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Author Topic: Balance Voltage in Storage  (Read 3011 times)

MostlyBonkers

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Re: Balance Voltage in Storage
« Reply #30 on: February 24, 2017, 10:41:49 AM »

I proposed something conservative, not some minimum requirement. Clearly the manufacturer's recommendations are working fine for people so far.

Extremely conservative I think Brian. I'd make it simpler:

Option 1: Leave plugged in and don't worry about it.

Option 2: Drop the SoC to 50%, unplug and set a reminder to check the SoC after a month in storage. Note the drop and set another reminder to check the SoC when it reaches 30% based on your estimate of the drop per month.

After that first check, I reckon you could leave the bike for six months. That is pure speculation though. I'd love to hear some more real world examples.

For some, I bet even my option 2 might be too much hassle. I reckon that my 2014 DSP was probably left plugged in at 100% for the two years or so before I bought it.  After all the head scratching I've done on this topic, I've defaulted to leaving it plugged in whenever it's at home. I don't bother unplugging it even when I know I won't use it for a week or two. That's very seldom though. It's pure laziness. I know it would be better to unplug it, but I can't be bothered to run it down before a few days off. I also don't want to forget top it up before I need it again. I forgot to plug my bike in once when I got home from work one night and it really stung the next morning!

I don't know what real world mileage a brand new 2014DS would have achieved. Mine could do about 65 miles of mixed riding when I got it, with me on it etc. I don't think that has changed after a year and 10,000 miles. Time will tell!

I wish the bearings were as good as the battery...
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BrianTRice@gmail.com

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Re: Balance Voltage in Storage
« Reply #31 on: February 24, 2017, 06:59:30 PM »

FWIW, there's a report on FB that their bike lost 45% SoC in two months while unattended.

I know there's a huge bias for anyone to assume that maintenance doesn't need to be done because nothing went wrong the last time you checked. But you check because something might have gone wrong and you want to make sure anything is taken care of.

So, 90% of the bikes 90% of the time discharge at a microscopic rate and have good cel balance. Newer bikes with better battery engineering are on the top of that list. But maybe that pre-2015 bike develops a very minor leak current (or the BMS acts up subtly) that doesn't even produce heat, but does discharge the battery at a rate of 10% per month. You'll never notice if you don't look and have a way to compare.

This was ground into me running military nuclear power plants, where you're meant to really check every dial in the plant for changes, and understand those changes and be able to explain them. Getting bored and acting like everything is fine works most of the time, until it doesn't. I like things that last a long time and are easy to work on, troubleshoot, and keep maintained. Building or having things that wear out is a drag. Not being able to understand what you want to take care of is a drag, which is why I am repulsed by modern cars.

I'm sure the responsible thing to do (plugged or unplugged) is to go check your bike SoC once a month while it's in storage, and do something about it if it's out of the 20-80% range (or 95-100% range plugged in). Think of it as protecting your investment.
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MostlyBonkers

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Re: Balance Voltage in Storage
« Reply #32 on: February 24, 2017, 07:31:58 PM »

Sage advice there Brian. Do what Brian says folks.

If you're an idle bugger like me, use my method but don't blame me if you check on your bike in spring and find it's bricked! [emoji848]
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domingo3

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Re: Balance Voltage in Storage
« Reply #33 on: March 01, 2017, 09:19:17 PM »

Cross posted from FB.  I am not Ron Van Hul and not sure if he's on here, but I do appreciate the information.  I'll be interested to see how/if Zero puts this information out.

Quote
Ron Van Hul
Ron Van Hul Last week I asked inquiries@zeromotorcycles.com:
Should I recharge when capacity is more than 50%
The answer:
No, only if it is below 50%. It is also important NOT to leave the bike plugged in all the time as stated in your owner’s manual. Zero will make a clarifying statement on this matter in the next few weeks. You can be ahead of the curve be doing this.
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BrianTRice@gmail.com

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Re: Balance Voltage in Storage
« Reply #34 on: March 01, 2017, 10:40:23 PM »

Cross posted from FB.  I am not Ron Van Hul and not sure if he's on here, but I do appreciate the information.  I'll be interested to see how/if Zero puts this information out.

Quote
Ron Van Hul
Ron Van Hul Last week I asked inquiries@zeromotorcycles.com:
Should I recharge when capacity is more than 50%
The answer:
No, only if it is below 50%. It is also important NOT to leave the bike plugged in all the time as stated in your owner’s manual. Zero will make a clarifying statement on this matter in the next few weeks. You can be ahead of the curve be doing this.


Clarity on this would be welcome. Presumably they've figured out better battery management somehow.
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stevenh

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Re: Balance Voltage in Storage
« Reply #35 on: April 13, 2017, 08:31:50 PM »

Balance plot over the winter (looks like a firmware issue to me...)

Steve
« Last Edit: April 13, 2017, 08:34:46 PM by stevenh »
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Kocho

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Re: Balance Voltage in Storage
« Reply #36 on: April 13, 2017, 10:00:42 PM »

Really interesting to see how the imbalance steadily increases. I have been keeping my bike off the plug 100% of the time when not in use, even during the off-season (so several months off the grid) and checking the balance periodically, and it has been always less than max of 6mV and within 1 mv from where it started when last charged, so insignificant change. I've been doing it since I got the bike, long before the Zero guidance started, simply because it makes sense on many levels and my empirical observations supported the theory. I'm glad Zero caught-up and changed their guidance.

As to why you see that increase, it could be hardware and/or firmware related, but definitely not what you want or expect from a properly functioning charging system ...
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stevenh

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Re: Balance Voltage in Storage
« Reply #37 on: April 14, 2017, 04:48:15 AM »

Back to 3mv tonight!

Steve
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BrianTRice@gmail.com

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Re: Balance Voltage in Storage
« Reply #38 on: April 14, 2017, 07:19:40 AM »

That is a really interesting trend line! I wonder if it's just one layer of cells or something with a nearly-immeasurable difference.

The slope indicates that 45mV are lost over a period of 60 days. 45mV / 3.65V nominal = 0.0123287671 or 1.23% difference in cell voltages.

If I do a little napkin math, (45 millivolts / 3.65 volts) * 28Ah / (60days * 24hr/day) = 0.00023972602A or 0.24mA average differential discharge over those two months to get that result.

I'm not sure what to do with that, but maybe it's food for thought for the right wizard here.
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mrwilsn

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Re: Balance Voltage in Storage
« Reply #39 on: April 14, 2017, 11:52:12 AM »

Cell balance is reported as a delta between cell with highest voltage and cell with lowest voltage....Looks like you may have a bad cell that is dropping voltage until the charger steps in and rebalances....You are still leaving it plugged in as you said in original post?

If the bike wasn't plugged in while stored that one cell might have fallen into no man's land.  Have you sent the logs to Zero? Or tried to analyze them yourself? Did you get the data from the logs? The BMS logs should be able to confirm if one cell is indeed a bad actor....Not sure you would see it in the MBB logs.

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BrianTRice@gmail.com

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Re: Balance Voltage in Storage
« Reply #40 on: April 14, 2017, 01:28:45 PM »

Cell balance is reported as a delta between cell with highest voltage and cell with lowest voltage....Looks like you may have a bad cell that is dropping voltage until the charger steps in and rebalances....You are still leaving it plugged in as you said in original post?

If the bike wasn't plugged in while stored that one cell might have fallen into no man's land.  Have you sent the logs to Zero? Or tried to analyze them yourself? Did you get the data from the logs? The BMS logs should be able to confirm if one cell is indeed a bad actor....Not sure you would see it in the MBB logs.

1% per 60 days is not an unreasonable rate, and can easily be checked monthly and fixed when appropriate, though.

But yes, BMS logs might show something interesting.
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stevenh

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Re: Balance Voltage in Storage
« Reply #41 on: April 15, 2017, 12:08:21 AM »

I do have both sets of logs.  I did have the bike plugged in until late March when I saw the new recommendations.  Its interesting that the balance voltage crept to 43mv, then reset to around 20mv, then back up to 63mv in two different ramps.

It took a few days of riding/recharging to get back to 3mv.  I am going to keep a close eye on the balance from now on and won't leave the bike plugged in for more than a day when it's at 100%.

Zero also recommended a firmware update (I have the firmware my bike shipped with in April of last year, I have yet to be back to the dealer). 

Steve
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