solar assisted trike to pull miniature gypsy wagon,need advi

Hi all, me and my friend are about to commence building 2 recumbent solar assisted trikes which will pull mini bowtop trailers to portugal to perform at boom festival in portugal. My main questions at the moment are regarding power and storage.
We will be towing a fair amount of weight and will need electric assistance uphills. Does anyone have an opinion as to whether a 250w geared hub motor could handle an uphill load? or would it most likely burn out? I was considering going for a 500w geared hub motor on 1 wheel and have the chain power on the other side. I guess that way i could just run at half power but be assured the motor could take the strain? Definitely wont be moving very fast so should be cool with the cops. Or do people think maybe a mid mount motor would be better? then i could put it in granny mode on the rear derailleur?
Also battery choice is getting a little overwhelming. Need something light so was thinking li-ion but very expensive,are lifePO4 safer than li-ion? Going to recharge via solar as it will be a 1000 mile journey. Have been warned about charging lithium with solar so need to buy a custom MPPT charge controller to get steady voltage to bats (or use inverter charger but will lose efficiency,would it be much loss)
Aiming at 2 flexible 200w solar panels (light type) so guessing they will give average output of 6/7 amps at 24v in the hotter climates of spain and portugal? Dont need to get there quick and hopefully will only have the motors on for a third of the time, and will be charging whilst riding so guessing this will do the trick? Sleeping for 3 hours in midday sun so bats should catch up then.Can always have a whole day off from time to time to recharge bats.
Please can anyone in the know get back to me with what they would go for in my situation, should have about £800 per bike inc. solar panels to spend on power and storage so not a massive amount. Links to products would be the most helpful.Thanks in advance, jimi.

I have a few thoughts, dunno if it answers all your questions

Charging directly with solar is a bit risky imho and a few precautions are required. Batteries don't like fluctuating charging voltage you absolutely have to pass thru a DC/DC converter, or a very smart charger. In essence the electric scheme is this:
Sun - pannel (variable votage out) - buffer capacitor (not mandatory, dampens fluctuations can be included in DC/DC) - DC/DC (fixed Vout) - charger (contolled V,I) - battery pack.
The whole chain from the output of the solar pannel to the battery can be one sole part that does the damping (capacitor), DC bus regulation and constant-current charing that is needed for Li-batteries of any type.

I work on these things for cars every day and I don't think we have any way (or need for now) to charge and discharge at the same time; as such it would be interesting to see if there is any system that could alow you to charge the battery while also using it for propulsion. Likely it would need a very smart DC/DC & BMS that regulates the battery voltage in real time consindering demand, supply and the SOC. Anyway, you may need to charge one pack while using another or just as you said, wait to charge.

Now, 200W pannels, are they 200W electric output or some random thermal fantasy watts? I ask these as I looked a fem months back for some pannels and they advertised a power of around 80W, 24V and only 2 amps. Since 2x24 obviously doesn't equal 80 I asked why and they said it's light-watts. After further questioning I saw they had no idea what they were talking about and at best the 80 number could mean the real measurable electric 48W divided by the efficiency of the conversion. All this to say that a number doesn't mean much, check.

Last think I have some ideas on are chemistries. LiFePo are more rugged and can take more abuse; if they fail they don't explode either, but they are heavy. LiPo are lighter, you can find some on hobbyking that are not expensive and they're good, but very sensitive to heat, charge, discharge. I wouldn't put these in a basket under heating pannels with doubtful voltage regulation and expect them to hold for 1000 miles. I would pick LiFePo4 or maybe even LMN (like cellman's) if the pannel/charger chain is well thought of and the pack can be kept reasonably cool, say below 40 and never over 50°C.

Seems like a cool project, good luck with things. If you have links of what parts you plan on buying put some, we could talk on something more palpable.

Hauling all that up hills is going to take 2000w. Or more. Think in terms of a lot bigger motors. Or even multiple larger motors.

Which then gets you into needing 10x the watthours. 10x as long to charge at 200w. 10x the cost for the battery pack.

It would work better if you didn't have the hills. On the flat, I can run my huge cargo bike, loaded up, on about 300w. But up a hill, it fries the motor to go slow. So to go fast uphill weighing 400 pounds including me, it takes 2000w to maintain 15 mph.

That's what I see on the wattmeter, not a simulator.

I don't say it can't be done, but it won't be simple and it won't cost 800. A 1000w chain drive ( mid mount) in a very low gear may get you up the hills, but you will still be using a lot more than 500-1000wh per day. It might work a lot better to just beg a plug someplace daily, than carry the weight of solar panels. Some panel might be worth hauling, but at some point you have to consider the weight you will lift up hills. That weight is a burden nothing can lighten, due to the laws of physics. To use less power up hills, lighten up as much as possible.

Any wind, and those trailers will drag you down too. Think about how to make them more aero, then open up the cover when stopped. Maybe that's already the plan, I had the picture in my mind of little covered wagons rolling down the road.

Thanks folks, hmm yes this isn't going to be simple. I was hoping to get away with smaller motors. Being trikes, we dont mind going very slowly (walking pace) on a granny speed ring up the hills if we can make it up on the flat. Aiming at 30 miles every other day. I was considering the following setup:
Mid Drive motor http://www.wooshbikes.co.uk/?cdkit Can't view spec so dont know wattage though
or this unbranded 250 watt 36v model http://www.ebay.co.uk/itm/New-upgra...Brushed-Motor-ELECTRIC-BIKE-KIT-/141255334190
Batteries - http://www.amazon.co.uk/lithium-battery-guarantee-electric-EROLLING/dp/B00CBGAWK4/ref=sr_1_15?s=cycling&ie=UTF8&qid=1397739712&sr=1-15 (x2 per bike if money allows)
Solar controller http://www.amazon.co.uk/controller-display-voltage-current-battery/dp/B00IHPQY6O/ref=sr_1_16?ie=UTF8&qid=1397739194&sr=8-16&keywords=solar+charge+controller
100w 12v panels (2x per trailer)
http://www.ebay.co.uk/itm/380687876...eName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
SLA battery used as float (not sure how big this needs to be if just used as a float but will probably be needed for other applications too so maybe a 24 AH
http://www.ebay.co.uk/itm/YUASA-NP-24-AH-12V-SEALED-LEAD-ACID-RECHARGEABLE-BATTERY-SLA-NP24-12-/271380347290?pt=UK_ConsumerElectronics_Batteries_SM&hash=item3f2f87799a
pure sine wave inverter http://www.ebay.co.uk/itm/1000W-2000W-1200W-1500W-2000W-pure-sine-wave-power-inverter-12v-soft-start-/191001764671?pt=UK_Gadgets&var=&hash=item2c7897a33f

Not sure if the SLA mentioned will be able to discharge enough amps quick enough to charge the bike bats, trying to find out what wattage/amperage the charger is rated. Looks like we will have to charge 1 battery while using the other.

Any ideas if this will work?

Thanks in advance

the battery selected requires a regular AC charger and is too small for climbing hills. the little bottom bracket motor is expensive and not adequate for hauling so much weight and if it had to deliver the power it would need a much larger battery.

really so much of this is just a pipe dream and until you have a long experience with ebike power you should hang on to your money. it will all be lost when the weakest link fails and you have no capability to maintain it or facilities to repair it while living this gypsy dream.

Ok,well we are going to do it one way or another, yes the wagons will fold down to below head height. Any ideas on the best method on a low budget? If all else fails we will have to just go with a very low gearing so we can pedal up the hills even without a motor.Remember we dont mind doing 2mph up hills if needs be.This method rules out the mid drives as they remove the ability to use the front gears. Maybe just the pair of 250w 24v hub motors we already have and spend more money on batteries. Any help greatly appreciated,but advice on not going ahead with the trip doesnt help.

I'd get a pair of the lowest speed geared motors for a 26" wheel and put them in 20" wheels or even 16" wheels.

Not that I would do this in the first place but if I had to do it "Junkyard Wars" style that's how I'd do it, maybe even three of the low speed 26" motors in 20" wheels, two rears and a front, all the same.

for most people, with a place to work and repair their bike, they could try to use something that is less reliable, as in junkyard wars, but he is gonna be living on the side of the road with no means of support and no way to find parts or even get access to them so he needs a 100% reliable system which would cost $2k at least, and he is gonna be pulling a bigger load than these guys who wanna use their ebike for picking up scrap metal in a trailer.

This is similar to my end goal with my Trike and you will need all the motor grunt yo can get mid chain drive has lots of advantages on tadpoles it shortens your chain runs so less snaped chains, can with planning actually help chain routing and gear shifting. You will want the largest spread of gears you can fit hub drive with enough guts for climbing on a expedition loaded Trike = bust wheels I tried this, you could power the trailer rather than the bikes no power limit on trailers :wink:
Look at Optima riders I highly recommend stealing their steering method but you will want a mesh sling seat for in the heat and comfort road buzz put a big fat 3-4" semi slick on the back 26 or 29 and you can ditch the suspension. Alu frames are not the best for road side repair box section builds often brake under long heavy loaded days of use. I have done Landsend to Edinburgh (uk) no trailer 2 100L bags on the riders rack camping out only shopping for food and gas bottles on route. It was before the birth of E-bike I walked lots of hills. Now I'm a wheelchair user and looking for a system to put my back on the road with my old 3 wheels
Tadpoles trailers and stopping put a brake on the trailer as well as back wheels hydraulic drums or discs from one lever for the front !

http://www.cyclone-tw.com/order-double.htm hope this helps mid drive duel free wheel.

http://www.cyclone-uk.com/ the best set up is shown on the blue frame gears are 32t,42,52 front 11,34 9s rear 10 = lots of bust chains.
Batteries do not go lipo LiFes are your friend evassemble.com headway cells no BMS use 2 packs and capacitorsbetween solar panels and hobby charger and balance leads see lithium conversion threads hear http://www.wheelchairdriver.com/board/viewtopic.php?f=2&t=1813&sid=0c22d8ab7d02b43f235cc1fc86c3822f

I know nothing about the cyclone controler and am looking for an alternative I have not used their motors yet either but the fit the type of bike in ? the best, you can get into the casing easy to mod if needed you will need the heat sinks for Spain.