El-Cheapo UPS Battery replacement: Can I use Lithium (LiPo)?

I think people are trying to avoid the big battery on the side and just replacing the dead acid internal ones with LFPs.
And Then bump up against the bms limit ie 7/9A as long as you buy a custom pack with bigger bms , you can use it , but you need to add a fan

I think some 2000w models has a fan built in , so can be a nice stepping stone ,plus they often take more than one battery doubling the bms limitation and capacity
 
A lithium can charge at upto 1c

Which lead acid charger can charge a lithium in an hour?
Lead acid charger are designed to do like 0.2c to not boil batteries

And desulfation cycles won't lift the cell voltage the lithium would just soak up that charge


And if you can find a cheap device that can push more amps than the bms allows

It disconnects the cells so worst case it just doesn't 't charge

If you had crappy lithium with crappy bms sure you might have problems but like i said , before it makes better sense to do one device change than a battery change every 18mnths, any seller keeping people in the lead acid cycle should be avoided
We get a ton of calls from dissatisfied customers who followed advice such as yours - who find that the device they are using does not charge their LiFePO4 batteries in the way that such internet experts advised.

You assume constantly regarding damage to the battery. It is far more complex than damage to the battery. Manufacturers have invested millions to ensure that specific lifepo4 chargers employ the correct current limiting criteria as a first line of defense, as opposed to relying solely on the BMS to protect the battery.

talking about cheap devices and cheap batteries - the topic of this thread, you are going to be constrained with cheap and basic BMS - which often will employ only over-charge, deep-discharge, and temperature controls . There are very few lead acid chargers that will safely and effectively charge a Lifepo4 battery to the proper charge.

How about automatic equalization modes constantly hitting the lifepo4 battery with 15v, either the BMS doesn't protect it properly given the short bursts, causing damage to the cells, or it completely disconnects requiring jump starts. Why do manufacturers go to such lengths to ensure that the LifePO4 charger limits voltage to 14.6V - while lead acid chargers without modification will routinely charge above this voltage forcing the BMS protection which if poor doesn't respond that quickly or simply switches off.

Then start looking at absorption and bulk charging stages with LifePO4 ideally functioning with short absorptions stages. The process is completely different to lead acid chargers which chargin in bulk stage to 80% with increasing voltages at full current, and then moving to absorption phases with decreasing current - running the risk of never fully charging your battery.

The lead acid charger most likely won't restart bulk charging untll your LifEpo4 battery is virtually depleted- this means that with the different discharge curves, you basically have to use all of the LifePO4 battery capacity before your charger decides to start recharging your battery.

So basically there are quite a few caveats that need to be checked bfore you can use a lead acid charger safely and efficiently on a lifepo4 battery - above are just a very few .

Frankly your advise is very poor.

Make sure that your lead acid charger is compatible with LifePO4 batteries, by checking the 5 or 6 different criteria , which often on cheap devices such as ups, alarm systems etc cannot be ascertained - or get a LifePO4 charger, or get a SLA battery that is double the capacity of your expected load.
 
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Then start looking at absorption and bulk charging stages with LifePO4 ideally functioning with short absorptions stages. The process is completely different to lead acid chargers which chargin in bulk stage to 80% with increasing voltages at full current, and then moving to absorption phases with decreasing current - running the risk of never fully charging your battery.

Janee, very risky to not charge your lifepo fully. They have been known to unionise and complain
 
Janee, very risky to not charge your lifepo fully. They have been known to unionise and complain
Janee -- You can routinely discharge your LifePO4 battery to 5%, subject it to 15V and pay 10 times the price of an SLA battery to get 80% of the capacity, amongst other things without any harm. Good luck.
 
We get a ton of calls from dissatisfied customers who followed advice such as yours - who find that the device they are using does not charge their LiFePO4 batteries in the way that such internet experts advised.

You assume constantly regarding damage to the battery. It is far more complex than damage to the battery. Manufacturers have invested millions to ensure that specific lifepo4 chargers employ the correct current limiting criteria as a first line of defense, as opposed to relying solely on the BMS to protect the battery.

talking about cheap devices and cheap batteries - the topic of this thread, you are going to be constrained with cheap and basic BMS - which often will employ only over-charge, deep-discharge, and temperature controls . There are very few lead acid chargers that will safely and effectively charge a Lifepo4 battery to the proper charge.

How about automatic equalization modes constantly hitting the lifepo4 battery with 15v, either the BMS doesn't protect it properly given the short bursts, causing damage to the cells, or it completely disconnects requiring jump starts. Why do manufacturers go to such lengths to ensure that the LifePO4 charger limits voltage to 14.6V - while lead acid chargers without modification will routinely charge above this voltage forcing the BMS protection which if poor doesn't respond that quickly or simply switches off.

Then start looking at absorption and bulk charging stages with LifePO4 ideally functioning with short absorptions stages. The process is completely different to lead acid chargers which chargin in bulk stage to 80% with increasing voltages at full current, and then moving to absorption phases with decreasing current - running the risk of never fully charging your battery.

The lead acid charger most likely won't restart bulk charging untll your LifEpo4 battery is virtually depleted- this means that with the different discharge curves, you basically have to use all of the LifePO4 battery capacity before your charger decides to start recharging your battery.

So basically there are quite a few caveats that need to be checked bfore you can use a lead acid charger safely and efficiently on a lifepo4 battery - above are just a very few .

Frankly your advise is very poor.

Make sure that your lead acid charger is compatible with LifePO4 batteries, by checking the 5 or 6 different criteria , which often on cheap devices such as ups, alarm systems etc cannot be ascertained - or get a LifePO4 charger, or get a SLA battery that is double the capacity of your expected load.
What you explain how a lead acid charges is exactly what a CC/CV lithium charger does

So at best i can deduce you are regurgitating what you have heard manufacturers tell you

So many specialists regurgitating myths and bullshit

Yes there are points that are valid in-between but the bullshit amongst it is a red flag

A lithium lifepo4 charges at a constant current , not spurts

You are conflating lfp with nmc which employs this pattern to prevent thermal runaway and only at certain stages of the charge cycle anyway

Many people think a lifepo4 isn't charging because the voltage isn't lifting , and quite frankly if you made suggestions that did not work maybe it is on you not the product, or maybe your understanding of how the product works
 
What you explain how a lead acid charges is exactly what a CC/CV lithium charger does

So at best i can deduce you are regurgitating what you have heard manufacturers tell you

So many specialists regurgitating myths and bullshit

Yes there are points that are valid in-between but the bullshit amongst it is a red flag

A lithium lifepo4 charges at a constant current , not spurts (EXACTLY!)

You are conflating lfp with nmc which employs this pattern to prevent thermal runaway and only at certain stages of the charge cycle anyway

Many people think a lifepo4 isn't charging because the voltage isn't lifting , and quite frankly if you made suggestions that did not work maybe it is on you not the product, or maybe your understanding of how the product works

Use cases that did not work involved people following internt fundi advice, contrary to the manufacturers which don't know anything about their product according to the fundi , and buying cheap B grade LifePO4, or inferior LifePO4 - which incidentally 70% of consumers are buying.

Additionally, I think the explanations went over your head - guaging from your response.

The specialists regurgitate potentials to protect against litigation - since risks do exist, contrary to youtube engineers who have no obligation to their viewers at all.

In any event, this is a fruitless discussion - since you have built a DIY battery and are now qualified as an expert to debunk professional manufacturers and engineers. You don't have the credentials to assert as you do. Thus it must be cosntrued as arrogance.

Thank heavens for the ignore button.
 
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Janee -- You can routinely discharge your LifePO4 battery to 5%, subject it to 15V and pay 10 times the price of an SLA battery to get 80% of the capacity, amongst other things without any harm. Good luck.
10x what you smoking dude
 
Chinese manuals do say a lot about understanding the product


Chinese copy pasta with often very little understanding

Some do but thet aren't making manuals
 
Use cases that did not work involved people following internt fundi advice, contrary to the manufacturers which don't know anything about their product according to the fundi , and buying cheap B grade LifePO4, or inferior LifePO4 - which incidentally 70% of consumers are buying.

Additionally, I think the explanations went over your head - guaging from your response.

The specialists regurgitate potentials to protect against litigation - since risks do exist, contrary to youtube engineers who have no obligation to their viewers at all.

In any event, this is a fruitless discussion - since you have built a DIY battery and are now qualified as an expert to debunk professional manufacturers and engineers. You don't have the credentials to assert as you do. Thus it must be cosntrued as arrogance.

Thank heavens for the ignore button.
LFP cells are made by a few manufacturers , ie you can count them on one hand most likely

And then trying to make out as if sioe dodgy manufacturer is popping out crap is laughable

B grade isn't this gotcha you make it out to be

No having built 6, 5 lifepo4 one LTO diy batteries does not make me a specialist


But does help spotting regurgitation with little understanding of how a bms and lifepo4 charging actually works
 
Janee -- You can routinely discharge your LifePO4 battery to 5%, subject it to 15V and pay 10 times the price of an SLA battery to get 80% of the capacity, amongst other things without any harm. Good luck.
Just bullshit it isn't 10x

Do you know what a bms does?

A lithium will degrade to 80%
A lead acid/gel degraded to useless, and thanks to peukert you would need a bigger lead to just match a like for like lithium capacity ie 100ah lead (50ah usable ) isn't equal to a 50ah lithium it is way inferior

most users are more likely to damage a lead acid than a lifepo4

lithium isn't the bogey man some like to make it out to be

Are there exception devices that won't olay nice yes , but that is just what they are exceptions

40% is ridiculous imo
If you have a failure rate that high you don't understand the math that is needed to select the batteries, or to solve the problem

people make bad device/battery choices and then blame the device or batteries

Because they miss some portion of the math

ie like the bms/battery amp rating
Or the charge rate of device is lower than needed

A lithium will charge full at any charge rate even at low Anps, how long it takes to get full is the party stopper , and naturally the voltage plays a role too , ie if float voltage is all you have the tail gets extremely long
 
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If selecting a lithium , to replace a lead acid , find the peak draw then calculate the amps at the bottom of a lithium voltage range, ie 10v on a 12v lifepo4 system
20v on a 24v
40v on 48v system (51.2 v battery)


That way you know the amp increase as the battery drains and voltage dips won't trip the bms
 
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The whole notion that a lithium has to charge at a specific rate is just bullshit

If that was the case lithium would not be usable as solar storage

With variable load and variable sun

A battery can jump from charging at varying rates and pivot from charging to supplying load and pivot back in minutes

Extremely few chargers would be able to exceed the charge rate of a lithium , and those chargers likely won't find their way onto this thread

The notion that anybody has to worry about limiting charge rate on a budget device is laughable

In fact i would wager that most people experiencing problems on small budget devices

Have a problem of too low a charge rate , ie they can't recharge what they have used in one shedding in the window they have power , to be ready for the next shedding

A lifepo4 battery in the flat portion of the graph can look like it isn't charging to the untrained eye

Or that off the shelf small lithium batteries aren't available with the correct amp rating bms to meet the needs of a ups

ie the problem isn't lifepo4
It is the understanding of how these things work and thus using batteries that can't supply the amps needed in the use case

Deducing that a lithium lifepo4 thus can't be used in a lead acid device , is just bad science

It is like using homeopathic dosage of paracetamol, and deduce that paracetamol can't work for headaches
 
When i wanted to get a solution for tv when shedding started i used what i had at home

ie ups and batteries i had lying around

When those lead acids gave in
I wanted to use lithium knew very little about it

Read up a bit so armed myself with some knowledge then

Going into solar/backup power retailers/specialists just revealed that most of them had no clue

Imagine asking them to purchase a lithium iRon phosphate battery

They inform you unfortunately they don't stock it , only stock lithium ion

Walk out the door , what is on the window , lifepo4 signage which is what ? lithium iron phosphate

Go home look up the specs of the devices they sell, they are all lithium iron phosphate

One common thing i found going into these specialist stores

While comparing prices ,listening to conversations i only wanted to laugh few had any meaningful understanding of how these things work , the one eyed leading the blind

Now naturally , after x amount of years some of them have gotten better , but the problem is

If you have flawed ideas of how these things work you can make flawed deductions

Have i made flawed deductions yes , confirmation bias is a thing

Many have no clue how to test an hypothesis, if you don't know how to test it how will you know if it is correct?

Many myths get propagated , and the worst is by so called "specialists"

Lifepo4 is a drop in replacement. For lead acid , they don't know why it is marketed as such or why it is the case

If it doesn't work in your scenario

Your scenario/device has a flaw sub standard design , brought about by budget cuts most likely

Your exception does not suddenly mean a lifepo4 battery isn't a drop in replacement for a lead acid anymore

The problem is though it is a drop in replacement , you have to select the battery carefully and at times be unable to find a battery with the right characteristics for the specific device and size constraint

Just because an off the shelf battery isn't available , does not mean it is impossible
 
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No that appeal to authority means nothing, they wanted to school someone that knows the discharge curve of a lifepo4

When in fact they made several false statements while trying
I think you missed the bit I highlighted.
 
I think you missed the bit I highlighted.
I saw that

The notion that if you can't change voltage settings you can't use lifepo4 is just bullshit

You don't need to change anything


Lithium iron phosphate cell voltage means a battery pack with a voltage rage that matches a lead acid battery voltage range

The worst that can happen is that you get a low voltage shutdown , jumpstart scenario

As some devices needs a battery present to start up

If he knew what he was doing he would have informed the user how to deal with it , and to expect it in a run flat scenario

And given a solution how to deal with that


Yes you need to know the charging characteristics of your device, not to be able to know if it will charge a lifepo4, it will

You need to know that the same way you need it for lead acid

To compare charge rate vs consumption

ie if your charge rate is lower than the avg amps you pull during shedding you have to accept you won't be able to deal with 4off -4on- 4off shedding scenario unless the capacity you have allows for time shifting the charging
 
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Why is a lifepo4 a drop in replacement ?

A lifepo4 cell is 3.2v range 2.5-3.65 normal use 3.75max according to spec sheets

And thus if you put 4 in a row its voltage range of 10v - 14.6v matches what a lead acid is subjected to in a ups/other lead acid battery device scenario

Edit : one exception 48v you have to use 4 x12v lithium or equivalent 16s 51.2v battery
As that matches the 4x12v lead acid range
The 15S 48v nominal battery has slightly lower voltage range , for this scenario you need to change the charge parameters (but normally devices in this size can change settings)

That is why it is a drop in replacement

Yes if you have a charging circuit designed for a lithium the lifepo4 will perform better in the sense that it will charge faster than it would in a lead acid focussed charging circuit , the lead acid device can't damage a lifepo4 as it is operating in its expected/design range
 
I saw that

The notion that if you can't change voltage settings you can't use lifepo4 is just bullshit

You don't need to change anything


Lithium iron phosphate cell voltage means a battery pack with a voltage rage that matches a lead acid battery voltage range

The worst that can happen is that you get a low voltage shutdown , jumpstart scenario

As some devices needs a battery present to start up

If he knew what he was doing he would have informed the user how to deal with it , and to expect it in a run flat scenario

And given a solution how to deal with that


Yes you need to know the charging characteristics of your device, not to be able to know if it will charge a lifepo4, it will

You need to know that the same way you need it for lead acid

To compare charge rate vs consumption

ie if your charge rate is lower than the avg amps you pull during shedding you have to accept you won't be able to deal with 4off -4on- 4off shedding scenario unless the capacity you have allows for time shifting the charging
I can't argue with you I don't have the knowledge, as a layman I go by what the manufacturer recommends.

I draw on my own experience I had with a SPS power trolley. When I replaced the gel battery with a lifepo4, the charger would run continuously and not cut out, subsequently the thing stopped working. I since bought a Synapse and adjusted the charging parameters manually to fit the profile recommended by the manufacturer and to date all is good.
 
I can't argue with you I don't have the knowledge, as a layman I go by what the manufacturer recommends.

I draw on my own experience I had with a SPS power trolley. When I replaced the gel battery with a lifepo4, the charger would run continuously and not cut out, subsequently the thing stopped working. I since bought a Synapse and adjusted the charging parameters manually to fit the profile recommended by the manufacturer and to date all is good.
agreed makes sense to fall back to manufacturer recomendations

the problem i find is that often manufacturers will default to no modifications , it is the easiest cover your arse response, especially if you know the devices charging circuit is sub standard

and thus what i was trying to say

if you are bad luck to have such a device, it makes sense to do a device change instead of sticking to 12-18 months lead acid battery replacments cycle

it is like car dealers that say if your service isn't done at one of their dealers the warrantee is void
how does servicing a car with exactly the same oils/parts as from the agents suddenly not good enough

easy scapegoats and milking is what they do
 
Manufacturers know that there are systems out there that will work off the bat, and that there are those that won't. Some alarm systems will keep sending you battery low notifications for no apparent reason as an example.

Manufacturers know that most consumers are not going to have the technical capacity to determine in which device such batteries will work and in which they won't. Or how to make modifications in cases where such are required.

Most manufacturers will also not willfully advise any customer to act contrary to the instructions of the manufacturer of any specific device if such device manufacturer specifically includes warnings of a specific nature simply because youtube diy entusiasts claims it's not necessary.

How do these internet experts reccommend that manufacturers handle all these scenarios with a blanket policy - if not to advise customers to adhere to the devices manufacturers instructions.

In the example of the car service it comes down to the manufacturer having to police a multitide of service providers who may or not be servicing the car to spec with compatible parts - or to just take it at face value that another provider has done everything to spec at a much cheaper cost.

Regardless of anything to the contrary, in our company we will always advise customers that there is a risk that the specific application may not work, and may be potentially hazardous - as such they should follow the instructions of the manufacturers and that anything else that they do is not guaranteed to work and is at their own risk. It's as simple as that and frankly - an idiot would require suppliers and manufacturers to do any different.

We are availabe to recommend any solution that is guaranteed to work, and consider a failure to inform customers of these risks as unethical - many suppliers won't do that because it jeopardises a potential sale.

I may point out that we have sold hundreds of such batteries which have been deployed with success in 90% of applications - there are 10% of applications where they did not work, sometimes with serious consequences.
 
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Manufacturers know that there are systems out there that will work off the bat, and that there are those that won't. Some alarm systems will keep sending you battery low notifications for no apparent reason as an example.

Manufacturers know that most consumers are not going to have the technical capacity to determine in which device such batteries will work and in which they won't. Or how to make modifications in cases where such are required.

Most manufacturers will also not willfully advise any customer to act contrary to the instructions of the manufacturer of any specific device if such device manufacturer specifically includes warnings of a specific nature simply because youtube diy entusiasts claims it's not necessary.

How do these internet experts reccommend that manufacturers handle all these scenarios with a blanket policy - if not to advise customers to adhere to the devices manufacturers instructions.

In the example of the car service it comes down to the manufacturer having to police a multitide of service providers who may or not be servicing the car to spec with compatible parts - or to just take it at face value that another provider has done everything to spec at a much cheaper cost.
under duress manufacturers are forced to change their bullshit stories


Independent service providers can now service cars under warranty, and the practice of voiding warranties is void. The date of implementation is 1 July 2021. From this date onwards, the Commission may act against market players not following the guidelines.23 May 2021

people are free to listen to bullshit claims, ie a high % can suffer uneconomical lead acid replacement cycles
while in fact only a small percentage would have a scenario where a lifep04 won't work because the device has sub standard charging circuit

those guys would do themselves a favour to get a new device

it is common sense to get out of lead acid with our use case , and like i said anybody suggesting people stay in the lead acid cycle are just not having their best interests at heart

internet experts often youtubers test bullshit claims / myths and often prove them false

if your claims can't be replicated/proven with scientific method it is just bullshit
and if it can it ain't bullshit
 
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