Geowats Posted February 13, 2023 Share Posted February 13, 2023 I have a buddy who modded his Master Pro to charge faster using 25 amps. Said something about bypassing the control board. Does anyone know how to do this? Quote Link to comment Share on other sites More sharing options...
Cerbera Posted February 13, 2023 Share Posted February 13, 2023 Is he keeping that in a fire-proof box ? I'd be asking if that was a wise thing to do before I asked how to do it... Quote Link to comment Share on other sites More sharing options...
Chriull Posted February 13, 2023 Share Posted February 13, 2023 5 minutes ago, Geowats said: I have a buddy who modded his Master Pro to charge faster using 25 amps. The master pro with 4800Wh and 134.4V should have an 32s8p config? With the 40t cells it has a standard charge of 2A (->2A*8=16A) and a rated charge current 6A (->6A*8=48A). With rated charge (and according discharge current) the 40t has just 250 cycles. So recommendable should be to use 16A instead of 24A. However cell tempererature monitoring should be done during charging. Charge currents are soecified in the manufacturers datasheet at 23°C, surface temperature has to be below 50°C, recommended below 45°C. Ewheels litech packs have temp alarm? 12 minutes ago, Geowats said: Said something about bypassing the control board. Does anyone know how to do this? Bypassing the control board means that one establishes a direct connection from the charger to the battery packs. Important is to ensure that the bms synchronization is still working after this mod! Both bms have to cut charging once a any single cell reached the overvoltage threshold! Whatever other funtionality/feature the motherboard offers and then are gone... Important for such a mod is to use a charge connector which can withstand the charging current and use adequate wiring. The charge wires and the battery pack connectors have to be able to withstand the charging current. At the bms are a couple of mosfets (for cutting the charge at single cell overvoltage) within the shrink wrap- they have to take the current, too! They are likely the main limiting factor - before modding one should try in any case how hot they get during a full charge from empty too full at high (summer) ambient temperatures. If they can withstand the current one should try charging them within the closed wheels shell again and check the temperature. If there are four good quality mosfets in parallel they could already struggle a bit at 24A (*)- 16A (**) could be again the better choice. (Power dissipation is proportional to the square of the current) (*) Very very roughly 4*0.4W=1.6W for longer time in the shrink wrap could imo be too much (**) In this linear xample this would reduce power dissipation to about 4*0.15W~0.5W. Which sounds much better, but still could be a bit much in such an enclosed enviroment... 1 Quote Link to comment Share on other sites More sharing options...
RagingGrandpa Posted February 13, 2023 Share Posted February 13, 2023 9 hours ago, Geowats said: Master Pro 25 amps Where does one find 3.3kW @ 120VAC in a household setting? Quote Link to comment Share on other sites More sharing options...
Chriull Posted February 13, 2023 Share Posted February 13, 2023 44 minutes ago, RagingGrandpa said: Where does one find 3.3kW @ 120VAC in a household setting? Sounds more like our standard over here with 230VAC with 16A... Quote Link to comment Share on other sites More sharing options...
RagingGrandpa Posted February 13, 2023 Share Posted February 13, 2023 ...and 8kg-worth of chargers? Quote Link to comment Share on other sites More sharing options...
alcatraz Posted February 14, 2023 Share Posted February 14, 2023 (edited) 50E batteries have a 2.45A standard charge rate. 8P make 20A then. I guess going over the standard charge by 25% isn't a huge deal. 25/20 But as others mentioned the cell temperature is important. You definitely want to reduce the charge current the farther you deviate from the goldilock zone of ~20C. After all, these cells are not made for vehicles specifically but electronics in general. Samsung isn't responsible if your wheel catches fire because you've had a habit of charging at 25A at 40C or 0C temperatures or whatever. In your shoes I'd want the ability to fast charge (for emergency use), but I'd avoid using it. I'd get a charger with adjustable current. Be careful with cabling. 25A can melt connectors/cables etc. Edited February 14, 2023 by alcatraz Quote Link to comment Share on other sites More sharing options...
Tawpie Posted February 14, 2023 Share Posted February 14, 2023 46 minutes ago, alcatraz said: I guess going over the standard charge by 25% isn't a huge deal. it'll probably shorten the cell life, by how much is anyone's guess. Quote Link to comment Share on other sites More sharing options...
alcatraz Posted February 14, 2023 Share Posted February 14, 2023 9 minutes ago, Tawpie said: it'll probably shorten the cell life, by how much is anyone's guess. Mm. Imagine if we had cooled/heated packs like on cars. Then fast charging would be ok. When those tesla cars supercharge. I bet that's a bit over the standard charge rate. They must have found a sweet spot. 3 Quote Link to comment Share on other sites More sharing options...
Geowats Posted February 16, 2023 Author Share Posted February 16, 2023 I can't thank you all enough for the input. I love our community of riders! Quote Link to comment Share on other sites More sharing options...
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