Best place to get a battery in Canada? 48V or 52V?

[tryptych]

Hello, I am new on these forums. I want to do a DIY ebike this winter but there are a lot of tricky decisions to make! I think I've decided on the Bafang BBS02 48v 750w middrive (even though it's not quite legal up here). I am having a lot of trouble deciding on everything else though. If someone could answer my three stupid newbie questions it would be much appreciated:

(1) Can someone give me advice on if I should get a 48V battery or a 52V battery? From what I understand the BBS02 can handle 52v?

(2) What would the performance difference be when comparing a 52V 12.5AH battery with one that is 48V 17.5AH? Assuming similar quality cells. I understand the 52V would give a tiny bit more power but specifically I'm interested if there is a range difference or if the higher voltage would result in similar range. What approximate range could I expect from each?

(3) Where is the best place in Canada to get a battery at a decent cost? Should I just order one off Amazon.ca? So far I'm leaning towards this package on Amazon it's $1155 CDN for the 850C + BBS02 + 12.8aH Shark Battery. But obviously it comes from China, so I am concerned. I'm curious if you guys would say it's a good deal, or if I can do better from some place within Canada (or within the US if the shipping/duty isn't massive).

Thanks in advance, any help is appreciated.

[73Eldo]

These guys are in Canada and seem to have a good reputation. I thought there was another one but just looked them up again and if I have the correct name their site has turned into one of those sketchy looking ones that doesn't have even the slightest mention of who or where they may be in the world.

https://ebikes.ca/shop/electric-bicy...batteries.html


48 vs 52 ? I don't think its a huge difference. A 48 has 13 cells or cell groups, a 52 has 14. I believe the 12ish AH are 3 in each group which is called a 3p so a 48v 13s3p would have 29 cells. To increase the range you need better quality which only gets you so far or just more cells but we are not talking a couple more, you need 13 more which is a big difference on the size and weight. Going to 52 just ads 3 cells so not a huge weight or cost penalty but gives you just a little extra.

For a 750w motor I like to start out with 2 miles per amp hour which is about 3km. There are so many variables that its really hard to estimate but using that seems to be a good starting point. That does assume you are only averaging a little over normal bike speeds on not extreme terrain or an extreme load. Not all urban stop and go and you are doing some pedaling. IF you are a larger person that wants to average over 20 mph with no pedaling you could maybe have trouble getting one mile per hour. It can also go the other way if you are on a light fast classic road bike and are a skinny athletic type person that only rides rails to trails at 13 mph you could easily get 4 miles per hour.

So that 12.5 ah pack I would estimate around 24 miles (38km). That should be reasonable and leave you a little reserve. In my case 24 miles was what I planned for but if I wasn't being especially lazy I could stretch that to 30 but that usually meant only the last bar on the battery meter still lit and it would only take one moderate power surge to trip the low volt cutoff and I would be pedaling a really heavy bike the rest of the way.

The other thing to think about if you are not a regular cyclist now is something we started calling ass hours. That is how long you can sit on a bike before things start getting really sore. When all I had was a 12 ah battery it didn't take me long before I could outlast the battery. That just took some daily riding with the right seat and grips and slight adjustments daily till I got there. I eventually ended up with a 20ah battery and I have never killed that, my ass wears out faster. I generally ride in an urban area so there is all types of traffic as well as hills so I usually estimate about 10 miles per hour so if I'm planning a 20 mile trip I figure that will take around 2 hours. When I'm actually moving my speed is likely in the mid teens but there are times waiting for a stop light or an area with a lot of pedestrians so it often seems to average out to that 10 miles per hour.

[Fred]

My 2 cents worth:

A 52V battery will give a little more zip and acceleration than the 48V, and perhaps a little higher top speed. I used to have a 48V BBS02 and it was plenty fast for me.

The best way to compare batteries of different voltage is to use watt-hrs (amp-hr x voltage) For the 2 packs you mentioned, the 48V is approximately 840Wh and the 52V about 650Wh. So you should get around 30% more range from the 48V pack. Also with 48V, there is less temptation to go super-fast than with the 52V. Riding faster depletes the battery faster.

Re expected range, obviously it depends - weight, wind, hills, tires, amount of pedalling, etc. My conservative rule of thumb is - with reasonable pedalling effort - about 10Wh/Km. This would tanslate to 65Km for the 52V and 84Km for the 48V. To me "reasonable pedalling" means I do about half the work. Therefore If running under throttle only, one would cut these ranges in half (33Km and 42Km respectively), but who runs a BBS02 throttle only?!

Hope this helps.

[tryptych]

Hope this helps.

Both posts above were very helpful, thanks guys. I am getting closer to pulling the trigger on the battery.

I've discovered that a friend of a friend makes batteries locally in Toronto. I've been quoted $1367 CDN for a 14p5s 1008wh using 21700 cells called "P42" - is anyone familiar with those? From what I'm told they are high quality. It's certainly a lot more expensive than the cheapo ebike batteries on Amazon but I suspect this unit would be much better quality, well made, more reliable, less likely to burn my house down. Plus it comes with a warranty.

I am curious if $1367 CDN ($1100 USD) for a heavy duty battery like this is a good price - what do you guys think?

[john1263e]

https://www.ebay.com/itm/333643326415?var=542739316280

[73Eldo]

My rough math says that is about 19.5ah for those of us that are more used to amps so that is on the large size for sure. That price for sure puts you into the premium range but if its local you don't have to deal with any special shipping or import costs which can really add up not to mention many other vendors are out of stock most of the time lately so if they can actually deliver one to you in a reasonable amount of time that is also a value. Range wise thats similar to what I have and I have never actually killed it in a single day. I'm sure someone else could but I'm middle aged and way out of shape so I just can't be on the bike for more than about 4 hours at a time. Maybe if I averaged 25 mph on the throttle only I could kill but that just isn't my style of riding and would for sure end up running over a pedestrian or getting run over by a car if I tried to maintain that speed in the urban area I live and ride in most of the time.

Will the custom physical layout for you? If so that could be a real bonus unless you happen to be riding an older geometry XL size hard tail frame. 70 21mm diameter cells are going to take up a good chunk of space and even for a pavement bike you want to try and keep the weight low so if they will do a custom shape to ideally fit your bike you will be way ahead of many other people that want that sort of battery capacity.

Similar to the physical layout what do they offer for mounting options? If their mounting system will work good for you that too is a bonus or money you may have to spend on top of someone elses packs. Things to consider on the mounting other than location is how often may you need to remove it? Do you ever have to lift the bike off the ground for any reason? Get it up stairs at work or home? Onto a car carrier? That pack is going to be heavy so being able to take it off the bike will make it much easier to lift. If you don't need to lift it then will it always be stored in a reasonable climate? Remember too hot or freezing isn't good in general and you should never charge them when they are really hot or near or below freezing.

If you don't ride your bike in the winter it may not be a big deal to take 10 mins to remove the battery in the fall and re install it in the spring but if you are going to ride in the winter you are going to want a mounting system that is quick and easy. Even for a street bike you don't want it just flopping around loose in a bag or duct tapped to a rack.

[Fred]

I assume you've thought about how you're going to mount the battery on your bike? If the local builder is constructing an oblong shaped shrink-wrap pack, you will likely end up mounting it on a rack on the rear. Many prefer something like a Dolphin or Shark pack format which mounts on the downtube using water bottle bosses. This gives a somewhat lower centre of gravity and more balance overall. and there are other mounting options (triangle bag, etc). The price for that pack seems a bit high to me and I should add that all the stuff on Amazon is not cheapo and poor quality.

[BK Xray]

Golden Motors Canada might be a good place to start. They sell the BBS02and quality batteries. I have bought several things from them and have no complaints. Great service before and after the sale. www.goldenmotorbike.com

[73Eldo]

That's the company I was trying to think of but didn't quite have the name right. They don't seem to have as big a rep as Grin does at least in the US but I also haven't heard bad things about them which is good.

[tryptych]

Great info again, thanks guys. I've done some comparison to the two links you've provided:

eBikes.ca
$1661 CDN ($1343 USD) with shipping for "52V 20 Ah Downtube Battery with Panasonic GA Cells, 40A BMS"

GoldenMotor.bike
$1241 CDN with tax and free shipping for "52V20AH Triangle Pack" with mystery cells (cell type not listed)


Questions:

• I assume both of the above are 18650 cells, and the "P42" 21700's I am getting (14s4p) (with a bluetooth smart bms and charger) for $1367 CDN are superior - can anyone confirm?
• My seller told me "p42 performs better in lower voltage for less sag and more usable range", is this accurate? Also with these cells I am told I can fast charge, up to 5-6amps.
• I also suspect that any battery on Amazon would be using the cheapest Chinese cells possible (otherwise they would list the cell type) - am I incorrect?

ps: for bonus points can anyone explain how I calculate the WH or AH when I only know the cells are P42 and they are 14s4p?

[AZguy]

Molicel 21700 P42A cells are rated for 4200mAh

So a 4p battery will give 4 × 4200mAh = 16800mAh = 16.8Ah

14s is nominally 14 × 3.7V = 51.8V

51.8V × 16.8 Ah = ~870Wh


Reality is that you will not get the full 4200mAh from each cell. For one thing that's an optimistic estimate for a brand new cell run at the most optimal load and if you were to run them from 100% SOC all the way to 0% that will significantly reduce their overall life. Nearly all electric bikes are set with a low-voltage cutoff (LVCO) that is at more like the 10-20% point.

The 51.8V is nominal. Fully charged a 14s pack is 14 × 4.2V = 58.8V and lets say the LVCO is set for 3.0V per cell (sort of on the low side but easy math ;-} ) so that would be 42V. So you can see that while the "nominal" voltage is 51.8V (why they refer to these as 52V packs) the actual voltage varies a great deal during the discharge cycle so the Wh is a lot less accurate than the Ah and why these cells are generally specified in Ah and not Wh.

They actually have what is termed a very high coulomb efficiency in that nearly all the Ah you put in you will get out. The inefficiency comes from it taking a higher voltage to push the Ah's in than the cell produces to push them back out. This is effected by the load a lot too since there is what is termed an effective series resistance (ESR) which is sort of like putting [small] resistance in series with the cell that causes a voltage drop during charge or discharge that is turned into heat. High loads (or high charge currents) will cause a greater voltage drop and higher loss and cell heating.

Chinese Amazon / ebay batteries often have capacities advertised that are at best exaggerations and very often outright lies

[tryptych]

Molicel 21700 P42A cells are rated for 4200mAh

So a 4p battery will give 4 × 4200mAh = 16800mAh = 16.8Ah

14s is nominally 14 × 3.7V = 51.8V

51.8V × 16.8 Ah = ~870Wh

Great info again, thanks AZguy.

Can anyone tell me a bit more about the advantages of using 21700 cells instead of 18650s? Am I getting more 'bang for the buck' by choosing P42's for my ebike?

More specifically: how will my 16.8 Ah battery made with 21700s and "P42" cells compare to a 20 Ah that is made with 18650s (for example the 18650 "Panasonic GA "cells that ebikes.ca uses in their 52v 20Ah which I mentioned in post #8)? Will the power and range be similar?

[AZguy]

Great info again, thanks AZguy.

Can anyone tell me a bit more about the advantages of using 21700 cells instead of 18650s? Am I getting more 'bang for the buck' by choosing P42's for my ebike?

More specifically: how will my 16.8 Ah battery made with 21700s and "P42" cells compare to a 20 Ah that is made with 18650s (for example the 18650 "Panasonic GA "cells that ebikes.ca uses in their 52v 20Ah which I mentioned in post #8)? Will the power and range be similar?

21700's should be able to give you more capacity in a given size and weight but unless weight and size have a very high value then from an energy capacity those are worse bang for the buck

Most electric bike batteries today are 18650's though, not by a little, far and away... there are likely very good reasons for that and unless I see not only better densities but better cost/value (and wider spread adoption) I don't see the point.. that can change and I'm completely open minded however

[73Eldo]

Are any of the tool people going away from 18650 yet? How about the battery powered yard tools/equipment? Especially when you start talking about lawn mowers I think you are getting into the same class many of us bikers are in. Just a quick search look like Ego which seems to be the company with the most product out there at the moment looks like they are 18650. Quick search hasn't lead me to any details about Toro's packs.

[BK Xray]

The Golden Motor batteries list LG cells which are good quality.

[Steampunk]

I have a Golden Motor triangle case 52v 21ah battery. 1000 miles so far . The second battery for my 3+ year old BBSHD .
battery performs perfectly. 50 to 60 mile range for me .