marc Posted March 24, 2017 Share Posted March 24, 2017 Do somebody know a site where a power bank is sold for EUC's with the appropriate plug? This would be nice when you do exceptionally a long distance without finding a plug. Even if you have a EUC with big battery (60km range), after 2 years the capacity decreases to the half or to one third of the initial distance range. For normal daily travel, even 20km range would still be enough but it is possible that you want to do more some day. A power bank can be the solution. Link to comment Share on other sites More sharing options...
JimB Posted March 24, 2017 Share Posted March 24, 2017 See this recent post: These power banks don't support the amperage or capacity required to effectively charge an EUC. Between carrying the power bank (and your charging brick) that would be a lot to carry even if you could get some limited results. Link to comment Share on other sites More sharing options...
JimB Posted March 25, 2017 Share Posted March 25, 2017 The other thing to note about this is that batteries are not 100% efficient - meaning it takes more energy to charge them then you can get out of them. Likewise, the transformers are not 100% efficient. So, consider that maybe you can get 80% usable out of the batteries. Then you have a transformer converting from the DC batteries to 120V AC - at 80% efficiency. Then you have the charging brick converting from 120V AC back to DC (for my wheel, 67V DC) at 80% efficiency. So, rough math, 0.8 * 0.8 * 0.8 = ~50%. Now with batteries, size & weight = power. (Assuming the same battery tech.) So consider the size of the battery pack in your wheel. You'd need a battery pack 2x the size of the pack in the wheel to have a reasonable hope of charging. Then of course, you'd need to make sure that the configuration of the battery could support the amperage draw needed by the wheel. If you really wanted to do this, you could consider building your own charging bank that would directly replace your power brick. Like @Slaughthammer mentions in his post: This will convert from the DC battery pack directly to the required DC output voltage (without going to 120AC in the middle). Of course, don't forget that you need a mechanism to charge the battery pack as well. There are alternatives, but you need to consider the amperage draw of your power brick. Check the back of your power brick. Mine indicates 120V @ 2.5A. Volts * Amps = Watts. So this is 300W. This looks like a beast (http://a.co/56JIS3l), but it only supports a max draw of 100W. No good! Now something like this might get'er done! http://a.co/2msY7H7 Make sure you're looking at the 400Wh model. It indicates an output of 300W. In case you're confused, Wh (watt-hours) is a measure of capacity. It holds power the equivalent of 400W for an hour. But look at the output, it only supports 300W output. So this would be able to charge your wheel at 300W for about 80 minutes. The 220Wh version of this power source only has an output of 200W - which wouldn't be enough for my wheel. Link to comment Share on other sites More sharing options...
swvision Posted March 25, 2017 Share Posted March 25, 2017 https://www.schoolofsurvival.com/build-tesla-powerwall/ Link to comment Share on other sites More sharing options...
Slaughthammer Posted March 25, 2017 Share Posted March 25, 2017 6 hours ago, JimB said: If you really wanted to do this, you could consider building your own charging bank that would directly replace your power brick. Like @Slaughthammer mentions in his post: This will convert from the DC battery pack directly to the required DC output voltage (without going to 120AC in the middle). Of course, don't forget that you need a mechanism to charge the battery pack as well. I actually have recieved this fine piece of technology by now. Did a quick test with an old laptop charger, 18,5V/3,5A nominal output. Using that, I was able to get close to one amp at 67,2V... so it seems to be rather efficient. Still waiting for GX16 connectors, and I havn't decided on what batteries to use for mobile use. Will see what I can get cheaply. Might be able to get a good bargain for A123 20Ah LiFePos. I plan on going for roughly 1 kWh, which would translate in just below 8 kg of Battery. That should give me quite a range boost! Only need to figure out a quick release for the connection to the wheel, so I don't rip of cables when I need to dismount the wheel in a not so elegant way.... Link to comment Share on other sites More sharing options...
US69 Posted March 25, 2017 Share Posted March 25, 2017 2 hours ago, Slaughthammer said: I actually have recieved this fine piece of technology by now. Did a quick test with an old laptop charger, 18,5V/3,5A nominal output. Using that, I was able to get close to one amp at 67,2V... so it seems to be rather efficient. Still waiting for GX16 connectors, and I havn't decided on what batteries to use for mobile use. Will see what I can get cheaply. Might be able to get a good bargain for A123 20Ah LiFePos. I plan on going for roughly 1 kWh, which would translate in just below 8 kg of Battery. That should give me quite a range boost! Only need to figure out a quick release for the connection to the wheel, so I don't rip of cables when I need to dismount the wheel in a not so elegant way.... I dont understand whats behind this? Sure you could step up small batteries to 67 volt....but even if this step up module is 100% efficiency...a Watthour stays a watthour? so no weight save, no place save? Link to comment Share on other sites More sharing options...
Slaughthammer Posted March 25, 2017 Share Posted March 25, 2017 The "power bank" (additional battery and step up converter) goes in my backpack and is connected to the chargeport of the wheel. Eventually, I will use that power bank (actually, I should call it power backpack) not only for boosting the range of my wheel, there's so much more applications for a 1 kWh moile energy source Link to comment Share on other sites More sharing options...
US69 Posted March 25, 2017 Share Posted March 25, 2017 1 minute ago, Slaughthammer said: The "power bank" (additional battery and step up converter) goes in my backpack and is connected to the chargeport of the wheel. Eventually, I will use that power bank (actually, I should call it power backpack) not only for boosting the range of my wheel, there's so much more applications for a 1 kWh moile energy source Ok, so you are willing to carry 8kg in your backpack? Wow, respect! :-) perhaps instead of liFEpo4-a123 you should go for 18650 instead, as they carry more wh per kg.... Link to comment Share on other sites More sharing options...
US69 Posted March 25, 2017 Share Posted March 25, 2017 best 18650 source for german/europe: www.nkon.nl Link to comment Share on other sites More sharing options...
abinder3 Posted March 25, 2017 Share Posted March 25, 2017 Just buy a new wheel with bigger batteries. Link to comment Share on other sites More sharing options...
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