eZee 36v 14ah battery dies at 11AH and my questions :)

[dsullivan]

I currently have a brand new eZee 36v 14ah battery pack from ebikes.ca (who helped me design and sold me everything for my first ebike.

*Note - when I received the battery it was holding a charge of 42v. After every charge I give it, it only reaches 37 or 38 volts.
Is this normal or is it a bad sign?

over 3 days I have discharged the battery on rides down around 7 amp hours the first trip
Then I recharged.
7 amp hours again and then I did a 1 hour charge to make sure I would have enough to get to work and home.
a full charge last night.

today I had some running to do so I drove it until cycleanalyst said 11 amphours then it just died.
Showing 32.4V and showing used 11ah I assumed I had about 2.5 to 3 amp hours left.

Not so bad except it died about 3.5kms from my house at the bottom of the biggest hills and I am not the best biker. Actually I am very close to the worst but I have been getting better.
So I walked the hills and biked the last 2 KMS to home.

First thought - Should I be counting AmpHours or Should I be counting WattHours?

Second how low should the BMS Volt cutoff on these eZee batteries be.

Third did I hurt the battery giving it a little 1hour charge the other day.

fourth is there some ritual I should do as a breakin for these batteries or should I just use them? Should I expect it to get better?

PS I am loving this bike.

 

[neptronix]

That battery is going to be within 41-42v fully charged, and fully discharged more around 30-33v.
It sounds like you have never charged it to full. Or there is a problem somewhere preventing a full charge from occurring.

 

[dsullivan]

Thank you.
I have the supplied HighRate charger that came with the battery from ebikes.ca

there was no information related to the use of the battery and charger so I have a couple of questions.
there is a key on the side of the battery. It has 3 positions. Open, off and on.

on I understand, off seems simple but what is open for?
If I hook up my cycleAnalyst while charging what number should I be looking for?

Thanks Dave

 

[neptronix]

No documentation on a battery of that price? geez... have you hounded ebikes.ca for answers yet?

I'm not familiar with this battery, but i do know that 36-38v is about half charged on a chemistry like this.

 

[richmpdx]

Well these are certainly appropriate questions/issues. But have you asked ebikes.ca, where you bought everything, or not? Sometimes even with good sellers things are not perfect, but a good vendor will try to work things out. But if you haven't asked...
Rich

 

[dsullivan]

Well since this just happened a couple of hours ago, I often like to research things first. If I find no answers on the web, I will then ask around on the forums then if I get nowhere, I will call the guys at ebikes.ca.

Asking on the forum is free. Calling ebikes.ca is $8 a call longdistance. Also emails can be slow.

I also know some of the guys from ebikes and our local ebike guru YPedal is often on here.

So yes and no to your question.

Thanks
Dave

 

[Russell]

I currently have a brand new eZee 36v 14ah battery pack from ebikes.ca (who helped me design and sold me everything for my first ebike.

*Note - when I received the battery it was holding a charge of 42v. After every charge I give it, it only reaches 37 or 38 volts.
Is this normal or is it a bad sign?

over 3 days I have discharged the battery on rides down around 7 amp hours the first trip
Then I recharged.
7 amp hours again and then I did a 1 hour charge to make sure I would have enough to get to work and home.
a full charge last night.

today I had some running to do so I drove it until cycleanalyst said 11 amphours then it just died.
Showing 32.4V and showing used 11ah I assumed I had about 2.5 to 3 amp hours left.

Not so bad except it died about 3.5kms from my house at the bottom of the biggest hills and I am not the best biker. Actually I am very close to the worst but I have been getting better.
So I walked the hills and biked the last 2 KMS to home.

First thought - Should I be counting AmpHours or Should I be counting WattHours?

Second how low should the BMS Volt cutoff on these eZee batteries be.

Third did I hurt the battery giving it a little 1hour charge the other day.

fourth is there some ritual I should do as a breakin for these batteries or should I just use them? Should I expect it to get better?

PS I am loving this bike.

For the eZee 36V/14Ah LiMn battery 42V is fully charged. If you are reading 37-38V after a complete charging cycle that is way too low.

First be sure your voltmeter or whatever you're using to check the voltage is working properly ( I use an inline wattmeter during charging).

Second, check the open circuit output of the charger. Some smarty-pants chargers will read a lower open-circuit voltage than they charge at but most will read the voltage they charge to, which in your case should be at least 42.0V. A little more is actually better since it will help the BMS balance the pack, for example my 12S LiPo charger reaches 50.5V or 4.208V/cell and I balance to 4.20V/cell.

Third, if the charger output voltage looks fine then leave it connected to the pack at least overnight to be sure the pack is fully charged AND balanced.

When breaking in a battery limit the depth of discharge until it has had several complete charging cycles. I stress COMPLETE because if you don't let the battery fully charge AND balance you risk having a low cell which will cause the BMS to cut out prematurely. A BMS will trip out for a number a reasons, one is low overall battery voltage, but it will also trip if just ONE cell goes too low.

-R

 

[d8veh]

It's always worth checking that whatever device you're using to check the voltage is showing an accurate result. We had a guy a few weeks back very worried by his low battery voltage, but when he eventually put a new battery in his voltmeter, everything was OK. You should check with at least two different devices if something appears to be wrong.

I heard that Ezee have just changed their 14aH batteries to different (higher discharge rate) cells. See if you can find out which ones you've got. If you've got the older low discharge rate cells and you use a lot of high power, 11aH sounds about right. The 14aH rating should be at a low discharge rate.

 

[dogman dan]

Not charging to full voltage does not sound good.

Anything we say is more or less a guess. Could be your charger has a problem, and is not fully charging the bat, or the batt itself could have had a defect.

Grin will sort it out for you, I'm sure.

 

[dnmun]

4th first. yes there is a definite need for a slow break in period. your pack was outa balance and never got fully charged up again. if your charger originally charged it up to 42V then put it on the charger again until it reaches 42V. don't keep riding it to total exhaustion. especially if it is so far outa balance. jmho

 

[dogman dan]

Just for clarity. What was the voltage after the overnight charge? Did it ever get back to 42v after that first ride?

What voltage doe the charger put out? I once recieved a new 36v charger that only put out 18v. Hopefully the problem is simply a bad charger.

 

[tofuuu]

Might sound dumb but did you reset the cycle analyst after you fully charged the battery? That might give you a more accurate measure.

 

[dsullivan]

Wow. Many replies since I last checked.
Thank you everyone.

Justin recently email me and educated me. He said after charging anything over 41.5 is a good full charge.
Since the last full charge came in around 41.9 I am very happy now.
My goal is to only run this battery to about a 50% DOD maximum unless I get caught a little short once in awhile.
I figure that should give me plenty of life from the battery.

I have reset the cycleAnalyst many times and I am also using a separate digital multimeter.

Back to one of my first question.
Ah vs Watt hours. - I am seeing now that I should probably be watching the WattHours to determine how much life I have taken from the battery. Is this correct?

 

[wesnewell]

Ah vs Watt hours. - I am seeing now that I should probably be watching the WattHours to determine how much life I have taken from the battery. Is this correct?

Before I hooked up a watt meter, I just watched the mileage I had ridden. After, I watched the pack voltage. Now I just use an led voltmeter. I found watching ah/wh not to work real good since many things can cause the battery to loose charge that won't register on the meter. Voltage is real time, not some calculation of stuff used.

 

[kevo]

Since the last full charge came in around 41.9 I am very happy now.

You have the right attitude (Hitchhikers Guide to the Universe: "Don't Panic")
These details come up. You've researched, tried, glitches, resolved - well done!

My goal is to only run this battery to about a 50% DOD maximum
I figure that should give me plenty of life from the battery.

Conservative, should last a long time. OTOH allow exceptions for those glorious ride days.

Your batteries (LiMn) will minimize balancing/maintenance hassles.
Like Wesnewell says, voltage is your friend for monitoring where your batteries are.
Just decide your hi/low limits and enjoy 8)

 

[dsullivan]

so today I had my 2 youngest children, Michael 13 and Lauren 10 over for our bi-weekly visit and they helped me test out the battery limits.
I know it's not good to go to the 100% dod on a battery but I just had to know where it was.

Here were the results.
the three of us riding around my subdivision and up a 1 km 6% grade eventually made it quit at 450WattHours.

The voltage declined nice and steadily obviously loosing power after 31V under load
and after reaching 30.5 voltsish it just dropped out.

We did this test around the neighborhood so we could easily pedal home

Success. I let the battery cool for about 1/2 hour then put it on the charger for a nice long soak. (overnight)

My understanding is that LIMN batteries can go right down to 25Volts at 100% dod, so the fact that my battery kicked out at 30% means my BMS Must be protecting it from over discharge
especially since my CycleAnalyst is set to default 26V cut off.

Is this a reasonable and accurate assumption.

 

[Russell]

It appears from your numbers that you actually drained the pack almost completely. You can't say that since 25V is 100% DOD that 30.5 or 31V is 70%, it doesn't work that way. Once the pack gets nearly fully discharged the voltage drops like a stone so my guess is you drained the pack to about 90% DOD.

I don't know what vintage your battery is but here is a graph Justin provided a couple of years ago for the batteries he sells. He has since had some packs upgraded with better cells however.



-R

 

[999zip999]

Don't run your pack to cut off.

 

[jateureka]

+1
Most 36V controllers have the LVD at 31.5V.

 

[dsullivan]

Did the drive to work today at full power, full speed. 8.7 Kms in 14 minutes including some winding trail riding for about 2 kms.

took 185 WattHours @ 21WH/KM according to the cycle analyst.
The drive home I did much slower (no time crunch) I restricted my amperage to 15Amps (The minimum that will still help me up our hillls)
and it took about 20 minutes, 121 WattHours @ 14 WH/KM and much more pedaling.

I got home with a good sweat on and still had room left in the battery. I through it on the charger and took a shower

 

[wesnewell]

You should have about 500 usable wh, so you should be able to go both ways wot with room to spare.

 

[dsullivan]

Thank you for the great explanations.
I have established that the BMS has a cutoff at 31V this gives me a usable 450Watthours
I am now getting use to watching both the WattHours used and the Voltage.

Yesterday I had a long day of riding 30KMs from home to work, then detour to the bike shop and finally a long drive home.
Ended around 430 WattHours and 32Volts left showing on the CycleAnalyst underload.

Felt like a good day.

Thanks Dave