Best electric bike for 20 miles to beach, solar charge and back

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BrianP BrianP
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Best electric bike for 20 miles to beach, solar charge and back

Would appreciate guidance on trying to find the best available electric bike that can get me 20 miles to the beach, use a solar charger to re-charge whilst there, and then 20 miles back home.

Even better if it can tow a lightweight trailer carrying a folding rowboat, Aerowherry even, or kayak.

Thanks, Brian

Paul (admin) Paul (admin)
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Re: Best electric bike for 20 miles to beach, solar charge and back

Brian,

This is a good thread to start....it will run for miles and miles. :-)

Solar panels are expensive and I doubt you can recharge it at the
beach. From an engineering view its better to fit solar panels at home
and charge the bike at home - you can then use smaller, cheaper panels
as there will be more hours available for charging.

Its more logical to find somewhere to plug-in near the beach or fit
longer range batteries. For immediate use next day you will have to
plug-in and charge overnight anyway.

What the country needs, therefore, is a plug-in system for electric
bikes at popular locations. You could pioneer this at your sailing
club??

-Paul

On 17/05/2011, BrianP [via UK HBBR Forum]
<[hidden email]> wrote:

>
>
> Would appreciate guidance on trying to find the best available electric bike
> that can get me 20 miles to the beach, use a solar charger to re-charge
> whilst there, and then 20 miles back home.
>
> Even better if it can tow a lightweight trailer carrying a folding rowboat,
> Aerowherry even, or kayak.
>
> Thanks, Brian
>
>
>
> _______________________________________________
> If you reply to this email, your message will be added to the discussion
> below:
> http://uk-hbbr-forum.967333.n3.nabble.com/Best-electric-bike-for-20-miles-to-beach-solar-charge-and-back-tp2952594p2952594.html
> To start a new topic under General Discussion, email
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> To unsubscribe from General Discussion, visit
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Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

In reply to this post by BrianP
I've built a couple of electric bikes, Brian, and 20 miles is pretty much at the upper end of their practical range, especially if pulling a load.  Solar charging is possible, but would need a big panel if you want to recharge fairly quickly.  My small folding electric bike (see photo below) will do about 20 miles if you take it steady and help out with a bit of pedalling, and only has a 10Ah, 37V battery.  If I were to use one of my 60 watt solar panels, that are around 600mm wide by 800mm long, then the realistic charge time from flat would be about 18 hours or so, assuming reasonable sunlight and a good conversion efficiency from the charger.  I've found that you tend to get around 1/3rd of the rated power from solar panels here in the UK.

Jeremy

Paul (admin) Paul (admin)
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Re: Best electric bike for 20 miles to beach, solar charge and back

Jeremy,

Can you reveal all about the motor, battery and controller? I'm interested in an electric bike also.

cheers
Paul
Timmo Timmo
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Re: Best electric bike for 20 miles to beach, solar charge and back

In reply to this post by Jeremy
Very ingenious bike. Like how unobtrusive the electrification is.

Would an electric quad bike offer more space for batteries, be more likely to have somewhere to mount a solar panel (or two) and make a better towing vehicle?

Tim.

From: "Jeremy [via UK HBBR Forum]" <[hidden email]>
Date: Tue, 17 May 2011 07:33:06 -0700 (PDT)
To: Tim O'Connor <[hidden email]>
Subject: Re: Best electric bike for 20 miles to beach, solar charge and back

I've built a couple of electric bikes, Brian, and 20 miles is pretty much at the upper end of their practical range, especially if pulling a load. 
Jeremy

BrianP BrianP
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Re: Best electric bike for 20 miles to beach, solar charge and back

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So if I took a spare extra battery with me, I could get there and back? Perhaps just use a folding solar panel to top up the used battery for the trip home?

Your folding electric bike looks very similar to my Birdy folder. I really like riding it, and now use it all the time instead of my MTB or road bike.


perhaps I could add the "electric" bit?

Brian
Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

In reply to this post by Timmo
It might do, Tim, but you can get a lot of battery in a small size now.  The batteries on my folding bike are model aeroplane lithium polymer packs, fairly cheap (around $160 for that pack, direct from Hong Kong) and probably right at the smallest/lightest end of those that are readily available.

One of my other electric bikes (now sold) had a different battery chemistry, lithium ferrous phosphate, which made for a pack about 50% heavier and a fair bit bigger, as you can see from the photo below (it's a 10Ah, 36V pack, so slightly less capacity overall than the pack on the folder).  The battery pack is the black box under the seat, the motor is a small Tongxin hub motor in the front wheel.



Jeremy
Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

In reply to this post by BrianP
Brian, you'd be better just fitting a bigger battery to get the range, as batteries last longer when they are less stressed.  I'd guess that something maybe three times the size of the battery on my folder should get you 40 miles with a bit of reserve for headwinds, lack of puff to pedal etc.

Jeremy
Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

In reply to this post by Paul (admin)
The battery is four 5Ah, 18.5V lithium polymer model aircraft batteries, wired to give 37V at 10Ah.  They are available from here: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9174

The motor is a Bafang geared rear hub motor, available from a lot of places in China, like this place: http://www.bmsbattery.com/rear-driving/304-bafang-350watts500watts-bpm--motor-e-bike-kit.html

The controller is a home-made one, but you can buy very good controllers from a chap called Keywin Ge in China.  He sells them on his ebay shop, here: http://cgi.ebay.com/36V-350W-brushless-controller-E-bike-scooter-/260782183051?pt=LH_DefaultDomain_0&hash=item3cb7d4528b

BMS battery also sell complete kits (less battery) that are OK: http://www.bmsbattery.com/41-rear-driving

Jeremy
Paul (admin) Paul (admin)
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Re: Best electric bike for 20 miles to beach, solar charge and back

Jeremy,

Thanks for the interesting links.

The UK limit for power output is 200W - do you know if BMS quote power input or output?

Also what is the "sweet spot" for voltage? I would tend towards Li-Ion batteries for cost reasons.

cheers
Paul
Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

The UK limit is more complex than that, and isn't actually measured in terms of power output at all during testing for compliance.  In theory, you're allowed 250 watts with no power assistance above about 15mph, but in practice there are a lot of 500W bikes around that are legal, plus there is absolutely no easy way for anyone to check in practice, anyway.

The test required under EN15194 is a simple acceleration test with no wind.  The bike has to not exceed a set speed at a set distance (10 metres, I think) after a standing start with a set weight.  It's easy to make a 1kW bike pass this bit of the test............

The other bit of the test involves ensuring that the motor ceases to produce power above 25kmh, something that in practice is tested very crudely on bikes with a pedelec function (it's easy to cheat the test).

The result is that most electric bikes pay lip service to the regulations.  There are no checks at all on legality and no requirement for any electric bike sold here to be compliant with either the old UK 200W EAPC regulations or the new EU 250W EN15194 regulations (both sets of regs are legal here at the moment).

Most kits are around 350 to 500W input, which is probably legal.  I'm running that little folding bike at just over 1kW, and it doesn't attract any attention whatsoever.  I've not heard of anyone getting picked up under the electric bikes regs and the general consensus is that if the bike looks fairly normal and is ridden sensibly the chance of being stopped and asked about it is near-zero.  Certainly I've been zapping about at 20mph plus on electric bikes for a couple of years now, including a fair bit of riding in the city, and I've never so much as attracted a glance from the police.  I friend who is a traffic officer told me that they have far, far better things to do than try and pin down a non-compliant electric bike.  His view is that the cost to the police force of trying to get someone to test a bike for compliance, or otherwise, would be so great as to not merit bothering about it.

I've run at everything from 24V up to 72V and either a 36V nominal or 48V nominal set up seems best for normal use.  The motors all have a Kv, the figure for rpm per volt, so more volts = more speed.  Current determines torque and this is set by the controller current limit (motors are current hogs, they will draw all the current they can and burn out unless limited).

Most hub motors have a voltage for a rated speed, so if you want more speed run a 36V motor on 48V (no harm will result as long as the current remains the same).  Conversely, if you want less speed run a 48V motor on 36V.

Be aware that the controllers have a built in low voltage cut off, to protect the batteries from over-discharge, so a change of voltage means either reprogramming the controller (some, like the ones from Keywin Ge I linked to above, will plug in to a PC and can have their settings changed) or changing the controller for one of the correct voltage range.  Controller voltage is nominal, so a 36V controller is OK from around 35 to 45V usually and 48V controller is OK for around 43 to 60V or so.

The cheapest batteries around are probably either the model aircraft packs I linked to or maybe some of the better Chinese electric bike suppliers.  There are lots of poor electric bike batteries around though, particularly those made from large arrays of (often sub-standard) laptop cells.  Virtually all are either lithium cobalt oxide or lithium ferrous phosphate, with the lithium cobalt oxide having the better energy density by a fair margin.  Lithium ferrous phosphate is a safer battery chemistry though and slightly more tolerant of charge abuse.

Both chemistries need robust charge and discharge management at the cell level to be both safe and reliable, so unless you're like me and an inveterate tinkerer you might be better off just getting an off-the-shelf pack.  Ping is a very good and reliable basic pack seller, it's one of his 36V 10Ah packs on my old recumbent (fitted to a home made case).  This pack worked very well for a couple of years and still seems to be perfect now (it's sitting unused in my spare room at the moment).  His packs all come with a battery management system and charger, but need a case.  He only sells the safer LiFePO4 cells though.  Here's a link to his online shop: http://www.pingbattery.com/servlet/StoreFront

Jeremy
Paul (admin) Paul (admin)
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Re: Best electric bike for 20 miles to beach, solar charge and back

Jeremy wrote
... so unless you're like me and an inveterate tinkerer you might be better off just getting an off-the-shelf pack.  
My 3rd daughter said I'm "a natural born fiddler"....so your mighty tomb of a reply is music to my ears. And did I mention my electronics background?  

Battery technology is improving amazingly and it looks like sealed gel batteries are now obsolete for e-bikes.

A lithium based battery could be useful for boats. LED lights don't really need 12V and smart phones charge from USB at 5V.....so a 6.6V LiFePO4 battery would be fine with a low dropout regulator for 5V. Ping claims 3000 cycles which gives 3 times the life of sealed gel batteries.

There will plenty to chat about on the Thames Raid!

You'll find me at the back of the pack with all the other sailors, facing backwards praying for a westerly.

cheers
Paul

PS many thanks for an excellent posting.
Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

I don't think you can still buy an electric bike with SLA batteries now, although some of the small electric scooters still use them.  In practice, the cycle life of SLAs, even really good AGM ones, rarely exceeds 300 to 400 cycles in electric bike use, because they are inevitably run down to around 20%b capacity or so all the time.

The two most popular lithium chemistries differ a fair bit in cycle life.  LiFePO4 is around 1000 to 2000 cycles, with maybe 3000 cycles if you use them carefully.  LiCoO2  has a cycle life that's a bit lower, maybe around 1000 cycles.  Both are really calendar life limited, as like all lithium cells they start to lose capacity from the day of manufacture.  In practice it's the calendar life capacity reduction that will probably have the greatest impact, after around 5 years the cells will have probably lost around 25% capacity or so, even if not used.

The longest cycle and calendar life comes from using nickel iron cells, but they are big and heavy for the energy they can store, plus they use potassium hydroxide as a liquid electrolyte, which isn't nice.  They do last well in excess of 30 years though, with no appreciable loss in capacity.  Not much use for a bike, but I'm considering using them as a supply for the lighting in the new house (I'm planning on using low voltage LED lighting throughout fed from a battery bank that will be charged by solar panels, with a top-up charge from the mains as required).

My electric boat uses a portable 80Ah, 13.2V nominal LiFePO4 battery pack.  It's about the size of a car battery, but less than half the weight, including the watertight case and battery management system.

Glad you found the electric bike stuff useful, it's a bit of a minefield getting parts, as they virtually all come from China and it's hard to tell which suppliers are OK and which are dodgy (and there are a lot of dodgy ones about!).

Jeremy
BrianP BrianP
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Re: Best electric bike for 20 miles to beach, solar charge and back

Thanks for so much help and links to good suppliers.

I find anything electronic, or electrical, does not easily register in my head, so just some basic questions.

If a 600 x 800 panel takes 18 hours, perhaps 3 of then laid on the sand would manage a 6 hours charge. The backpackers are using roll up flexible panels. Could three of these possibly work. Only go to beach on nice hot sunny days!

If a three times the size battery were used instead, would that be 3 x the price? So about £300?

Front wheel motor seems easier to add on. Rear one is geared? Is that like a 3 speed for peddling type gearing? Which is best front or rear? Rear ones seem larger and presumably more power?

Is there something like a throttle on the handlebars, or do they just switch on and off by button or some kind of sensor?

Could we start a thread on Eco house design? I would love to sell up and build a small low cost to run eco home. My brother-in-law is a builder looking for something to build in this recession. Seems very difficult to find a website which works for finding a small eco home and covers glass house crops, power production etc as a unified subject.

Brian  
Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

The whole solar panel thing is a bit of  minefield, as they are rated when exposed to sunlight at 1000W per square metre over the panel area.  In reality, this is the sort of figure obtained at noon on the equator, so we can expect to get a lot less here in our northern latitudes.  Additionally, panels laid flat get less energy than those mounted so that they are perpendicular to the sunlight shining on them.

Flexible panels are usually a lot less efficient than rigid ones, and some rigid ones are far less efficient than others.  Mono-crystalline and poly-crystalline cells are the most efficient, by fair margin, over amorphous cells.  Most roll-up type flexible panels use amorphous cells, so are intrinsically lower in output.

The 600 x 800 60W rated panels that I'm using are rigid mono-crystalline ones, with an active area of around 0.38m² and an efficiency of around 16%, which is pretty typical (although many companies claim more, claims that need to be taken with a pinch of salt).

Three of the panels I have would give you around 50 to 60 watts of charge power in good sunlight when laid flat.  If you had a battery that was the same capacity as mine (370 watt hours), then it would take around 6 hours to charge.  If the battery was a bit bigger, say 15Ah (to give you a bit of reserve power in the event of a headwind, allow for towing, etc) then the charge time would increase to around 9 hours.

Your right, three times the battery capacity would be around three times the price.  Bear in mind that the model aircraft batteries require charge management and some form of over-discharge protection, too.  My advice would be to buy a more expensive, but ready-to-run, option like a Ping battery pack, which comes complete with charger and battery management system.

A front wheel motor is easier to add.  Both are geared internally though and of equal power.  The rear wheel motor needs more frame space as a rule, as the width of the motor makes the hub wider than a standard hub when fitted with a gear cluster.  Front hub motors can be slightly wider, too, but can generally be made to fit standard forks OK.  The spare 20" wheel with Tongxin hub motor that I have (the one that was fitted to my old recumbent) is 100mm wide at the hub, which can usually be squeezed into a set of 80mm wide front fork drop-outs.

There's usually either a twist grip or thumb throttle, but most can also be fitted with a pedal sensor, which gives automatic power assistance as you pedal (power assistance stops when the pedals stop going around).  The latter system (referred to as pedelec) tends to give better range, as it relies on pedal assistance to some degree.

The eco house is a subject dear to my own heart.  Our new build will be timber post and beam, with a timber and natural insulation exterior insulated panel system.  The roof will similarly be super insulated and will have a mix of photovoltaic panels for charging the low voltage lighting batteries and solar hot water panels.  We're hoping that the relatively low heating requirement can be supplied by a vertical bore ground source heat pump.  The challenges I face are mainly with the foundations.  I don't want to use concrete, both because of the high embodied energy and because I'm building on the site of an early post-medieval mill site (I will have the mill leat and surrounding woodlands in my "back garden).  Consequently there are a lot of archaeological remains just below the surface, which the local archaeological trust don't want disturbed (neither do I, as it happens).   Currently I'm looking at using small scale screw piles, which have the blessing of English Heritage in terms on minimal impact.  The challenge will be gaining approval etc.

Jeremy
Paul (admin) Paul (admin)
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Re: Best electric bike for 20 miles to beach, solar charge and back

Brian, Jeremy,

To give you an idea of PV panel sizes here is a picture of our solar thermal panel on the roof and PV panels on the conservatory roof. The outer PV panels are rated at 180W each in strong sunlight...just enough for an electric bike at medium speed. They are 5ft by 3ft.

The whole array is rated at 490W although I have never got more than 400W into the grid, due to losses in wiring and the inverter and a mismatch between the panels. The 2 middle panels were a bargain on ebay but don't match perfectly with the outer panels, so they don't deliver full power.

On the other hand the solar thermal panel can deliver almost 2kW in strong sun with about 80% efficiency compared to 16% for the PV panels. It uses evacuated tubes that work remarkably well in cold or cloudy weather - on a sunny day in February I switched off the water pump and the panel reached 93C!
You can follow the construction thread here:
http://www.navitron.org.uk/forum/index.php/topic,1426.msg9818.html#msg9818



-Paul
Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

Thanks for the link, Paul.  I'm looking at getting enough solar hot water to minimise the need for electric top-up (gas and oil aren't really an option, and I can't justify a woodburner just for hot water).  There's only the two of us, and I have around 25m² of available south facing roof space that the planners can't moan about (the new house is in an Area of Outstanding Natural Beauty, so has stringent restrictions on appearance).  I like the start of the thread with the Douglas Adams references.  We knew each other and I worked with his good friend, Richard Creasey, on his BBC "Hitch Hikers Guide to the Galaxy" web project (H2G2).  Here's an old link to some stuff I did for the BBC on H2G2: http://www.bbc.co.uk/dna/h2g2/A687233  BTW, H2G2 is a very interesting community and splendid legacy that Douglas has left behind.

I'm not going to go for a grid tie system, as the costs of getting approval etc seem prohibitive, and anyway, I'd prefer to have a more efficient low voltage bus in the house for lighting, computer peripherals etc.  It seems daft to convert low voltage DC from PV panels to mains voltage AC, then down convert it back to run LED lighting and low voltage equipment.

I've found that I can get around 20% more from the PV panels I have by using a maximum power point tracker.  This optimises the loading on the panels to get the most out of them in any given conditions, although having them mounted flat on the boat makes for pretty poor efficiency - I'm lucky to average more than about 30% or so of their rated capacity.

Jeremy
BrianP BrianP
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Re: Best electric bike for 20 miles to beach, solar charge and back

These Stealth electric bikes look amazing! http://stealthelectricbikesunitedkingdom.com/

50 miles range, 4500 Watts, 50 miles an hour. Must be very expensive.

http://stealthelectricbikesunitedkingdom.com/the-bikes.html

Brian

Jeremy Jeremy
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Re: Best electric bike for 20 miles to beach, solar charge and back

I was acquainted with the chap that builds them (they're Australian, imported into the UK) and all the reports I've heard suggest they are very good for what they are designed for, which is off-road trail riding.  There is a design and build thread somewhere on the Endless Sphere forum from around 2 years ago that details how the bikes were designed and built, I believe, but I've not been able to find it from doing a quick search there.

They are illegal to use here (and in Australia) on the road, unless Type Approved and registered as a motorcycle, something that I've found out the hard way with my own electric motorcycle build to be pretty tough going.

The true range is a lot less than 50 miles, most people reckon they are OK for around 25 miles or so, more with a bit of pedalling or if speeds are kept down.

As mentioned above, to be road legal in the UK electric bikes have to have a maximum power assist speed of 15mph and a maximum power of 250watts.  Whilst I think that you can easily get away with maybe double that power without raising suspicion, having more than ten times the legal power is likely to raise a few law enforcement eyebrows, I'd have thought.

Jeremy

 
BrianP BrianP
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Re: Best electric bike for 20 miles to beach, solar charge and back

Kit cars have a system of inspection and regulation with the SVA. People also build motorcycle choppers and specials so they must have a way of registering them? Perhaps this could be the same, as a special custom motorcycle?
Brian
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