WARPed1701D Posted June 29, 2017 Share Posted June 29, 2017 After a ton of searching and reading I've concluded that battery capacity, longevity, and what we can do to preserve them has been the topic of many conversation on this forum. It is understandable too. After all the ability of the battery to safely deliver in an array of circumstances and environmental conditions makes the difference between a safe ride and a face-plant. Replacement power packs also seem to cost about the same as half of a new wheel! Ouch! I've been concentrating on what I can do to preserve the capacity of the battery in my newly ordered Inmotion V8. For the type of wheel the V8 has a relatively low capacity and so a restricted range compared to say the KS 16S but wins in the area of waistline and weight. I'm loath to start another thread when there are so many already but I have a few questions that appear to have, so far, been unanswered. Conventional wisdom on the forum derived through discussion and a heavy reliance on the information from Battery University (batteryuniversity.com hereafter referred to as BU) is that if you can get away with only charging to 80% and performing 50% discharge you will return you the best bang for your battery buck with regards to increasing the number of charge cycles by 4 or 5 times. BU reports that EV's such as the Nissan Leaf and Tesla models do this by charging to 80% capacity for a "full tank" and considering 30% to be an "empty tank". This maximizes charge cycles of the hugely expensive batteries and then by dynamically increasing this usage range beyond the initial 50% limit as the battery ages the vehicle is able maintain mileage specs over a number of years. BU considers a full charge discharge cycle to take a single cell's voltage from 3.0V (empty) to 4.2V(full). So following their suggestion of say an 80% capacity charge and only 50% usage to 30% capacity suggests a charged cell voltage of 3.96V and a discharged cell voltage as 3.36V. This is where I want help. The thing is, in the interest of safety I understand most EUC manufacturers artificially increase the "empty" voltage of a cell above 3.0V. From information I read on this forum from Jason Inmotion's cutoff voltage is 68V (over a 20 series 2 parallel setup) giving an empty cell voltage of 3.4V. With this in mind, ignoring any safety aspects of potential for restricted current delivery at low voltages, to achieve the best balance of capacity and longevity from my V8 battery I should charge to 80% (according to a 3rd party too such as the Charge Doctor, not the V8's battery indicator) cell capacity (3.96V) and then discharge until the V8 considers the tank dry (actual 3.4V) which in reality BU would consider still to be 33% actual cell capacity. Thus I consumed only 47% capacity. Do you agree with this conclusion? If I were to charge to 80% and discharge to 30% following the Inmotion battery indicator only for both levels then I'm guessing I'd actually be charging to 4.04V (80% of the 3.4V to 4.2V range, 86% of actual 3.0 to 4.2V cell range) and discharging to 3.64V (30% of the 3.4V to 4.2V range, 53% of actual 3.0 to 4.2V cell range) meaning I actually only get to use 33% of the real battery capacity vs the 50% I think I'm using. In another post on the forum in Jason's initial review of the V8 prototype he says that the V8 remained responsive and performed well right down to empty. So, if Inmotion keeps so much power in reserve and the wheel appears solid even at lower voltages I'm thinking of doing the 80% charge via Charge Doctor and drain to near flat as my usual routine to hit that balance of range and longevity (unless it is cold, then I’ll leave extra in the tank). What are your thoughts, first on my initial battery conclusions and then on my consideration to use the battery down to Inmotion’s definition of empty? I appreciate your input. P.S. If we can keep the discussion relatively layman that would be awesome! Link to comment Share on other sites More sharing options...
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