1000w 60v trike help with battery's please

[somervillearron]

Hi



So I have a 3 wheel trike it was initially a green power bz500 like in the link here

Electric Mobility Scooter BZ500 - Green Power

Take the next step in your journey to greater independence with the stunning Retro model BZ500 Electric Mobility Scooter by Green Power. Part of our range of luxurious yet affordable products.

www.mobilitypower.co.uk

So we bought it but everything was blown on it even though it was only 7 months old!

So literally all that was used was the frame and the X5 12v 20ah battery's all the wiring and motor controller and motor where all discarded.





So I bought a 60v 1000w motor and a seperate 64v/48v 1000w motor controller.





So to get down to my issue the scooter runs just fine but my issue is as soon as it gets to 48v bang on it basically cuts out it's go stop go stop but from 60v down to there it's perfect!



Am I correct in saying this is what it means by 64v/48v? Does that mean it stops at 48 as there not lithium batterys and can't be totally discharged? Sorry I just have no clue what so ever here........



Can I ask also see the 500w 60v the scooter was originally it was rated at something like 14 miles what should I be getting out of it the way it is just a rough estimate?





See the battery's are pretty old they do need replacing now but my main question is if I go for lithium ones like these

Lithium Battery 12V 20AH LiFePO4 BMS Emergency Storage Power RV Solar Camper ATV | eBay

Battery Specifications： Voltage: 12.8V Standard Capacity: 20Ah/256Wh Battery Cell Type: Lithium Iron Phosphate BMS-Discharge Protection Voltage: 8V Standard Continuous Discharge Current: 10A Max. Continuous Discharge Current: 20A Discharge Temperature: -20°C -60°C Charging Temperature: 0°C -55°C...

www.ebay.co.uk

Am I correct in saying since these are lithium they can be ran down to 15% or there around?



So how if the controller cuts off at 48v would I get around this do you get special controllers for lithium or is there something I'm missing here?





Sorry I probably sound really stupid here I've just absolutely no clue with this end of things give me car electrics I'm all over it but these motor controllers and battery's I'm learning







So can someone tell me is it normal to cut off at 48v?

If I got lithium would I be able to go below the 48v and get more range as a result?





Thanks a lot

 

[ccihon]

It's a common assumption that a battery's charge level is like a gas tank level - full to empty. Actually, a fully charged "60v" battery pack likely crests to a 100% charge at a voltage well above that, and is "empty" or at a zero charge level at 48v or maybe even more. The battery management system, if there is one, will often cut power entirely at the lower limit to protect the cells. Below is a voltage vs. usable charge percentage for AGM cells, which may be what you have, but is similar to Lithium cells. The AGM may be more forgiving, but with Lithium cells it is important to not let them drop very low as this can damage them. The "percentage" of the battery is the amount of usable capacity remaining, not the voltage compared to zero.

Each Lithium cell would generally be fully charged at 4.2v, and considered fully discharged at 3.0v - you would use 16 cells to make a "60v" pack, so 100% is actually 67.2v, and empty is 48v (16 x 3.0V). From the chart for AGM batteries I found below, it appears the usable capacity for them is a bit less. As the batteries age, you will often find they do not charge to their full voltage capacity. Lithiums, especially new ones, will extend you range I would think - just don't use the voltage measurement as a percentage of total to suggest usable range or capacity.

16 Cells x 4.2 Volts/Cell = 67.2 Volts Fully Charged

 

[fechter]

If the controller is made for 60v, it's normal for it to cut off at 48v to protect the battery.
The controller may be programmable to lower the cutoff voltage if made for a 48v battery. This may be in software or sometimes there's a wire you connect or disconnect to switch from 60v to 48v systems.

A lithium battery will give more range before hitting the cutoff voltage and last for many more charge/discharge cycles compared to a lead-acid battery. Also much lighter and smaller.

The range estimates of most scooters is exaggerated. Range will depend on total weight, speed, hills, etc. and my vary widely depending on conditions. For a slow moving scooter, you should get pretty good range. There are some computer models that can be used to accurately predict the range. Speed affects the range the most.

 

[amberwolf]

So I bought a 60v 1000w motor and a seperate 64v/48v 1000w motor controller.

Which specific one? Link to the actual item page may provide info not in your post (such as controller HVC, LVC, current limit, etc) that can help answer some questions.

So to get down to my issue the scooter runs just fine but my issue is as soon as it gets to 48v bang on it basically cuts out it's go stop go stop but from 60v down to there it's perfect!

That is probably the controller LVC engaging, to protect your batteries from damage that can lead to a fire.

Am I correct in saying this is what it means by 64v/48v? Does that mean it stops at 48 as there not lithium batterys and can't be totally discharged? Sorry I just have no clue what so ever here........

Batteries all have a useful voltage range, outside of which they don't function properly or at all, and which can cause damage to them that can lead to fires.

Controllers have LVCs and HVCs to prevent going too low or too high, and most lithium batteries have BMS in them that also have these limits. The actual voltages of the limits and how they are engaged vary from device to device, so you have to look at the manual or data sheet for each device to see what they are and how they work. If such data is not provided, it can be determined experimentally, as you are doing presently, but it is better to know what it is supposed to be so you can verify that it is working as designed.

Lead-acid batteries don't have BMS or other protection built in, so they depend on the charger and controller HVC / LVC to protect them. The LVC for each kind can be different, but almost all the controllers these days are setup more for lithium packs than lead. If yours doesn't say which, it's probably setup for lithium.

Can I ask also see the 500w 60v the scooter was originally it was rated at something like 14 miles what should I be getting out of it the way it is just a rough estimate?

If the system you are now using uses the same power under the same riding conditions (terrain, wind, weight, riding style, speed, etc) as the original system, and has the same cutoff limits, then using the same batteries you would get the same range.

If the system you are using now uses a different amount of power under the same conditions as the original, with the same limits, then the same batteries will get a proportionally different range based on the difference in power usage.

If the conditions aren't the same, then the usages aren't directly comparable, and you would have to experimentally determine your range (as you are doing), or use a wattmeter / coulometer to "count" the capacity used by the battery over a certain amount of distance and/or time, to compare to the total capacity the battery actually has (as measured by a test, rather than comparing to the label which may be inaccurate due to age, wear, or marketing).

Am I correct in saying since these are lithium they can be ran down to 15% or there around?

If they have a BMS they will protect themselves against overdischarge, but the controller should have an LVC that does this first. You'd need to check the manual or spec sheet for each one to see what that is and/or if they have one.


Note that not all batteries perform equally--some are more capable than others at delivering current (A, Amps) which is what your system uses to get moving and to go up hills/slopes. If the new batteries can't supply as many A (not Ah, different thing), as the originals, the system will not perform as well, accelerating and climbing slower than before, though once the load lessens they may recover and still reach the same top speed.

In general lithium will supply more Ah (capacity) than the same Ah rated lead (SLA, AGM, FLA, etc) battery, and weigh less, and this will usually give you more range for the same Ah rating. How much more depends on your actual usage and conditions, since it takes more power to go up hills, accelerate faster, ride against the wind, or ride over less than perfect road surfaces.


Some of the lead-replacement lithium batteries may not be able to supply as many A for initial accleration and hilll climbing as the lead they replace, so you need to check what your controller's current limit is, and make sure the replacements you get are rated to supply that much current, continuously, or more.

Lead-acid chargers are different than Lithium chargers, so you usually want to replace the charger if you change battery types from one to the other.

 

[somervillearron]

Thanks a lot for all the information it's great to know about the low voltage control so I'm reading I can replace a resistor with a 100k pot to adjust the low voltage control for if I'm replacing my battery's with lithium and a new charger
As am I correct in saying lithium can go down to 20% no problem but with the current 48v lvc I'm only getting12v out of the whole 60v pack! But I'm unsure what resistor that needs changing I'm gonna upload a pic of my controller

 

[somervillearron]

So I'm going for these

https://a.aliexpress.com/_mst6c3I

So I'll need to get the lvc taken down

 

[somervillearron]

Here's some pics

 

[Muramura]

Id say for sure get a battery with more Ah for it to not hit 48v as fast, also to not voltage sag too, since your battery is old old. 60v batteries are less uncommon then 72v or 52v but you should be able to find them for a reasonable price.

 

[somervillearron]

Id say for sure get a battery with more Ah for it to not hit 48v as fast, also to not voltage sag too, since your battery is old old. 60v batteries are less uncommon then 72v or 52v but you should be able to find them for a reasonable price.

There agm 12v 20ah the now mate X5 so 60 volts

They did when nearly new go for miles no issue before it got the 48v so there definately buggered!


The new ones are 12v 25ah lithium

https://a.aliexpress.com/_mOhKGm8

So initially I'm gonna have the 5 like now but as I say there gonna be lithium over AGM and also 5ah more

Also as I will be able to run them down to say 25volts over 48volts and there will be a better discharge rate I will be able to get really far with them! And over time I will add some extra battery's there is space for x12 of these battery's in total as I have a large space under the seat also that is unused. Really the plan is X10 battery's
And a 3000w 10 inch hub motor for the front and upgrade the rear differential mounted motor to 2000w possibly just depends on what it's like with the 3000w hub motor and the 1000w together? I assume it will be quick because rite now it's far from slow!


I have also considered doing away with the differential and drive shafts at the rear and selling them and using the money to get two 3000w hub motors for the rear wheels as it will be direct drive and less heavy really I could have 3000w on 3 wheels!

Definately a project see the pics don't do these scooters justice the suspension system and frames are really heavy duty and we'll designed plus the braking system is good aswell and it can easily take two people in comfort see where I live we have large cycle paths all the way around the town and loads of good areas to go as well plus this technically being a road legal mobility scooter having headlights indicators etc it's basically a tax free motorbike! Just need to be carefull with the speed
But I was wanting to have 3000w on the one key and if the other key/is on the other controllers and motors come on plus the speed limiter on it also so with X10 battery's I would be able to travel a reasonable distance at a good speed

 

[somervillearron]

Thanks for the input guys if someone could tell me what resistor does the low voltage control I would appreciate it

If you need other pics please ask also I would be open to a better controller that would be easier to put a lower low voltage control on as I plan on getting a 3000w motor anyways so getting a new controller will be a must at one point anyways......but I badly need to remove this low voltage control get it down to say 25volts as I've got these X5 lithium batteries coming anytime soon so having it the way it is I'm getting very little of the pack that's actually usable

 

[amberwolf]

with the current 48v lvc I'm only getting 12v out of the whole 60v pack!

That is how batteries work.

You cannot use "60v" out of the pack, as that's not how this stuff works. For instance, if you were to discharge down to 25volts you would destroy your batteries permanently.

There is a certain amount of capacity, measured in Ah or Wh, and that capacity is related to a small voltage range.

I do not recommend altering the LVC of the controller, or you risk damage that can lead to a fire. The LVC is there to protect against that.

Even if there is no fire, you will have to buy new batteries for every ride because you will have destroyed the set you ride with by discharging it below it's LVC.

 

[amberwolf]

So I'm going for these

https://a.aliexpress.com/_mst6c3I

Given their size, those almost certainly do not actually have 25Ah capacity. Like most of the cheap batteries you will find on Aliexpress, ebay, amazon, etc., I would guess that at best you will get half of that, and probably a lot less, and it's quality will probably be low enough that you'd be better off replacing with generic lead-acid.

FWIW, any "shop(number)" store you see on aliexpress is not likely to be selling genuine anything, nor know anything about what they sell, if they couldn't even be bothered to give their business a name you could trace and find info on.

If you find a battery of some size/type/capacity/etc for a certain price, on average, and then find places selling something with similar or greater specs for cheaper (especially a lot cheaper), it's probably not what it says it is.

 

[amberwolf]

I plan on getting a 3000w motor anyways

Then you will also need to get batteries that can supply that much power without damaging them or destroying them or starting a fire. You'll also need wiring from the batteries to the controller to handle that current.

3000w / 60v = 50A, so at minimum the batteries must be able to supply that continuously. If they can't, they'll at best perform terribly or shutdown the entire system. At worst they could be damaged or destroyed, or even start a fire (later on or right then).

If you are *also* using another 2000w on a second motor, you then need 5000w total from the battery, which is 5000w / 60v = ~84A, so now you need batteries that can supply *at least* 84A continuously.



So...why do you need 3000w, or 5000w? Have you done simulations or calculations that show you require that much power to do the job you need the vehicle to do for you, under the conditions you need it to do the job? If not, you should do that before you decide to change parts out.

Also note that some localities define mobility scooters as having certain speed and power limits, and when you exceed those they aren't mobility devices anymore, and require licensing, registration, taxes, etc, or are even just flat out illegal to use on public ways (with varying consequences for the rider).

 

[somervillearron]

That is how batteries work.

You cannot use "60v" out of the pack, as that's not how this stuff works. For instance, if you were to discharge down to 25volts you would destroy your batteries permanently.

There is a certain amount of capacity, measured in Ah or Wh, and that capacity is related to a small voltage range.

I do not recommend altering the LVC of the controller, or you risk damage that can lead to a fire. The LVC is there to protect against that.

Even if there is no fire, you will have to buy new batteries for every ride because you will have destroyed the set you ride with by discharging it below it's LVC.

Sorry as I say Im learning but I was maybe not clear the current battery's are out of the bike as there totally dead tried them on the pulse charger etc there unrecoverable......there the old lead acid or gel type I know they go down to 48v only to protect them as that type can't be discharged much further

But I have on order replacement lithium batterys which I thought you could discharge to 70% so 30% is left over? So if correct 30% is 18v so I was thinking I could change the low voltage discharge to 25volts safely?

As I say I am learning so please bare with me!

 

[somervillearron]

Then you will also need to get batteries that can supply that much power without damaging them or destroying them or starting a fire. You'll also need wiring from the batteries to the controller to handle that current.

3000w / 60v = 50A, so at minimum the batteries must be able to supply that continuously. If they can't, they'll at best perform terribly or shutdown the entire system. At worst they could be damaged or destroyed, or even start a fire (later on or right then).

If you are *also* using another 2000w on a second motor, you then need 5000w total from the battery, which is 5000w / 60v = ~84A, so now you need batteries that can supply *at least* 84A continuously.



So...why do you need 3000w, or 5000w? Have you done simulations or calculations that show you require that much power to do the job you need the vehicle to do for you, under the conditions you need it to do the job? If not, you should do that before you decide to change parts out.

Also note that some localities define mobility scooters as having certain speed and power limits, and when you exceed those they aren't mobility devices anymore, and require licensing, registration, taxes, etc, or are even just flat out illegal to use on public ways (with varying consequences for the rider).

So the plan was to have 1000w as it's ok for what a mobility scooter should be as these are sold new with that spec


Then I was wanting a seperate front motor on a seperate X5 battery's for the front wheel that will be on a seperate key that won't be carried while on public roads that would be for off-road areas like what we have loads of around here..sorry please ignore if I jump around subjects and can be hard to understand I have ADHD so I tend to do that!



See when you say simulations etc I have no idea mate I do understand having the correct guage of wiring etc I do know what I am doing in that regard I've just no idea when it comes to wattage powerx speed etc I take it 3000w is total overkill?

See what it has at the moment is ok but not what I want Its ok for driving around but not the trails although it does go down them ok just struggles a little so the idea was having 3x wheels being driven rather than 2 or sometimes 1 as it's a open diff on the rear

I take it adding 1000w to the front would give me plenty power? I'm probably misunderstanding I thought two 1000w motors would give me more power but no extra top speed? Or am I experiencing a lot of mechanical loss due to the diff between the motor and wheels?

So if you recon a hub motor at 1000w would give me what I need that's great or would I need to go for 2000 or 1500w to get that extra few mph?

And don't worry the battery's I bought wherent those in the link just the same rough specs I know from experience you get what you pay for I bought proper 20ah 12v battery's they where much more expensive but I needed battery's either way and from what I've seen with two temporary 30v Bosch lithium's I have the performance is better although as I say I couldn't get them last 48v when I thought they could do 25v safely

 

[amberwolf]

But I have on order replacement lithium batterys

I hope those aren't the ones you linked, as they almost certainly wont' do what they say or what you want them to. If you link the ones you did get we can give you an opinion on them so you can either use them or try to cancel the order, etc.

which I thought you could discharge to 70% so 30% is left over? So if correct 30% is 18v so I was thinking I could change the low voltage discharge to 25volts safely?

No, you will destroy the batteries. (assuming they don't have any built in protection against that), and you can't get drastically more capacity out of htem by using a drastically lower LVC.

The LVC is what it is because *all* batteries of *all* kinds have only a narrow range of voltage that they operate in. Different chemistries have different ranges, but they are usually built into packs and used as sets that are close enough to the LVCs of these systems to

Don't mess with your LVC, you'll just cause yourself unnecessary grief.


Before you go any further, I highly recommend you read up on how batteries work; the first place could be Battery University, or AllAboutCircuits, etc. It will save you time and trouble and grief and money.

Next you should always read the manufacturer spec sheet for the battery you intend to use, that includes testing information and discharge curves, etc., to be sure it will even work for your application, that it's LVC and HVC match the use you want to put it to.

If there is no manufacturer spec sheet available for the battery from the seller, check the manufacturer. If there isn't one or there isnt' a known manufacturer, don;t get that battery, because it might not even be what the seller says it is, and you haven't got a way to tell (no data to compare it to). (sellers lie all the time about stuff so they can sell more of it) There are plenty of places to buy things from, so you can usually avoid any places that you can't be *certain* are selling the thing they say they are.

 

[amberwolf]

See when you say simulations etc I have no idea mate I do understand having the correct guage of wiring etc I do know what I am doing in that regard I've just no idea when it comes to wattage powerx speed etc I take it 3000w is total overkill?

To find out how much power you need, you must first sit down and define the specific job(s) you need the whole system to do for you, and the conditions it has to do that job under, and how long (far) it has to do it.

Then you can go to places like the simulators at ebikes.ca and make guesstimates of what it will take to do that job under those conditions for that long. It will take some experimentation and practice learning how whatever simulator or calculator(s) you use work, then trying different setups under your specific conditions to see if they will do what you want.

(these simulators/etc will also help you understand the relationships between voltage, power, speed, current, torque, load, etc., so that you can better choose things to do the jobs you need them to do without just guessing and hoping and possibly wasting money and time).

Then you can go get parts that can do that job.

Regarding legalities, if they are important to you (they aren't to everyone) you'll have to check your local laws/etc. It may not matter if you have access to the extra power--just having it on there might not be allowed. (and having stuff on it you aren't using is extra weight that the stuff you *are* using then has to push around, so it can't do as good a job as it would otherwise, and will have to work harder to do it, shortening your range).

 

[somervillearron]

To find out how much power you need, you must first sit down and define the specific job(s) you need the whole system to do for you, and the conditions it has to do that job under, and how long (far) it has to do it.

Then you can go to places like the simulators at ebikes.ca and make guesstimates of what it will take to do that job under those conditions for that long. It will take some experimentation and practice learning how whatever simulator or calculator(s) you use work, then trying different setups under your specific conditions to see if they will do what you want.

(these simulators/etc will also help you understand the relationships between voltage, power, speed, current, torque, load, etc., so that you can better choose things to do the jobs you need them to do without just guessing and hoping and possibly wasting money and time).

Then you can go get parts that can do that job.

Regarding legalities, if they are important to you (they aren't to everyone) you'll have to check your local laws/etc. It may not matter if you have access to the extra power--just having it on there might not be allowed. (and having stuff on it you aren't using is extra weight that the stuff you *are* using then has to push around, so it can't do as good a job as it would otherwise, and will have to work harder to do it, shortening your range

To find out how much power you need, you must first sit down and define the specific job(s) you need the whole system to do for you, and the conditions it has to do that job under, and how long (far) it has to do it.

Then you can go to places like the simulators at ebikes.ca and make guesstimates of what it will take to do that job under those conditions for that long. It will take some experimentation and practice learning how whatever simulator or calculator(s) you use work, then trying different setups under your specific conditions to see if they will do what you want.

(these simulators/etc will also help you understand the relationships between voltage, power, speed, current, torque, load, etc., so that you can better choose things to do the jobs you need them to do without just guessing and hoping and possibly wasting money and time).

Then you can go get parts that can do that job.

Regarding legalities, if they are important to you (they aren't to everyone) you'll have to check your local laws/etc. It may not matter if you have access to the extra power--just having it on there might not be allowed. (and having stuff on it you aren't using is extra weight that the stuff you *are* using then has to push around, so it can't do as good a job as it would otherwise, and will have to work harder to do it, shortening your range).

Thanks a lot btw so I have looked into it I'm going for a 2000w 60v hub motor for the front wheel which will allow all 3 wheels to be driven for if on mud or any non solid surface and will give me the speed id like


What I have done aswell I've went for 21 18650 2900mah cells and a BMS for each battery box giving me the 12v 20ah or there around that I need,this way I know what I have is the output etc I expect I wasn't planning on aliexpress ones just used that to show you all the specs I wanted.....so I've hollowed out each battery box I have 5 and I plan on making a seperate box using a literal bucket of good cells I've collected from devices over time so I should have around 8 12v20ah battery's in total for a reasonable cost I built packs for a leasure battery last year and they all work great I just don't know alot about discharge rates and stuff but physically safely building a pack I can do.. .


So one more question see I have the space for x12 battery's I am wondering am I better splitting the pack in two use one for each motor?
So that's two 60v packs or should I wire them so it's all one 60v pack? See my thinking was having the smaller motor for efficiency and the larger one for power I don't know I'm maybe being silly here but this is why I am asking people with experience



Also sorry can I ask see having 1000w at the back and 2000w front using them together would I only get the benefit of the larger motor power wise or do they work together like the way two engines would? I'm assuming I would just be wasting battery having the 1000w running alongside the 2000w? But the one benefit I can get is getting out of ruts as I can have all 3 wheels go and even have power to the back more than front and vice versa

 

[Chalo]

I'm going for a 2000w 60v hub motor for the front wheel which will allow all 3 wheels to be driven for if on mud or any non solid surface and will give me the speed id like

You might like the idea of humming along at high speed, but know this: trikes don't like high speed. They like to turn over at high speed. The track width of that trike looks like it was intended for powered-wheelchair type speeds, not main traffic lane speeds. That's what "mobility scooter" means. It's made for oldsters to roll to the store for more cancer sticks and scratch-off lottery tickets.

Also, if one of your driven wheels wants to run faster than the others, the slower motors are just along for the ride. Above the speed they'll carry you by themselves, they won't help much at all.

So, don't be that guy. You have a slow trike that was designed to be slow. Let it be what it is.

 

[amberwolf]

Sounds like you have it all figured out, so good luck with your project.

 

[somervillearron]

Just for future reference for anyone with a similar question relating to swapping lead acid to lithium with lvc.


A good lithium pack CAN be taken down all the way but it's not recommended but CAN be done without damage

So with a 60v system the lvc on the controller will cut you out at 48v wasting a lot of the packs capacity which is fine for lead acid and is to protect them but for lithium it's wastefull.

So if you remove the low voltage control you would need to monitor your voltage and charge at say 20v, but its not recommended it would be a better idea to replace the resistor with one that will cut out at 20v automatically.

The BMs of the new lithium pack will handle what the lvc would have done on the lead acid pack

I have done a lot of research regarding this over the space of a week or more I was told on here you can't discharge a lithium pack so low but this is incorrect a lithium pack can easily be taken down 80% without any damage or long term effects


There are many guides on YouTube showing how to remove or adjust the lvc on the controllers.

But if you have replaced your lead acid with lithium maybe check the voltage the next time it cuts out to make sure your not leaving most of your pack unused as personally I was having mine cut at 48v so only really getting 12v out if a whole 60v pack!

Ever since can now travel atleast twice the distance safely and 3 times is possible but you do experience power loss at the lower voltages but it's bearable if you make a mistake but not recommended to do on purpose


..
Thanks for all the information guys it's really appreciated I do understand not everyone knows everything! 90% of the info I got on this thread was perfect! But also even the one part saying I couldn't discharge the lithium as much as I suggested 30v that even helped as It made me do some research

 

[Chalo]

A good lithium pack CAN be taken down all the way but it's not recommended but CAN be done without damage

This isn't only untrue (and unsafe), it is so harebrained that it discredits anything else you said in the past or say in the future. That's assuming "all the way" means zero volts rather than 3V/cell.

 

[amberwolf]

So with a 60v system the lvc on the controller will cut you out at 48v wasting a lot of the packs capacity which is fine for lead acid and is to protect them but for lithium it's wastefull.

a lithium pack can easily be taken down 80% without any damage or long term effects

That is 80% of the *total capacity*, or *total voltage range* of the cells/pack, which is not 0V to whatever full voltage, it is the pack-LVC to pack-HVC.

Let's do some math to see how this really works:

If you have a "60v" pack, that is made of 16 series Li-Ion cells, then their absolute total range per cell is perhaps 2.8v to 4.2v. Not 0v to 4.2v. This gives you about 1.4v per cell of actual voltage range from full down to empty. So 80% of the voltage range is 0.8 * 1.4v = 1.12v. 4.2v - 1.12v = 3.08v. Which is not far below what many controllers already use for an LVC. For those with an LVC around 3v/cell, which in the case of 16s 60v packs would be 3 x 16 = 48v. That would be about 80% of the total voltage range available to the cells.

So your controller with a 48v LVC is *already* set to use 80% of the pack's capacity as defined by pack voltage.

But this is actually much more than 80% of it's actual capacity as defined by Ah or Wh, which is normally how capacity is defined.

2.8v would be completely empty for most of the Li-Ion cells. Between 2.8v and 3.0v there is very little capacity in most cells. You can check the cell data for various cells to see how that works.

Other voltage ranges for the cells themselves apply for other chemstries; you can look up the data for those if you like.

Cell manufacturer datasheets have this information, as do sites with good qualified testing data like http://lygte-info.dk

A good lithium pack CAN be taken down all the way but it's not recommended but CAN be done without damage

If by "all the way" you mean to 0V (or anywhere below the cell's minimum safe voltage as defined it's manufacturer data sheet), then no, this is not true.

Doing so creates a fire risk, making it unsafe to continue using the cells at all, as you then have no way of knowing when an internal failure will happen that starts a fire.

It could be the very next time, or a hundred cycles later, etc. But you can't know when the damage you did to the cells will come back to burn down the battery, vehicle, and wherever it is stored and kill whatever living things were in the structure when it happens if they can't get out in time.


If by "all the way" you mean only to the cell's minimum safe voltage as defined it's manufacturer data sheet, then yes, and that is what has already been stated (in less specific terms) by others in guidance to you.