What's the most 'universal' low-cost battery format?

[-Pete-]

I'm just starting to convert our family bikes to e-bikes, and would like to use a battery format that's good value for money and will be around for a few years. What do you think are the most universal batteries I should be looking at? I'm interested in lightweight 36V packs, around 8-13Ah. Are Hailong cases the standard, for conversions? Which version should I be looking at? Are bottle batteries interchangeable? And of course, where's the best value for money place to buy them? Thanks.

 

[Nealh]

Battery case designs come and go, nothing is very universal for too long. The silver fish battery design though has been around for a good dozen years, it is a behind the seat battery design but there is no reason one cant fit it elsewhere.

The hailong for instance can be confusing there are two types both non compatible and both can use 4 or 5 discharge connection.
Bottle batteries have been around a while but the bog standard type now utilise 3 or 4 different base connection designs so again one if wanting extra batteries has to be 100% certain that the model bought is of the correct design.

 

[-Pete-]

Battery case designs come and go, nothing is very universal for too long. The silver fish battery design though has been around for a good dozen years, it is a behind the seat battery design but there is no reason one cant fit it elsewhere.

The hailong for instance can be confusing there are two types both non compatible and both can use 4 or 5 discharge connection.
Bottle batteries have been around a while but the bog standard type now utilise 3 or 4 different base connection designs so again one if wanting extra batteries has to be 100% certain that the model bought is of the correct design.

Thanks, as I’m converting 3 or 4 bikes I’d like to have the same battery fitting for all of them, and possibly a choice of capacities. But light weight and cost are more important to me than range.

 

[guerney]

The hailong for instance can be confusing there are two types both non compatible and both can use 4 or 5 discharge connection.
Bottle batteries have been around a while but the bog standard type now utilise 3 or 4 different base connection designs so again one if wanting extra batteries has to be 100% certain that the model bought is of the correct design.

That's profoundly irritating - those are "Dumb" (no proprietary, Canbus or other battery communication system) batteries connected to controllers with only two wires, why do they need 4 or 5 pins anyway? What are the other pins for?

 

[vidtek]

That's profoundly irritating - those are "Dumb" (no proprietary, Canbus or other battery communication system) batteries connected to controllers with only two wires, why do they need 4 or 5 pins anyway? What are the other pins for?

They are for other functions-such as communicating with a controller or adding an USB connector.

 

[flecc]

That's profoundly irritating - those are "Dumb" (no proprietary, Canbus or other battery communication system) batteries connected to controllers with only two wires, why do they need 4 or 5 pins anyway? What are the other pins for?

The other pins are there primarily to prevent you using anyone elses battery.
.

 

[guerney]

They are for other functions-such as communicating with a controller or adding an USB connector.

Hmmm... when my battery warranty runs out, I'll have a really good look inside my battery mount, before wiring in rear indicators to help at roundabouts.

 

[Nealh]

The dumb batteries can use four of the pin a pair obviously for discharge and a pair for on bike charging, some of the battery carriers have a charge point on the base because the battery charge point may be covered or awkward to connect to when on the bike.

 

[Nealh]

Thanks, as I’m converting 3 or 4 bikes I’d like to have the same battery fitting for all of them, and possibly a choice of capacities. But light weight and cost are more important to me than range.

10ah typically should bet around 35miles but if only shorter rides then something smaller will suffice. For light one really wants 10 2p or 20 cells nut the cells need to be the best so cost then rears it's head.

 

[Nealh]

The two smallest lightest types would be the two bottle examples in the links.
36V 8.7AH E-Bike Battery Water Bottle Type 36V Lithium ion- Battery Only | eBay

LED 36V 5Ah 9Ah Lithium Mini Bottle Ebike Battery for 200W-500W Electric Bike | eBay

Buying from Aliexpress might be cheaper or if buying three or four of the same type from the same buyer one might get a slight discount.

The x - go brand bottle type has four differing base contact designs and is a design type sold by a lot of vendors.
24V 36V 10Ah 250W 350W 500W Li-ion Lithium Battery Kit Electric Bicycle E-Bike | eBay

The silver fish type are heavier and bigger and popular with behind the seat type, they have a handy handle to pull up and out.
36V10Ah Silver Fish Battery Electric Bike Battery E-bike Battery 800564239737 | eBay

electric bike battery 18650 36v battery pack silver fish fit MiFa, Rex, Prophete, Aldi 500w bicicleta eléctrica bateria 36v|Electric Bicycle Battery| - AliExpress


After these one is in to the Hailong /Polly type of case.

 

[Bikes4two]

A question really:

• if choosing something like one of the smaller bottle batteries like the 36v 5Ahr ones, are they not a battery configuration of 10S2P?
• If only 2P then is not the maximum current draw of the cells a more critical issue?
• For instance, taking the Samsung INR 18650-29E
• 
• for a 2P configuration then the max continuous discharge is 5.25A which at 36v gives 189w. Similalry for the 'not continuous discharge' rate it is 2*8.25*36v = 594W

Or am I over simplyfying this point (and I am a beginner in this stuff )?

Is there a power diversity factor to be considered somewhere along the line?

 

[Nealh]

Yes when deciding on a particular battery esp 10/12/13s x 2P then the cell used needs to be checked out and that it can deliver the current.
I made own drinks bottle battery 12s2p, I have used genuine LG hg2 25a 3000mah rated cells for my 20a max discharge. Theoretically though even at my low PAS 1 current draw my battery capacity is approx. 5.4ah but enough that can get up to 30 miles run time on flat terrain.

For any 2p battery one needs at least 15/20a cells for that though one likely will need some one to cell it properly with 20 genuine cells.

 

[harrys]

One obsolete design is the Dolphin battery. Too bad. I have a 52V and 36V model. I can still find them on sale occasionally, but I'm not buying a new one,


The commercial 10S-2P bottle batteries really limit you on cell capacity. I bought three from Unit Pack Power. The best one used GA cells, and was 7.5AH. I pnce squeezed 30 miles out of it, but more reasonable expectations are 20-25 miles. The cheapest one used generic cells, and today, that yields about 15 miles before running flat. I hope to repack it with 21700 cells in a 10S-2P configuration. If the cells I bought live up to their advertising, that will be 10AH. Otherwise. I don't recommend these smaller packs. Just too small and still kind of large for their cell capacity.



I finally bought an inexpensive ebike (I'm mostly DIY) that uses the Silverfish. Those are really well made batteries, but you can't use them in a DIY bike. I also bought a Hailong battery this summer from Unit Pack Power. I have not installed it yet, or even charged it. It's a 48V15AH using 13S-3P 21700 cells. I think 21700 cells make for good capacity while keeping size down. This Hailong is only 90 mm high.

Shrink wrapped packs are pretty versatile. I put them in a bag on the rear rack with plenty of padding. Sometimes I'll put two smaller ones in parallel. I haven't found a frame bag that I really like yet. but I've using a baggy one for my cruiser bike.

The trouble with shrink wrapped is that the commercial ones are often made too cheap. They have the cells contacting each other instead of in spacers. Then you might only have two layers of battery shrink wrap between two caes that are many volts apart.

 

[-Pete-]

One obsolete design is the Dolphin battery. Too bad. I have a 52V and 36V model. I can still find them on sale occasionally, but I'm not buying a new one,
View attachment 44772

The commercial 10S-2P bottle batteries really limit you on cell capacity. I bought three from Unit Pack Power. The best one used GA cells, and was 7.5AH. I pnce squeezed 30 miles out of it, but more reasonable expectations are 20-25 miles. The cheapest one used generic cells, and today, that yields about 15 miles before running flat. I hope to repack it with 21700 cells in a 10S-2P configuration. If the cells I bought live up to their advertising, that will be 10AH. Otherwise. I don't recommend these smaller packs. Just too small and still kind of large for their cell capacity.

View attachment 44770

I finally bought an inexpensive ebike (I'm mostly DIY) that uses the Silverfish. Those are really well made batteries, but you can't use them in a DIY bike. I also bought a Hailong battery this summer from Unit Pack Power. I have not installed it yet, or even charged it. It's a 48V15AH using 13S-3P 21700 cells. I think 21700 cells make for good capacity while keeping size down. This Hailong is only 90 mm high.

Shrink wrapped packs are pretty versatile. I put them in a bag on the rear rack with plenty of padding. Sometimes I'll put two smaller ones in parallel. I haven't found a frame bag that I really like yet. but I've using a baggy one for my cruiser bike.

The trouble with shrink wrapped is that the commercial ones are often made too cheap. They have the cells contacting each other instead of in spacers. Then you might only have two layers of battery shrink wrap between two caes that are many volts apart.

View attachment 44773 View attachment 44774 View attachment 44775 View attachment 44776

Thanks, that’s useful information. I’m interested to know why you don’t think the Silverfish batteries can be used for DIY?

 

[Nealh]

For 10s2p they are fine for light weight bikes of if your mileage is only local less then 25 - 30 miles max, they only take and hour or two to top up. No use carting around a 8lb 15ah battery when a 3lb 5/6ah will d the same thing.
As already mentioned one doesn't need more then 5/6ah for low mileage, but cell choice is critical. Any cell choice has to really be 20a rated for 2p, these are rare in ready built packs so one has to get someone to build a pack or if a self builder one has the choice of the available cells on the market.
Admittedly getting hold of really good cells is challenging at the moment but there are a few available if one opts for some lesser known brands, do the home work search out independent reviews and one can find Taiwan or China brand cells that stand up to the big brands and are on a par with them for half the price in some cases.

 

[-Pete-]

For 10s2p they are fine for light weight bikes of if your mileage is only local less then 25 - 30 miles max, they only take and hour or two to top up. No use carting around a 8lb 15ah battery when a 3lb 5/6ah will d the same thing.
As already mentioned one doesn't need more then 5/6ah for low mileage, but cell choice is critical. Any cell choice has to really be 20a rated for 2p, these are rare in ready built packs so one has to get someone to build a pack or if a self builder one has the choice of the available cells on the market.
Admittedly getting hold of really good cells is challenging at the moment but there are a few available if one opts for some lesser known brands, do the home work search out independent reviews and one can find Taiwan or China brand cells that stand up to the big brands and are on a par with them for half the price in some cases.

I'm very much a DIY type of person and like to 'think outside the box'.

I agree that the cells are the most important factor, so I've been thinking of building my own packs.

Hence my original question: Which small/lightweight/cheap battery cases should I use? I've been looking at empty bottle batteries, or might buy one with cells and re-cell it later on. But once I choose a form factor / discharge connector, I want it to be available for a good few years, and it'd be nice if I could buy reputable battery packs if I can't be bothered to make my own.

Because the 250W TSDZ2 is limited to 18A and I intend to mostly use low-assistance modes I did wonder about Samsung 25R 20A in 1P for an ultra-light pack. Or take a chance on BAK N18650CNP which are half the price.

Which spot welder? KWeld, Malectrics and Sequre all work out around £200-250 by the time I've bought a Turnigy Nano-tech and paid shipping and taxes. It's a lot of money for something I'll rarely need. Is there anything useable & reliable for half that?

 

[Nealh]

In #10 the third link to the style of bottle type xgo use have been about for a good few years and empty ones are available on AliExp.

The BAK cell looks like a worthwhile one to try and independent sources appear to back that up with it's performance, what isn't known is life cycle but at the price it is likely worth a punt and one option I'm looking at.

 

[Nealh]

The 25r in 1p might be pushing things a bit even at 10a one will only get 1600mah down to 3.2v so range will be very short or if one can be sure of a max 5a draw then 2100mah.
One might be better at 1p with the Moli p42a where one will get at nearly 3500mah at 10a or approx.3600mah at 5a.

I think 2p is then least one should probably opt for with 18650 though really depends on the terrain usage and mileage, for 1P then the Moli makes it a possibility. At 1p I can see a Moli at low current <5a delivering about 12 -15 miles or 50 - 70 mins run time

 

[-Pete-]

The 25r in 1p might be pushing things a bit even at 10a one will only get 1600mah down to 3.2v so range will be very short or if one can be sure of a max 5a draw then 2100mah.
One might be better at 1p with the Moli p42a where one will get at nearly 3500mah at 10a or approx.3600mah at 5a.

I think 2p is then least one should probably opt for with 18650 though really depends on the terrain usage and mileage, for 1P then the Moli makes it a possibility. At 1p I can see a Moli at low current <5a delivering about 12 -15 miles or 50 - 70 mins run time

Good point, I was only looking at peak discharge current... I'll need to check the graphs.

Do you have an opinion about welders? I can see £40 occasional use might work ones, and £250 probably reliable ones, but not much in the middle.

 

[harrys]

I got into battery repair this summer, replacing cells in two batteries that had gone unbalanced. I bought an inexpensive portable spot welder. Those deserve a thread of their own. Tradeoffs, the main one being lack of power, requiring thinner nickel strips. For replacing a row of cells, not so bad. I was already familiar with replacing the BMS, and using shrinkwrap.

After successful replacement, I decided to order some cells, and built a battery, Several years ago, I had a custom battery made by a builder, He charged me $5usd/cell for Panasonic 18650-GA cells, still a can't miss choice. Hard to find today, at almost 2x the price. For that reason, it's's difficult to justify building. I bought this summer, a blue shrinkwrapped 13S-2P for $80usd, and a 13S-3P for $107usd. using 21700 cells. While rated 10AH and 15AH. I'm seeing 8AH and 12AH.

My own 13-2P cost $130 for (budget ?) cells, $22 for BMS, and a few bucks for spacers, etc. However, I believe it's safer. The casings will never short circuit against each other and flame up. I'm using Lishen cells rated for 5AH, and they will deliver that on a tester at 500mA draw, drained down to 2.8V, On a bike where the controller shuts off at 3V/cell, I'm taking 4AH to recharge a 2P, so I guess that's realistic,