Charging LTO at Max Speed?

Batteries, Chargers, and Battery Management Systems.
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Re: Charging LTO at Max Speed?

Post by john61ct » Jun 09 2021 12:47am

Username1 wrote: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/produ ... 852dBJW5Uk
Unless you get specific recommendations with Ali then you must assume it's likely to be crap.

If you roll the dice and end up being happy with it, keep posting each year that you are still happy

that would be a great service to the community.

Getting a proper **charger** that auto terminates would be better than a dumb PSU.

An Elcon charger is a more **known** good quantity

Also Brusa, DeltaQ, whatever Thunderstruck is selling these days.

Of course nearly everything is made in China, that is not the issue.

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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 09 2021 6:48pm

flippy wrote:
Jun 08 2021 4:33pm
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.
Because it's awesome to recharge that fast, and I don't want a shit battery that wears out in 3 years, can't handle freezing weather, and would burn my house down if not treated just right. LTO is vastly superior in every single stat except energy density, so why trade all that just for more range?
flippy wrote:
Jun 08 2021 4:33pm
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.
I won't be using a CV stage at all. That would be counter productive for fast charging. In fact the datasheet for these cells makes no mention of a CV stage. I believe a standard charge is CC at 1c then disconnect.
flippy wrote:
Jun 08 2021 4:33pm
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....
Now you're just making up numbers. Regular lithium is more like 3 or 4 times the capacity per volume at most (not 6x), and at 35 mph you would get more like an hour of run time (not 20 minutes). This range is in line with a lot of ebikes and escooters out there.
Last edited by Username1 on Jun 09 2021 7:24pm, edited 13 times in total.

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Re: Charging LTO at Max Speed?

Post by john61ct » Jun 09 2021 6:57pm

3 times the density is 1/3 the weight.

So, you meant a third to a quarter the density.

Or 3-4 times the weight (or volume).


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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 09 2021 7:21pm

You misunderstood. I was referring to "normal lithium" (not LTO) being only 3-4x. That was a direct reply to the statement that "normal lithium" fits 6x in the same volume. I edited that post to make it clearer.

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Re: Charging LTO at Max Speed?

Post by flippy » Jun 10 2021 4:30am

Username1 wrote:
Jun 09 2021 6:48pm
flippy wrote:
Jun 08 2021 4:33pm
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.
Because it's awesome to recharge that fast, and I don't want a shit battery that wears out in 3 years, can't handle freezing weather, and would burn my house down if not treated just right. LTO is vastly superior in every single stat except energy density, so why trade all that just for more range?
flippy wrote:
Jun 08 2021 4:33pm
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.
I won't be using a CV stage at all. That would be counter productive for fast charging. In fact the datasheet for these cells makes no mention of a CV stage. I believe a standard charge is CC at 1c then disconnect.
flippy wrote:
Jun 08 2021 4:33pm
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....
Now you're just making up numbers. Regular lithium is more like 3 or 4 times the capacity per volume at most (not 6x), and at 35 mph you would get more like an hour of run time (not 20 minutes). This range is in line with a lot of ebikes and escooters out there.
its abosutely no problem to make a battery last 10+ years. i do so in a daily basis, its litteraly the core of my business. hell even the scooter my wife uses every day to drive 50 miles has done so for 7 years now and it still has 87% of its orignal capacity.

you thinking you can get full capacity from a battery without doing CV is hillairous. you need to cut off 25% of the rated capacity or more depending on how fast you charge. and with your plan of pushing a couple hundred amps into a battery you can safely cut that to 30~40%.

you have been breathtakingly bad informed on how battery charging works. the harder you charge the less capacity you get if you shut off when you hit your CV portion as you hit that faster the harder you charge.

my capacity claims are done on the sizes of the chinese lto batteries you want and "regular" high capacity lithium chemistries in 18650 cells. at best its 5x the volume difference.
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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 10 2021 1:06pm

flippy wrote:
Jun 10 2021 4:30am
its abosutely no problem to make a battery last 10+ years. i do so in a daily basis, its litteraly the core of my business. hell even the scooter my wife uses every day to drive 50 miles has done so for 7 years now and it still has 87% of its orignal capacity.
From what I've seen most lithium used in ebikes/escooters last about 1000 cycles. Charging once per day that's 3 years at best. What cells are you using that last longer than 1000 cycles without thermal management?
flippy wrote:
Jun 10 2021 4:30am
you thinking you can get full capacity from a battery without doing CV is hillairous. you need to cut off 25% of the rated capacity or more depending on how fast you charge. and with your plan of pushing a couple hundred amps into a battery you can safely cut that to 30~40%.

you have been breathtakingly bad informed on how battery charging works. the harder you charge the less capacity you get if you shut off when you hit your CV portion as you hit that faster the harder you charge.
So I'm "hillairous" and "breathtaking bad informed" for following the spec sheet? It says ≥90% capacity when charging at 6c which I already mentioned pages back. Neverminded that I've already decided to compromise at 4c.
flippy wrote:
Jun 10 2021 4:30am
my capacity claims are done on the sizes of the chinese lto batteries you want and "regular" high capacity lithium chemistries in 18650 cells. at best its 5x the volume difference.
Well at best 18650 lithium cells are something like 3.7v 3.5ah or 13wh. Yinlong sells 18650 LTO cells which are 2.3v 1.5ah or 3.5wh. That's less than a 4x advantage.

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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 10 2021 7:42pm

I just read that the 80% rule only applies to continuous loads, which are considered 3+ hours. If I'm not mistaken, then you should be able to use the full 50a on 14-50. That would allow 10kw charging, making 6c possible for LTO batteries up to 1.3kwh.

The other thing I realized is that some 14-50 receptacles only have 40a breakers and wiring. I guess because not all stoves need that much power and there's no 40a receptacle, so it's allowed by code I think. Since I'm trying to make this work on standard outlets that any home has, maybe I'd limit charging to 8kw to guarantee any 14-50 receptacle could handle the power draw.

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Re: Charging LTO at Max Speed?

Post by fatty » Jun 10 2021 9:31pm

Username1 wrote:
Jun 10 2021 1:06pm
...for following the spec sheet? It says ≥90% capacity when charging at 6c...
When citing a datasheet, it would be helpful to attach it to your post so we can see the conditions specified.
I'm certainly interested in learning.
Last edited by fatty on Jun 10 2021 9:40pm, edited 1 time in total.

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Re: Charging LTO at Max Speed?

Post by fatty » Jun 10 2021 9:35pm

Username1 wrote:
Jun 10 2021 7:42pm
The other thing I realized is that some 14-50 receptacles only have 40a breakers and wiring.
No, this would break code and is unsafe.
Username1 wrote:
Jun 10 2021 7:42pm
Since I'm trying to make this work on standard outlets that any home has, maybe I'd limit charging to 8kw to guarantee any 14-50 receptacle could handle the power draw.
We can debate the relative merits of your application of LTO (and largely fail), but "making this work on.. any home" is even more confusing. Why does this matter? Nobody else is trying to do this.

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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 11 2021 12:14am

fatty wrote:
Jun 10 2021 9:31pm
When citing a datasheet, it would be helpful to attach it to your post so we can see the conditions specified.
I'm certainly interested in learning.
Sure, I just figured out how to attach it. This was sent to me from Yinlong. This is for their 30ah prismatic cell.
fatty wrote:
Jun 10 2021 9:35pm
No, this would break code and is unsafe.
Are you sure about that? I've definitely seen it done before (40a breaker, 50 receptacle), and I read online that it's done because there is no 40a receptacle so it's allowed as an exception for stoves (maybe it's smaller apartment sized stoves that do this).

I think most dryers only use 14-30 (not everyone has a dryer either), so the only available high power outlet is often the stove. If they do indeed use 40a breakers sometimes (without breaking code), then 40a is the highest power already wired in everyone's homes.

fatty wrote:
Jun 10 2021 9:35pm
We can debate the relative merits of your application of LTO (and largely fail), but "making this work on.. any home" is even more confusing. Why does this matter? Nobody else is trying to do this.
Sure I could wire up an even more powerful 60a receptacle in my own home, but out of interest I'm just exploring the idea of making something that works anywhere, without installing new wiring. Of course it doesn't have to be done this way.
Attachments
30ah spefication.pdf
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Re: Charging LTO at Max Speed?

Post by john61ct » Jun 11 2021 7:22am

Everything in a wiring path should be rated at least as high ampacity as the circuit breaker. With that latter rated higher than the greatest load that will be plugged into that circuit.

Getting an electrician in to install the right wiring to the appropriate location is not an optional expense

your talking about bringing the charging rig and batteries into a kitchen or washroom

reeks of hazardous penny pinching.

Not saying it can't be done safely if all the bases are covered

but one weak link boom you've burned down someone's home

and I really doubt insurance would pay out.

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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 11 2021 9:31am

Fair enough, it may not ultimately be a good idea. I am talking specifically about using a kitchen outlet (not bathroom) but I get your point. It wasn't about saving money, but rather the convince idea of being able to charge in any home. Like I said, I can have my own wiring done for free.

In terms of 40a circuits on 50a receptacles being to code, I found where I previously read that. I've haven't read the actual electrical code, but I'm inclined to believe this because I've seen it done before. If that's correct, it's actually adding a layer of safety to take it into account only charging with 40a. If I even go this route at all, of course.

https://diy.stackexchange.com/questions ... 0-amp-plug

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Re: Charging LTO at Max Speed?

Post by fatty » Jun 11 2021 2:39pm

Username1 wrote:
Jun 11 2021 12:14am
Sure, I just figured out how to attach it. This was sent to me from Yinlong. This is for their 30ah prismatic cell.
:thumb:
Username1 wrote:
Jun 11 2021 12:14am
Are you sure about that? I've definitely seen it done before (40a breaker, 50 receptacle), and I read online that it's done because there is no 40a receptacle so it's allowed as an exception for stoves (maybe it's smaller apartment sized stoves that do this).

I think most dryers only use 14-30 (not everyone has a dryer either), so the only available high power outlet is often the stove. If they do indeed use 40a breakers sometimes (without breaking code), then 40a is the highest power already wired in everyone's homes.
Addressing in reply below
Username1 wrote:
Jun 11 2021 12:14am
Sure I could wire up an even more powerful 60a receptacle in my own home, but out of interest I'm just exploring the idea of making something that works anywhere, without installing new wiring. Of course it doesn't have to be done this way.
Again, residential standards/limitations are irrelevant here.
As with any serious engineering challenge, learn what the commercial/industrial professionals are doing first. You need to be researching DC Fast Charging standards -- everything from supply to location to layered safeties and interlocks.

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Re: Charging LTO at Max Speed?

Post by fatty » Jun 11 2021 2:54pm

Username1 wrote:
Jun 11 2021 9:31am
Fair enough, it may not ultimately be a good idea. I am talking specifically about using a kitchen outlet (not bathroom) but I get your point. It wasn't about saving money, but rather the convince idea of being able to charge in any home. Like I said, I can have my own wiring done for free.

In terms of 40a circuits on 50a receptacles being to code, I found where I previously read that. I've haven't read the actual electrical code, but I'm inclined to believe this because I've seen it done before. If that's correct, it's actually adding a layer of safety to take it into account only charging with 40a. If I even go this route at all, of course.

https://diy.stackexchange.com/questions ... 0-amp-plug
First, stackexchange is not code. Second, it should be obvious why you should not trust the answer that includes "I am not sure whether it is legal to plug a 40A rated appliance into a circuit breakered for 50A".

The exception cited is actually de-rating the circuit breaker for the intended load, not up-rating the receptacle. The wiring in such an exception must still be safe for a 50A load. Otherwise, if the circuit breaker fails closed, the wiring burns your house down.
I have an arc-welded screwdriver I was holding without flash PPE to show for this. Never, ever do this.

A better comparison would be a 20A receptacle on a 15A circuit, which is obviously unsafe and breaks code.

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Re: Charging LTO at Max Speed?

Post by john61ct » Jun 11 2021 4:27pm

Yes to be clear, if the receptacle handles only 40A the breaker should be 40A

even if everything else could handle more.

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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 11 2021 4:40pm

fatty wrote:
Jun 11 2021 2:54pm
First, stackexchange is not code. Second, it should be obvious why you should not trust the answer that includes "I am not sure whether it is legal to plug a 40A rated appliance into a circuit breakered for 50A".

The exception cited is actually de-rating the circuit breaker for the intended load, not up-rating the receptacle. The wiring in such an exception must still be safe for a 50A load. Otherwise, if the circuit breaker fails closed, the wiring burns your house down.
I have an arc-welded screwdriver I was holding without flash PPE to show for this. Never, ever do this.

A better comparison would be a 20A receptacle on a 15A circuit, which is obviously unsafe and breaks code.
I was referring to the second answer actually.

Anyway I wasn't sure what the wiring was rated for in this situation, I just knew I'd seen a 50a receptacle with a 40 breaker before. It does make sense that the wiring would need accommodate the same as the receptacle (50a), even when derating the breaker. So what is even the point of derating the breaker? Is it done to avoid overloading a 60a panel or something else?

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Re: Charging LTO at Max Speed?

Post by fatty » Jun 11 2021 5:25pm

Username1 wrote:
Jun 11 2021 4:40pm
So what is even the point of derating the breaker? Is it done to avoid overloading a 60a panel or something else?
Yes, there is a limit to the ratio of total branch current to main breaker current (which, of course, protects the busbar from overload). Could also be to protect the connected appliance -- some specify required circuit breaker.
But it could equally be that it just happened to be what was on the contractor's truck or in stock at Home Depot that day, and was good enough.

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Re: Charging LTO at Max Speed?

Post by Username1 » Jun 11 2021 5:50pm

That makes sense, those reasons all crossed my mind as well. So I guess you could just switch out a de-rated breaker like this to match the receptacle and all would be fine.
Last edited by Username1 on Jun 11 2021 9:24pm, edited 3 times in total.

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Re: Charging LTO at Max Speed?

Post by fatty » Jun 11 2021 9:22pm

Username1 wrote:
Jun 11 2021 5:50pm
So I guess you could just switch out a de-rated breaker like this to match the receptacle and all would be fine
Actually, this is not advisable without a proper direct inspection. You have to assume the wiring is not to code, and that the lower-current circuit breaker was sized for the wiring, not the outlet. But based on your aspirations in this thread, it should be trivial to measure the wire on both ends to verify before changing the breaker.

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