Can't decide what batteries to choose

sysrq

1 kW
Joined
May 7, 2018
Messages
323
Hello, first humble post on this forum from a newbie.
Will try to keep it short.
Which battery to choose for Tongsheng 350W motor on a classic aluminum low cost road bike frame.
Hoping to cover some 70-80km in 3 hours for semi-recriational or non-recriational commuting/lightweight touring purposes.
Ordered some 36V 26aH triangle battery from HalloMotors on Amazon, but since it's still not dispatched I'm starting to think about some LTO batteries again.
Knowing that it's hard to find suitable LTO cells for a triangle battery then there is no other choice but to choose something else like lifePO4 headway cells from a local seller.
These ones
https://www.amazon.com/MiSolar-Energy-Lithium-Titanate-Replacement/dp/B078RWMGN3
probably will too be too awkward to fit on a bike for a proper weight distribution.
Currently don't feel confident enough to make DIY battery pack with BMS and initial balance charging as it might take too much time in case if something goes wrong, could try though.
LTO could be better compared to other chemistries which always need to be charged since you never know when you might need a bike. Anather thing is safe handling and charging if one happens to live in a flat or even semidetached house.
Looks like should have waited couple of more years till the LTO batteries become more well known among average consumers and local distributors.
 
There's a few good reasons to choose LTO. I just spent $1500USD on my set. But I'm not convinced that it's right for most people. Here are some reasons:

1. You ride in sub-zero temps regularly, or live where you have 40*C+ temps in the shade.
2. You want to charge in 15 minutes or less.
3. You need insane amounts of power for very short times. (This one is mine - I need 150A)
4. The same battery for >3-4 years is really important.

If you don't have a pressing desire for any of those features, there's no good reason to go to LTO. Quality 18650s will probably be your best bet, or if you want to save some money and are willing to do a bit of DIY, hobby LiPos will save you some money.
 
I like the idea of LTO batteries, but the scarcity of appropriate BMS or suitably compact high rate chargers, and the lack of ready made integrated systems, is a barrier for me. I can either have an ongoing science project, or I can depend on something for daily transportation, but my bike can't be both.
 
Hehe... Lowest cost per mile ("kilometer") overall. <- (period) :)
 
Chances of fitting three of those in a triangle are about zero. However, two in the triangle and one on the handlebars would be one option. One on a rear rack might be easy peasy too.

Pricy. This option would be for somebody really serious about the biking. a thou for 300wh? wow. But a very good quality bike battery in 500wh could still be easily 500 bucks.

The distances you talk about would need a lot more than 500wh for most people. I always assume the idea is to have help the whole ride, not just the hill. But younger people are lot more fit than me. I give old fart ranges, like 25-35 watt hours per mile. so your LTO battery of 300 wh would take me about 20 k.

So I'd say look for something in 36v 20 ah, or around at least 750 wh. Which will fit in a triangle of many bikes. Then if you need more range, next year buy another, and carry it on the rear rack only when you go for the long ride.

If you live in Canada, this is what I would suggest.

http://www.ebikes.ca/shop/electric-bicycle-parts/batteries/b3623-lim-dt.html
 
Oh, I skimmed your link. I thought those were SLAs you were replacing. My bad.

If you were going to spend nearly $900 on that, I have a better way to spend your money:

3 lots of these: www.aliexpress.com/item/5pcs-Lithium-titanate-battery-2-4V-10AH-LTO-battery-for-DIY-12V-24V-motor-ebike-accu/32830978708.html = $264

These are genuine 12Ah, not 12Ah SLA replacements, so to build an equivalent one (5 cells) you're looking at 144wh instead of their 100wh.

Add one of these for safety - www.aliexpress.com/item/Customize-LTO-battery-BMS-80A-common-port-circuit-protection-board-2-4V-lithium-titanate-battery-BMS/32847727973.html = $155

2 hours of soldering one lazy Sunday afternoon, and Bob's your uncle, and you can go electrified cycling with him.

For $419 - half of what you were going to pay, you get a battery 44% larger, and you can configure it however you please to get it between the triangle.
 
Sunder said:
Oh, I skimmed your link. I thought those were SLAs you were replacing. My bad.

If you were going to spend nearly $900 on that, I have a better way to spend your money:

3 lots of these: www.aliexpress.com/item/5pcs-Lithium-titanate-battery-2-4V-10AH-LTO-battery-for-DIY-12V-24V-motor-ebike-accu/32830978708.html = $264

These are genuine 12Ah, not 12Ah SLA replacements, so to build an equivalent one (5 cells) you're looking at 144wh instead of their 100wh.

Add one of these for safety - www.aliexpress.com/item/Customize-LTO-battery-BMS-80A-common-port-circuit-protection-board-2-4V-lithium-titanate-battery-BMS/32847727973.html = $155

2 hours of soldering one lazy Sunday afternoon, and Bob's your uncle, and you can go electrified cycling with him.

For $419 - half of what you were going to pay, you get a battery 44% larger, and you can configure it however you please to get it between the triangle.

Thank for prompt replies.
Ordered those 12Ah LTO ones as they can be quickly recharged on the go almost anywhere. Should fit into large triangle Ibera bag when stacked with one 8 cell pack and one 7 cell pack with BMS (width 2.87402 inches or 73mm + protective side panels). Don't like those ready made dolphin and bottle batteries as they don't look stealthy enough and might require additional vibration dampening.
I think this charger should do.
https://www.aliexpress.com/item/84W-42V-2A-Charger-smart-quick-lithium-LTO-Charger-for-15S-36V-lithium-titanium-battery-2/32842760364.html?spm=a2g0s.9042311.0.0.xNTZkk

Are they any good for soldering? Asked them to send them with pre-punched holes and screws.
This might sound dumb but is there any need for initial balance charging on these cells even if they are sent with identical voltages?

Will see the available range when used with 36V Tongsheng torque assist eco mode.
 
Probably LTO batteries would be the most useful with regenerative breaking to smoothly slow down on downhills for increased safety while saving the rims or brake pads. Some small hub generators in front and back could do the trick. Theoretically they could be used as a back up drive in case the mid-drive fails.
 
https://www.aliexpress.com/item/Customize-LTO-battery-BMS-80A-common-port-circuit-protection-board-2-4V-lithium-titanate-battery-BMS/32847727973.html?spm=a2g0s.9042311.0.0.W9mVJO
I wonder if all the necessary wiring like balance leads is included?
 
"Hoping to cover some 70-80km in 3 hours"... So of course you are going more aerodynamic... like the velomobiles? At LEAST with a wind screen, cowling... (Velomobile? eg:)
content_19.png


v1.jpg


:mrgreen:
 
sysrq said:
https://www.aliexpress.com/item/Customize-LTO-battery-BMS-80A-common-port-circuit-protection-board-2-4V-lithium-titanate-battery-BMS/32847727973.html?spm=a2g0s.9042311.0.0.W9mVJO
I wonder if all the necessary wiring is included?

The balancing loom is usually included, but the charge and discharge wiring, you usually make yourself. It's always a good idea to individually charge and balance the batteries before assembly. The best way to do that is to put them all in parallel, and charge to 2.8v, and leave them there for a few hours. Simple and quick.

Doesn't need to be exact, as long as it's over 2.65 or so, and preferably under 3.0v. Use a hacked USB charger with constant attention if you have to.

I'm also personally not a fan of punched holes alone in anything that moves. Fine for stationary applications. Fine if you have a piece of copper and some washers stiffening up the connection... But just the nuts and bolts straight through a thin tab, when your bike is bouncing up and down? I have zero proof it's not good enough, but there was one guy here who lost a battery after only a dozen rides, took it apart, saw the tab torn and blamed the assembly method. Again, zero proof that was the cause... But just common sense to me says I'd rather do it better. Stiffen up the join with something.

As for that charger... It's 2A. 0.16C... It'll take you 6 hours to charge from flat. These babies can take 10C, or less than 6 minutes charge.

Sure, you're not going to carry around a 120A charger, but 2A? You're buying a Ferrari, and insisting it stays in first gear. 350W discharge, ~80w charge... On batteries that can easily do 20-30x that rate.

@LockH - A bit overkill? I've done 100km in 3 hours without ANY power assist. Sure that's when I was training 3 x weekly for a triathlon, but with 350w, 80km in 3 hours is not granny cruising, but you won't exactly breaking a sweat.
 
@LockH - A bit overkill? I've done 100km in 3 hours without ANY power assist. Sure that's when I was training 3 x weekly for a triathlon, but with 350w, 80km in 3 hours is not granny cruising, but you won't exactly breaking a sweat.

Hehe... "Back in the day" when I got out of high school pedaled a bike 1000+ miles in just over 6 days. Was "pedaling my butt off", eating four meals daily and still losing weight. :) Current rolling on a recumbent, but the force against aero grows as speeds increase? ... and not in a linear way, but increasing...
aero_bike_and_drag_a.gif
 
Sunder said:
The balancing loom is usually included, but the charge and discharge wiring, you usually make yourself. It's always a good idea to individually charge and balance the batteries before assembly. The best way to do that is to put them all in parallel, and charge to 2.8v, and leave them there for a few hours. Simple and quick.
Doesn't need to be exact, as long as it's over 2.65 or so, and preferably under 3.0v. Use a hacked USB charger with constant attention if you have to.
Probably will use some voltage regulator. https://electronics.stackexchange.com/questions/159146/how-to-charge-lithium-titanate-battery-with-lower-voltage?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa How powerful the charger should be in this case?
Sunder said:
I'm also personally not a fan of punched holes alone in anything that moves. Fine for stationary applications. Fine if you have a piece of copper and some washers stiffening up the connection... But just the nuts and bolts straight through a thin tab, when your bike is bouncing up and down? I have zero proof it's not good enough, but there was one guy here who lost a battery after only a dozen rides, took it apart, saw the tab torn and blamed the assembly method. Again, zero proof that was the cause... But just common sense to me says I'd rather do it better. Stiffen up the join with something.
Getting away without some filling material like epoxy or something more appropriate to save weight would not be the best idea. Used to build some battery packs while working as a service technician for walkie-talkie company, not sure if I would do it again lol.

Sunder said:
As for that charger... It's 2A. 0.16C... It'll take you 6 hours to charge from flat. These babies can take 10C, or less than 6 minutes charge.

Sure, you're not going to carry around a 120A charger, but 2A? You're buying a Ferrari, and insisting it stays in first gear. 350W discharge, ~80w charge... On batteries that can easily do 20-30x that rate.
As far as I know almost any linear or non-linear power supply can be used in this case, it's just a matter of right voltage. Could grab any hefty transformer lying around and add some bridge rectifier with capacitor while monitoring the current.
Sunder said:
@LockH - A bit overkill? I've done 100km in 3 hours without ANY power assist. Sure that's when I was training 3 x weekly for a triathlon, but with 350w, 80km in 3 hours is not granny cruising, but you won't exactly breaking a sweat.
Have only done 130km in about 5 hours on regular basis. Now aiming for e-assist in order to keep up against headwinds and hills while reducing dependability on weather.
 
How long would it take to charge with this one?
https://www.aliexpress.com/item/420W-42V-10A-Charger-3-stage-smart-LTO-Charger-Fan-for-15S-36V-lithium-titanium-battery/32842748758.html?spm=2114.search0104.3.33.63472aebkMm15u&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_10151_10344_10068_10130_5722815_10324_10342_10547_10325_10343_10340_10341_5722915_10548_10698_5722615_10696_10192_10190_10084_10083_10618_10307_10301_10303_5722715_5711215_10059_308_100031_10103_10624_10623_10622_5711315_5722515_10621_10620,searchweb201603_25,ppcSwitch_5&algo_expid=e6dc62bd-2fed-4c6d-b517-7478d49dba43-5&algo_pvid=e6dc62bd-2fed-4c6d-b517-7478d49dba43&transAbTest=ae803_2&priceBeautifyAB=0
Probably an hour at least.
 
For initial balancing, doesn't have to be powerful at all. You just want to make sure all cells are at the same SOC.

Difference between 2.6 and 2.8v on most LTO is 5% SOC, so anything over 2.65v is fairly close. But if you try to balance it at 2.4v, you could be at 80%, or you could be at 20%, too hard to tell.

I'm seriously thinking about doing a "Quick 'n Dirty" guerilla charger for charging at petrol stations on the road, etc. Same design as you. A transformer to reduce 240vac to 110vac, then a bridge rectifier to convert to 150vdc.

My main concern though, was current limiting. A normal wall socket can do 2.4kw. A 15A socket (common in shopping centres and stadium etc) can do 3.6, while a proper car charger can do 6.6kw. The battery I'm building has such a low internal resistance, it will soak up any of those, and more, meaning I'd trip the fuse/RCD if I don't limit current.

I thought about a current limiting resistor, but it'd have to shed way too much heat.

Beyond that, I'm clueless as to how I could limit the power. Any suggestions?
 
sysrq said:
How long would it take to charge with this one?
https://www.aliexpress.com/item/420W-42V-10A-Charger-3-stage-smart-LTO-Charger-Fan-for-15S-36V-lithium-titanium-battery/32842748758.html?spm=2114.search0104.3.33.63472aebkMm15u&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_10151_10344_10068_10130_5722815_10324_10342_10547_10325_10343_10340_10341_5722915_10548_10698_5722615_10696_10192_10190_10084_10083_10618_10307_10301_10303_5722715_5711215_10059_308_100031_10103_10624_10623_10622_5711315_5722515_10621_10620,searchweb201603_25,ppcSwitch_5&algo_expid=e6dc62bd-2fed-4c6d-b517-7478d49dba43-5&algo_pvid=e6dc62bd-2fed-4c6d-b517-7478d49dba43&transAbTest=ae803_2&priceBeautifyAB=0
Probably an hour at least.

15 cells x 12Ah x 2.4v nominal = 432wh

420W charger will get you to 95% full in an hour. Normally, the current has to fall for the last few percent, but the beauty of LTO, is that the termination voltage is relatively high compared to the bulk of the capacity. So in a 15 cell battery, the last 5% still creates a 3v potential difference. With relatively low internal resistance that again, LTO provides, like 1mOhm per cell, you're still looking at complete pack IR of <20mOhm, so you'll be charging at full rate, right until the battery is full.
 
Sunder said:
For initial balancing, doesn't have to be powerful at all. You just want to make sure all cells are at the same SOC.

Difference between 2.6 and 2.8v on most LTO is 5% SOC, so anything over 2.65v is fairly close. But if you try to balance it at 2.4v, you could be at 80%, or you could be at 20%, too hard to tell.
Will see.
Sunder said:
I'm seriously thinking about doing a "Quick 'n Dirty" guerilla charger for charging at petrol stations on the road, etc. Same design as you. A transformer to reduce 240vac to 110vac, then a bridge rectifier to convert to 150vdc.
That's a rally high voltage pack there. Aren't transformers a bit too heavy to take on board? There could be some SMPS based lightweight ultrahigh switching frequency chargers.
Sunder said:
My main concern though, was current limiting. A normal wall socket can do 2.4kw. A 15A socket (common in shopping centres and stadium etc) can do 3.6, while a proper car charger can do 6.6kw. The battery I'm building has such a low internal resistance, it will soak up any of those, and more, meaning I'd trip the fuse/RCD if I don't limit current.
Probably will have to wait for dedicated LTO charging stations.
Sunder said:
I thought about a current limiting resistor, but it'd have to shed way too much heat.

Beyond that, I'm clueless as to how I could limit the power. Any suggestions?
Probably not fully qualified to come up with the right answer in this case. There is no way of getting more power than it's available. Even when using light bulb trick it will have to be big for this application. Soft start circuits could be used if there are some current surges.
 
I was thinking the transformer would be fist sized, but now looking at the current I want, yeah, that's not going to work. To get to the currents I want, not only are they heavy, they're pretty expensive too.

My application is a motorcycle, not an eBike, hence the high power/voltage.

I currently have two high quality Meanwell SMPS delivering a total of 600w built into the bike. But SMPS isn't cheap, and get pretty big for the kind of power I'm thinking of too.
 
Sunder said:
I was thinking the transformer would be fist sized, but now looking at the current I want, yeah, that's not going to work. To get to the currents I want, not only are they heavy, they're pretty expensive too.

My application is a motorcycle, not an eBike, hence the high power/voltage.

I currently have two high quality Meanwell SMPS delivering a total of 600w built into the bike. But SMPS isn't cheap, and get pretty big for the kind of power I'm thinking of too.

Even for LTO charging with low C rate will increase it's lifespan.
 
sysrq said:
Even for LTO charging with low C rate will increase it's lifespan.

That's not a real issue. At the fastest a standard power point can deliver, I would be charging at 1/10th of what the LTO cells could safely take.

At the rate I am charging, it's more like 1/40th.
 
All of these
https://www.aliexpress.com/wholesale?catId=0&initiative_id=AS_20180514055339&SearchText=lto+charger
chargers seem a bit too overpriced compared to this one
https://www.aliexpress.com/item/600A-2S-24S-Cells-Lithium-LiPo-LiFe-LiTO-BMS-Smart-Balancer-Display-1500W-24S-Charger-Li/32834380091.html
So, I'm refusing to buy any charger with short charging time at the moment.
Maybe something small enough with large fan would be worth buying.
 
Sunder said:
Oh, I skimmed your link. I thought those were SLAs you were replacing. My bad.

If you were going to spend nearly $900 on that, I have a better way to spend your money:

3 lots of these: www.aliexpress.com/item/5pcs-Lithium-titanate-battery-2-4V-10AH-LTO-battery-for-DIY-12V-24V-motor-ebike-accu/32830978708.html = $264

These are genuine 12Ah, not 12Ah SLA replacements, so to build an equivalent one (5 cells) you're looking at 144wh instead of their 100wh.

Add one of these for safety - www.aliexpress.com/item/Customize-LTO-battery-BMS-80A-common-port-circuit-protection-board-2-4V-lithium-titanate-battery-BMS/32847727973.html = $155

2 hours of soldering one lazy Sunday afternoon, and Bob's your uncle, and you can go electrified cycling with him.

For $419 - half of what you were going to pay, you get a battery 44% larger, and you can configure it however you please to get it between the triangle.

Just as I should have thought, AliExpress is trying to sell me different BMS for LTO and are refusing to send specifications cause it's a new model.

''it is a new product, we have not sell in AliExpress, But its quality is better than before,You can trust our profession,''
 
If you are not confident in DIYing a pack, a good option is a pack from Unit Pack Power.

https://unitpackpower.aliexpress.com/store/1178407

These guys make pretty good quality packs. worth a look.
 
A quality plug-and-play battery with a company you can call up if the charger or BMS goes out you can get a replacement. Just in case customer service does mean something. Building a battery can be a little over rated with all the parts. Especially for a 48v 52v battery.
 
lionman said:
If you are not confident in DIYing a pack, a good option is a pack from Unit Pack Power.

https://unitpackpower.aliexpress.com/store/1178407

These guys make pretty good quality packs. worth a look.

Too late, received those 15s 12Ah 2.4v LTO pouches. Now can't stop thinking about some faster 10 amp charger, otherwise using LTO becomes a bit more pointless. Saw some 10 amp 36v LED power supply on amazon which is more than three times cheaper.
https://www.amazon.co.uk/360w-Regulated-Switching-Power-Supply/dp/B00F195CTE
Why does chargers have to be more expensive if they only have some cc/cv circuit added?
Or this one which is only 1.1kg,
https://www.mouser.co.uk/ProductDetail/MEAN-WELL/SE-450-36?qs=M1W9nuUSIjrfyUt4ZXNO1g%3D%3D
compared to this one which is 3.5kg.
https://www.dhgate.com/store/product/600w-output-42v-10a-charger-36v-ebike-scooter/401569742.html
Then there is adjustable ones like these, which could be used for initial balance charging.
https://www.amazon.com/LM-High-precision-High-stability-Certification-Communications/dp/B071DBP5XK
Still three times cheaper.
This 40 amp as well, a bit cheaper than aliexpress.
https://www.amazon.co.uk/Supply-Control-3-5-36VDC-Adjustable-SE-1500-36/dp/B07B1SY9M2.
There aren't any reasonable 10 amp 0-42V laboratory power supplies either.
Only this one, but too expensive compared to other options.
http://uk.farnell.com/ea-elektro-automatik/ea-ps-2042-10b/power-supply-1ch-42v-10a-adjustable/dp/1840121?MER=mktBestSellerB
 
Back
Top