Erratic Battery Reading

Pineman

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Battery was charged to 100 percent. Rode 13.8 miles and battery read 44 % I took the battery off to transport the bike to the house. When I got to the house, I put the battery back on the bike and checked the voltage. The voltage read 70%. Has anyone experienced this?
 

Nelson37

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You mean does anyone have your weight, your road conditions, your hills, and rode your route at your speed, and experienced a change in battery voltage that you describe, on a battery just like yours?

No.

Do Lion batteries have a rebound?

Yes, they do.

Is it usually this extreme?

No, but there is no way to even guess without a LOT more information.

Also, getting a reading on battery State Of Charge remaining is not a simple thing, if using a voltmeter, give exact numbers, if a simple 3-5 LED readout, define.
 

Pineman

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You mean does anyone have your weight, your road conditions, your hills, and rode your route at your speed, and experienced a change in battery voltage that you describe, on a battery just like yours?

No.

Do Lion batteries have a rebound?

Yes, they do.

Is it usually this extreme?

No, but there is no way to even guess without a LOT more information.

Also, getting a reading on battery State Of Charge remaining is not a simple thing, if using a voltmeter, give exact numbers, if a simple 3-5 LED readout, define.
I shouldn't have said voltage. I was reading the percent battery on the display. I guess what I'm asking is what is the true percent battery when it read 44%. If I would have let the bike sit for 15 minutes and then checked the percent battery on the display and it ten read 70% would the 70% battery reading accurate?

Also, to gather more data would it be helpful if I changed my display to read in volts instead of percent battery?
 

Nelson37

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It is quite possible BOTH readings were "accurate".

Voltage gives a rough, very rough, GUESS at what actual percentage of charge is remaining. There is no way to accurately "meter" battery capacity in real-time, on a bike.

Voltage is at least a test you can independently replicate. The depth of rebound here is somewhat extreme, but after a sustained period of heavy power drain, caused by load and/or hill-climb and/or speed, could be reasonable.
 

rinejl

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Battery was charged to 100 percent. Rode 13.8 miles and battery read 44 % I took the battery off to transport the bike to the house. When I got to the house, I put the battery back on the bike and checked the voltage. The voltage read 70%. Has anyone experienced this?
Yes, I have experienced the same thing. After a 5 mile ride my display on my Aventon Level read about 50% but when I got home and turned my bike off and then back on in about one half hour it read almost full. I understand that the bike's display about remaining battery charge is just approximate. I try to have a full charge each time I take my Level on a ride. I wouldn't worry about it.
 

Pineman

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Yes, I have experienced the same thing. After a 5 mile ride my display on my Aventon Level read about 50% but when I got home and turned my bike off and then back on in about one half hour it read almost full. I understand that the bike's display about remaining battery charge is just approximate. I try to have a full charge each time I take my Level on a ride. I wouldn't worry about it.
My wife has a new 48V Aventon. We road 13 miles and when we got home her power display showed full bars. My 52V Magicycle read 77 percent. I just want to know if my power reading is accurate while riding on the trail. I don't want to get stuck with a dead battery.
 

Nelson37

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First, get a voltmeter. Next, start using it.

Then, get a wattmeter for the bike, charge thru it, and record the stated results. You could get a wattmeter for the wall outlet on the charger but then you would need to know the charging profile and electrical efficiency of the charger, which is not AT ALL a simple thing to measure. Notice how the charger gets warm? That is wattage being USED, by the charger, but NOT going into the battery.

After that, spend a few weeks analyzing watts IN, and watts OUT, and comparing those numbers with voltmeter results, voltmeter being used immediately after a ride and again an hour or two afterwards. Also immediately BEFORE a ride.

After doing all that, and ONLY after doing ALL of THAT, will you have some basic understanding of how your battery is currently performing.

Then, you will need to learn that the performance observed, declines steadily and fairly consistently, every day, until one day the decline will start to accelerate, and some time after that, you need a new battery.

While you are at that, you should also learn that there are several behaviors and procedures followed by you, the end user, that can and will accelerate or slow down that decline.
 

Pineman

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First, get a voltmeter. Next, start using it.

Then, get a wattmeter for the bike, charge thru it, and record the stated results. You could get a wattmeter for the wall outlet on the charger but then you would need to know the charging profile and electrical efficiency of the charger, which is not AT ALL a simple thing to measure. Notice how the charger gets warm? That is wattage being USED, by the charger, but NOT going into the battery.

After that, spend a few weeks analyzing watts IN, and watts OUT, and comparing those numbers with voltmeter results, voltmeter being used immediately after a ride and again an hour or two afterwards. Also immediately BEFORE a ride.

After doing all that, and ONLY after doing ALL of THAT, will you have some basic understanding of how your battery is currently performing.

Then, you will need to learn that the performance observed, declines steadily and fairly consistently, every day, until one day the decline will start to accelerate, and some time after that, you need a new battery.

While you are at that, you should also learn that there are several behaviors and procedures followed by you, the end user, that can and will accelerate or slow down that decline.
Sounds like a lot of work, particularly for a novice. Hopefully I am overreacting to my fear of being stranded on the trail with a dead battery. I did see an independent review of the Magicycle where the reviewer ran the bike to 5% percent battery.
 

Nelson37

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Ok, we'll try the short version.

The "guage" is a rough guess. You need to know how your battery works and performs. Hopefully understand how and why that will change.
 

Pineman

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Ok, we'll try the short version.

The "guage" is a rough guess. You need to know how your battery works and performs. Hopefully understand how and why that will change.
Yea, I am going to keep a log. Miles, terrain, est. use of throttle, starting/ending percent battery level, starting/ending battery voltage (from display) and starting/ending watts draw. I think my battery is giving me what I expected. Thanks everyone for you feedback. Much appreciated.
 
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