cg Posted July 17, 2015 Share Posted July 17, 2015 One of the cells are dead in my cheapo unicycle. And, altough I am trying to see if I can get the right single cell replacement, I would like to order a new battery also.This is what I can meassure on my current battery with a dead cell, so I guess it should be one of those standard battery packs that goes up to 67V.Do you know any trustworthy places where I can order a single battery?I have looked at alibaba, But I find crazy stuff like this:16S1P Samsun g cell electric unicycle battery 60v 2200mah and I am not sure how good samsun g batteries are... (notice the subtle space between samsun and the g) Recommendations for where to get battery packs please Link to comment Share on other sites More sharing options...
esaj Posted July 17, 2015 Share Posted July 17, 2015 The kind of pack you want is exactly what that alibaba-link points to: 60V nominal voltage (well, 57,6-59.2V if we're being picky, the nominal voltage per cell is usually 3,6-3,7V, sometimes nearer to 3,8V, the total voltage is 16 times that). The 67.2V is with fully charged (maximum voltage) cells, but usually everyone lists them by nominal voltages, also the total capacity should be calculated with 60V; for 16S1P, 60V * NUMBER OF AMPHOURS = Watthours, so for example 2200mAh (2,2Ah) cells => 60V * 2,2Ah = 132Wh, so you can really compare the packs' capasities.If that supplier uses authentic Samsung/Sony -cells, they're high quality. Do note that ordering from overseas can be costly due to shipment costs (high Wh Li-Ion packs are a flight risk, don't know if it affects the shipping prices or if they have to be shipped by sea), and possible customs duties & taxes.You could ask stores selling the wheels if they sell battery packs, at least funnybike.fr seems to sell F-wheel -packs: http://funnybike.fr/16-accessoires (Scroll down a bit, use Chrome or Google translate). Check that the voltage is correct (I'd expect F-wheel to use normal 16S -packs) and that the connectors match, at least they look similar as in my Firewheel (XT60 for power, some smaller for charge-side, don't know what the third one is for, regenerative breaking? Still looks similar to my Firewheel), I ended up ordering the new packs for the Firewheel as custom hand-made here in Finland from a company, and they're going to cost a pretty penny... I did ask packs directly from the factory, and they gave me the quotes for 264Wh, 528Wh and 696Wh (so-called 779Wh for Firewheel F779), but having seen what kind of "quality" the original packs were (one of the power wires was held in only by the shrink wrap, the BMS protections are oversensitive and can cut power during riding if it's not shunted), I decided I'll have it custom-made, and get better BMSs (not as sensitive to cut out) per pack (originals use one BMS for 4 packs), better cells and warranty under more stricter Finnish consumer protection & law in process... In the end, the price is pretty much the same (well, a little more expensive) that I would have had to pay for F779 -packs from the factory with shipping, customs & taxes. Link to comment Share on other sites More sharing options...
Chuts Posted July 30, 2015 Share Posted July 30, 2015 I ordered my battery from Hengji Lithium Battery Co on Alibaba. A 260WH, 67.2v, 16S2P battery pack. They accept PayPal as payment method which for me gave me extra reason to choose them.As a battery manufacturer for power tools, electric vehicles including scooters and ebikes and CE certified I was somewhat confident in their products. Emailed the sales rep regarding current prices and she got back to me regarding battery configuration and BMS recommendations. Weather or not I needed battery charger etc and shipment cost right to my door.They advertise that they use the LiCoxNiyMnzO2 type of lithium battery. Which is supposed to be safer than the standard 18650 but without loosing any capacity for only a little extra on the price. This was not something she tried to up-sell me on. This is simply the type they use as their standard offerings.Battery was supplied with the BMS pre installed (10 Amp BMS). Contained inside a hard plastic box and shrink wrapped. The power leads came without any sockets in them and you will need to solder on your own.http://www.alibaba.com/product-detail/Lithium-ion-Battery-pack-59-2V_60019205057.htmlThis is a photo of the battery... minus the extra parts I have attached to the power leads. Link to comment Share on other sites More sharing options...
cg Posted July 30, 2015 Author Share Posted July 30, 2015 Hey @Chuts, that battery, seems to have bit to low voltage, as far as I understand I need 67V over the pack,It seems that seller doesn't have any 67VEdit:Indeed, after reading @esaj's post I realize that it probably is the nominal voltage that the factory reports... 3.7*16=59,7Regarding your photo, it seems that you only have two wires attached, shouldn't there be four? Link to comment Share on other sites More sharing options...
Chuts Posted July 30, 2015 Share Posted July 30, 2015 Yes, manufacturer and some sellers use the nominal voltage as the advertised number so 59.2 is the nominal voltage.With regards to the wires you only need the two. Check out your current charger for your EU it will usually show which pins are the + and -Most EU use the 3 pin aviation socket which means the 3rd isn't used. IPS such as mine use 4 pin and only 2 are used.Edit - The additional leads you see in the link that you had for your original post are balance cables which allows a charger to monitor each individual cells within a pack and makes sure each are given a balanced charge. Only good if you have a charger which supports this and for that many cells. Although I believe not really needed for Lithium Ion batteries. Balance cables for Lithium Polymer batteries is usually more common and more of a requirement as lipo batteries are usually supplied in soft pouch format and are more susceptible to bloating from overcharge. Link to comment Share on other sites More sharing options...
esaj Posted July 30, 2015 Share Posted July 30, 2015 Regarding your photo, it seems that you only have two wires attached, shouldn't there be four?I was actually wondering this too... is there no BMS in the pack? Or maybe it allows charging through the discharge-side (I think that's how it migh occur with regenerative braking too, if it really recharges the pack?)? How do you charge it, do you have a separate "smart" charger that knows when to stop?With regards to the wires you only need the two. Check out your current charger for your EU it will usually show which pins are the + and -Yes, but if you open up your wheel, you should see four wires coming from the battery (actually from the BMS of the battery); there are 2 wires for the BMS charging side and 2 for discharge side. The BMS handles controlling the charging.The additional leads you see in the link that you had for your original post are balance cables which allows a charger to monitor each individual cells within a pack and makes sure each are given a balanced charge. I don't think any wheel comes with a "smart" charger that's capable of balancing the cells by itself, instead the balancing seems to be done by the BMS (if the balancing was done by the charger, there would need to be more wires than two?). See here, the white wires (which look yellow at parts, because there's tinted tape on top) are the balancing cables of the Firewheel BMS, and go between the cell pairs:Only good if you have a charger which supports this and for that many cells. Although I believe not really needed for Lithium Ion batteries. Balance cables for Lithium Polymer batteries is usually more common and more of a requirement as lipo batteries are usually supplied in soft pouch format and are more susceptible to bloating from overcharge.I've understood that balancing is needed for Li-Ion too in the long run. If the voltage difference between two cells becomes too great, it can actually lead to what is called "cell reversal" (https://en.wikipedia.org/wiki/Rechargeable_battery#Damage_from_cell_reversal), where the current will flow in wrong direction and destroy the cell. Lithium Polymer batteries meant for RC-devices (radio controlled cars, helis, planes etc.) usually don't have BMSs and I think they need separate "smart chargers" to prevent overcharging leading to cell(s) getting destroyed (or even catching fire/exploding) and for balancing:http://www.chargery.com/productImage/balance system/7-10-cell-voltage.jpg Link to comment Share on other sites More sharing options...
hobby16 Posted July 30, 2015 Share Posted July 30, 2015 With regards to the wires you only need the two. Check out your current charger for your EU it will usually show which pins are the + and -Hmmm, something doesn't add up. You need two wires for charging and two wires for discharging (ie powering the mainboard). What the hell happened to your pack's wires Although I believe not really needed for Lithium Ion batteries. Balance cables for Lithium Polymer batteries is usually more common and more of a requirement as lipo batteries are usually supplied in soft pouch format and are more susceptible to bloating from overcharge.Don't believe that! LiIon needs as much balancing as LiPo. If you don't balance, you'll end up overcharging one or more cells and kill them. I agree that killing a 18650 cylindrical cell is less spectacular than a soft-pouch LiPo, but they are both dead all the same by overcharge.Anyway, our wheel charger are not intelligent chargers, they don't terminate charge, so they must only be used with battery packs with BMS. Link to comment Share on other sites More sharing options...
Chuts Posted July 30, 2015 Share Posted July 30, 2015 @esaj and @hobby16 I think you are both thinking of an external battery connecting directly into the EU motor and main board. Your method would mean once the internal battery is empty you plug in your external and run from that. My method is connecting an external battery to the EU's charge socket, creating a parallel connection with the internal battery and increasing capacity. Meaning both internal and external will drain at the same time. You don't need any additional leads because your internal battery is already connected where needed.The charger I'm referring to with regards to balancing cells would not be a charger that is supplied with any EU. I'm talking about a professional charger that would cost you hundreds (If talking about USD) would probably cost more than most mid level EUs.Charging either internal or external batteries I use my standard IPS charger that came with my wheel. Or if both batteries have similarly low in voltage I charge them together with a parallel connecter and leads I soldered myself. The charger that I have has a light on it which is red when charging and turns green when at full charge. It can detect when it can no longer conduct significant forward current to keep charging the battery and switches off. I think this is a standard with all EU chargers, right?. I usually check on the voltage with a multimeter to measure and make sure that they have been fully charged once finished. This is why I don't think balance cables are needed. Link to comment Share on other sites More sharing options...
esaj Posted July 31, 2015 Share Posted July 31, 2015 @esaj and @hobby16 I think you are both thinking of an external battery connecting directly into the EU motor and main board. Your method would mean once the internal battery is empty you plug in your external and run from that. My method is connecting an external battery to the EU's charge socket, creating a parallel connection with the internal battery and increasing capacity. Meaning both internal and external will drain at the same time. You don't need any additional leads because your internal battery is already connected where needed.I'm not a qualified electronics engineer (unlike @hobby16, who is), but I think you are NOT creating a parallel connection, but instead re-charging the internal battery on-the-go, and all the drain by the wheel goes through the internal battery (the wheel uses the internal battery, which is then constantly being recharged by the external battery).The charger I'm referring to with regards to balancing cells would not be a charger that is supplied with any EU. I'm talking about a professional charger that would cost you hundreds (If talking about USD) would probably cost more than most mid level EUs.Yes, this is what I think also, the chargers that come with EUCs are the "dumb" kind, the actual charging logics are handled by the BMS inside the battery pack.Charging either internal or external batteries I use my standard IPS charger that came with my wheel. Or if both batteries have similarly low in voltage I charge them together with a parallel connecter and leads I soldered myself. As the plug used by IPS has 4 pins, I'm wondering if 2 pins are for recharging and 2 pins are for discharging? So when a charger is connected to the external battery, it uses different 2 pins than when the external battery is connected to the charger-port of the wheel (ie. to the internal battery)? Could be wrong though...The charger that I have has a light on it which is red when charging and turns green when at full charge. It can detect when it can no longer conduct significant forward current to keep charging the battery and switches off. I think this is a standard with all EU chargers, right?. I usually check on the voltage with a multimeter to measure and make sure that they have been fully charged once finished. This is why I don't think balance cables are needed.I'm not sure on this either, but the red light on the charger seems to just turn green when the charging current drops low enough. From my observations with the Charge Doctor and the Firewheel charger, the light turns green when the charging current drops to 0.25A or below, BUT THE CHARGING STILL CONTINUES. What I think is happening is that the BMS starts to run the cell balancing once the charging current drops low enough, so keeping the charger connected until the charging current drops all the way to 0.00A (which can sometimes take like an hour after the light has already turned green) is a good thing. Lithium-Ion batteries are charged in (at least) two phases: Constant current, and then constant voltage. I think the cell balancing occurs only at the very end? Here's the charging graph of my Firewheel from totally empty to totally full (until the charging current drops to 0.00A):So at the start, the current is (almost) constant, and the voltage rises from about 56V to 67.8V (so that's actually around 4.2375V per cell). Once the full voltage is reached, the charging current starts to drop towards 0. I'm not sure, but I assume that the cell balancing won't occur until at the very end, as the balancing uses very little current, here's some random spec-sheet for some 16S Lithium-Ion BMS from Aliexpress:The balancing current is 40 +- 10mA, which PROBABLY means that it won't occur until the (nearly) full voltage has been reached and the charging current is around 40 +- 10mA, and it's balancing to near to the maximum voltage per cell. Also it lists the charge- and discharge-side specs, which PROBABLY means that the "dumb" charger is doing nothing but providing power to the BMS, which handles the actual charging of the cells and controls the charging with protections like preventing overcharge (overvoltage of cells), disconnecting on overheating and the discharge-side protections. Link to comment Share on other sites More sharing options...
Chuts Posted July 31, 2015 Share Posted July 31, 2015 @esajI'm not a qualified electronics engineer (unlike @hobby16, who is), but I think you are NOT creating a parallel connection, but instead re-charging the internal battery on-the-go, and all the drain by the wheel goes through the internal battery (the wheel uses the internal battery, which is then constantly being recharged by the external battery).I believe it to be a parallel connection because if I press the power button on my EU to off, essentially switching off the internal battery it is still powered until I unplug the external battery. This i believe would suggest that the power socket is not only exclusively connected to the internal battery but also to the motor and board. I know someone locally with an Airwheel and it is the same for them too.As the plug used by IPS has 4 pins, I'm wondering if 2 pins are for recharging and 2 pins are for discharging? So when a charger is connected to the external battery, it uses different 2 pins than when the external battery is connected to the charger-port of the wheel (ie. to the internal battery)? Could be wrong though...Some time ago I had opened up the EU and checked the underside of the female charge socket and the only wires are soldered to the corresponding pins as per my photo earlier of + and - Link to comment Share on other sites More sharing options...
Chuts Posted July 31, 2015 Share Posted July 31, 2015 However reading original post again I think @cg is wanting to rip out the internal battery and replace it with a new battery, so maybe you guy are right about the wiring and requires a more complex battery/BMS setup. Whereas I'm coming from the direction that the internal battery is working fine and extending it with external battery pack. Link to comment Share on other sites More sharing options...
cg Posted July 31, 2015 Author Share Posted July 31, 2015 However reading original post again I think @cg is wanting to rip out the internal battery and replace it with a new battery, so maybe you guy are right about the wiring and requires a more complex battery/BMS setup. Whereas I'm coming from the direction that the internal battery is working fine and extending it with external battery pack.well I consider both, I am mostly considering upgrading my existing battery pack so I set two cells in parallel for each of the original cells, I think I saw someone do that in the french forum. Link to comment Share on other sites More sharing options...
hobby16 Posted July 31, 2015 Share Posted July 31, 2015 well I consider both, I am mostly considering upgrading my existing battery pack so I set two cells in parallel for each of the original cells, I think I saw someone do that in the french forum.Indeed. I have made an English translation of this interesting mod, with permission of the author. Look up the "Batteries" categorie on my blog Link to comment Share on other sites More sharing options...
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