Is it feasible to charge (by solar) a 36-volt SLA?

36-volt SLA battery (Ebikekit) going through a 22am controller to the 500-watt hub motor. Not sure if all that matters, but I'd like to find out how feasible it is (or not) to charge the battery using solar power.

While I'm at work the sun shines for about six straight hours (sometimes longer if I stay longer) and here in Georgia we get far more days of sunshine than we do of cloud and rain. At home I'll just plug it in (since it will be at home during mostly night hours in which the sun is in China. )

I have no idea where to begin. Any thoughts?

This is the battery kit I'm using: http://www.e-bikekit.com/shop/index.php?p=product&id=10&parent=2

Thanks for any info. Like I said, I have no idea where to begin on this.

MikeFairbanks said:

36-volt SLA battery (Ebikekit) going through a 22am controller to the 500-watt hub motor. Not sure if all that matters, but I'd like to find out how feasible it is (or not) to charge the battery using solar power.

While I'm at work the sun shines for about six straight hours (sometimes longer if I stay longer) and here in Georgia we get far more days of sunshine than we do of cloud and rain. At home I'll just plug it in (since it will be at home during mostly night hours in which the sun is in China. )

I have no idea where to begin. Any thoughts?

This is the battery kit I'm using: http://www.e-bikekit.com/shop/index.php?p=product&id=10&parent=2

Thanks for any info. Like I said, I have no idea where to begin on this.

Click to expand...

Mike:
Check out the following pass topic.
http://endless-sphere.com/forums/viewtopic.php?f=6&t=13091&p=193922&hilit=solarbike#p193922

It is the easiest way without a lot complex setup such as inverter DC-AC-DC. Three solar panel at 36v charge the 36v battery pack with a simple charger hack.

Ken

Hi Mike,

I have both a solar panel and a wind generator sitting in the garage that I plan to use as a charging station. More so I can say the trike is off the grid than actually practical, but also for the fun of playing with the stuff.

Anyway, if you are going to make a fixed charging station at school, I would just use a large deep cycle 12V battery hooked directly to the solar panel. Then use a small 12V to 110V inverter between the 12V battery and your standard 36V charger. This is not the most effecient way to charge the trike batteries from the solar panels, but it will be collecting juice even when the trike charger isn't hooked up. Another advantage is that you could also plug in the charger for another voltage or chemistry, such as for a 48V LiFePO4.

My solar panel came with the necessary interface for charging 12 volt batteries, and a small inverter for 12V to 110V.

That is the best route to go. Charging directly from the panels will require harder to find stuff. 24v charge controllers are common, but only the 12v ones are inexpensive. It will take a large panel to gather enough sunlight to charge the 36v 12 ah battery completely, but a smaller one would work if you have only a need to get a partial recharge.

Using this method, of course, means the apparatus can be at home.

In any case, it will take a fairly large panel to produce several hundred watthours a day. For instance, here in the extremely sunny SW, the average insolation time year round is only 6 hours, and most likely it's 4-5 where you are. You can look up insolation time on maps. So you need to size your system big enough to provide all the watthours you need in no more than 6 hours. So a 45 watt system is not going to put out enough. I always figured it would take at least a 150 watt panel.

There is, of course, the option of rigging the three sla's into a paralell bank of 12v batteries. They you can charge that right off the panel with a 12v charge controller. But the advantage of storing ALL the energy the sun gives your panels makes a second battery to run an inverter from a better idea. Size that battery big enough, and you could have energy saved for the rainy day, as well as extend it's lifespan greatly.

I'm wondering if anybody has succesfully used an ebike hub motor as the turning generator of a windmill to create a electric charge.
I read about this idea on another forum but don't know of an outcome.

SLAs don't need any charge controller if the panel doesn't put out more than C/3, say 400 milliamps in your case. Below that current good quality batteries will recombine hydrogen and oxygen when they start gassing near the end of charge. The panel voltage needs to be high enough; on a cold day two 12 volt panel might be enough but three would work on the hottest days. Lead-acid chemistry is not so good with solar because battery lifetime depends on fast charge and full absorption, so toward the end of a charge power will be wasted unless you use a more complicated setup with multiple or diversion chargers. LiFePO4 is more flexible in that it doesn't need an immediate full charge so a large pack will happily take whatever the PV will give it over the day, then you can top it up later after the ride home. If the setup ends up wasting much power, nowadays I'd go for a grid-tied microinverter and separate charger. Operating at the panel maximum power point will easily compensate for the DC-AC-DC conversion losses, and excess power goes to the grid.

Hi there,
I think the more elegant way to recharge these batteries is to use an output's parametrable MPPT charger and set the output to 36V .(money loss)
I also think that the more common way is to take a primitiv standard charge controler, put it on a 12V battery and plug a 300W inverter which is connected to a standard charge controller. (power loss)
I've also seen some 12V-36V lithium charger... there should be some for sla (maybe a compromise)
I will start to sell such solar stations for ebike in some weeks
Concerning the use of ebike-motor for windturbines motor. Maybe with a different rewiring to reach the correct Kv but...
"correctly" extracting power from wind is way more complex as it seems. To make it simple you must watch out that:
-the cogging of the motor is low enough to allow porpeller to start the rotor with low wind (16Km/h)
-the motor is able to reach the cut-in speed at this point also (enough voltage)
-the motor power curve is similar to the one of the rotor (and that's the main problem, it's not possible without strong electronics)
At the end, most of hobby builder end with a turbine which "works" but starts very late, doesn't produce much in comparison with the diameter of the rotor and burn in flame at the first storm. And forget about vertical wind turbines, Savonius rotors are really not efficient, and darrieus are a pain in the A## for the auto-start (actually, if they are build to be efficient, they cannot start alone). They are also very hard to build/equilibrate and are exactly as noisy a HAWT if efficient
And yes, I'm manufacturing small wind-turbines :-D

There are always hundreds of these on ebay.

Every VW/Audi getting shipped/transported has one (because unlike Toyota and Honda, German clowns still can't figure out how to make low quiescent current electronics). They plug into the cigarette lighter port, and stick in the window.


http://cgi.ebay.com/ebaymotors/ICP-VW-Volkswagen-Solar-Charger-12-volt-DC-_W0QQcmdZViewItemQQhashZitem4cf491f8bfQQitemZ330520721599QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_500wt_1182


Buy 3 of them. Cut the plug off. Wire one up directly to each battery. Done.

Yup, that would work, but take awhile. One of those 45 watt Harbor freight kits might make a good starting point. Then see if bigger is needed for your daily needs.

lol "german clown"
tss tss tss

With theses "pannels" you can really wait a looong time to get something stored in your batteries.
http://www.ehow.com/list_7637396_vw-solar-panel-specs.html
They are rated 4W. This means that they will, in real life, give you about 2 to 3 Watts, if you orient them well and you follow the sun during the day. let's say that you are a good worker and you stay about 10 Hours at work, on these 10 hours only 5 or 6 hours will be efficient (more than 1.5W on this pannel" so at the end of the day you will get (in the best case) about 12-20W/h to use... it's ok for system leakage.. but IMHO I really doubt that this will be of any interest for battery charging
ah yes, and if you buy three of them you will get at the end of the day about 30-60W/h stored in your batteries.
For a 40Km commute with a bafang the right size of pannel should be in the 100W nominal range.
Gruß,
H.

I suppose you could make a waterwheel. That would be cool if you lived next to a creek or river.

MikeFairbanks said:

I suppose you could make a waterwheel. That would be cool if you lived next to a creek or river.

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What about a big hamster wheel in the schoolyard, recycling kids energy to charge your bike

MikeFairbanks said:

While I'm at work the sun shines for about six straight hours (sometimes longer if I stay longer) and here in Georgia we get far more days of sunshine than we do of cloud and rain. At home I'll just plug it in (since it will be at home during mostly night hours in which the sun is in China. )

Click to expand...

I assume that the solar panels are already installed at your work place. What are they used for now? That's the first thing I would try to find out. How are they hooked up? What's the final output? 12V, 24V, 36V etc... If 36V, then you are all set. If the output is tied to the electricity grid, then just plug in an AC outlet as you would at home. If 12V, 24, 48V then I would consider a DC-DC converter. Don't do DC-AC then AC-DC, it's very wasteful.

Have fun.

Yeah, this is kind of a tough one. I have an 12 volt battery bank charged by two 125 watt pv panels and I was looking for an easy way to charge the ebike. What I ended up doing was buying an rc hobby charger called the 1010b icharger (Hobby King). This is basically a dc to dc converter that is made to be powered by a 12 volt battery like the one in your car. The neat part is that you punch in your battery type (lead, lipo, nicad, etc), the number of cells (up to 18 cells for lead for 36 volts total on mine) and the charge rate in amps (up to 300 watts) and hit start. It will monitor the charging automatically and will cut off when done. There are other chargers like this out there including ones that will charge at 10 amps. Just look around. Hope this helps.

I got stoked by the idea of solar charging my bike at first. But then I did a little calculation. If you spend say, $200 on the solar set up, that same amount of cash would recharge my bike for the next 24,000 miles of riding. Surely parts of the setup would last that long, but I decided that not driving my car that 24,000 miles was a pretty big enviromental contribution by iteself. More than enough to offset the damage from using $200 of electricity.

Now, if I found panels for cheap at a yard sale, then the deal would be different. But the price at typical retail outlets for solar is too high.

if you're going to put together a solar panel, it should be done for more than just recharging your e-bike batteries

dogman said:

I got stoked by the idea of solar charging my bike at first. But then I did a little calculation. If you spend say, $200 on the solar set up, that same amount of cash would recharge my bike for the next 24,000 miles of riding. Surely parts of the setup would last that long, but I decided that not driving my car that 24,000 miles was a pretty big enviromental contribution by iteself. More than enough to offset the damage from using $200 of electricity.

Now, if I found panels for cheap at a yard sale, then the deal would be different. But the price at typical retail outlets for solar is too high.

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So true. If you already have a solar system at home it works out ok. For me, I started out with a 45 watt Harbor Freight system and I kept adding to it. It was like an illness, I kept going until I cut my monthly electric bill in half. Now I'm working on cutting gasoline bill in half. 8)

I live in a condo. Solar panels or wind mills might get me in trouble.

I'm wondering if anybody has succesfully used an ebike hub motor as the turning generator of a windmill to create a electric charge.
I read about this idea on another forum but don't know of an outcome.

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http://www.scorpionsystem.com/

Here is an rc motor company that if you scroll down on the link says. Wind turbines coming soon. I assume they mean a wind turbine using their "scorpion" motor?

There was a thread here on ES about someone buying a white hub motor that had been used as a windmill generator, and they were going to use it as a bike motor again. I wish I could remember who it was or at least when, but I think it was late 2009.

RTLSHIP said:

I live in a condo. Solar panels or wind mills might get me in trouble.

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Can you do something like this?

no, I'm on the bottom floor. I could set it in my porch, but it only gets afternoon sunlight. Bedroom window sills are a possibility, too.
By the way, that's a pretty nice set up.

Mike,

It's definitely feasible, and not that expensive if you DIY the panels. Then you make 3 separate panels, so you can use 3 separate and very cheap 12V charge controllers without having to worry about disconnecting your pack. I wouldn't set up to do 36V, because you'll quickly outgrow those lead batteries, and a charge controller to do 36V won't be cheap, and done in 12V pieces gives you all kinds of flexibility going forward.

As Dogman pointed out, it's not something to do if the intention is to save $, but to do it because you can, because it will increase your range to infinity (as long as you stop for long enough), and because it would be just plain cool to any egeek or lover of the environment, make the project well worth the effort.

I think most of the cheap cells put out .5 volts, so when looking at cells to buy, you probably want close to 100, because they are very fragile and you want to end up with something in the neighborhood of 72 cells. The 6x3" cells are typically 4A output, so that's 2 watts. After all losses along the way call it 1W, and assuming your 6 hours at the office spans mid day with a good angle to the sun, I think you could count on 4wh per cell, or 250-300wh pumped into your batteries while parked on a sunny day in total from your 3 panels that are about 3 square feet each. 3 lightweight panels 1ftx3ft made so you can stack them for the trip seems a reasonable size. I've heavily discounted the output, so it's realistic numbers.

Go for it and please share the process with us.

John

RTLSHIP said:

no, I'm on the bottom floor. I could set it in my porch, but it only gets afternoon sunlight. Bedroom window sills are a possibility, too.
By the way, that's a pretty nice set up.

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Thanks, I originally had only one panel (the blueish one) and that one sat flat on the floor in the summer and leaning up against the wall in winter (when the sun is lower). The home made stand makes it easier to angle the panels to the sun but you don't have to have one. Just set a panel out there facing South as much as possible, add a charge controller and some kind of golf cart type battery with a fuse on the positive terminal and you're off to a good start.

After that, there are a number of interesting ways to charge your e bike. Personally, I like using lipo and the 12vdc rc charger.

A nicad setup could work out well in this situation. I already read that SLA will not work out do to the unpredictability of weather asell as the delicacy of SLA.
Is it possible to overcharge lipo? or do you a smart charger or some diode?
I do have one of those hurricane radio & light kits with a mini solar panel and dynamo hand crank. it works off nicad cells with an alkaline backup. I have no experience here.