kiitick Posted January 5, 2022 Share Posted January 5, 2022 I purchased a used sherman with a little over 3,000 miles on it. I LOVE it. So much so that I sold my v11, because it wasn't getting used. I've noticed that the battery will charge to 100v but when I take it off the charger, it drops down to 98 volts right off the bat. I'm not sure if this is normal behavior, or if I need to look at getting a new battery pack, or adjust the voltage in the settings. Any suggestions? If you think I need a new battery set, any idea where I can pick one of those up? (E-wheels doesn't have them in stock, and with the new max, I don't know if they will.) 1 Quote Link to comment Share on other sites More sharing options...
Denny Paul Posted January 5, 2022 Share Posted January 5, 2022 This video walks you through how to update the firmware on your sherman. I think updating the firmware will likely address the voltage issue you're talking about. Quote Link to comment Share on other sites More sharing options...
supercurio Posted January 5, 2022 Share Posted January 5, 2022 Yes, you need to calibrate the voltage to 100.8 at the end of the charge, close to when the wheel will shut itself off. Then the voltage reported will be closer to 100.6V to 100.2V after rest, depending on how fast you charged the wheel. Quote Link to comment Share on other sites More sharing options...
kiitick Posted January 5, 2022 Author Share Posted January 5, 2022 I updated it to the most recent version, which took care of the pedal dip, and allows me to manually adjust the voltage. I'm not sure how to manually take a the voltage other . than what the screen and EUCworld show. I know I FOR SURE don't want to overcharge the batteries, that's bad. Quote Link to comment Share on other sites More sharing options...
RagingGrandpa Posted January 5, 2022 Share Posted January 5, 2022 36 minutes ago, kiitick said: the battery will charge to 100v but when I take it off the charger, it drops down to 98 volts right off the bat Leave the charger connected until its light turns green, and then check this again... there should not be a sudden drop as you described, if the charging current had finished properly. (Regardless of firmware calibration) 24 minutes ago, kiitick said: I FOR SURE don't want to overcharge the batteries No worries there- the charger sets the final voltage, not the EUC. (Messing with the EUC firmware or settings cannot cause overcharging.) 2 Quote Link to comment Share on other sites More sharing options...
kiitick Posted January 5, 2022 Author Share Posted January 5, 2022 54 minutes ago, RagingGrandpa said: No worries there- the charger sets the final voltage, not the EUC. (Messing with the EUC firmware or settings cannot cause overcharging.) That is a HUGE relief. I'll put it on my charger again, and calibrate it. I wasn't too sure about that. 2 Quote Link to comment Share on other sites More sharing options...
Tawpie Posted January 5, 2022 Share Posted January 5, 2022 (edited) I would leave it on charger for a couple of hours after the light turns green to allow the cells in the packs to balance. It is very important for battery longevity that the cells are balanced, you want to get in the habit of leaving it on charger for an hour or two after every full charge. Besides, I kind of think the green light on the charger is a bit optimistic anyway—short charging times are attractive even when it's not really fully charged... who's gonna know? There are a couple of very long threads and a video on this forum about charging and balancing—they're worth a read if you're into the nitty gritty but the tl;dr pretty much comes down to "green light plus an hour or two every time you charge". Edited January 5, 2022 by Tawpie 1 Quote Link to comment Share on other sites More sharing options...
supercurio Posted January 5, 2022 Share Posted January 5, 2022 (edited) @Tawpie on Sherman it's even easier because the board takes extra care slowing things down near the top of the charging curve which leaves plenty of time to balance as well. And then the wheel shut itself off, the user knows that it's both fully charged and balanced 🙂 Edited January 6, 2022 by supercurio 3 Quote Link to comment Share on other sites More sharing options...
kiitick Posted January 7, 2022 Author Share Posted January 7, 2022 Ok, tested yesterday and today. I'm the charger after it's green, I manually set the voltage to 100.8. I think I'm seeing some sag as I ride (it's cold here right now). Because after about 2 miles, my voltage is down, and my percentage in euc world shows 90%. When I stop, the percentage bounces back some, as does the voltage. 2 Quote Link to comment Share on other sites More sharing options...
Tawpie Posted January 7, 2022 Share Posted January 7, 2022 (edited) On 1/6/2022 at 9:12 PM, kiitick said: after about 2 miles, my voltage is down, and my percentage in euc world shows 90%. When I stop, the percentage bounces back some If you've got EUCWorld set to use the fancy battery percentage, it's attempting to estimate the % remaining mileage and isn't a good representation of your battery state of charge. I'd make sure it's set to standard or custom (I don't know the 'empty' voltage for the V11 but it should be easy enough to find). It's pretty common for the voltage to go down rapidly from full—some of the 'charge' is surface charge and that gets burnt off quickly. But after the initial drop off of a volt or two, it should go down fairly linearly at 15-20 Wh/mile (that's an ish number, it totally depends on how you're riding at the moment and cold makes the consumption per mile appear to be higher because the batteries aren't as efficient when they're cold). Edited January 9, 2022 by Tawpie oops, if you burned kWh/mile you wouldn't get far 2 Quote Link to comment Share on other sites More sharing options...
supercurio Posted January 7, 2022 Share Posted January 7, 2022 Looks good! Congrats on your calibration. Now you gained a bit of range as well, since the tiltback will occur later and matching the desired cell voltage better. 2 Quote Link to comment Share on other sites More sharing options...
kiitick Posted January 8, 2022 Author Share Posted January 8, 2022 I just made the change. Went 18 miles and my battery in euc world showed 70%. Which is great. I'm a larger rider, so I figure 50 kw per mile at 25-30 mph. I can't wait to take it for a longer ride! My v11 would be less than 30% after that distance. Thanks for all the suggestions. The Sherman really is a thing of beauty. Quote Link to comment Share on other sites More sharing options...
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