First build and battery seems to die too quick.

[LewTwo]

Better balance is achieved the more centered and lower the battery mass can be located (i.e. on the downtube).

If you do want to put one on a rack then get a better rack. I use the cheapest thing I could find:
https://www.amazon.com/dp/B0089WYU1G
hmmmmm ... price has gone up a bit

I had to get one of these to attach the front of the rack to my seat post:
https://www.amazon.com/dp/B001V537I0

I considered two of the BTR 48V 10AH LiFePO4 batteries with one mounted on each side of the rear wheel in plastic 30 caliber ammo boxes. Just a thought ....

You are only limited by your imagination and you ability to make it physically work.

 

[fatty]

When I contacted UPS about trying to return a 720 Watt Hour battery to an Ebay vendor they just laughed

:lol:

 

[DrkAngel]

You were a victim of "creative marketing" = "alternative facts"!
Dimensions indicate a 13s3p 18650 build.
48V 20Ah = 6667mAh cells, best actual cells are ~3500mAh
So, premium cells would give you a 48V 10.5Ah
Likely, however, they would have used 2600mAh or 2200mAh
Giving you an actual 48V 7.8Ah or even a 48V 6.6Ah battery
In their description - "5: Maximum operating current: 13A rated" indicates a cheap cell 2C common rating for 2200mAh cells!

For a 1000w hub kit you would want, at minimum, a (48V. x 25A = 1200w) x 90% efficiency = 1080w) 25A+ rated battery to sustain 1000w maximum motor output, (25A+ controller needed also - Voilamart 1000w rear wheel kit typically - 26A)!

Full throttle (26A controller) will deteriorate (damage) 13A rated battery very quickly! 750w mode will help ... some ...

Advertised = 48V x 20Ah = 960Wh - $113.54/kWh
Actual = 48V x 6.6Ah = 316.8Wh - $344.06/kWh (likely)

 

[LewTwo]

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.

That particular EBAY vendor has lousy feedback and is no longer active on EBAY.

You will likely have to go thru all the EBAY refund steps:
1.) Leave a negative review
2.) Ask for a refund
3.) Wait ....
4.) Ask ebay to "step in"
5.) wait ...
6). Ask ebay to "step in" again
7.) wait ...
8.) Ask ebay to "step in" the third time

You are likely to get a refund but it will take persistence.
I eventually got my money back but it took a while

 

[E-HP]

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.

Charge it to 80% then use it for backup power for your cell phones, etc., when the power goes out.

 

[magilacutys]

So I’ve narrowed it down to two options I think for a new battery candidate. What do you guys think?

UPP Official U004 Battery (US Warehouse) A Grade Triangle Battery - 48V/52V 20Ah Electric Bike Lithinum Battery for 1800W/1500W/1000W/750W Bafang Voilamart AW Ancheer and Other https://www.amazon.com/dp/B081PPC91W/ref=cm_sw_r_cp_api_glt_i_V6T8DPY6EE8EDPJ0PHQJ?psc=1

Unit power pack 48v 20ah. Will this one be a good fit? I know it will mount easier than the other option.


https://www.btrpower.com/collections/48v-ebike-battery/products/ebike-battery-48v-18ah-lithium-ion-battery-pack-with-5a-charger-50a-bms-fit-for-1000w-1500w-motor

Btrpower 48v 25ah. I’ll have to figure out a good mounting option and it’s a little bit more expensive but it is 25ah. Is it worth the extra price for the extra 5ah and headache of mounting it?

 

[E-HP]

So I’ve narrowed it down to two options I think for a new battery candidate. What do you guys think?

UPP Official U004 Battery (US Warehouse) A Grade Triangle Battery - 48V/52V 20Ah Electric Bike Lithinum Battery for 1800W/1500W/1000W/750W Bafang Voilamart AW Ancheer and Other https://www.amazon.com/dp/B081PPC91W/ref=cm_sw_r_cp_api_glt_i_V6T8DPY6EE8EDPJ0PHQJ?psc=1

Unit power pack 48v 20ah. Will this one be a good fit? I know it will mount easier than the other option.


https://www.btrpower.com/collections/48v-ebike-battery/products/ebike-battery-48v-18ah-lithium-ion-battery-pack-with-5a-charger-50a-bms-fit-for-1000w-1500w-motor

Btrpower 48v 25ah. I’ll have to figure out a good mounting option and it’s a little bit more expensive but it is 25ah. Is it worth the extra price for the extra 5ah and headache of mounting it?

"A grade cell" = generic Chinese cells. My first pack was the 52V20Ah version. It worked fine, just don't expect them to perform like quality name brand cells.

24lbs is a lot of weight just to get an extra 5Ah from that LiFePo pack.

 

[john61ct]

Yes first you need to select a good cell. Then A-grade just means "not QA rejects" aka factory seconds.

Means the best **that** production line makes. If it's a crappy product Grade A doesn't make it any better.

Conversely, you might order LG MJ1, great cell, yes genuine not counterfeit

but if the seller is passing off Grade B or GF grade C

might as well be buying some crappy generic, won't perform nearly as well

 

[magilacutys]

Interesting. I did some reading and thought that that unit power brand was a trusted brand on the cheaper side. But it seems like maybe not? Those btrpower lifepo4 seem to be better quality? This whole thing is frustratingly complicated. Hard to determine quality from crap unless you wanna drop $600-1000 for a battery which I don’t want to do on this build. I’m just trying to get my feet wet in the ebike world.

 

[DrkAngel]

Quality batteries will typically post the brand and model of cells used ... ?

Found 48V 6.4Ah bricks :
"Sanyo UR18650WX 1600mah cells manufactured by Panasonic which are 25a rated power cells. This module can push 100a and has a 150a in-line fuse on it."
Great power but lower power density, means larger battery build for same capacity.
$50 each but safety shipping charge required (~$40). (DIY FOR 5% DISCOUNT)
Parallel 2 or ?

2 - 48V 12.8Ah $140 + BMS extra
3 - 48V 19.2Ah $190 + BMS .. "
4 - 48V 25.6Ah $240 + BMS .. "

Add a 13s Bms ...

 

[E-HP]

Interesting. I did some reading and thought that that unit power brand was a trusted brand on the cheaper side. But it seems like maybe not? Those btrpower lifepo4 seem to be better quality? This whole thing is frustratingly complicated. Hard to determine quality from crap unless you wanna drop $600-1000 for a battery which I don’t want to do on this build. I’m just trying to get my feet wet in the ebike world.

UPP has accurate listings, meaning they are clear about the cells used. The grade A work OK, as long as you don't expect brand name cell performance. You can order a UPP pack with most brand name cells as well, and the listings will be clear about that. The UPP build quality may have declined over time, but the two triangle packs I've gotten have performed well. You just need to read the specs, and be satisfied with getting what you pay for, or are willing to pay for. You shouldn't complain if you underspend on the most important part of your ebike. My generic cell pack still has plenty of life left in it, since I didn't abuse it, and treated it like a generic cell pack. My brand name cell pack is awesome though.

https://www.ebay.com/itm/U-P-P-Ebike-52V-Battery-Hard-Triangle-Case-Switch-20AH-21AH-28AH-Brand-Cells-/254134391018

 

[magilacutys]

Is the btrpower lifepo4 pack a higher quality than the upp grade a batteries?

 

[MadRhino]

Good batteries are never cheap. Those dreaming of a cheap battery for their ebike, are the target victims for the crooks. Lots of components can be found very cheap and let you build a good ebike, but the battery is not one of them.

 

[docw009]

Is the btrpower lifepo4 pack a higher quality than the upp grade a batteries?

If it is LiFePO4, then it's relatively safe. That would be my reason for choosing one, but only if I were building e-trike for a someone else. Packaging of most BTR batteries seems like they're best suited for the rear tray in a trike.

48V18aH, 11 pounds, 10.4" x 6.25" x 3.75"

I put a UPP battery in an ebike I gave my sister. Paid extra for Samsung cells. I guess that if I had been really conscious of safety, I would have paid $100 more for EM3EV pack.

 

[LewTwo]

If it is LiFePO4, then it's relatively safe. That would be my reason for choosing one, ....

Lifecycles are also rated in multiples of thousands rather hundreds.

A exception being being the Samsung-Panasonic NCR18650B which seems to offer higher capacity, safety and longer life using a proprietary technology they call NNP. However the discharge curve is NOT as flat as LiFePO4.
Datasheet: https://www.imrbatteries.com/content/panasonic_ncr18650b-2.pdf

 

[john61ct]

The best LFP small cell is A123, now Lithium weeks

None other comes close for longevity

Nor would any of the 3.6-3.7V chemistries NCR18650B, maybe 10-15% life cycles if you're lucky

Even the crappiest LFP will be 5x lifespan

But lower energy density

 

[MadRhino]

Yep. So far battery technology had not succeeded to combine long life with high density. Long life batteries are heavier and bigger, while very high energy density batteries can be worn out very quickly. That is a compromise that one need to make, wether building priority is performance or durability. My first performance bikes were burning batteries like gas. Now I find myself lucky because I can do a second year before replacement. High power batteries are improving, long life batteries too, but it can be a long time before we can have both compact AND durable. Bikes are not like cars. There is a very limited space and size available to build a good bike. That is why high density battery chemistries are normally preferred.

 

[LewTwo]

Bikes are not like cars. There is a very limited space and size available to build a good bike. That is why high density battery chemistries are normally preferred.

Horses for courses ....

It depends on what one wants in an E-Bike. I note that one of the bikes in you signature is capable of 50MPH and the other is 70MPH. I agree that there is limited space. However if one wants a E-Bike to go the store and/or tool around the neighborhood then the space is adequate for a battery that has emphasis on economy, reliability, longevity and return on investment rather than maximum power density.

 

[MadRhino]

Bikes are not like cars. There is a very limited space and size available to build a good bike. That is why high density battery chemistries are normally preferred.

Horses for courses ....

It depends on what one wants in an E-Bike. I note that one of the bikes in you signature is capable of 50MPH and the other is 70MPH. I agree that there is limited space. However if one wants a E-Bike to go the store and/or tool around the neighborhood then the space is adequate for a battery that has emphasis on economy, reliability, longevity and return on investment rather than maximum power density.

Yes of course. Requirements command compromises. One may choose to give up some speed for range, lightess for durability, etc...
That is the main advantage to build our own, to best suit our own requirements.