old-boy-on-a-wheel Posted September 12, 2020 Share Posted September 12, 2020 Can I charge and Mten3 from a Bestek 300w pure sine wave inverter? 1 Quote Link to comment Share on other sites More sharing options...
Camenbert Posted September 13, 2020 Share Posted September 13, 2020 (edited) Should work but all these steps kill the efficiency (12VDC to 220VAC to 67VDC) A step up 12V->67V on Aliexpress will be way cheaper (few £ only) and for sure more efficient. You can set the V and Amps as required (advising to take a 5A and use it at 50%, 2.5A, eventually with a fan if it run hot). These are so cheap I also consider to add it permanently to my car, with a switch to turn it on when needed (and while driving, a car battery is only about 500Wh so you'll drain it otherwise) Edited September 13, 2020 by Camenbert 1 Quote Link to comment Share on other sites More sharing options...
RockyTop Posted September 13, 2020 Share Posted September 13, 2020 9 minutes ago, Camenbert said: Should work but all these steps kill the efficiency (12VDC to 220VAC to 67VDC) A step up 12V->67V 2A on Aliexpress will be way cheaper (few £ only) and for sure more efficient. You can set the V and Amps as required. These are so cheap I also consider to add it permanently to my car, with a switch to turn it on when needed (and while driving, a car battery is only about 500Wh so you'll drain it otherwise) I did this. The charger that I got could take an input of 12v- 60v with an adjustable output of 12v-90v with a top output of 900w. With a 12 volt input I can only get 0.7 amp charge at 84 volts. I would need a 60 volt input to get the 900w. It works but just getting an inverter is quicker easier and charges faster in my case. I could get a step up converter. At that point no money has been saved. 1 Quote Link to comment Share on other sites More sharing options...
Camenbert Posted September 13, 2020 Share Posted September 13, 2020 3 hours ago, RockyTop said: With a 12 volt input I can only get 0.7 amp charge at 84 volts 0.7A x 84V = 58W, the Chinease on Aliexpress exaggerate indeed their spec but that much is a record You need to see what is the max A input, take 75% of the value to not run it too hot, x13.5V, then you have the real power of that stuff. On this one, it's 20A, so it will be 20Ax75%x13.5V= 200W, despite announcing 1200W (?!); Or 3A on 67V, what is more than enough, with great efficiency and no need to think about taking the AC charger with you. https://fr.aliexpress.com/item/32739799613.html Quote Link to comment Share on other sites More sharing options...
RockyTop Posted September 13, 2020 Share Posted September 13, 2020 (edited) 1 hour ago, Camenbert said: 0.7A x 84V = 58W, the Chinease on Aliexpress exaggerate indeed their spec but that much is a record You need to see what is the max A input, take 75% of the value to not run it too hot, x13.5V, then you have the real power of that stuff. On this one, it's 20A, so it will be 20Ax75%x13.5V= 200W, despite announcing 1200W (?!); Or 3A on 67V, what is more than enough, with great efficiency and no need to think about taking the AC charger with you. https://fr.aliexpress.com/item/32739799613.html The advertised wattage is best case scenario at the highest input voltage. To get the 900 watt I would have had to put in the 60 volt. Even with the 0.7 amps I had to add two fans to keep it from over heating. I used an older version of this unit. https://www.amazon.com/Numerical-Regulator-10V-120V-Converter-Adjustable/dp/B01GFVI6R6/ref=sr_1_4?crid=2GHSM06CFRXDB&dchild=1&keywords=dc+to+dc+boost+converter&qid=1600029263&sprefix=dc+to+dc+boost+%2Caps%2C334&sr=8-4 EDIT: I actually reworked a system that another member had built. I was about to build the same thing when another member offered to build a few units for us. The original system got too hot. I had to make an aluminium box with fans for it. Edited September 13, 2020 by RockyTop Quote Link to comment Share on other sites More sharing options...
OneLeg Posted September 14, 2020 Share Posted September 14, 2020 I posted a thread on charging a unicycle from 12V solar or a car using a DC to DC boost/step up transformer.... The only issue is that to go from 12V to 84V you are going to need many AMPs and very thick cables.... I decided to configure my batteries at 48V and used less amps... The Boost transformer I used allows you to post the AMPs output.... to reduce the load... 1 Quote Link to comment Share on other sites More sharing options...
RockyTop Posted September 14, 2020 Share Posted September 14, 2020 19 minutes ago, OneLeg said: The only issue is that to go from 12V to 84V you are going to need many AMPs and very thick cables.... Yep! To get 1.5 amps at 84 volts you will need to start with 10+ amps At 12 Volts. 5 amps at 84 volts would be 35+ amps at 12 volts. 1 Quote Link to comment Share on other sites More sharing options...
Trampoline_matt Posted March 16, 2021 Share Posted March 16, 2021 I have one of these to try to make a charger for 84 volt wheel from 12 volt vehicle. When I get it together for testing, I’ll post results here. Good, bad or other. I would like 2.5 amps into 84 volt wheel. ( 210 watts )https://www.amazon.com/gp/aw/d/B076TTBKFG?psc=1&ref=ppx_pop_mob_b_asin_title Quote Link to comment Share on other sites More sharing options...
alcatraz Posted April 6, 2021 Share Posted April 6, 2021 The smaller the pack capacity the slower you ought to charge it (generally). The datasheet of the cells in use contains the charge rate. Quote Link to comment Share on other sites More sharing options...
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