squat from solar.

And then your idea of the weight seems off to me, by about 100 pounds. Maybe less, but a decent bed and cooking stuff still weighs a bit. Likely you need to carry your potable water. You need to carry a lot of stuff to fix the bike, you will need everything with you.

I propose a compromise. You might carry 300w of panel, especially if you get the lightest possible type. But plan on a morning ride, followed by a noon charging session, and then an afternoon ride. Carrying it so 100w of panel is always exposed might work fine, but a 4'x 8' panel area wont go for charging on the fly.

Now lets do some math on the battery size. Lets say you can ride using just 200w and pedaling up the rest. And you are getting at least 75w out of your panel on the fly. And you need to go 40 miles before you stop for the day charge. Speed won't be much more than 15 mph. How do I know that? I've toured with camping gear. So call it 3.5 hours of riding, at 125 watts. Your battery needs to be about 450 watt hours.

You will need at least a 48v 10 ah pack. But really, you'd be a fool to carry less than 48v 15 ah. That will be enough to do the 40 miles, if the sun doesn't shine.

You are completely wrong to want to skimp on the battery. Get something very simple and reliable unless you are very experienced with batteries from RC toys. Get a lifepo4 or limn type pack with a bms. Rule one on battery is the spec on the side is not always what you get out on the road. And whatever your real world capacity is on day one, it's less than that later on. So get 15 ah.

Discharging while still charging won't be a problem, other than your battery needs to be big enough to get you there. The bms won't matter either, it won't be really doing anything on the charging circuits until you are fully charged.

16s if you go lifepo4, 14s if you go limn. If your solar charger is a tad lower voltage than your packs full voltage, that's not so bad. Remember, 90% of the time you will be riding on a pack that is at 53-54v. Except at the very start of a ride, your panel voltage will still be high enough at 56.8v to flow in. Question is, will the panels put out that much?

 

[encore8899]

The panels will are the new super light ones so i wont have problem with the wind unless i'm in a storm.
And they are 20% efficient sunpower panels so the area is only 3 100w panels of 21"x42"
Why can't I charge on the fly? That's the whole point. :lol:
Its going to be too much trouble to tilt panels so I will leave them as is unless i'm off the trike.
I live on the west coast so we are hot and sunny most of the time. plus were in a drought. I'll probably want to do some west coast touring first, to see how that goes.

When I backpack for 4 or 5 days my pack is only ~28 lbs without water. including all food. but I don't plan on just eating pack food.

Good point I'll definitely get the 15ah battery.
What's the typical max charge amps for Limn??
I remember you recommended sun-thing28 for batteries... Any other asia vendors you recommend?
http://www.ebay.com/itm/NEW-48v-15ah-LiFePO4-Battery-5A-Charger-BMS-For-Ebike-Kits-Powerful-8-Weeks-Gift-/131244468263?pt=US_Rechargeable_Batteries&hash=item1e8ec7a827
or
http://www.ebay.com/itm/Electric-Bicycle-ebike-48V-15AH-Lithium-Li-ion-Battery-and-charger-US-seller-/331037670108?pt=Cycling_Parts_Accessories&hash=item4d1361fadc

http://www.alibaba.com/product-detail/48V20Ah-lithium-ion-battery-for-electric_1273651051.html
cheap but kinda scared to buy from them....

I haven't received the panels yet, but we'll find out. 8)

 

[dogman dan]

I would have thought 100w of panel would be close to 21x42. That is a fairly reasonable size, You could make a trailer with a top that size. We've seen talk of these superlight panels before, but I had no idea they had such small surface area.

But if you include some tilt into the sun, you might be tilting it in a way that will catch wind as you ride.

Other than the wind drag, there is no reason I can see why you can't charge on the fly.

If you can gather say 150w average all day, you could travel 15 mph with another 100w of pedaling and never use the battery at all till you got to the hills. Then have the whole capacity to get over a mountain. Or go faster, but use only 100w from the battery. That would mean 7 hours of riding time from a 48v 15 ah. Then maybe do a plug charge overnight.

As for the weight, yes, you can pack light. But if you will not be at faucet at the camp, you will have to carry water. 10 pounds of water is mandatory for a tour out here where I am. It could be 50 miles to another drink, and if you break down, you will nearly die with just the two gallons. Same goes for food, why pack light food if it just needs water you have to carry? All this may not apply where you will be riding, but it does here in the desert.

Then the tool kit can easily be 5 pounds. Mine includes another tire and tube. It all adds up fast.

 

[dogman dan]

The newest "cheap battery" around is in the USA. Cali battery.

 

[encore8899]

Yes each 100w panel is 21x42"...
I'm actually considering tilting them slightly UP so that I can get a fraction of lift while going a decent clip. =)
It think 150W avg is pretty conservative. But even then that's 750watts in a good 5 hour day. Especially with a mppt controller. I make and sell solar generators... With my personal one, I have a fan that I run at night until the inverter shuts off at low voltage. The next day I charge up with 2x 75 watt panels. So 150watts total and it only takes probably 3-4 hours good sun hours for a complete charge at 15amps mppt. I've been running it for about 2 years, and the 12v Lead Acid battery is still going strong. 300watts with an mppt should only take me about the same time at a constant 8amps, maybe less. Yes i'm shooting for around 5 hours of riding. I think with the vibrations, my ass, my brain, and my leggs will be too tired to go more.

I'm never going to be that far from a drink. There's too many people and mini malls in the west coast. If I were going up the 5 fwy then that would be different cuz there's nothing out there except hot desert. Prob similar to N mexico. But I would never go that route. Its a very boring stretch. People drive at least 85mph on that hwy and no bikes allowed anyways. When I backpack I carry 3 liters and that lasts me about 5-6 hours depending on the difficulty. I think I can get by with a 3 liter bladder and a large water bottle.

But's I haven't even bought the bbso2 yet, so a bit premature. I'm trying to figure out who to buy it from. Yes your right All this gear adds up not only in weight but my wallet as well!! i'm prob gonna have to sell my second car to support it!

 

[dogman dan]

Well, before you spend too much, make a cardboard or Masonite mock up on your panel mount. Go ride it, an see what the drag will be like. 66x 42 is a big ass sail. That's why I was thinking as I have before, one panel always in the sun, two more can be unfolded, and angled to the sun better when you stop. 22x42 a lot less drag.

Nice thing about a very un aerodynamic bike, it matters a lot less if you ride real slow. I learned that touring with my cargo bike. But if you get a headwind, you could be well screwed till it stops. On my last tour, I ended up doing the 80 mile last leg home starting at about 3 am, because a headwind was forecast to begin by 8 am. It did, but I was 25 miles from home by then and made it on the battery I had. I had to have a lot of battery left for that last 25 miles because of a large mountain between me and home.

Anyway, bla bla, I'm saying with the huge sail on the top, you'll have to look for the right weather to ride into wind. Up the coast, it should be mostly cross winds, and generally not super hard. But a week of Santa Annas could shut you right down if you can't get the panel off the roof.

Also, consider that you could encounter a storm wind, enough to throw the bike around and wad it into a nice tangle. Big sails love to fly.

Re water, yes, up the coast will not be far from water, or plugs. I thought you might have been thinking of a ride down the 8, or up the east side of the sierras. My brother that lives in LA always heads for no people every chance he gets.

 

[John in CR]

I sure hope there's not much wind where you're headed, and in any event I'd go with less panel while riding and keep it much more narrow to stream line. Definitely don't tilt it up...imagine zipping down a hill and a gust of wind comes creating lift and you suddenly need to brake or steer. Make the supports foil shaped, so they don't create lots of drag, so something you can shape like wood is a better choice. A little more weight is nothing compared to the aero drag, and if you're going solar, then efficiency is paramount. Worrying about battery bulk and then plopping a 15lb charge controller on there is like drinking a diet Coke with a bucket of fried chicken. There are very small solutions.

Another consideration is the panel support structure. Yes the panels can be flexed a bit, but if allowed to flex back and forth like will happen in the wind with thin light panels like those, then the cells will quickly fracture resulting in a very short life.

Have you already purchase everything but the battery? If not, then I'd recommend going with more battery. 1kwh can be relatively light and compact. I'd fly about half that much panel, but construct it so double or triple can fold or slide out when stopped, so more but narrower modules. Then simply employ a bit of strategy and schedule long lunch breaks to take full advantage of best sun, and angle it for best energy conversion. With a good construction plan, the panels can double or triple up while riding, which will add greatly to the rigidity and help avoid destructive rapid flexing mentioned above. That could allow you to carry even more panel than you planned, and when you add in a 2 hour or longer leisurely lunch/recreation break during peak sun, you can add meaningful charge. At just 50-80 miles a day, that's only 4 hours in motion at 20mph, a matter of simplicity. That leaves most of the day parked and good angle to the sun, so with a good strategy and fold up panels you're looking at easily harvesting energy not just to move, but camping lights and music too, especially if you add some pedal assist. Think of the panels in operation while riding as primarily a sun shade, and whatever energy harnessed while riding a bonus. Aerodynamics and a daily ride plan are far more critical.

While parked, if there's wind at all, then you'll need a way to stake down or tie off the bike. It's so light that the original plan will surely get blown over without you aboard.

 

[skeetab5780]

Take all that solar stuff off and buy some more batteries it will do you better in the end.

 

[encore8899]

Well, before you spend too much, make a cardboard or Masonite mock up on your panel mount. Go ride it, an see what the drag will be like. 66x 42 is a big ass sail. That's why I was thinking as I have before, one panel always in the sun, two more can be unfolded, and angled to the sun better when you stop. 22x42 a lot less drag.

I'm going to ride it locally and do a bunch of testing before I go out. Just wondering have you guys actually done this to know that it will act like a sail?? Or are you just saying it will? AFAIK, I haven't seen anyone else do this with lightweight panels. This is the only post I found with a similar topic...
http://endless-sphere.com/forums/viewtopic.php?f=3&t=60662&p=907465&hilit=solar+trike#p907465

Right now the platform sits flat. I'm not tilting it at all. I will try cardboard first and see how it feels before I install the panels. I've been riding it on 20-30 mile rides already without cardboard and it doesn't seem to add much drag. Mostly to test the stiffness of the mounting. And I do understand aero drag. In the past I have made cf/fiberglass air dams and wings in my car racing days. If it doesn't work well with the cardboard, I'll make some changes. Already thinking about the next generation already.

Actually I made a HUGE difference changing the tires from the monstrous schwalbe touring tires to lightweight skinny 1" slicks. And saved ~75% rotational weight. I'm talking a 26x1.75 to a 26x1" rear!! The previous guy even put fix a flat on the fronts. Nuts. I don't even know how ppl ride with touring tires. Now it powers forward with every pedal stroke. FWIW, I'm a bit of a weight weenie so I've trimmed as much weight as possible already. mfr suggested weight is b.s. ahhaha :lol: We will see how the aero is after I test with the cardboard. I'd still like as much panel as possible. Like I said in my original post, I want to try to minimize or eliminate plug charging.

Anyways, I've never had an electric motor on a bike before... so I'm just happy to have that! The solar panels with shade will just be a bonus! So thanks for all the suggestions. It helps a lot.

I need to get the the motor and battery now. Any group buys on bbso2's?? Or honest alibaba sellers? hehe

 

[wb9k]

The weight of the panels is irrelevant. It's the surface area that matters.

 

[encore8899]

wb9k,

Are you referring to surface area in terms of aero lift/drag or solar charging potential??

And imho weight always matters... remember the outrider guys double trike with the ginormous heavy panel?!
They quit partly due to weight in the mtns and their broken drive shaft. I bet fully loaded that thing was 300lbs easy...
http://endless-sphere.com/forums/viewtopic.php?f=28&t=17848&hilit=genasun

I dunno about you, but I'd rather push an 80lb trike up a hill rather than a 120lb trike. Especially if I drain my batteries!! but who knows maybe you're lance armstrong on roids.... :lol:

 

[parabellum]

wb9k,

Are you referring to surface area in terms of aero lift/drag or solar charging potential??

And imho weight always matters... remember the outrider guys double trike with the ginormous heavy panel?!
They quit partly due to weight in the mtns and their broken drive shaft. I bet fully loaded that thing was 300lbs easy...
http://endless-sphere.com/forums/viewtopic.php?f=28&t=17848&hilit=genasun

I dunno about you, but I'd rather push an 80lb trike up a hill rather than a 120lb trike. Especially if I drain my batteries!! but who knows maybe you're lance armstrong on roids.... :lol:

Just make sure to have your Gopro on while riding, so you can share with us how wrong we are, from bird view perspective. :lol:

 

[wb9k]

wb9k,

Are you referring to surface area in terms of aero lift/drag or solar charging potential??

And imho weight always matters... remember the outrider guys double trike with the ginormous heavy panel?!
They quit partly due to weight in the mtns and their broken drive shaft. I bet fully loaded that thing was 300lbs easy...
http://endless-sphere.com/forums/viewtopic.php?f=28&t=17848&hilit=genasun

I dunno about you, but I'd rather push an 80lb trike up a hill rather than a 120lb trike. Especially if I drain my batteries!! but who knows maybe you're lance armstrong on roids.... :lol:

I'm talking about drag potential. A sail is a sail, the weight/strength only determines how much wind it takes to tear it apart, not how much wind load it presents to the whole system (before breaking). Weight matters for other reasons, but not this one. Same with charging potential.

 

[dogman dan]

I never rode with a sail that big. But I spent a lifetime carrying around 4x8 sheets of plywood.

Do they make a sail? Hell yeah, I've thrown a lot of plywood off the second story rather than go hang gliding with a sheet of plywood. When your feet leave the roof, chuck that damn thing. I've seen guys on the ground get flown because they hung on.

That was a lot of wind of course. But your design as John says, could easily get tossed upside down with you in it by a passing whirlwind.

But hey, go prove us wrong. We love to be shown what works in the real world. I still think the best approach to solar will be less area deployed when riding, and then fold out more at the noon stop.

Put some cardboard on your frame, and go ride, see what happens. See what happens when it gets windy and it's parked. 3 square meters of sail in the right conditions would make my windsurfer haul ass, hanging on for dear life. Find out what happens when a big gust of wind hits you couple meters of sail.