A legal question or two....

[Woosh]

Good point. I'm unsure of what generator to buy yet, I certainly won't be buying anything else until (if) the ebike kit arrives and is installed, and also works well. The charger which the battery arrives with shouldn't overtax a 800W petrol generator, I don't think, but it would be good to purchase a generator capable of supporting a rapid charger in the first place.

Assuming you plug your charger into the 220V socket of the inverter generator, your standard charger charges at 2A and uses 85W on average. That's a very low output for your generator.
Let's assume you need 720WH on average per day. Using a normal charger, that would take 10 hours. Petrol cost will be high.
If your charger can take 850W input, you would only need to run the generator for 1 hour. That will cut your fuel bill.
If you have a battery that can be charged at 1C, you'll need C to be 720WH.
If you have a battery that can only be charged up to 0.5C, you will need two or spend 2 hours per day charging it.
0.5C: LiFePO4, Tesla 2170
1C: ? ask the forum

 

[Deleted member 33385]

Assuming you plug your charger into the 220V socket of the inverter generator, your standard charger charges at 2A and uses 85W on average. That's a very low output for your generator.
Let's assume you need 720WH on average per day. Using a normal charger, that would take 10 hours. Petrol cost will be high.
If your charger can take 850W input, you would only need to run the generator for 1 hour. That will cut your fuel bill.
If you have a battery that can be charged at 1C, you'll need C to be 720WH.
If you have a battery that can only be charged up to 0.5C, you will need two or spend 2 hours per day charging it.
0.5C: LiFePO4, Tesla 2170
1C: ? ask the forum

Thank you! That's all very interesting information. I clearly need to do some reading. I'll measure how many watts my charger uses and make certain I buy a generator which can support up to 0.5C charging (the £200 cheapo in post #86 looks likely fine for normal and moderately rapid charging at 4A, I'm not sure that my battery cells can handle a charger with 850W input, and whatever that output turns out to be, and really don't fancy trying, without a lot of research), to minimise the time that the generator needs to be on in the bike trailer (a faster charge minimises the likelihood of detection by noise, and as you pointed out, uses less petrol), while I am in motion using the other battery on the bike. Or I might stop at a layby for a sandwich, while it charges quickly, or stroll about taking in the sights, or go shopping pushing about the trailer containing my folded bike, while the battery charges, if it doesn't charge very fast. Or of course ride while charging the second battery.

My ebike kit is now being delivered by UPS on Thursday! From London! There is even a genuine UPS tracking number! Enraged at the prospect of the usual 6 week wait for a delivery from China (post Brexit too, anything could happen after Jan 1st 2021), when I had made all efforts to ascertain the stock levels in each of their warehouses in the UK, Belgium and China - only to be told it was being shipped from China anyway, I had angrily pressured the seller to switch the kits over several hours: A 52T ebike kit was going to be sent from China (when I was told it was in stock in Belgium, prior to making the payment), but now only a 52T chainwheel will arrive from China, and the 48T ebike kit from London. I'll switch the chainwheels later (if) when the 52T chainwheel eventually arrives from China (with perhaps a tariff), but look forward to measuring the watts used by my charger and electrifying my ancient Dahon Helios (and possibly myself) tomorrow night... Here's a video of a guy installing a similar but UK illegal 750W kit on a Dahon Jetsteam:

If that all goes well and it works, I'll hatch my fiendish plan involving an ancient Dahon Helios, a bike trailer, second battery, rapid charger, lots of wood and a suitable generator for unlimited (possibly legal) and reasonably economical ebike mileage. It isn't terribly green, but right now I can't see any other cost-effective way I can cover 240 miles on a ebike.

My only worry now is water ingress... I've got lots of heat shrink sleeves and some Bostik... I might need more Bostik.

 

[Woosh]

your generator is fine, it's the battery that needs to be specially selected.
That's why I asked if you have already committed your budget.
Now you have bought your battery, there is little more you can do.
Most Lithium ion chemistry only allow charging at 2A.
If you want fast charging, you also need to keep the battery at around 25-30 degrees C.

 

[Deleted member 33385]

your generator is fine, it's the battery that needs to be specially selected.
That's why I asked if you have already committed your budget.
Now you have bought your battery, there is little more you can do.
Most Lithium ion chemistry only allow charging at 2A.
If you want fast charging, you also need to keep the battery at around 25-30 degrees C.

Yes, I have already ordered and paid for a 36V 19.2ah battery pack made with 60 X 3200mAh LG Cells, and I have no idea if these can be rapidly charged, but if my build goes well, I'll be in the market for a second battery, and am open to the idea of purchasing one more capable of rapid charging, if it isn't prohibitively expensive or wildly unsafe. I'd rather not be an onlooker while my wooden trailer flashes and bursts into flames on the side of the road, or while I'm towing it - lithium fires are horrible. Do you have any recommendations of suitable cells and/or charger to use? I'd prefer to buy a pre-made battery pack and matched rapid charger with a guarantee, rather than make it all myself. I've just Googled LiFePO4, Tesla 2170 and they look very expensive... I wonder how much would a similar 19.2ah pack would cost, utilising such cells? It's only £299 for another LG cell 19.2.ah pack. More Googling required methinks...

 

[vfr400]

Charge rate is limited by the design of the BMS. Unless you check it out, and know what you're doing, don't go over 4 amps.

Fast charging can have an affect on battery life. As I've already explained to you, recommended charge rate is 0.2C, which would be 5 hours.

 

[WheezyRider]

Yes, I have already ordered and paid for a 36V 19.2ah battery pack made with 60 X 3200mAh LG Cells, and I have no idea if these can be rapidly charged, but if my build goes well, I'll be in the market for a second battery, and am open to the idea of purchasing one more capable of rapid charging, if it isn't prohibitively expensive or wildly unsafe. I'd rather not be an onlooker while my wooden trailer flashes and bursts into flames on the side of the road, or while I'm towing it - lithium fires are horrible. Do you have any recommendations of suitable cells and/or charger to use? I'd prefer to buy a pre-made battery pack and matched rapid charger with a guarantee, rather than make it all myself. I've just Googled LiFePO4, Tesla 2170 and they look very expensive... I wonder how much would a similar 19.2ah pack would cost, utilising such cells? It's only £299 for another LG cell 19.2.ah pack. More Googling required methinks...

LG cells, but which ones? There are all sorts. As vfr says, you also need to know the specs of the BMS in the pack.

This is the cheapest micro generator I've seen:

Error 410 | Screwfix

Thousands of products at low trade prices | FREE next day delivery available | 30 day money back guarantee on all orders.

www.screwfix.com

 

[WheezyRider]

If you had LG MJ1 cells (these are bigger capacity than the ones you are ordering, but it will give you an idea)

Test of LG 18650 MJ1 3500mAh (Green)

lygte-info.dk

So normal charge current 1.7A (0.5C). You have a 10s6p cell config, so 6x1.7 = 10.2A. So in this case you could charge the pack at 10A, IF the BMS can handle it and heat does not build up too much.

So find out what your cell type is and BMS spec and you might be able to charge at a higher rate.

 

[WheezyRider]

The LG 3200mAh cells could be these:

Test of LG 18650 MH1 3200mAh (Cyan)

Standard charge current per cell 1.55A

 

[Benjahmin]

Why not talk to Jimmy at e-bike batteries? This is the sort of thing that he'd love to throw around.

 

[Deleted member 33385]

LG cells, but which ones? There are all sorts. As vfr says, you also need to know the specs of the BMS in the pack.

This is the cheapest micro generator I've seen:

Error 410 | Screwfix

Thousands of products at low trade prices | FREE next day delivery available | 30 day money back guarantee on all orders.

www.screwfix.com

The LG 3200mAh cells could be these:

Test of LG 18650 MH1 3200mAh (Cyan)
Standard charge current per cell 1.55A

That's a great bit of searching - I'm guessing if these cells are cheapish, it's likely those are contained in what seems to be an impenetrable battery pack, impenetrable without voiding the warranty impenetrable.

That generator is a good find! The kit arrived last week and I started installation at 3.33pm, finished at 12.03am. It took a lot longer than I anticipated because the crankset simply would not come off, and I had to build up the pannier with a piece of wood, because the battery was too long and I need my folding bike to fold. The first pedal came off with some effort, using the crankset remover, but the left pedal was stuck fast. I got about to about 8mm and threaded the aluminium pedal arm with the steel crankset remover. I tried hammering it off but got nowehere, applied a lot of WD40 but that didn't help. Eventually I used the damaged crankset remover to fashion a vertical spike by embedding it into a thick piece of wood (drilled hole), put the vertical spike on the floor, placed the axle over that and hammered like mad on the pedal. It took a lot of hammering but it eventually came off... the bottom bracket itself had also seized, cue yet more hammering. The kit installation itself was a breeze but there is no way that I can see to open the battery to inspect the cells: Hair dryer and plastic prys? It's a metal shell, or metal bonded plastic. No screws anywhere. Looks like it's glued together.

The C18 Controller shows no detailed battery information, only a charge remaining percentage, which is the way Bafang released those. I'm loathe to risk unofficial firmware. Is the security code lock stored on the board in the motor or only in the controller? If stolen and it's kept on the controller, it'd be easy to just get a new controller and sell the bike on, with my hidden GPS tracker attached...

It's wonderful at my age being able to tackle all the local hills, with ease! I ascended 10 miles of hills within half an hour (mostly using the illegal throttle, which has now been removed), and the battery was still showing 100% charge. And my bike still folds! I've ordered a gear sensor to protect the cassette. The only trouble now is the gears - I bought my Dahon Helios from a friend many years ago and for some reason it has an 8 gear shifter and 7 speed cassette. It's present hillclimbing gear was inaccessible before I installed the Befang 48T, now I only have the three fastest gears until the 52T eventually arrives in several weeks from China. I'm worried about the strength of the chain because it's never been replaced and there is so much more force acting on it now by the motor. Best to change chain and cassette together, they've worn into each other pretty well, I don't want skipped links. Does anyone know if this cassette is compatible with my Helios?

https://www.amazon.co.uk/Sram-Cassettes-Cassette-Metallic-11-32T/dp/B000NNX2P4/

I might be able to get better battery life with the full range of gears. What is the PC-38 spec? What is the ideal chain to buy? I'm a bit clueless about bikes.

It may be very costly to buy a spare battery from China after 1st Jan... even from the EU. The good news is, assuming 2000 lifetime charges plus the cost of the bike, accessories and upgrades = 1p per mile for 120,000 miles... if I get 60 to 90 miles with this battery each charge. It's yet to be fully tested for range.