Charge bike with gasoline generator While driving?

Obviously it works, tid guy have done it https://youtu.be/anjfCKvnEmU

But wonder a few things.
1. If i have a 500watt electric motor, can i have like a 700watt generator or will i need a more powerfull generator?

2. I need a charger between the generator and battery, what charger and how do i connect it to my battery and generator? Is the a correct charger? https://www.amazon.com/GISIAN-600Watt-Inverter-Display-Emergency/dp/B07VP31KPQ/ref=mp_s_a_1_14?keywords=600+watt+charger&qid=1579695493&s=automotive&sr=1-14

3. What about voltage? This is the rear wheel i was gonna use, its a 36 volt
.https://www.ebay.com/itm/36V-500-800W-Electric-Bicycle-E-bike-Conversion-Kit-26-Rear-Cycling-Motor/163899794380?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D20190917065201%26meid%3D2e9d354ae56d41e6844e4d861a302172%26pid%3D100935%26rk%3D5%26rkt%3D12%26mehot%3Dpf%26sd%3D264531736505%26itm%3D163899794380%26pmt%3D1%26noa%3D0%26pg%3D2332490&_trksid=p2332490.c100935.m2460

Can i connect three 12v batteries together? Real ebike battery cost like 250 dollar and i cant afford that. Theese batteries maybee? https://www.amazon.com/Weize-Rechargeable-Battery-Electric-Scooter/dp/B081BFNTDB/ref=mp_s_a_1_8?keywords=36v+battery&qid=1579696224&sprefix=36v&sr=8-8

Cheaper, lighter and more efficient to just get one of those gas bike kits.

Illegal in Sweden. I tried it just for fun and a big dissadvantage is that you need to pedal it to start. And also it cant go shower than like 5mph since it has no gear.

A 500W generator located on a rear child carrying trailer, easy to do.
The genie would spit out enough amps at 120V to get you a 5-8A charge rate from a dc charger. I looked into it. 500W/120V=4.5A from the genie, look at the battery chargers input voltage and amps to see if it will work. My dell chargers, will do 20.50V at 4A OUTPUT, on a 2A INPUT (from the outlet)

$150 motorized bicycle gasoline kit - loud, cheap, easy to install, cant ride it everywhere because its loud.
2stroke or 4stroke, trimmer motor 30-50cc or 70cc which they call 80cc. Mixing oils and gas on 2stroke, but can go long distances.
Motors dont last that long.

I've pondered a "hybrid" setup, trimmer motor driving gears + electric hub, ebike for when silence is wanted in parks, pathways where gas is unwelcomed. Gas on roadways.

Adds too much weight.

Conclusion: Just buy a larger battery and a better charger. Charge up faster, get going quicker after your GrandeVenteshit cup of poo at starbucks.

kristinos said:

1. If i have a 500watt electric motor, can i have like a 700watt generator or will i need a more powerfull generator?

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depends. if you have a battery between the generator and motor to buffer the load for startup load spikes, etc., then that will probably work fine. otherwise it depends both on how large (and how long) those startup spikes are, and on how the generator responds to overloads, whether it will work with just a generator and no battery. often a controller that's say, 20A may spike up to 25-30A momentarily

it also depends on how well-regulated the generator output is. if the generator does not stay wihtin the hvc and lvc range of the controller, then the controller will keep shutting down, and if the generator voltage exceeds the specs of the parts inside the controller, it may be damaged or destroyed. for a 36v controller that's usually somewhere between 30-32v and 42v; you'd have to check your specific controller when you get it to be sure what it needs.

2. I need a charger between the generator and battery, what charger and how do i connect it to my battery and generator? Is the a correct charger? https://www.amazon.com/GISIAN-600Watt-Inverter-Display-Emergency/dp/B07VP31KPQ/ref=mp_s_a_1_14?keywords=600+watt+charger&qid=1579695493&s=automotive&sr=1-14

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if the gneerator does not itself output the correct voltage range for your controller, and you are not using batteries, then you don't need an inverter or charger. you need a complete power supply that can output the correct votlage for your controller, at sufficient current to satisfy the full startup spike load of the controller, worst case, for the longest period the controller may demand that current (including for hills).

if the generator is wall-voltage ac output, like most are, then you need something similar to a charger, but higher current, that can continously power the controller at the max current the controller may draw under it's max possible load (startups, hills). the meanwell elg or hlg series led psus would work, as long as you get one that has higher wattage output than your cotnroller needs. for instance, the hlg-600h-42a 600watt unit would probably work for a 36v 500w controller, but not for an 800w. (it would still work, but voltage would drop so the system won't have the 800w it's asking for, so it won't have as much torque under load as it's meant to. that may not matter for your application. if it didnt' have enough, you could buy a second unit and parallel it with the first, and then you would have enough power as long as the gneerator can output enough, too).

there are conversion losses in each stage, of up to 20-30% (or more, depending on design of the units used), so if you had a 700w generator that couldn't output any more than that 700w absolute max without shutting down, and the power supply (psu) you use between it and the controller is only say 80% efficient, the controller would only get about 560w at the controller input. if the controller is only 80% efficient, too, then you only get around 448w to the motor (and the motor will have an efficiency too, so you probably only get around 358w at the wheel, max, under those conditions). since you don't want the generator to shutdown (if tha'ts how it responds to overload) then you'd adjust the power supply's current limit so it never draws enough power from the generator to cause shutdown. might take some experimentation. or just get a bigger generator.


there are lots of psus that can do the generator-to-controller conversion...but the meanwell hlg series is potted and sealed so they're weatherproof and vibration/impact resistant, and will survive being used on a bike, whereas anything that is open-frame / not sealed and potted is not weatherproof and parts can break off inside from vibration if they werent' designed for operation on a bike. (this even happens inside ebiek controllers sometimes, usually with the biggest capacitors...but the psus have relatively heavy transformers inside that can break off or break the circuit boards, under vibration. happens to regular ebike chargers, too, when carried on the bike).

3. What about voltage? This is the rear wheel i was gonna use, its a 36 volt
.https://www.ebay.com/itm/36V-500-800W-Electric-Bicycle-E-bike-Conversion-Kit-26-Rear-Cycling-Motor/163899794380?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D20190917065201%26meid%3D2e9d354ae56d41e6844e4d861a302172%26pid%3D100935%26rk%3D5%26rkt%3D12%26mehot%3Dpf%26sd%3D264531736505%26itm%3D163899794380%26pmt%3D1%26noa%3D0%26pg%3D2332490&_trksid=p2332490.c100935.m2460

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i wouldn't reocmmend that one, at $1000 economy shipping plus the $165 item price, it's a terrible deal, especially since you'd probalby have to pay a large vat / customs fee on that, too. go to amazon (or ebay) and look up the yescom kits. they're usually about $250 including shipping, sometimes up to $350, and people here on the forum have had good luck with them (i've never used them).

as for voltage, for a 36v kit it's usually 42vdc max, around 30-32v minimum but you have to check the actual controller when you get it for it's lvc marking, or actually test to see what voltage it stops working at as the voltage gets lower.

Can i connect three 12v batteries together? Real ebike battery cost like 250 dollar and i cant afford that. Theese batteries maybee? https://www.amazon.com/Weize-Rechargeable-Battery-Electric-Scooter/dp/B081BFNTDB/ref=mp_s_a_1_8?keywords=36v+battery&qid=1579696224&sprefix=36v&sr=8-8

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those batteries will "work", but they wont' last very long simply because they're lead acid. if you get a year out of them you'd be lucky. they last logner if always kept charged, charging immediately after you stop riding every time, etc. (if you leave them uncharged, they are physically damaged by sitting that way, the longer they sit the worse the problem, called sulfation or sulphation, which is not easily (or at all) reversible for this type of lead acid battery).

if you use them as a buffer between generator/psu and motor to handle the current spikes, you can get a smaller psu and generator, and the battery won't see nearly as much load either, so it will last longer, not being discharged very much and usually kept full, as long as the psu is set to the float-charge voltage of teh three batteries in series.


keep in mind that the cost of the generator plus the psu(s) you'll need almost certainly greatly exceeds the cost of a good ebike battery and charger, unless you just need a really huge distance range for riding.


what specific range are you looking for, under what conditions (terrain, wind; is it in traffic with stops/starts, or just nonstop riding, at what speeds, what weight total with you, bike, cargo, etc)?

all of those will determine how big a battery you would need, if you don't use a generator.

if you need a really long range under high-power-usage conditions, then the generator/psu would probably be a better deal.

but if you only need a short range under low-usage condtions, the battery is probably a better deal and is smaller and less complex to setup on the bike.

kristinos said:

Illegal in Sweden. I tried it just for fun and a big dissadvantage is that you need to pedal it to start. And also it cant go shower than like 5mph since it has no gear.

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keep in mind that the various pas-type kits may also require you to pedal to start, and keep pedalling to keep going, even if they have a throttle. you'd have to check the specifics for any particular kit before you order it. if it doesn't say, then you'll only find out once you install and test it, exactly how it operates (there are quite a few variations). some don't even have throttle capability at all (doesn't matter if you hook up a throttle it just doens't work in those cases).

some of them may also only operate up to a certain speed, and then just shut off. depending on where they were designed to be sold, then to comply with local law there that speed may be very low (much lower than you can just plain pedal a regular bicycle at). so again, you must check this before you buy. many do not have any way to override this, and probably don't say if you can or not, so you should assume you cannot override it (though you can certainly experiment with it when you get it to find out, don't be disappointed if it can't be made to go faster than the stated limit).



keep in mind aobut the generator / psu system is that it's going to be relativley large and heavy, and unless you get a pretty good brand of generator (like honda, which is expensive) it's likely to be very loud especially under higher loads. if you ride a regular type of bicycle, then most likely you'll end up having to put it on a trailer, as it may be heavy enough to make the bike's handling very poor, if it will even fit on the bike at all.

if it's something liek a longjohn cargo bike, then you could probably put it in the cargo area, if it's not too large for that.

from a quick google, a 500w generator may weigh anywhere from around 20lbs to 30lbs+, the size of a backpack or so. a 1000w generator may weigh anywhere from 25lbs to 40lbs+, the size of a large backpack to a camping backpack.


those meanwell hlgs are around 7-8lbs each, and about the size of a hardback book.


those sla batteries are around 6-10lbs each, and about the size of a brick or two each.

Yes i need a long range. Was gonna idé it know when it gets a bit warmer and do som long trips. Like 300km a day.

Someone mentioned i may not need a charger between battery and generator if i dont use batteries, im gonna use batteries so, i only need a charger?

This is the specifications och the generator:
Motor: 4 stroke

-tank: 2,1L
- Max effect, 230 V AC: 800 VA (Maximal effect of engine 1000W)
- Max continous effect, 230 V AC: 700 VA
- max time of running: 4,1 hours on one full tank (on 100% effect)
- Frequens: 50 hz
- sound: 58dB (7m distance)
- weight: 9kg
- Size: Length 425mm, width 230mm, height 380mm

Thought about something like this a while back, when I was day dreaming about bike-packing. A 3-6 month holiday around Australia by bike. The thought went something like:

1. Either a large RC nitro, or a small string trimmer petrol motor;
2. An alternator from a small car;
3. A smallish battery - mostly for buffering. Many people don't realise that a 750w motor will not use 750w until you reach about 40km/h on the flat. If you are going slower than that, it could easily be drawing just 200-300w. So the alternator could be significantly under-driven, yet still be generating enough power "on average" that it charges the batteries on the flat, and the motor drains the batteries on hills.
4. Either hack the regulator from the alternator, or put a very efficient DC boost converter in between.
5. Ride and keep an eye on the state of charge. If I ever get too low because I'm consistently using more than my micro generator was making, I'd either stop for a break, or slow down/pedal until the generator caught up.

I never even started the project. I still see little reason why it wouldn't work on a larger cargo bike designed for bike packing... But no way would I do that on an urban commute. Just no point. It'd be fragile, dangerous - to you and anyone you hit (It might be securely mounted on your rear rack now - but if you go high side, what could it do to a human skull?), it'd get you a lot of police attention - If gas bikes are illegal, you'd be explaining to every cop, let alone nosy civilians that this isn't a gas bike, and I bet at least half the cops will issue the ticket first, and shrug their shoulders and say let the judge sort it out.

Get a bigger battery, and the biggest charger your country's standard power point will support. It'd be a lot easier.

If you are going to do it, get an coulomb counter, and measure peak power drawn, as well as average power over the entire battery cycle. From that, you can probably figure if you can get away with using a smaller generator/jerry rigged generator.

I did try this once, and it did work. I have a lighter small generator now, but at the time I had one that was 50 pounds, for 800w. Then, to make it even worse, my charger was only about 100w.

So it did not work all that great, I lugged 50 extra pounds in the basket of a trike for 100w. Clearly not worth it. Just buying more battery, like 10 pounds more battery, worked so much more effectively to extend range. In my case, that extra 50 pounds sucked up about 90w, so there I was gaining about 10 watts.

But if you want to do this, it can work. You need the lighter two stroke, 700w generator. They are about 30 pounds. Those will put out about 500w continuous. Then you need a powerful charger, but not over 500w. So something like a 10 amps charger. Those get a bit pricy, so if you are spending a lot anyway, I would suggest get a satiator. Its the finest charger out there, and its adaptable to any battery you may have later on. its a 7 amps charger, or less if you want it.

lastly, you need to look at the batteries max charge input rate. Don't fry your battery management system by putting 10 amps into a BMS designed for a max of 5 amps.

But in the end, its still a lot of weight. So if you are going to spend 5 to 7 hundred, just getting another battery would be similar cost, and much much lighter. I used to tour with 48v 40 amp hours, weighing about 30 pounds total, and it gave me 60-80 miles of range at 15 mph. That may be a better solution than carrying gas generators. Just one 20 amps hour battery will give you some real range, and you can add to it later if you need more.

But one place you do need a generator, is if you ride into the mountains, where there simply are no plugs. I did this a lot, car camping with my e bikes and a generator. Works great, and occasionally the generator is used when the power is out at the house for hours.

Lastly, why not go solar, if you plan to spend $400 or so? You could tow a trailer with a 100w panel on it. Those cost about what the generators cost, and are about three feet long. Not that many watts, but it would amount to about 600 watt hours per day more.

oh that's a cool idea! Only if the generator was more lightweight... and again you have to take fuel with you.

Ideally, you want your battery pack to be able to accept a charge rate that is fairly close to the energy consumed while riding. For instance, when I ride with PAS, the motor is pulling about 250W and my legs supply the balance. So, over a long ride, you want to be replenishing the battery at a rate that gives you the desired range based on the battery capacity and charge rate. My crappy pack will only take a 5A max charging rate, or right around 250W.

You should do the math, based on your riding style, consumption, battery pack, and charge rate assumptions, to see if pencils out first. Personally I like my silent ebike, so I'd want to charge faster and turn the damn noise machine off for a lot of the riding with that set up.

can make sense for bivouacs

add batteries

trailer 30-50lb inverter genset

add more batteries

size charger near max genset output

ample fuel supply

enjoy electric camping

Yes you can string 3 SLA 12v batteries to get 36v. They charge slowly though. Good for 30km.
300km a day if you can't afford $250 is a fairy tale though.

kristinos said:

Someone mentioned i may not need a charger between battery and generator if i dont use batteries, im gonna use batteries so, i only need a charger?

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if you read my post, it explains what you need for different circumstances. if you have questions about it, please quote specific parts and ask specific questions about those, so i can help you understand what you need to do to accomplish your goals.

you must use something to convert the generator power to dc for the controller, whether you use batteries or not. you cannot connect the controler to the ac outlet on the generator, unless you like making smoke come out of boxes. that dc converter can be a charger or a power supply of the types i explained in my post.

if you use batteries, and they have sufficient capacity to get you where you're going without much or any help, then you only need a small dc converter between generator and controller/motor system, along with the batteries.

if you need a longer range than your batteries can provide by a signficant amount, then your generator / dc conversion system must provide power to the batteries at the same or faster rate as the controller/motor uses it up.

if you don't know how fast it will use it up, then your safest bet is to ensure the g/dcc system can continously output the maximum power the controller/motor can possibly use. then you can't run out of power until the generator runs out of gas.

- Max effect, 230 V AC: 800 VA (Maximal effect of engine 1000W)
- Max continous effect, 230 V AC: 700 VA

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va generally means volts times amps, and v * a = watts (w).

so the peak watts is 800, and it can handle spikes of up to 1000w, though how long those can be it doesn't say.

but the most it can handle for any length of time is 700w.

so if the dc conversion unit (power supply (psu), charger, etc) you use between the generator and the batteries has an efficiency of say, 80%, then the maximum watts you can get out of the generator/converter is about 560w.

if the controller/motor system needs more power (like if you're riding uphill, or at fast enough speeds, or against enough headwind), then it depends on the converter and the generator how they handle overloads, for what will happen.

if the converter is like the meanwells, it does it's own adjusting and keeps the power provided to the controller/motor constant, at the max it can handle. if ti's like many regular power supplies, it shuts off to protect itself, and the motor shuts off too.

similarly, if the gneerator just governs itself to keep power output constant at it's max ability, the system will just keep chuging along at the best it can do. if it's like some, it may shut off it's output (or blowa fuse), and then the whole system shuts off too.


in another case, let's say you use some small batteries like you linked to, between gen/dcc and controller/motor, and just a small charger, like say a 100w charger, as the dc converter.

as you ride along, if you are using only about 100w average, then you can ride as far as the gas tank will get you.

but if you ride faster or go up hills, and the contorller/motor starts using up power faster (say, 500w) than the charger can charge the batteries (100w), then the batteries run out after a short period of time. the charger cannot support the load, so its output drops over time to it's minimum voltage as the batteries drain, if that is lower than the controller's lvc then the controller/motor shuts off at that point.

but if you had the big power supply on there instead of the little charger, then it would support the load of teh controller/motor, and keep you going until the gas tank runs out. once the gas ran out, then the batteires would give you whatever small range they're capable of, and hopefully at least get you to a gas station.


anyway....there's a number of ways to setup this type of system, and to help you find the best way, we need specifics on exactly what you are riding, your weight and it's weight, the total weight of other stuff you'll carry like generator, cargo, batteries, backpack of whatever, etc., the terrain youll ride over, the way you ride (start / stop traffic, or continuous nonstop traffic, etc) how fast you ride, wind conditions, etc. the more you specifcy the better advice we can give you.


one thing i can tell you that there isn't a battery at any price that you can easily/safely carry on the bike, without a trailer, that is likely to get you 300km, by itself, unless the motor/controller system does not use very much power (whcih usually means it's not doing much of the work, and your pedalling is instead doing most of the work).

the generator could do it as long as you can carry enough gas and it can supply enough power long enough.

the cost of a reliable generator and power supply sufficient to run the bike (depending on your riding style/needs) that will also survive riding around on a bike in the weather, is probably greater than $250.

E-HP said:

Ideally, you want your battery pack to be able to accept a charge rate that is fairly close to the energy consumed while riding. For instance, when I ride with PAS, the motor is pulling about 250W and my legs supply the balance. So, over a long ride, you want to be replenishing the battery at a rate that gives you the desired range based on the battery capacity and charge rate. My crappy pack will only take a 5A max charging rate, or right around 250W.

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the charging rate is actually irrelevant , during normal operation / riding, for a generator->charger/psu->battery->controller->motor system where the charger/psu output is parallel with the battery terminals and controller input (presuming battery either has no bms or has a common charge/discharge port).

as long as the charger/psu is capable of sufficient power to run the controller by itself, it will essentially be doing so, and the battery is just a "capacitor buffer" to supply short spikes in demand.

so the charger/psu can be capable of far more power output than the battery could actually be charged at, and that's fine, as long as the battery is not run down (say, generator runs out of gas) very far, far enough for the charge rate to exceed the battery's ability to absorb it.

to accomodate that condition/circumstance, and adjsutable-output charger/psu would be used, so it's current limit is lowered to the max the battery can handle charging at, until it is recharged, and then the system can be used normally again. or a separate charger carried just for this purpose, either to plug into a wall or into the generator's outlet in place of the psu, etc. a number of different setups can be created that work around this issue.

E-HP said:

Agreed, as on as the rider is monitoring the situation it works fine. I was thinking about my pack, with BMS and separate charging port.

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yes, with something like yours the whole system is limited by the rate at which the battery can accept charge. if it can only accept 100w of charge, then if the system uses more than 100w, the range is limited by the ratio of how much greater the usage rate is vs the charge rate.

as long as usage never exceeds charge rate, range is size of gas tank and tenderness of butt.

Maybe just lose the battery to save weight. Those smaller inverter generators put out 2000W, so you probably don't need a buffer if you size the power supply to handle that.

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yes. the primary use the battery is, is as a buffer for spikes above the ability of the gen/dcc system to supply, so if it can supply even the largest spikes, battery is not needed.

the secondary use the battery is, is as a backup in case the gen/dcc fails or runs out of gas. or must be shut off due to noise, for whatever reason, but motor power is still required.

This thread make me wonder what the actual ebike laws say. If it doesn't restrict the electric sources, and a generator powered one is acceptable, then it seems like a loophole to exploit, but I'd rather have that 50 lbs sitting lower on the bike. On the other hand, those generators are only good for ~1600W continuous, and 2000W peak, so the power to weight ratio is pretty miserable.

none of hte ebike laws i have seen even attempt to define the power source, only the number of motors and the total power level (not usually specified at what point in the systme it is measured).

if they define an ebike as a "battery electric bicycle" then an argument might be made that they must contain / be powered by a battery, but it still doesn't exclude the charging method for that battery being a portable generator on the bike itself.

if there is a law (which may not be within the bicycle or even transportation sections of the law!) that forbids operating a generator on a moving bicycle, or while moving (not "moving *vehicle*" because many laws specifically exclude bicycles from the vehicle definition!), *then* you could only run it while stopped.

also, if there is a law that forbids "gasoline powered" bicycles, it would also exclude any gasoline-powered generators from providing the power to an ebike.

if you had a *diesel* generator, you could still use it, as long as diesel is not included in the legal definitions of gasoline. if diesel isn't specifically excluded from the gasoline definitions, then it would probably be considered the same thing once a court case came up about it.

if you had a *propane* generator, then you could still use it, again as long as no law excludes it's use.


so, it all depends on the law of the area you're in...most places you could probably do this kind of series hybrid legally.

how the law enforcement officers *treat* you may differ from what the law specifies, depending on their understanding of your system and the law, and their personalities and prejudices. they might stop you and issue a ticket (or confiscate/etc depending on laws there, etc), even if you aren't breaking the letter of a law, because they might believe you are breaking the spirit of the law (such as if they think the noise or safety hazard of a gasoline generator is effectively the same as that of a gasoline engine). but it would be up to a judge to determine if that ticket/etc was valid or not, based on the actual law and the actual system, and previous case law, etc.

similarly, someone hearing/seeing you ride past may believe you're using a gasoline engine and not like it, and complain to leos, initiating the above.

pffffffft at laws
there are laws to not speed
meant to be broken
do you go double the speed limit then?
common sense is to do what every other criminal does, 5-10 over the limit.

As usual, I don't read enough before posting.

Re the battery,, yes, you can use a lead battery, like three 12v batteries in series for 36v. yes, you need a charger for it, not the one you linked to, but a proper 36v lead charger.

And again, it needs to be more powerful than what is typical for charging lead acid scooters or bikes. Those are usually not over 2 amps chargers. 2 amps x 36v is only 72 watts. This is about what I had when I tried this, some 12 years ago. You will need a fairly expensive charger, such as a 10 amps, to get even close to 500w of 36v flowing into the system while it runs.

Again, given the high weight, and still fairly high cost of such chargers, that are usually for golf carts, look at the 7 amps satiator from Grin Technology for your charger. it would put out 36v nominal, actually 42v or so, at 7 amps, in a much smaller, lighter package than the big chargers for golf carts. Weatherproof, so it can be permanently installed on the bike or trailer. 7 amps of 42v would be 300w, which is enough to cruise at 20 -24 kph, even with all the extra weight in a trailer.

But again, the best advice remains,, get a larger lithium e bike battery, and a satiator to go with it, and recharge pretty fast at meal stops and such. Really, carrying your power is not needed in Europe. There are plugs.. In the US west though, you could have a 200 mile route with no plugs anywhere. Basically, its better to be light, and just charge where you can, than carry generators, unless heading out into a wilderness.