First build and battery seems to die too quick.

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magilacutys   100 µW

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First build and battery seems to die too quick.

Post by magilacutys » Mar 12 2021 12:17am

Wudup my ebike bros! First post here, love the board.

So I decided over the winter I was going to build a budget bike. I had a roadmaster 26” mtb collecting dust in the garage so all I needed was a kit and battery. I did some research and watched some YouTube videos then grabbed the cc and hoped on eBay...

I ordered this voilamart 1000w rear wheel kit. https://www.ebay.com/itm/Electric-Bicyc ... 890.l49292

And I bought this 48v 20ah battery
https://www.ebay.com/itm/Li-ion-Battery ... 890.l49292


Got everything put together and it worked great except for the pas (I’m pretty sure the magnets are too far away from sensor on my bike, but I haven’t had a chance to get a new bracket setup yet) but the throttle works great. So I hoped on it and took for a test drive to my buddies.

At first everything was great, this thing really hauls! Then I hit a big hill. I pedaled but the bike did most the work. Perfect. That’s what I want. What I did notice however is that my battery indicator dropped all the way down when pulling the hill. It went back up as soon as I got to the top and let off the throttle though, so I figured it’s just the gauge when it’s under a big load. Get to my buddies about 4 miles away and start showing it off. My buddy hops on to take it for a spin and the thing completely shuts off because of a dead battery when he’s about 2 blocks away. He pedals back and I throw it on the charger and it turns right back on. Now I charged the battery when I first got it, but it had been sitting for about a month and a half before I got the bike together so I figure the battery wasn’t fully charged. Charge it while at my buddies for a couple hours and it gets me home just fine.

So I plug it in and let it charge all night then take it for another ride. Again after about 5 miles it loses a lot of power and I have to pedal pretty heavy to get home. It doesn’t completely shut off this time though.

So what should I start troubleshooting? Is my battery shot?(I did buy a warranty) Not really sure how to properly test it. something else? Any help would be greatly appreciated.


Here’s a pic of my bike. I plan to de-badge it and figure out a battery case if I ever get it running right.
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LewTwo   100 kW

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Re: First build and battery seems to die too quick.

Post by LewTwo » Mar 12 2021 1:14am

hmmm .... "48v 20Ah 13S3P Lithium ion Battery Pack"

I am guessing that battery is overrated.
They do not mention the cell chemistry so assume LiCoO2.
13 cells in series when would barely hit 47 volts (13 x 3.6).
They claim 3.7 volts per cell (then they would have to be the more expensive NMC cells).
I would expect 14 cells in series.

20 Amp Hours divided by 3P would be 6600 mAhr per cell.
I do not think that they do not make those in an 18650 cell.
Reference: http://www.benzoenergy.com/blog/post/wh ... ttery.html

Maybe I have screwed up the math somewhere.

If any of those cells drained below 3 volts you may have damaged the battery.
If you can not get it to hold a charge then it may be time for an autopsy :(
Last edited by LewTwo on Mar 12 2021 1:27am, edited 1 time in total.
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Re: First build and battery seems to die too quick.

Post by fatty » Mar 12 2021 1:26am

LewTwo wrote:
Mar 12 2021 1:14am
hmmm .... "48v 20Ah 13S3P Lithium ion Battery Pack"

I am guessing that battery is overrated.
They do not mention the cell chemistry so assume LiCoO2.
13 cells in series when would barely hit 47 volts (13 x 3.6).
I would expect 14 cells in series.

20 Amp Hours divided by 3P would be 6600 mAhr per cell.
I do not think that they do not make those in an 18650 cell.
Agree with your conclusion, but 14p is advertised as 52V.

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Re: First build and battery seems to die too quick.

Post by LewTwo » Mar 12 2021 1:32am

fatty wrote:
Mar 12 2021 1:26am
... but 14p is advertised as 52V.
I will restrain myself from commenting on the ancestry of sales, marketing and advertising types.
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

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Re: First build and battery seems to die too quick.

Post by fatty » Mar 12 2021 1:36am

magilacutys wrote:
Mar 12 2021 12:17am
And I bought this 48v 20ah battery
https://www.ebay.com/itm/Li-ion-Battery ... 890.l49292
Sorry to say, but as above, your battery is garbage. A real battery would cost at least triple.
See Grin or em3ev to get a better sense of battery cost/capability.

Then, if you like eBay, check out BtrPower

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Re: First build and battery seems to die too quick.

Post by amberwolf » Mar 12 2021 1:39am

magilacutys wrote:
Mar 12 2021 12:17am
I ordered this voilamart 1000w rear wheel kit. https://www.ebay.com/itm/Electric-Bicyc ... 890.l49292

And I bought this 48v 20ah battery
https://www.ebay.com/itm/Li-ion-Battery ... 890.l49292
I think the problem is the battery, but not that it's broken, but rather than it is not as advertised. :(

Even in the unlikely event that it is as advertised, it's only about half as capable as your kit needs it to be, for your usage.

$110 is awfully cheap for that amount of battery *and* free shipping (because it still costs them money to ship it, even if they don't charge you, it's embedded in the price of the item). Usually if it seems too good to be true, it is. ;)

AFAICT from the listing, it is a 13s 3p battery. If that's 18650s, then to be 20Ah each cell would have to be 6.7Ah. I don't know if there are any such cells, and if there are, they are probably be too expensive to use in a sub-$100 pack. ;)

The normal continuous current they list is 10A, which is only about 3.34A / cell, and decent ones could do that, as it would only be about 0.5C for a cell that could actually do 6.7Ah (which I seriously doubt these can).
The maximum current they list is 13A. 13A / 3p is 4.34A, which is reasonable for a good cell, but they list a maximum burst of 40A, which would be 40A / 3p = 13.3A, which would take a pretty good cell to handle for long without heating up and being stressed out. They don't say how long it should take that current draw, but a few seconds absolute max is my bet, and I wouldn't do that to this pack at all ever.

The voilamart kit at 1000w for 48v will draw under heavy load (like a hill) 1000w / 48v = 21A, and it could draw more than that depending on the exact controller's current limiting. That's twice the packs' "rated" continuous current, and nearly twice it's "maximum" current, so that's already being very hard on it. But since this pack is very unlikely to be what they say it is, it's probably really being harder on it than that, which heats up and overstresses the cells, and probably also unbalances them (since they're unlikely to be matched at all to each other, and very likely quite dissimilar cells, even assuming they were new cells and not recycled scrap cells (which unfortunatley has been a common problem in cheap packs, and even individually-sold cells like Ultrafire and the like),


To fix the problem temporarily, you could try leaving the charger on the pack continuously for at least several hours after charging is done, but it will more likely take days to weeks if it's badly unbalanced. This gives a chance to low cells to catch up to full ones, and improve the performance of the pack from what it is at the moment (though it won't make it any better than it was to start with).


To fix it permanently, you'll need a better battery pack that can handle at least the 21A your controller will ask of it under heavy loads, continously, and potentially momentary peaks of much higher than that. YOu may find these cheaply, but I would recommend looking around the forum at various "trusted" seller / vendor threads and posts, to see where people have been able to get known-good packs that stayed good and working. Grin tech, Em3ev, and similar places would be a starting point.

They're likely to cost significantly more, but the battery is the heart of the whole system, and if it cant' supply the power your system asks of it, the system cant' do what you want it to do. ;)



A quote from the listing, for posterity:
This listing was ended by the seller because the item is no longer available.
Details about Li-ion Battery 48V 20AH Volt Rechargeable Bicycle 1000W E Bike Electric Li-ion See original listing
Li-ion-Battery-48V-20AH-Volt-Rechargeable-Bicycle-1000W-E-Bike-Electric-Li-ion
Item Ended
Condition: New
Ended: Feb 12, 2021 , 8:47AM
Price: US $109.91
[14 sold]
Shipping:FREE Economy Shipping from outside US
Item location:Shenzhen, China
Seller:im.best_seller (885 )

Item specifics
Condition: New: A brand-new, unused, unopened, undamaged item in its original packaging (where packaging is ... Read moreabout the condition
Country/Region of Manufacture: China
MPN: Does Not Apply
Origin: Cn(origin)
Brand: Unbranded
Type: Rechargeable Battery
Application: For 54.6v Electric Bicycle Scooter Weight: About 2.5 Kg
Amp Hours: 20 Ah Size: 238*66*60mm
Chemical Composition: Li-Ion Model Number: 48v 20ah
Voltage: 48 V Nominal Capacity: 20000mah
UPC: Does not apply

high capacity 48v 20Ah 1000w 13S3P Lithium ion Battery Pack For 54.6v E-bike Electric bicycle Scooter with discharge BMS + charger
Product Parameters
Battery brand: okoman
Battery Type: 18650
Single cell voltage: 3.7V
Combination: 13 Series 3 and
Nominal voltage: 48V Input voltage: 48V Output voltage: 48V
After the combined capacity: 20000mAh (20Ah)
Battery Dimensions: 238 * 66 *60mm (There may be a 10 mm error) 3 * 13
Outside packaging: Blue PVC
Inside with protective circuit: overcharge, over discharge, over current, short circuit protection!


The battery charging requirements: please in the shop to buy another charger!
1: the need for a dedicated lithium battery charger;
2: Charging voltage: 48V
3: Charge current: greater than or equal to 5A

The battery discharge requirements:

1: Output 18 lines, length 200mm, red and black each one
2: Enter the outlet line leads to a 2.1 length 200mm
3: Rated discharge current: greater than or equal to10A
4: maximum instantaneous current: 40A
5: Maximum operating current: 13A
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john61ct   100 GW

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Re: First build and battery seems to die too quick.

Post by john61ct » Mar 12 2021 2:26am

Pity more beginners don't post here for advice before throwing money away.

A good quality battery

meaning that will not only meet minimum requirements when new in good condition

but also last more than a few dozen cycles doing so

will cost much more than the rest of that sort of build.

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Re: First build and battery seems to die too quick.

Post by 99t4 » Mar 12 2021 2:43am

Also the lithium batteries don't like sitting at full charge for extended periods.
magilacutys wrote:
Mar 12 2021 12:17am
Now I charged the battery when I first got it, but it had been sitting for about a month and a half before I got the bike together...

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Re: First build and battery seems to die too quick.

Post by Manbeer » Mar 12 2021 6:43am

also that kit comes with a controller that will draw ~30 amps peak. a quick workaround to make it useable would be to attach the 2 blue jumper wires and limit the top speed. in this mode iirc its 16mph/22a max. since it generally gets up to that top speed so fast the battery wont sag too badly

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Re: First build and battery seems to die too quick.

Post by lstoch » Mar 12 2021 7:42am

Hi

13S is correct for a 48V battery. 13 x 3.7V = 48.1V
Lithium ion cells operate between around 28V (when drained) and 42 volts (when fully charged)
The battery's capacity will depend on the capacity of each cell. if for instance each cell is 2.6Ah, then a 3P battery will give you 3x2.6=7.8Ah. If each cell is 3.5Ah, then the battery's capacity would be 10.5Ah. Either way, neither is very much for a 1,000W direct drive motor!

But the problem with the battery might be with the BMS/PCM that's been installed. A 48V 1000W motor typically has a max current draw of 30A. if the PCM is rated anything less than this the battery will cut off.

The fact that your battery doesn't always cut off, though, is puzzling.

If the amperage of the PCM is incorrect, you will encounter the problem when going uphill or opening up the throttle fully - that's when you'll be drawing high amperage.

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Re: First build and battery seems to die too quick.

Post by lstoch » Mar 12 2021 7:49am

PS - also, the max amp draw of the cells in parallel must also equal around 30A for that motor. That means for a 3P battery, each cell must have a max amp draw of at least 10A. 3 x 10 = 30.

cheap cells will never accomplish this. Also, good quality low Ah cells often do not - some examples:

Samsung 26J - max amp draw = 5.2
Panasonic 29F - max amp draw = 10
Samsung 35E - max amp draw 8 - 10

So, even if the BMS/PCM is rated at 30A, use of the wrong cells could cause problems as well as damage to the cells.

Leonard

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Re: First build and battery seems to die too quick.

Post by magilacutys » Mar 12 2021 8:56am

Thanks for all the quick responses. Awesome to find a board so active in this day and age. I only know of one other.

I figured it was the battery. I knew it was cheaper, but I saw a guy on YouTube do the same build with success and it had a $10 warranty through allstate so I pulled the trigger on it. I will start looking into getting my money back and looking for a new battery. I have a hard time wrapping my head around all the battery specs so that’ll be fun...

Is there any way to test the battery or verify it’s not as described without taking it apart?

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Re: First build and battery seems to die too quick.

Post by lstoch » Mar 12 2021 9:23am

My suggestions:

1. Ask what cells are being used (doesn't mean you'll get an honest answer)
2. From my experience (we assemble ebike batteries in SA), Samsung, Panasonic, Sanyo, Sony are fine - there may be others. Once you know the brand an model number, google it and check the specs - Ah, continuous and max amp draw ratings. Beware, some suppliers in the east package cells such they look identical to the brand makes.
3. Confirm that the max amp draw of the PCM/BMS is 30A
4. Multiply the max amp draw of the individual cells by the "P" value (as in S13Pn, when n is the number of cells in parallel). This must also be greater than or equal to 30A
5. Multiply the Ah rating of each cell by the P value. This will confirm the battery's capacity

If all of the above is in order, you should be ok.

Leonard

PS if you're still nervous, buy from a branded supplier and pay the bigger bucks

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Re: First build and battery seems to die too quick.

Post by E-HP » Mar 12 2021 10:01am

magilacutys wrote:
Mar 12 2021 12:17am
And I bought this 48v 20ah battery
https://www.ebay.com/itm/Li-ion-Battery ... 890.l49292

So I plug it in and let it charge all night then take it for another ride. Again after about 5 miles it loses a lot of power and I have to pedal pretty heavy to get home.
So maybe good news; you got what you paid for. Doing some rough math, and looking at the Grin simulator, if you bought a legitimate 48V20Ah battery with verified cells, you'd probably pay $500- $600 or so (maybe $450 if you built it yourself). On throttle only, that might give you 25-30 miles. So, $550/27.5 miles = $20/mile. You paid $100 to go 5 miles, or $20/mile. You got as good a deal as buying a quality battery, dollar-wise!

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Re: First build and battery seems to die too quick.

Post by john61ct » Mar 12 2021 10:18am

You can do objective testing with the right gear and knowledge

but that does not mean your "Allstate insurance" will give you money back

Too much is obscure or judgment call, they won't have battery experts available to advise.

But you learning how, and getting the gear required, will serve you well in future.

Resistance testing is way variable, nebulous and arcane to start with.

Same with Power testing, close second.

So start with CC discharge Capacity testing,

from a Full 4.2V charge fully balanced

down to 2.8V

at a 0.05C current rate relative to their claimed capacity, likely only takes 10-15 hours rather than the full 20

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Re: First build and battery seems to die too quick.

Post by MadRhino » Mar 12 2021 9:56pm

Just looking at the bike on the picture, the small battery does tell either very short range, or very low power. I sure would choose better cells, but most of all more of them.
Make it fool-proof, and I will make a better fool.

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Re: First build and battery seems to die too quick.

Post by dogman dan » Mar 13 2021 6:10am

Pretty much what they all just said. Just looking at it, its just not big enough to actually have 20 ah of 48v in there. Hard to say exactly, but the package looks like about 10-12 ah at most, and that would be with really good cells.

Yours are really bad. One thing about a really cheap pack, I bought one once, and it burned my house down. Its still a really rare thing, and I just got really " lucky". But even so, charge that thing outside.

The others are spot on, your 30 amps controller is whacking that thing too hard. This makes the battery deliver even less capacity, when you use it too hard for the type of cell. Try to use it more at a trickle, till you get to the hill. It takes some practice, but you can extend your range some.

Using a lower power setting is the thing to do. The other thing to do is try to balance the battery better. The charger tries, but when the battery is new, or it has been discharged deeply enough to shut off, the next charge may not get it 100% full. To force a balance, charge it, unplug, wait half an hour, then ride around the block. Then recharge it again, and repeat the wait and the ride. Do this about 5 times. You may see some improvement.

Lastly, a higher quality cell battery, from an honest vendor will be the ultimate fix. If you are in the USA, you have money coming.

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Re: First build and battery seems to die too quick.

Post by magilacutys » Mar 13 2021 1:58pm

I’ve started a return request with eBay. We’ll see where that goes.

Im now looking for a true 48v 20ah battery that won’t break the bank. That btrpower seems to have a one for 359. I’ll keep looking too. Any other advice for battery buying? Thanks again for all the input.

Edit: brrpower has a 18ah for 329 https://www.btrpower.com/products/ebike ... eq=uniform

Or a 35ah for 399 https://www.btrpower.com/collections/48 ... 000w-motor

Would it be worth it to get the 35ah?

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Re: First build and battery seems to die too quick.

Post by docw009 » Mar 13 2021 3:46pm

Return request? Let us know if that happens. It will have to go back to China by ship, with a hazmat label. That probably costs more than what you paid for the battery. These sellers aren't dumb. They gotta have some way to skate past paypal.

This is a 39 cell pack. In powerwalls, it's a common game to add the total Ah from all the cells. 20000/40 says you have 500mah (.5ah) cells which you probably do. That's how they beat the spec game.

Should have been advertised as a 48V7AH pack, effectively delivering 5AH,

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Re: First build and battery seems to die too quick.

Post by docw009 » Mar 13 2021 4:06pm

Those BTR batteries are LiFePO4. 3"x6"x10" and almost 15 pounds. LiFePO4 weighs more, but is less likely to catch fire. Still, that's a bit a weight on your rack. You can get a UPP battery with the exploding LiMnC that is 20AH and 2 pounds less.
https://www.ebay.com/itm/UPP-48V-20Ah-E ... SwgjVgQzwP

It's also a PITA to have batteries on the rack. I've done it. How do you keep them on the bike. Bungee cords look clumsy and the batteries still fall off. You have to put them in a bag for looks. All that height interferes with getting on/off the bike. And looking at your single post rack, that's going to break off bouncing along with 12-15 pounds..

You might look at a downtube or triangle battery. Get the weight where it belongs.
https://www.ebay.com/itm/New-Version-52 ... SwVRdfGVSC

https://www.ebay.com/itm/New-36V-48V-52 ... SwLURgQeqA
Last edited by docw009 on Mar 13 2021 4:12pm, edited 3 times in total.

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Re: First build and battery seems to die too quick.

Post by fatty » Mar 13 2021 4:08pm

E-HP wrote:
Mar 12 2021 10:01am
So maybe good news; you got what you paid for. Doing some rough math, and looking at the Grin simulator, if you bought a legitimate 48V20Ah battery with verified cells, you'd probably pay $500- $600 or so (maybe $450 if you built it yourself). On throttle only, that might give you 25-30 miles. So, $550/27.5 miles = $20/mile. You paid $100 to go 5 miles, or $20/mile. You got as good a deal as buying a quality battery, dollar-wise!
Haha, great analysis!
:thumb:

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Re: First build and battery seems to die too quick.

Post by fatty » Mar 13 2021 4:13pm

docw009 wrote:
Mar 13 2021 3:46pm
Return request? Let us know if that happens. It will have to go back to China by ship, with a hazmat label. That probably costs more than what you paid for the battery. These sellers aren't dumb. They gotta have some way to skate past paypal.
Indeed -- per another thread, it seems that sellers who do accept returns omit the required hazmat label.
docw009 wrote:
Mar 13 2021 3:46pm
This is a 39 cell pack. In powerwalls, it's a common game to add the total Ah from all the cells. 20000/40 says you have 500mah (.5ah) cells which you probably do. That's how they beat the spec game.

Should have been advertised as a 48V7AH pack, effectively delivering 5AH,
Interesting -- good explanation

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Re: First build and battery seems to die too quick.

Post by LewTwo » Mar 13 2021 6:57pm

fatty wrote:
Mar 13 2021 4:13pm
docw009 wrote:
Mar 13 2021 3:46pm
Return request? Let us know if that happens. It will have to go back to China by ship, with a hazmat label. That probably costs more than what you paid for the battery. These sellers aren't dumb. They gotta have some way to skate past paypal.
Indeed -- per another thread, it seems that sellers who do accept returns omit the required hazmat label.
docw009 wrote:
Mar 13 2021 3:46pm
This is a 39 cell pack. In powerwalls, it's a common game to add the total Ah from all the cells. 20000/40 says you have 500mah (.5ah) cells which you probably do. That's how they beat the spec game.

Should have been advertised as a 48V7AH pack, effectively delivering 5AH,
Interesting -- good explanation
Reference UN3480 for International regulations on shipping Lithium Ion Batteries.

All common carriers require a hazardous material contract for any lithium battery over 300 watt hours.
(USPS limit is 100 Watt Hours)
48 volts x 7 Amp hours = 336 watt hours.
That exceeds the 300 watt hour limit that can be shipped by a consumer.

However at 48 volts x 5 Amp hours = 240 watt hours.
That does not exceeds the 300 watt hour limit that can be shipped by a consumer.

Regardless, the common carriers are going to go by the vendor's rating:
48 volts x 20 Amp hours = 960 Watt Hours.
When I contacted UPS about trying to return a 720 Watt Hour battery to an Ebay vendor they just laughed :(
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

magilacutys   100 µW

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Re: First build and battery seems to die too quick.

Post by magilacutys » Mar 13 2021 8:22pm

If I can’t return it the seller will get a negative review and I’ll just have to find a different project for the battery.
docw009 wrote:
Mar 13 2021 4:06pm
Those BTR batteries are LiFePO4. 3"x6"x10" and almost 15 pounds. LiFePO4 weighs more, but is less likely to catch fire. Still, that's a bit a weight on your rack. You can get a UPP battery with the exploding LiMnC that is 20AH and 2 pounds less.
https://www.ebay.com/itm/UPP-48V-20Ah-E ... SwgjVgQzwP

It's also a PITA to have batteries on the rack. I've done it. How do you keep them on the bike. Bungee cords look clumsy and the batteries still fall off. You have to put them in a bag for looks. All that height interferes with getting on/off the bike. And looking at your single post rack, that's going to break off bouncing along with 12-15 pounds..

You might look at a downtube or triangle battery. Get the weight where it belongs.
https://www.ebay.com/itm/New-Version-52 ... SwVRdfGVSC

https://www.ebay.com/itm/New-36V-48V-52 ... SwLURgQeqA
I’m not real comfortable with the “exploding” battery. I am open to moving the battery location to the middle of the bike. How do you know that vendor is reputable? I’ve done a search but didn’t find anything. Is there a thread here that has a list of trusted vendors?

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Re: First build and battery seems to die too quick.

Post by LewTwo » Mar 13 2021 8:55pm

docw009 wrote:
Mar 13 2021 4:06pm
Those BTR batteries are LiFePO4. 3"x6"x10" and almost 15 pounds. LiFePO4 weighs more, but is less likely to catch fire. Still, that's a bit a weight on your rack. You can get a UPP battery with the exploding LiMnC that is 20AH and 2 pounds less.
https://www.ebay.com/itm/UPP-48V-20Ah-E ... SwgjVgQzwP
Some of BTR's batters are LiFePO4. Others are LiCoO2 .... be sure to look carefully.
The other very big advantage of LiFePO4 is life cycles measured in the thousands rather than the hundreds.
I believe all of BTR batteries are constructed from Lithium Polymer Envelope (pouch) cells.

Someone correct me if I am wrong but exploding Lithium Batteries are usually the result of some sort of abuse. To put his into perspective let us not forget that nearly all of us have ridden in petrol fueled vehicles and they use that same liquid to produce molotov cocktails. Who has never seen the remains of burned out petrol fueled vehicle?
Last edited by LewTwo on Mar 13 2021 9:24pm, edited 1 time in total.
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

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