Flyingppg

I have this kit and we are very pleased with it. However the supplied controller is limited to 15a peak load (from memory) and this seller doesn't seem to offer anything other than a 36v battery so not sure what happens at 48v? The wheel is is also available in either screw on free wheel or cassette (cst) versions. Check carefully which one is which and make sure you order the right one for you. The wheels certainly support both disc and v brakes. We like the rack battery because we also have paniers for shopping, but maybe you are 20 years younger than me. :-) I agree with others that a geared motor is best. Much lighter, much more torque on hills and the planet gearing has a free wheel built in so no drag when off motor. Don't look at motor watts alone.

Greetings, We have a motorhome and recently I bought a Yosepower 36v 13ah 350w kit for my partner and fitted it to one of our hybrid bikes. We cycle a lot when abroad. She doesn't like the hills, I don't like waiting and neither of us like having a domestic! Neither of us are getting any younger and I foresee a time soon when I will also add the same kit to my bike. It's been a good purchase. However these large capacity bike batteries take some charging when you only have 12-13.5vdc to start with in 1200wh of leisure batteries. So what to do? Of course you can simply use an inverter but this is weight and a loss of efficiency plus when you want to go out, 2a with the supplied charger means waiting about if you forgot to put the battery on charge. I've ended up building/buying high output 12v to 42v cccv dc-dc chargers from standard cheaply available modules and components on eBay, some plywood, and teak Ronseal wood stain inspired by the eclectic mix of videos on YouTube. Next is an upgrade to the solar charging system to a 250w panel and mppt solar charger for the batteries on the motorhome. I'm amazed that 250w panels can be bought for around £100 if you shop about. I also found a ready made mppt solar boost converter charger for £28 but that seemed like cheating. Only problem is I seem to be enjoying my partners bike kit and solving the charging problem more than she is or indeed riding the bikes. I would be interested to hear what others are doing to address this particular challenge of in vehicle charging? Kind regards Richard

Hi, my partner and I have a pair of 622 hub (700c wheel) hybrid bikes that I fairly recently fitted a Yosepower 350w rear wheel kit to hers also running their 13ah 36v rack battery. It's been a nice conversion for both of us because she can now keep up and I'm not waiting at the tops of hills. I had no experience of e-bikes previously but I otherwise have a professional engineering background. When I was fitting it I realised that the 12x10mm e-hub axle mis-centred the wheel by 1mm compared to the QR hub that it replaced but I adjusted the v-brakes accordingly, the torque washers in my judgement make a decent interference fit with the frame and otherwise it works fine. However I see others are filling the drop outs a little to properly centre the wheel because of the thicker axle. I'm always reluctant to go permanently removing metal unless absolutely necessary so interested in what the issue and risks really are from those with real experience? For example, is the wheel going to come out under power at speed at some point or is this more a bike specific issue for some where others have operated their conversions, albeit with a 1mm mis centred wheel, without a problem and one has to make an engineering judgement for your own particular bike/kit conversion?

Yes, point taken. http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures

All batteries perform less well when cold but you should find that after a little riding it will warm up and then start to go better. You can safely store your battery in the cold (the manufacturers must have specified something in the manual about temperatures) and the cold also means you don't have to give it a bit of charge so often if in storage over a long period. You can charge it safely cold too. Personally I prefer my battery to be at room temperature, and so keep it in the house, so it performs better from the start but you aren't doing your battery any harm by keeping it in the garage so long as it is also dry.

Correcting myself: 10a and 90v output. Can be powered from between 10 to 60v dc.

No, it's not stepped like that. You can have any maximum current/voltage you like output up to 10a and 60v, power source and battery state of charge permitting and it will cccv charge up to those limits and then turn off when the battery is "full", in actual fact when the charging current drops to around 5% of the maximum limit set. I'm getting into the habit of sometimes charging my battery up to 41v if going on a shorter ride to try and make my battery last longer.

Might do but it's behaviour when operating below 42v is unclear from the listing also if it switches off when charging reduces below a certain threshold, usually you want it to around 100ma. What you can't do with lithium it's leave it on trickle charge and you need a charger that will turn off completely at full charge.

If you want to go the inverter route and you're charging with a commercial charger the input amps will be written on the charger and over stated. For a typical 42v 2a 230vac charger a 250w pure sine wave inverter will be more than enough but still much heavier and less flexible in the motorhome and much more expensive than the simplest option of the mppt 7210a unit I suggested before. Have you got a solar panel on your motorhome already? If you do, if I were you, and this is what I actually do in my motorhome, I'd run the 7210a limited to 3a output (I'm charging at 42v) from the 12v power output on your existing solar charge controller (you need one rated at 20 amps or more). You will be pulling max 15 amps from your solar panel and batteries. This is also the usual limit from a standard cigarette lighter socket. This way if you draw too much and flatten your leisure batteries too far your solar charger will cut the supply to the 7210a bike battery charger. The 7210a also has a timer facility so you can limit the charging time too if you want to. When you are driving, if your bike battery will take it, you can also up the amps out of the 7210a because you have the benefit of the vehicle alternator but be mindful of the current draw from the 12v input. That 7210a can put out 600w, and draw over 50 amps at 12v! I just stick to 3 amps. I can also divert the power from my solar panels direct to the 7210a for charging, for example when driving. Doing this you can, of course, be sure you never flatten your leisure battery and the 7210a will do the best mppt it can from the solar panel whenever the sun is shining. My one real criticism of the 7210a is that the fan is really noisy and so I changed it in mine, 99p for two 40mm fans on eBay. Really annoying. I'm never running it that hard. The mppt tracking can also be a bit flaky if going pure solar and drops out from time to time when a cloud goes over but then it was less than £30. Good luck!

So no testing information, and no references to share from the guy that sees these things as all important. And as you've already pointed out without such things anything you say is about as useful in the real world as faith and religion. I'm afraid I can't reconcile your lack of understanding of, what must be, basic core knowledge to someone with your declared experience and expertise. Or maybe you just what to make commercial gain from other people's effort without being prepared to share yourself. That seems like a parasite. Maybe you have been living off grid too long? You started with the sneering aspersions and I was always told if you can't take a bit then don't give it out. You seem found out to me.

Oh I see, you haven't actually tested anything. You're just getting this stuff from a book, internet, or more likely a forum I bet, but since you like your references and have them what are they because I'd like to read them too? I've actually tested a 2 year old pure sine wave inverter coupled to the 230vac bike charger that came with my battery and measured the power in vs the power out, also those three dc-dc chargers I suggested, when charging the same bike battery. The dc-dc chargers were always more efficient with a higher power out/power in ratio (closer to 1) than the inverter 230vac charger and they became more and more efficient if you had more dc volts on the input, ie 24v charging a 42v battery is more efficient than driving the charger with 12v and so on. The inverter combo is also 3x heavier.

If you have a better more efficient method let's hear it.

Absolutely. Ring a power company and ask them to connect you up to the mains. I think the original question was can one charge a, say, 36v bike battery from a 12v source, I guess because you are in your car or motorhome, without using an inverter. Yes you can and it is more efficient to do so. All that power conversion introduces losses (heat) so best not to do as much of it as you possibly can plus why cart around an inverter if you don't need to? But if on the other hand you are at home with, say, a roof full of solar panels and using a grid tied inverter to push your excess power back up to the grid then that's a good reason to be using an inverter at home. However I have a feeling you really don't know your inverters from your transformers from your switched mode power supplies. By the way, buy also the sister dc-dc buck converter of the middle boost converter I suggested and you could charge any electronic gadget you own from a 10v-60v dc source with just those two chargers.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F182671320308

Not strictly true. Most MPPT charge controllers are dc-dc step down "buck" converters but MPPT charge controllers that are dc-dc step up do exist and not expensive such as this: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F182671320308 This item is a configurable cccv charger, about 70% efficient. So on a really sunny uk day plugged into a 250w panel you might get 3.5 amps at 42v from it.

No need for an inverter and better not to use one in fact. You don't say the voltage of your battery? You want a CC (constant current) CV (constant voltage) boost converter. If you are reasonably technical you can make one from one of these with a few other bits and bobs: https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/222757752356 You can easily charge at 42v 6amps with a bit of cooling with one. Details on YouTube here: If you are less technical and 2-3 amps at 42v will do you try one of these: https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/152355318529 If you aren't very technical at all or just want an easy solution then get one of these: https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/182671320308 Lots of YouTube videos on these. Just search for 7210a. The beauty of the last one is that you can of course also run it from a solar panel but it will also run just as happily from a 12v battery (in fact anything from 10 to 60v and so will the others) Bear in mind all of these are dc-dc cccv boost converters and they need setting up carefully for your particular battery. These devices are not plug and play. You can't charge a battery from a supply with higher voltage than your battery with one of these. You absolutely need to read up on charging voltages and currents for your particular battery. Here is a good article for that: http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries I own and have made very nice very flexible chargers from all three. If you want to run them indoors, make a 12v psu from a PC power supply. About £25 on eBay and lots of YouTube on doing that too.