Charging LTO at Max Speed?

stan.distortion said:
Anyone happen to know what's the highest charging C rate for LTO and how they'd respond to higher rates than recommended?
See the mfg data sheet for the specific model.

Usually a 10-min charge from empty is considered fastest, likely reduces longevity but starting point is 10,000 cycles anyway.

That is 6C

Personally 2C would be my limit, need a 30-min break for a rest stop.

 
john61ct said:
stan.distortion said:
Anyone happen to know what's the highest charging C rate for LTO and how they'd respond to higher rates than recommended?
See the mfg data sheet for the specific model.

Usually a 10-min charge from empty is considered fastest, likely reduces longevity but starting point is 10,000 cycles anyway.

That is 6C

Personally 2C would be my limit, need a 30-min break for a rest stop.

Makes it easier to find a suitable plug, too.

Still it would be useful to know the theoretical maximum rate without energy-intensive cooling, superconducting materials, etc. Shuttle vehicles that can charge during their stand time would have a lot of viable applications. (Especially once there are robot taxis.)
 
There is no bright line not a B&W issue but greyscale balancing between the need for charging over 6C and sacrificing a greater percentage of lifespan cycles.

And the data is extrapolated by modelling, not actual testing directly

since each cell model is different, temperatures are an important factor.

In practice, maximising longevity is not as critical as with li-ion where 300 cycles is pretty good

10,000 cycles is 27 years

but "cycles" if more than once a day are highly variable

There are city buses in China that plug in at every stop, usually less than 2minutes' charging

So 200 of those in a day, how does that compare to one cycle overnight?

If I wanted to push higher than 6C, I would use temp sensing, ideally at the centre of the cells, to set an upper limit

not just absolute max temp statically

but restricting the **rate** of heat gain

as a proxy for accelerated wear
 
Username1 said:
I did some research on receptacles. Nema 14-60 (240v 60a) is the highest power for home use, but it's basically never used. The 14-50 seems to be the highest found in homes, used commonly for stoves. They're also used for welding and found in campgrounds I've read. I also read that in some places anything above 50A is supposed to be hardwired according to code.

Taking these things into account it seems using 14-50 is best.
If any "electrical [you] can have done for free", why does using a common residential plug matter?

For anybody naked charging at 10kW, the plug style is the very least of your concerns and last of your design criteria.
 
fatty said:
Username1 said:
I did some research on receptacles. Nema 14-60 (240v 60a) is the highest power for home use, but it's basically never used. The 14-50 seems to be the highest found in homes, used commonly for stoves. They're also used for welding and found in campgrounds I've read. I also read that in some places anything above 50A is supposed to be hardwired according to code.

Taking these things into account it seems using 14-50 is best.
If any "electrical [you] can have done for free", why does using a common residential plug matter?

For anybody naked charging at 10kW, the plug style is the very least of your concerns and last of your design criteria.

heavy-duty-chrome-plated-wirenut
 
fatty said:
If any "electrical [you] can have done for free", why does using a common residential plug matter?

For anybody naked charging at 10kW, the plug style is the very least of your concerns and last of your design criteria.

Sure I could wire a 60a receptacle or whatever but I like the idea of making it as practical as possible. Most houses already have a 50a receptacle for the stove (possibly dryer too?), which you could easily put a splitter on for easy access without any extra wiring needed.

By the way, what is naked charging? I'm hoping to use a single power supply with wall plug and proper quick connectors to the battery, no higher than 50-60v on the top end. Surely this could be done safely if that's what you're getting at.
 
Username1 said:
Sure I could wire a 60a receptacle or whatever but I like the idea of making it as practical as possible. Most houses already have a 50a receptacle for the stove (possibly dryer too?), which you could easily put a splitter on for easy access without any extra wiring needed.
I like the idea of being practical, but those circuits can't be split (per code), and charging in your kitchen isn't practical (or advisable -- see below).

Username1 said:
By the way, what is naked charging? I'm hoping to use a single power supply with wall plug and proper quick connectors to the battery, no higher than 50-60v on the top end. Surely this could be done safely if that's what you're getting at.
Naked charging is what you're proposing: charging off a power supply without any safeties, and without BMS protection. It's maximally dangerous and such a 10kW charge should only be done barricaded outdoors or in an approved (uninhabited) facility, regardless of chemistry.

My point is that you're so far from residential code-compliant or safe, that building around a common residential plug is backwards. You're deep into industrial power and should be consulting with Eaton if you really want to do this, not an ebike forum.
 
The EV DIYers cover this territory all the time.

If you're willing to spend a couple grand it can be both easy and safe.

Not including the electrician wiring in suitable outlets into a safe detached shed away from inhabited structures.

It is OP's lack of knowledge and deluded desire to do this for just a few hundred that is implying safety issues.

eBikes do not usually need more than 3-5 kW, and most get by on well under one.
 
You guys are making a lot of assumptions...

1. Who said there won't be a bms, or protections for the power supply?

2. What is so inherently dangerous about charging inside? This chemistry basically can't catch on fire from my understanding, whether from overcharging, heat, puncture etc. It's not like I'd even leave it unattended while charging, we're only talking about a 15 minute charge or less. Assuming you took the right precautions I don't see why it couldn't be done, but I'm open to hearing why not. By the way I was talking about 8kw charging or less, not 10kw.

3. Charging in your laundry room or kitchen could be practical, it depends on your situation. From a little browsing I've seen both splitters and extension cords for 14-50 being sold. They aren't cheap but look heavy duty. Assuming they are safe I don't really care if they aren't code compliant, if that's even the case. I'm still spit balling ideas and learning at this point, so again I'm happy to hear why something wouldn't work. A couple examples of those accessories...

https://www.evseadapters.com/products/nema-14-50-y-splitter/
https://www.amazon.com/ClearMax-Extension-Ergonomic-Superior-Conductivity/dp/B089HZ93RJ/ref=sr_1_6?dchild=1&keywords=nema+14-50+extension+cord&qid=1623119920&sr=8-6

4. A few hundred dollars, what? I never said any such thing. In fact you were the one suggesting I start out cheaper and smaller scale. I simply don't fancy spending 10 grand on some fancy domestic power supply, so I'm looking around for relatively cheaper options. Even something from China will cost 4 digits. I'm also not against getting something of quality used but it's hard to find with the specs I want. Also, the whole point of this thread is to discuss and gain knowledge. I won't even be attempting anything before I learn a lot more.
 
please ignore john fatty and chalo, they dont have a clear understanding of the basics and you end up in the woods like that.

what you want is no a problem from a technical perspective. but the problem is amps mostly, this is what makes it so expensive so there need to be a good technical motivation from your use case to warrant such a setup. its becomes a proper technical challenge as well as everything needs to handle 250A comfortably...

from your initial specs you only have a VERY small battery and one with a EXTREMELY low voltage of 30ish volts with a 12S 40Ah LTO pack that hardly holds 1kWh of usable energy.
getting a charger that can push into the 10kW range is not the problem, getting one that can do 250A is. and no, "smart" chargers for SLA batteries dont do it.

you need take a step back and look at your actual use case here. please excuse me that i dont dig the whole topic up, but what limitations does your vechicle and use case actually have to warrant a need for 10 minute charging? clearly its not size considering you can fit LTO cells.

prehaps LTO is the right choice, but can we look at your case objectivly and see what your actual needs are and select the right setup for you?

1: what would your vechicle consume to be able to do a full day of driving without recharging?

2: is there any real technical limitation to not increase the voltage of the system? (in order to lower the amps)

3: what size, weight and volume limits do you actually have?
 
flippy said:
please ignore john fatty and chalo, they dont have a clear understanding of the basics and you end up in the woods like that.
That could be so but I have a lot to learn as well, and john and others have helped me understand a lot. Now about the details of the project itself...

Firstly you can ignore whatever specific battery setups and types of chassis I was throwing around before. This is all up for change at this point. For the chassis, initially I was thinking about using a cargo bike or sit-down escooter type of build. I've since realized because the battery volume is small enough (must be to fast charge off residential power), it could potentially even go in a standup escooter. So this is all up for change.

That said there are some battery specs I'm narrowing down on. Those being 8kw charging (to make use of 240v 50a outlets), a fully charged voltage no higher than about 50v-60v (for safety reasons), and a minimum of 4c charge rate (for 15 minute fast charging). These constraints mean a maximum capacity of 30-40ah (1450ah) . I've decided on Yinlong cells since they are easily available (now directly from the manufacturer), and come in many shapes and sizes. I'm currently considering their 30ah prismatic cells because of their dimensions/shape, and because they provide a 1p setup (another key thing I'm aiming for).

I should mention that although I did have a specific practical use in mind previously, this is now just a project I'm interested in due to my interest in the properties of LTO. Those being extreme fast charging, extreme lifecycle, and ability to handle freezing temperatures which are huge advantages. I simply have a keen interest in making a ride with an extremely durable, fast charging battery, that can be easily charged at home.
 
i am sorry, but is you goal to make something actually useful or just a experimental setup as a hobby to play around with over the weekends? or an experimental thing that you might want to use properly? this is important.

i see a lot of people that see 1 or 2 things about a certain battery chemistry (like cholo and lifepo4) and hard lock onto that and completly ignore everything else. i am trying to help you figure out if your current road is not leading you into a world of dissapoitment and just a big money pit that doesnt work. because this is something that has been seen here many times before here.

i ask again:

1: what would your vechicle consume to be able to do a full day of driving without recharging?

2: is there any real technical limitation to not increase the voltage of the system? (in order to lower the amps)

3: what size, weight and volume limits do you actually have?

if you need help to answer these questions then please ask.
 
Am I reading this right, Toshibas 10Ah high power density LTOs can take over 600 amps charge for 10 seconds (when at 50% capacity)?
https://www.global.toshiba/ww/products-solutions/battery/scib/product/cell.html
 
As I said, there is no specific usage in mind. Broadly speaking it will be used like any other ebike/escooter, to get around. So yes it's a fun project meant to see what could be made to take advantage of the properties of LTO, but the goal is to have something useable.

flippy said:
1: what would your vechicle consume to be able to do a full day of driving without recharging?
This is going to be dictated by the battery, not the other way around. The goal is here 15 minute or less fast charging done at home.

flippy said:
2: is there any real technical limitation to not increase the voltage of the system? (in order to lower the amps)
Yes, safety. I've decided to stay within a reasonably safe upper voltage limit of 50-60v. I'm leaning more towards 50v for this reason.

flippy said:
3: what size, weight and volume limits do you actually have?
Again, the battery has a certain size/weight due to home fast charging constraints, so I'll be finding a chassis to fit the battery I have in mind, not the other way around. There's some leeway in how I configure the battery (ah per cell, arrangement etc.) but only so much. Regardless, the chassis will be in the realm of an ebike/escooter, not something heavy duty like an emotorcycle.
 
stan.distortion said:
Am I reading this right, Toshibas 10Ah high power density LTOs can take over 600 amps charge for 10 seconds (when at 50% capacity)?
https://www.global.toshiba/ww/products-solutions/battery/scib/product/cell.html

Yes Toshiba has a range of high power LTO cells which can take ultra extreme charging/discharging beyond what other manufacturers seem to provide. Their high energy density range is also superior. They make 200wh/l prismatic cells, whereas Yinglong and others seem to be around 150wh/l.

I would use Toshiba cells, but I don't think you can really purchase them new without being an OEM, so Yinlong is the next best thing.
 
Username1 said:
stan.distortion said:
Am I reading this right, Toshibas 10Ah high power density LTOs can take over 600 amps charge for 10 seconds (when at 50% capacity)?
https://www.global.toshiba/ww/products-solutions/battery/scib/product/cell.html

Yes Toshiba has a range of high power LTO cells which can take ultra extreme charging/discharging beyond what other manufacturers seem to provide. Their high energy density range is also superior. They make 200wh/l prismatic cells, whereas Yinglong and others seem to be around 150wh/l.

I would use Toshiba cells, but I don't think you can really purchase them new without being an OEM, so Yinlong is the next best thing.

Thanks, I'd seen some brands I'd never heard of claiming 60C and was taking it with a pinch of salt but if Toshiba has those kind of figures in their own documentation then LTO is definitely capable of reducing overall pack size in motorsports (regen). I can see why some busses are charging at stops now, 1 minute to get over 50% (80% in the linked doc)... that's quicker than putting fuel in a tank.

Btw, I checked on charging with welding transformers earlier, limiting the current to within the transformers 100% duty cycle rating would be tricky. Some old welding plants had battery charging as a feature but it would have been designed for the job, not just something else a regular welding transformer could be asked to do.
 
Username1 said:
2. What is so inherently dangerous about charging inside? This chemistry basically can't catch on fire from my understanding, whether from overcharging, heat, puncture etc.
At those power levels, even something like a marginal connection can start a fire due to the tremendous amounts of heat that can be generated. That's even if the battery is 100% safe.
 
stan.distortion said:
Thanks, I'd seen some brands I'd never heard of claiming 60C and was taking it with a pinch of salt but if Toshiba has those kind of figures in their own documentation then LTO is definitely capable of reducing overall pack size in motorsports (regen). I can see why some busses are charging at stops now, 1 minute to get over 50% (80% in the linked doc)... that's quicker than putting fuel in a tank.
By the way, it's possible other manufactures make similar high power version of LTO. There is certainly a distinction between high power and high energy versions. I was just trying to point out that Toshiba seem to be the leader in LTO performance.

On this topic, check out this page from Toshiba. This year they are supposedly releasing a new cell which basically combines the high power and high energy version into one. For home charging the high energy type already max out the available power, but maybe these new cells have even better longevity/performance when used in the 6c and under range. Interesting anyway.

https://www.global.toshiba/ww/products-solutions/battery/scib/next/hp-cell.html
 
Username1 said:
As I said, there is no specific usage in mind. Broadly speaking it will be used like any other ebike/escooter, to get around. So yes it's a fun project meant to see what could be made to take advantage of the properties of LTO, but the goal is to have something useable.
flippy said:
1: what would your vechicle consume to be able to do a full day of driving without recharging?
This is going to be dictated by the battery, not the other way around. The goal is here 15 minute or less fast charging done at home.

that was not the question. i asked what you actually -need- in power. that has nothing to do with charging.

Username1 said:
flippy said:
2: is there any real technical limitation to not increase the voltage of the system? (in order to lower the amps)
Yes, safety. I've decided to stay within a reasonably safe upper voltage limit of 50-60v. I'm leaning more towards 50v for this reason.

the voltage has nothing to do with safety. the amps you are taking about is a MUCH bigger problem here. 250A is enough to jump start 3 pickups at once. even the slightest loose connection or issue will result in MASSIVE problems. this is a LOT more dangerous then you think it is. this is why the voltage needs to go up and the current down.

Username1 said:
flippy said:
3: what size, weight and volume limits do you actually have?
Again, the battery has a certain size/weight due to home fast charging constraints, so I'll be finding a chassis to fit the battery I have in mind, not the other way around. There's some leeway in how I configure the battery (ah per cell, arrangement etc.) but only so much. Regardless, the chassis will be in the realm of an ebike/escooter, not something heavy duty like an emotorcycle.

you need to select the right battery for the application, not the other way around. that is like buying a semi+trailer for driving down the street. if you actually give the information that is needed we can see what your -actual- needs are.

i seriously doubt you understand how big the "250A issue" really is. just the cables and connections needed to transfer that power is insane, heavy, seriously expensive and dangerous.
if you were to make a 72V battery the voltage would by around 90A, a LOT more managable but still too high for DIY usage imho. i would rather see a 120~144V battery if you really want to go up this hill.

lets be clear: 250A requires 3/0 awg wire and equally rated connectors, thats 95mm2 wire for the non-americans and very firmly into the realm of "industrial grade, use both hands and body weight" connectors. thats 3~4x thicker then regular welding cable if you need to visualise it or better said: the copper core is the same diameter as a american dime.
 
flippy said:
i seriously doubt you understand how big the "250A issue" really is.

At the absolute maximum we're talking about 160a, not 250.

flippy said:
you need to select the right battery for the application, not the other way around. that is like buying a semi+trailer for driving down the street. if you actually give the information that is needed we can see what your -actual- needs are.

What application/needs are you talking about? I'm just repeating myself now, but there's no highly specific use for this. It's to create a personal ebike or escooter to get around on, capable of ≤15 minute home fast charging on a 50a receptacle.

That being the goal, it absolutely dictates the battery size to a large degree. This could be fit onto a variety of ebikes/escooters one way or another. There are controllers out there that can handle the amps, and different motor winds to suit whatever speed I choose (to a degree).
 
i am still missing WHY you need to recharge in less then 15 minutes after consuming ~1kWh of energy. it would seem that increasing the battery size would decrease the need for such a charging need.

160A does not change the metrics (or imperial :mrgreen: ) any better in practical terms. the wires get a bit thinner and you can scale 1 tier lower in your connectors but its still WAY too much. you still need pretty absurd cables, connectors and cell busbars.
especially if you run a 35mph scooter or whatever at the most. that does not even break 4~5kW in actual average consumption.

if you want to get 1~1.5kWh into a 24v battery in 15 min or less you will need to hit 250A accoriding to the charts if you include the taper off at the end.

a 72V battery (wich is still the standard for scooters) gets you about 55A for 1kWh in 15 minutes if you were to ignore the taper off. about 80A if you include it. those numbers are actually somewhat doable.

a battery like this at 24V range is simply not feasable or better said: affordable. its simply nonsensical to make such a battery in such a low voltage.


still, LTO is stupidly big compared to a regular lithium battery. you can fit 6x the capacity in the same volume. if you can store that much you dont need to charge so fast in the first place. hell, even china gave up on LTO for their eletric buses in favour or regular lithium cells....
if you want to fit the battery into a lot of vehicles you certianly need to consider size, you also aint getting far on 1kWh at 35mph on a scooter, you will drain that battery in 20 minutes....
 
john61ct said:
The EV DIYers cover this territory all the time.
Those "all the time" 10kW chargers are still Level 2, using a validated (usually (salvaged) on-board) DC chargers.
That's a far cry from the Chinese power supply proposed here.
 
flippy said:
please ignore john fatty and chalo, they dont have a clear understanding of the basics and you end up in the woods like that.
Funny, we say exactly the same thing about you and your blind obsession with dangerous charging and impractical 18650s.

You realize you're giving largely the same advice we already gave pages back in this thread, right? Or did not read this one either?

Back on ignore :roll:
 
It is routine in mobile off-grid use cases for big alternators to charge deep cycling banks

at well over 250A, even seen 15+ kW at 28V

and mains chargers to get doubled up to deliver close to that as well.

Yes you need solid know-how, purchase quality infrastructure, etc

but it is not rocket science.

And yes, staying under 60V is much safer than going lots higher.

I understand that your vehicle and use case is not the main point, you just want a context that justifies 6C charging.

So start off with 2C charging, then add more capacity later as you build up your skillz?
 
Back to chargers... Can someone explain why something like this would be a bad idea, other than just "it's chinese". Serious question i want input on this.

https://wemaxpower.en.alibaba.com/product/1600158425594-819922260/Laboratory_research_8000W_50V_160A_64V_125A_80V_100A_100V_80A_125V_64A_Switching_adjustable_power_supply_battery_charger.html?spm=a2700.shop_plgr.41413.23.6bf0852dBJW5Uk
 
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