Battery Mania

[Tigertone]

Having just completed a conversion of my wife's Giant bike to a pedal assisted rear hub drive, I was anxious to try it out. So, for my first ride I made it short and steady and all went well so I decided to up the tempo by going further. The journey was mixed terrain and 6miles later and with half a tank of duice left all was going swimmingly until, ...Oops... The battery cut out and refused to come back on until 30 minutes later and pushing the bike up an extremely steep and long hill. So, with home still 4 miles away I decided to hit the gas. finally arriving home feeling slightly knackered after my hill climb, I notice the battery power was still on a quarter.
After a bit of research it appears the the sudden battery power down could have been caused by one or two cells starting to fail and over heating causing the BMS to shut things down.
So, here IAM: Looking for a new battery pack. The question is though, Do I go cheap or invest in something of better quality such as Samsung or Panasonic new 21700 cells ? Any thoughts? What do you suggest???

 

[Stefan Mikes]

Buy a proper quality e-bike.
The brand name Giant comes to one's mind.

 

[indianajo]

The name of the cells inside is a temptation to lie by small unreliable battery manufacturers. Nobody cuts their new battery open to see what is really in there. ***** is the land of counterfeiters, a pile of 3rd tier cells could easily be wrapped by plastic logos of a major manufacturer. Cost, a print shop run, one wrapping operator.
Stay with one of the 3 or 4 known good assemblers. Reenetron, em3ev, ebikeling. Look on parts forum for more opinions. Some good reputation ebike vendors sell dolphin etc replacement batteries for not a lot. At much higher cost Giant shimano bosch sell replacement batteries that have good reputations. Finding a patented connector to fit one of those might be a problem.

 

[PCeBiker]

@Jenny Mao sells quality batteries.

 

[PCeBiker]

.. with half a tank of duice left all was going swimmingly until, ...Oops... The battery cut out,..
After a bit of research it appears the the sudden battery power down could have been caused by one or two cells starting to fail and over heating causing the BMS to shut things down.

It was most likely caused by voltage sag.

If you have a brand new battery, your battery cutout because of voltage sag not cell imbalance.

You drained all your cells too hard.
The voltage dropped and your battery cut out.

 

[RickBradford]

One trick I discovered after a cut-out caused by excessive voltage sag is to disconnect the battery and then re-connect it.

If you don't do this, some motors will continue to act as if the voltage is too low. Disconnecting and reconnecting gives the motor a chance to reboot itself, it seems.

The battery I have is fitted with a poor, or no, BMS - going up a steep hill, the voltage can sag by up to 5 volts, often putting it close to the cutout point, before it recovers on a downhill stretch.

 

[Slaphappygamer]

At 46v, my power drops. I can feel it. With voltage sag, my battery drops to about 2 volts. I usually charge when I get to 46 volts. Voltage sag is normal, to a point. You’ll get more familiar with your battery the more you use it.

 

[harryS]

This was the first ride on your new battery? Id suggest recharging it and do another try. As this is a DIY conversion, do you have any readouts on battery health.? A voltage would be great, as the battery bar icons are not very useful. Do you own a voltmeter?
.
Here are some voltage landmarks.
36V battery: Max charge 42.0V, Half Charge `36V. Lowest Voltage: 30V-31V
48V battery: Max charge 54.6V. Half Charge 47V, Lowest voltage: 42V-43V
.
'All batteries, except the biggest ones, have some voltage sag. Around 2 volts at 100-200 watts. So it's possible for your battery to cut out when still a few volts above minimum. If your battery is old with weak cells, that sag could grow to 4 -6 volts.

 

[Gionnirocket]

I'm always a dick

Having just completed a conversion of my wife's Giant bike to a pedal assisted rear hub drive, I was anxious to try it out. So, for my first ride I made it short and steady and all went well so I decided to up the tempo by going further. The journey was mixed terrain and 6miles later and with half a tank of duice left all was going swimmingly until, ...Oops... The battery cut out and refused to come back on until 30 minutes later and pushing the bike up an extremely steep and long hill. So, with home still 4 miles away I decided to hit the gas. finally arriving home feeling slightly knackered after my hill climb, I notice the battery power was still on a quarter.
After a bit of research it appears the the sudden battery power down could have been caused by one or two cells starting to fail and over heating causing the BMS to shut things down.
So, here IAM: Looking for a new battery pack. The question is though, Do I go cheap or invest in something of better quality such as Samsung or Panasonic new 21700 cells ? Any thoughts? What do you suggest???

Get yourself a quality battery.. otherwise you'll have more days like today.
Just as important as quality cells, you need a reputable builder so that you can trust the cells are authentic and you won't have other quality issues.
EM3EV is known for their builds as is Jenny Mao

 

[AHicks]

This was the first ride on your new battery? Id suggest recharging it and do another try. As this is a DIY conversion, do you have any readouts on battery health.? A voltage would be great, as the battery bar icons are not very useful. Do you own a voltmeter?
.
Here are some voltage landmarks.
36V battery: Max charge 42.0V, Half Charge `36V. Lowest Voltage: 30V-31V
48V battery: Max charge 54.6V. Half Charge 47V, Lowest voltage: 42V-43V
.
'All batteries, except the biggest ones, have some voltage sag. Around 2 volts at 100-200 watts. So it's possible for your battery to cut out when still a few volts above minimum. If your battery is old with weak cells, that sag could grow to 4 -6 volts.

I'm with Harry (above). You very well may need a new/different battery, but geez, check out the one you have properly to make sure the battery is actually the issue. Otherwise you're just throwing parts at your issue, hoping one will fix it.....

 

[Tigertone]

Buy a proper quality e-bike.
The brand name Giant comes to one's mind.

Thanks for your response. I recently visited a bike shop and there were lots of E bikes all stacked up on one another and when I asked if the were for sale the response was. " No. They're in for service" More to the
Point, perhaps some of them needed more than a service. There were some new ones too. Marked up at £10k and when I asked why was they so expensive the man said," well they have GPS and two battery's " now, I'm sure there was more to it than that, rubber belts, hydraulic brakes ect ect. I can also see that the top bike manufactures such as Bosch are
Pushing the technology boundaries and I praise the for that, but my wife doesn't want a grey bike costing £10k or even £2k, She wants her orange Giant bike but with a bit of assistance. And so far I have spent £500 on the conversion and it's looking great.

 

[Tigertone]

Get yourself a quality battery.. otherwise you'll have more days like today.
Just as important as quality cells, you need a reputable builder so that you can trust the cells are authentic and you won't have other quality issues.
EM3EV is known for their builds as is Jenny Mao

Thanks for your reply, sounds like good advice to me. Actually sometime ago I converted my bike to a mid drive TSDZ2 and I fitted a 17.5Ah battery pack with Samsung battery's and I've never had a spot of bother with it. Plus a managed two 30k rides before having to charge it up. So, what I have done this time by buying an unbranded battery has turned out to be a false economy and I am learning some big lessons with this build.

 

[Stefan Mikes]

And so far I have spent £500 on the conversion and it's looking great.

You actually burned £500 and are risking burning your home with a battery fire.

Vall E+ 2 (2022) | Women Trail bike | Liv Cycling UK

www.liv-cycling.com

Ten thousand quids? Really?

 

[Tigertone]

Get yourself a quality battery.. otherwise you'll have more days like today.
Just as important as quality cells, you need a reputable builder so that you can trust the cells are authentic and you won't have other quality issues.
EM3EV is known for their builds as is Jenny Mao

Once again, this all sound advice.

 

[tomjasz]

You actually burned £500 and are risking burning your home with a battery fire.

Vall E+ 2 (2022) | Women Trail bike | Liv Cycling UK

www.liv-cycling.com

Ten thousand quids? Really?

Forever the asshat. You whine when any kit fella remarks about your ride, but when the opportunity arises you piss on someone else’s parade. We can easily guide someone towards a battery builder every bit as good as found on your overpriced sissy bike. Some of us just ride, not ride to brag or for self aggrandizing. BTW most experienced builders were on eBikes YEARS before you. There were 3, that’s right three total eBikes in shops within 200 miles of my home in 2012.
Kit building on a favorite quality bike continues to be a practical solution, and safe batteries are readily available.

 

[tomjasz]

21700 cell

I’m thrilled about my newest 21700 packs.
And regardless of @indianajo many of us DO open our batteries and only recommend builders we KNOW use grade A cells.

 

[Gionnirocket]

I’m thrilled about my newest 21700 packs.
And regardless of @indianajo many of us DO open our batteries and only recommend builders we KNOW use grade A cells.

Are your 21700 pack a Jenny Mao production?

 

[tomjasz]

Are your 21700 pack a Jenny Mao production?

Both, 36V 20Ah shrink wrap. And 48V 20Ah Reention Poly case.
confirmed 50E cells. I wish they used pure nickel ribbon but the nickel coated steel are appropriately sized.

 

[Gionnirocket]

Both, 36V 20Ah shrink wrap. And 48V 20Ah Reention Poly case.
confirmed 50E cells. I wish they used pure nickel ribbon but the nickel coated steel are appropriately sized.

I've not looked into the specific differences and I'm sure pure nickel would be a bit more weather proof, but within the case does it necessary need to be?
Is the nickel/steel more resistive electrically? Perhaps it's stronger physically? I guess a lot has to do with the quantity of the steel and the nickel plating.
Are the cell end caps pure nickel?
For example many home services are aluminum, same as the electric company's distribution lines. You could go with copper service cable, but the occasion that the aluminum ones fail are practically nil.

What was Jenny's reasoning (other than cost)?

 

[Tigertone]

Thank you all for your helpful replies, but, I must take issue with the thread about risking burning my house down. I think when charging any battery any sensible person will try not to leave chargers on over night unless we have to and checking a charging battery is not getting too hot. One point though about overnight charging, my neighbor charges his car over night because the electricity is cheaper. Anyway, whether we like it or not, we are living in a digital society and more and more people are shunning expensive shop bought e bikes simply because they can't afford to pay the absorbent price being asked for a new E bike. So, back to battery's I will be shortly purchasing a well known branded battery pack and I will let you know how I get on.v Thanks