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| dsquire:
--- Quote from: S. Heslop on June 11, 2014, 03:54:18 PM ---One of each of those batteries costs £35 (although maybe they'll rob me with delivery charges). I suppose it's not too much to take a risk on, and if it works out I can buy maybe a couple more packs to get more range. I also need a balance charger. I see this one in alot of videos and the price doesn't seem so bad. I guess I should buy a better multimeter too since my current very cheap one isn't that reliable. The costs add up! Usually I try not to think too much about the price of things and get surprised when I suddenly run out of money, but for this project i'm keeping a log of everything I spend. I'm curious to see how much I spend in total (tools n all) so I can compare it to just buying an electric bike. I also suspect if I make a video it'll be the first thing people will want to know. --- End quote --- Stan I guarantee it will cost you more to build than to buy. It will be more fun to build and you will learn more so that is a big plus. --- Quote ---eBike videos on youtube tend to have real bitter comments. People getting upset that it was based upon a cheap bike, people getting upset that it's cheating and an affront to the purity of cycling, people getting upset that it's too complicated for them to bother building, etc. So i'll be interested to see how a video I'd make would fare. --- End quote --- I wouldn't worry about most of the comments on youtube. When you read them they appear to be coming from kids that aren't even potty trained yet so how can you expect anything better. Carry on with your build here, I'm going to be sitting by watching. Thanks for showing what you have done to date. :D :D Cheers :beer: Don |
| vtsteam:
Steve that charger you linked to will only charge 6 cells at a time, and charges a whole pack across the output leads (all in series). Your proposed system has 7 cells so it wouldn't work unless you charged the 3 and 4 cell packs individually. That's possible as long as your packs are removable -- in other words each pack attaches individually to your bike with connectors. The charge rate is 5 amps max, which means with 5000 mah packs they would each take an hour to charge from full discharge. That would mean for your proposed 10 Ah pack, 4 hours to charge (theoretically) by shifting and monitoring the 4 packs around during that time. The further disadvantage is that this charger doesn't charge each cell in the pack individually. That means you have to balance individual cells periodically, by discharging and recharging them on a special balance connector board -- a pain in the neck. And waste of electricity and time. Also sometimes these "smart" chargers have a cutoff minimum voltage and will refuse to charge a whole pack if an individual cell gets too low. The pack may not be bad if that one low cell could be charged individually, but the charger is not capable of recognizing this, and can't charge cells individually. People throw away perfectly good battery packs with these types of chargers as a result. The type of charger I use charges each cell individually. That keeps them balanced automatically without the need to discharge and recharge them periodically. It also can't fail a pack for overall low voltage -- it treats each cell individually. This type tends to be a "dumb" charger -- without a microprocessor and little or no readout (other than an LED showing when each cell is charged). In other words -- fewer "features" but they do the job better. I don't know how electronics oriented you are but I can contrast the two types of chargers as: Type 1 has a single voltage regulator attached to a single microprocessor. It charges across the whole pack. It needs a complex internal program for guessing the state of cells in a battery pack. It needs multiple adapter connectors and leads for attaching to different brands and sizes of manufacturer's connectors used on the main battery pack power lead. It also needs a balancing connector board. All these advertised leads and boards look like added features -- but they're really just unfortunate needed complexity due to the way it charges. Type 2 has multiple voltage regulator circuits -- one for each battery cell -- each one is treated individually. It's dumb It doesn't guess anything. It also charges across a different battery connector, called the "balance connector" which is standardized across almost all battery manufacturers. It therefore doesn't come with a bunch of adapter battery leads or a balance board. It doesn't need them. I'll look into chargers tonight and see if I can find something reasonable that would work better -- bottom line is, yes you can use that charger you linked to, but you will need to spend a lot of time and attention shifting and monitoring battery packs, and it may refuse to charge a good pack at some point. re. meters: For a bike I would personally be tempted to just use cheap universal automotive type analog meters. However there are now some nice Chinese LED digital readouts for V and A -- I got one recently. And with a 100A shunt resistor (usually purchased separately) they would work in the range you will be using. These are really components, not cased meters. Personally I find digital readouts less good as a warning device than an analog pointer, and the automotive type are cased and ready to go. |
| S. Heslop:
--- Quote from: dsquire on June 11, 2014, 04:34:21 PM --- I guarantee it will cost you more to build than to buy. It will be more fun to build and you will learn more so that is a big plus. --- End quote --- Oh yeah i'm definitely enjoying myself and learning stuff - but I also enjoy totally over-thinking videos! I'm mostly copying Matthias Wandel's style of videos, but I find the types of comments I get pretty interesting. Especially the ones that get upset about the price or effort it takes to build a thing compared to buying it. So I thought I might try pre-emptively address that kind of response in an electric bike video and see how (or if) people react. |
| S. Heslop:
--- Quote from: vtsteam on June 11, 2014, 05:03:26 PM ---Steve that charger you linked to will only charge 6 cells at a time, and charges a whole pack across the output leads (all in series). Your proposed system has 7 cells so it wouldn't work unless you charged the 3 and 4 cell packs individually. That's possible as long as your packs are removable -- in other words each pack attaches individually to your bike with connectors. --- End quote --- That's a shame. It'll hopefully get me started for testing the motor though. |
| vtsteam:
Hmm after looking at specs of about 5 different chargers, it looks like the one you linked is a sheep in wolf's clothing. The digital display and bunch of cords makes it look like the "smart" type 1, but I think it may actually combine type 1 and 2. I think it can charge individual cells through the balance connectors on the side of the main unit, but includes cords to charge across the pack, and cords to use an auto battery for charging Lipos as a power source. If so that's a good deal. The only drawback is that it doesn't charge 7 cells. So you will have to charge your 4 battery packs individually. If this is a combo type 1 and 2 charger -- I don't see anything better for the price range. There might a way to charge the two 3S packs together (using a made up wiring harness) reducing charge time by an hour. |
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