Battery Weight vs Range... a dilemma

[cyclebuddy]

So, one of my e-bikes is powered by a 350w Bafang MaxDrive motor. It came with a 374Wh 10.4 Ah Samsung 29E Pinky celled battery pack which, then, was a respectable if mediocre cell... I bought a second at the same time which the dealer was keen to clear at £150... that was IIRC 2019?

Anyway, one pack typically gets me 25-28 miles, given the terrain I ride and the way I ride. On the odd occasion I've take the second battery in a back-pack to extend my range.

Both batteries after 5 years are still good, given my storage, alternating usage, and care regime, but I suspect they're likely coming to end of life...

So my question is this:

If you take a common format, let's say Hailong (which I can easily change to), what is the weight penalty of one 20Ah battery against say a smaller capacity (lets say 13/14Ah, of which I'd need two)?. Cost is largely irrelevant... it's weight that bothers me. Obvs, a 20Ah Hailong is going to use higher capacity/better cells that a 13/14Ah one, but at what weight increase given a typical ride for me is increasingly becoming 30-40+ miles? The spare in a back-pack, when I need it, is increasingly becoming an uncomfortable burden/necessity... I'd rather not take a back-pack.

So boiling it down to basics, how heavy is a 20Ah Hailong vs a 13/14Ah one given the cells needed to provide that capacity?

The other reason I'm asking is that a better/higher capacity cell would allow a higher current cell to rinse the motor, which the Pinkies just aren't capable of doing.

What would you choose/do?

 

[Sturmey]

....... I'd rather not take a back-pack........

What you need is a good pannier rack.
I have just come back from a hilly ride this morning. (76 Km). I was carrying a total of 32 Ah at 36V volt battery paralleled and weighing nearly 8 kilo. No problem with a good touring rack and keep the weight low. Also plenty of room for snacks, rain gear, tool etc.

 

[guerney]

So boiling it down to basics, how heavy is a 20Ah Hailong vs a 13/14Ah one given the cells needed to provide that capacity?

My 19.2Ah battery made with LG MH1 cells weighs 3.6kg, if that helps. I chose the largest my BBS01B kit seller had available, because I needed maximum possible range with high level of assistance. I've learned since of the other advantages of a large capacity battery for hill climbling, trailer haul hill climbing, longevity because individual cells are less stressed in a larger capacity pack than a smaller one discharging the same current etc. My bike and I don't care about weight, so I might even consider using something like this longer lived 3,000 charge cycle 30Ah 11kg lifepo4, if I was certain my 36V BBS01B controller or DPC18 display wouldn't throw a fit at it's fully charged 43.8V - I presently have a spare controller, so could risk finding out, if I can find a very cheap compatible display. Perhaps a stolen DPC18 display will turn up on ebay, going mega cheap because it's been cut off some other dude's Bafang mid-drive conversion.

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[Peter.Bridge]

So, one of my e-bikes is powered by a 350w Bafang MaxDrive motor. It came with a 374Wh 10.4 Ah Samsung 29E Pinky celled battery pack which, then, was a respectable if mediocre cell... I bought a second at the same time which the dealer was keen to clear at £150... that was IIRC 2019?

Anyway, one pack typically gets me 25-28 miles, given the terrain I ride and the way I ride. On the odd occasion I've take the second battery in a back-pack to extend my range.

Both batteries after 5 years are still good, given my storage, alternating usage, and care regime, but I suspect they're likely coming to end of life...

So my question is this:

If you take a common format, let's say Hailong (which I can easily change to), what is the weight penalty of one 20Ah battery against say a smaller capacity (lets say 13/14Ah, of which I'd need two)?. Cost is largely irrelevant... it's weight that bothers me. Obvs, a 20Ah Hailong is going to use higher capacity/better cells that a 13/14Ah one, but at what weight increase given a typical ride for me is increasingly becoming 30-40+ miles? The spare in a back-pack, when I need it, is increasingly becoming an uncomfortable burden/necessity... I'd rather not take a back-pack.

So boiling it down to basics, how heavy is a 20Ah Hailong vs a 13/14Ah one given the cells needed to provide that capacity?

The other reason I'm asking is that a better/higher capacity cell would allow a higher current cell to rinse the motor, which the Pinkies just aren't capable of doing.

What would you choose/do?

20Ah Hailong - on short trips you get the benefits of higher voltage (more power) so after 30-40 miles it would only be half empty and you've got that reserve if you need it. I bet the weight penalty is less than 1kg between a 20Ah Hailong and a 13/14 Ah Hailong - you don't want to be hauling spare batteries around.

 

[soundwave]

bbshd flat out full everything with a throttle on a 24-25kg bike will get you 17-20 miles with a 20ah batt.

 

[saneagle]

So, one of my e-bikes is powered by a 350w Bafang MaxDrive motor. It came with a 374Wh 10.4 Ah Samsung 29E Pinky celled battery pack which, then, was a respectable if mediocre cell... I bought a second at the same time which the dealer was keen to clear at £150... that was IIRC 2019?

Anyway, one pack typically gets me 25-28 miles, given the terrain I ride and the way I ride. On the odd occasion I've take the second battery in a back-pack to extend my range.

Both batteries after 5 years are still good, given my storage, alternating usage, and care regime, but I suspect they're likely coming to end of life...

So my question is this:

If you take a common format, let's say Hailong (which I can easily change to), what is the weight penalty of one 20Ah battery against say a smaller capacity (lets say 13/14Ah, of which I'd need two)?. Cost is largely irrelevant... it's weight that bothers me. Obvs, a 20Ah Hailong is going to use higher capacity/better cells that a 13/14Ah one, but at what weight increase given a typical ride for me is increasingly becoming 30-40+ miles? The spare in a back-pack, when I need it, is increasingly becoming an uncomfortable burden/necessity... I'd rather not take a back-pack.

So boiling it down to basics, how heavy is a 20Ah Hailong vs a 13/14Ah one given the cells needed to provide that capacity?

The other reason I'm asking is that a better/higher capacity cell would allow a higher current cell to rinse the motor, which the Pinkies just aren't capable of doing.

What would you choose/do?

You can calculate the weight of any battery from the number of cells. The capacity doesn't mean anything and doesn't necessarily affect weight. 18650 cells weigh about 50g each, so 2kg for 40 cells 2.5kg for 50 and 3kg for 60. Add about 1kg for the case, BMs and receiver. A 21700 cell weighs about 66g, so adjust your calculation accordingly.

By way of example, a 50 cell 36v battery with the highest capacity 18650 cells will have 5 x 3.6ah capacity = 18ah, and the cell-pack will weigh 2.5kg. A 50 cell pack with 2500mah cells will weigh the same, but only have 12.5ah capacity.

When you buy a battery, you have to take all these characteristics into consideration along with the price.

 

[matthewslack]

I'm impressed with @guerney's 3.6kg for 19.2Ah. My 28Ah (13Ah + 15Ah) cheap solar batteries add up to 7kg.

I agree with lose the backpack.

 

[guerney]

I'm impressed with @guerney's 3.6kg for 19.2Ah. My 28Ah (13Ah + 15Ah) cheap solar batteries add up to 7kg.

I agree with lose the backpack.

I did worry that I'd been palmed off with a fake LG MH-1 celled battery, but they weigh 49g each, and the plastic case doesn't weigh much, neither do the small BMS and nickel strips - if they're rerwraps, the underlying cells are pretty good fakos whatever they are. I haven't included the weight of the mount, but it's light. Or perhaps my cheapo digital luggage scale is rubbish.

Test of LG 18650 MH1 3200mAh (Cyan)

 

[Peter.Bridge]

My 48V 20Ah battery (2170 ?) weighs 4.9kg

 

[guerney]

Tested my cheapo digital luggage scale with cast iron weights: 0.5kg weighed 0.54kg, 1.2kg weighed 1.31kg... and I reweighed my battery - it's even lighter now! The plastic case is pretty thin... whatever, it gets me 43 miles at highest level of asistance over mixed terrain with the controller limited to 15A and 100% "Keep current".... and more importantly, hasn't exploded into a house consuming fireball yet. I'll weigh it again when fully charged lol, it's 36V at the mo.

 

[cyclebuddy]

What you need is a good pannier rack.

I hear you. But this bike is for good weather touring on Norfolk back roads. I do have a rack on another e-bike for commuting, but don't want a rack, panniers or mudguards etc - i.e. excess weight - on this one for the specific purpose this particular bike is being used for... it's dry weather, all day/weekend touring.

My bike and I don't care about weight...

I do care about weight on this e-bike, for this purpose of general touring (it's the bike in my avatar). My other e-bikes I have for general use and those are geared and work well for practicality so weight is less of an issue for me there.

...so after 30-40 miles it would only be half empty and you've got that reserve if you need it. I bet the weight penalty is less than 1kg between a 20Ah Hailong and a 13/14 Ah Hailong - you don't want to be hauling spare batteries around.

That was exactly my thought too... my rides on this bike for this purpose can only get longer. I'm getting fed-up with the burden of carrying a spare battery.

The capacity doesn't mean anything and doesn't necessarily affect weight. 18650 cells weigh about 50g each, so 2kg for 40 cells 2.5kg for 50 and 3kg for 60. Add about 1kg for the case, BMs and receiver. A 21700 cell weighs about 66g, so adjust your calculation accordingly.

Surely the density (i.e. individual cell weight) would be more on a higher capacity cell, wouldn't it? Have I got that wrong?

I agree with lose the backpack.

That really is what I want to do. A backpack is cumbersome and becoming a real pain. The bike is otherwise "lightweight" (relatively) and powerful (comparatively), and it's a real joy to ride when unincumbered around the Norfolk wilderness... where none of the practicalities of a commuter or general-purpose e-bike with racks, panniers, mudguards, lights and all that other essential paraphernalia are needed that tend to bog you down and hold you back.

I'm definitely erring towards a much bigger battery...

 

[Nealh]

So, one of my e-bikes is powered by a 350w Bafang MaxDrive motor. It came with a 374Wh 10.4 Ah Samsung 29E Pinky celled battery pack which, then, was a respectable if mediocre cell... I bought a second at the same time which the dealer was keen to clear at £150... that was IIRC 2019?

Anyway, one pack typically gets me 25-28 miles, given the terrain I ride and the way I ride. On the odd occasion I've take the second battery in a back-pack to extend my range.

Both batteries after 5 years are still good, given my storage, alternating usage, and care regime, but I suspect they're likely coming to end of life...

So my question is this:

If you take a common format, let's say Hailong (which I can easily change to), what is the weight penalty of one 20Ah battery against say a smaller capacity (lets say 13/14Ah, of which I'd need two)?. Cost is largely irrelevant... it's weight that bothers me. Obvs, a 20Ah Hailong is going to use higher capacity/better cells that a 13/14Ah one, but at what weight increase given a typical ride for me is increasingly becoming 30-40+ miles? The spare in a back-pack, when I need it, is increasingly becoming an uncomfortable burden/necessity... I'd rather not take a back-pack.

So boiling it down to basics, how heavy is a 20Ah Hailong vs a 13/14Ah one given the cells needed to provide that capacity?

The other reason I'm asking is that a better/higher capacity cell would allow a higher current cell to rinse the motor, which the Pinkies just aren't capable of doing.

What would you choose/do?

Not 29E cells if 10.4ah/374wh (10s4p) as the figures don't add up.
Cells must have been 26F as 29E would give 11.6 ah (10s4p).
Besides that battery weight will be the same.

One 20ah battery will be approx. 1.25kg - 1.4kg lighter then a pair of 10.4 ah.

 

[Nealh]

18650 = 47/ 48g typically.
21700 = 68/69g typically .

20ah would likely be Sam 50E or LG M50 21700's so 40 cells, 2,76kg.
10.4ah would both be 40 cells as well, 7.68kg.
Typically one will be near 4.8 kg lighter, a little more weight is saved as only one case , one BMS , less wiring and less nickel interconnectors used.

 

[saneagle]

Surely the density (i.e. individual cell weight) would be more on a higher capacity cell, wouldn't it?

No. 21700 is bigger than 18650, so weighs more and has more capacity. All cells of the same size weigh approx the same, regardless of capacity.

 

[soundwave]

not got any left now but those fake pink wrapper ones are like 28-32g

 

[soundwave]

2 years old

2016

 

[Nealh]

Any genuine 18650 cell will be in the area of 46g - 48g no matter the mah rating, likewise a 21700 /68g, 20700/58- 62g and 20650/55-58g.

 

[guerney]

Any genuine 18650 cell will be in the area of 46g - 48g no matter the mah rating, likewise a 21700 /68g, 20700/58- 62g and 20650/55-58g.

According to my cheapo digital luggage scale, my battery weighed:

3.49kg

https://www.pedelecs.co.uk/forum/threads/new-project-started.46218/post-700688

... in January this year. Now it appears to weigh 3.28kg... so either my scale is rubbish (very likely), or the cells are genuine fako rewraps. 50 LG MH1 x 49g = 2450g, leaving either 1040g or 830g for the case, wires, nickel strips, fish paper, solder, fiberglass wire lagging, switch and BMS. Bit late now to demand a refund, on the other hand the battery performs well, as far as I can tell. Maybe I should buy one of those ebike battery load tester things, or simply wait till the battery pack dies then weigh the case and a cell after disassembly.

https://www.amazon.co.uk/Vastarry-Electronic-Capacity-Monitoring-Constant/dp/B0B7N7RB3Q

 

[cyclebuddy]

Not 29E cells if 10.4ah/374wh (10s4p) as the figures don't add up.
Cells must have been 26F as 29E would give 11.6 ah (10s4p).
Besides that battery weight will be the same.

One 20ah battery will be approx. 1.25kg - 1.4kg lighter then a pair of 10.4 ah.

Ah, I stand corrected... 26F then,,, it's been 4 years since I opened one of the packs. 18650 pinkies though. I guess one battery of higher (double) capacity will logically be the best route to take.

 

[Peter.Bridge]

Just weighed my Hailong 48v 20Ah 960Wh battery - 4.8kg
My wife's Wisper 36V 700 Wh (19.5 Ah ?) battery, I think has LG cells - 3.5 kg

I think getting a 20Ah battery that weighs 3.5 kg is not much extra weight (how much does your existing 374Wh battery weigh ?) for
1) a lot more range
2) higher voltages / more power on shorter journeys