Drop in LiFePo4 replacement batteries.

[Cuppa]

A post primarily for Terry ...... but anyone else feel free to chip in.

Lots of talk on on a 4wd forum ( & others) I frequent about the Itechworld drop in offering, including from those who have seen them in action & are impressed when compared to their own AGM's.

I believe that these batteries are spruiked by a well oiled marketing strategy by folk who infer expertise, but with little/no evidence to back that up. Badged /branded but little detail or support. 3 year warranty on a battery which costs almost 3 times an AGM, but cheaper than any other LiFeP04 offerings, including other 'drop in' offerings. (ie batteries with built in BMS).

I suspect that whilst the batteries themselves *may* be ok, that it is their built in BMS which is likely to result in short battery life (just out of warranty?)

Unfortunately there are plenty of folk who cannot recognise, nor accept that the marketing spiel is probably more about saying what customers want to hear as opposed to reflecting reality.

Can anyone provide informed information to either support or contradict my beliefs? I would like to 'warn' friends about the risk on this other forum, but lack the necessary understanding of the details. Has anyone yet examined the BMS of these or other drop in offerings to see how they work? Happy to get email/PM if uncomfortable about posting thoughts/evidence on the forum.

[Newcastle George]

Cuppa, you may want to compare them with those available from New Energy developments

George

[BruceS]

Well I'm not going to get into a bunn fight but just point out that there is a difference in between a BMS and a CMS.
BMS is Battery Management System.
CMS is Cell Management System.

I have no idea what 'cells' are in any of these 'drop in' batteries but if they are the type that have 4 X 3.2v (nom)cells, then cell monitoring is important.
On the other hand if you charge gently, deplete them gently, never charge past 85% or discharge below 35% then you might not need to monitor them at all! (then you may as well use AGM!!)
I did see where one of these batteries was built up with many (hundreds?) of little AA type cells?

Discussion has started. Please be careful in regarding libel .............
https://www.google.com/search?client=fi ... tion+libel

[El Gringo]

No idea on those batteries - they don't share much info, just blurb.

Just for comparative info I have confirmed that these do have cell monitoring, might be worth considering.
http://www.lithiumbatterysystems.com.au/
I like that they have built in solar and alternator inputs too.

They also do a "build your own battery" they don't use Winston cells though - they do claim theirs are tier1

Cheers,

[Mrcoolabah1au]

We’re the boss tell me the difference BMS and CMS

[Gone Bush]

I replaced our 3 AGMs with a single 300Ah pack from EV Power in WA. I have visited their place a couple of times and came away very impressed with their knowledge and general attitude. While there I saw them building BMS boards from scratch (a blank cct board) for orders from Norway and Germany for rooftop solar systems.

That's a good endorsement, imo.

EV Power also does "drop-in" replacement batteries and I would have no doubt whatsoever that a lot of thought and scrutiny has gone into the internal BMS's. They will ship interstate.

https://evparts.com.au/evh12v120ah.html

I'm very happy with the 300Ah pack I bought from them. Installation was very neat and the cost was excellent. I think a buyer of the drop-in batteries would be equally pleased.

[T1 Terry]

We are doing comparative testing of 4 x 12v 100Ah Winston battery that we have built so they have all been properly condition charged to suit house battery use. This test is all being recorded by Victron 712BMV battery monitors and cell logging battery monitors that will produce a graph to show just what is seen at the terminals and what actually happened inside the battery at cell level.


If you are looking at drop in batteries,
1) this is the first question to ask any lithium battery supplier, are there different requirements when first charging the cell between an electric vehicle battery (that is what these cells were originally produce to power) and a house power battery. If they come back with an answer that sounds like it came from a politician, lots of words that say nothing, or they say there is no difference and they balance charge the cells or they are from a matched set, be polite but go else where, they don't have a clue.
2) Next is the internal BMS and cell balancing,
Type1A) does the BMS just monitor total battery voltage and disconnect the battery if the voltage is too high or too low, yet does not know if any individual cell voltage is too high or too low.
or
Type 1B) are the cell voltages monitored and is the voltage goes excessively high it disconnects the battery.
or
Type 2) do they rely on a cell top boards that double as a short circuit loss type balance system that activates at a high cell voltage and basically conducts a controlled short circuit across the cell terminals and turns the short circuit current into heat and that conducts down through the negative battery terminal, it is inside a sealed box so it doesn't have anywhere else to go.
or
Type 3) Does the cell monitor also control the charging and stops the charging if a cell reaches the maximum safe voltage and keeps the charging disconnected until a set time period has passed AFTER the high cell has dropped below the alarm voltage level. For this to be effecting, the discharging must remain connected so the battery is actually supplying a load to use up the over charge in the high voltage cell to get the voltage back down.
Let's look at the types:
With type 2, these boards are inside a sealed case, how is that short circuit balancing heat generated going to escape? If the cell is already at an over voltage state it will already be suffering heat stress, adding more heat is not going to improve the situation is it?
Now think about how many amps the battery is charging at and how much heat would have to be generated to burn off that much current ..... a lot eh, and there is no way those little balance boards could handle that much heat without failing themselves.
These short circuit type balance boards often try to sell themselves as current bypass boards, seriously, how could that work without actually connecting a circuit from the positive to the negative terminal. That is not a bypass, it is a short circuit. They generally limit this short circuit current to 0.5 amps so the tiny electronics don't burn out, remember there is no air movement in there to cool them. If the solar or DC to DC charger or the mains charger is charging at the same 0.5 amps you would think the system was stuffed. It would be charging at between 20 amps and 100 amps, how is 0.5 amp short circuit going to stop the cell voltage continually climbing till it's really hot inside and stuffed?
These little balance boards generally also have an over voltage sensor that sends a signal in each cell top board to the next board that is daisy chain linked to a control box that disconnects the battery. This cut off signal is anywhere between 3.8v and 4.2v, mass production of the components means each board could be any where between these two voltage points. This means the cell is seriously over voltage and getting hot inside, the short circuit board is burning off 0.5 amps trying to get that cell voltage back to 3.65v, so that is adding heat to the inside of the cell via the negative terminal.
Once this balance board brings the cell voltage back down, what happens, the battery reconnects and the charging starts again ..... you can see what is going to happen to that already hot cell can't you ..... Remember that little balance board with the temperature sensitive electronics .... that is getting very hot and will fail, not if but when.

Proper cell balancing charge an induction coil or capacitor circuit from each cell via cable connection, not mounted on top of the board so this unit is remote from the actual battery. At a timed interval, milli seconds to seconds, they disconnect from the cell and link all the charged circuits together so they can voltage balance, then separate that balancing connection and connect back to their respective cells.
The induction coil voltage is either the same, higher or lower than the cell voltage, so current either doesn't move, transfers into the cell until the voltage is the same between the coil and the cell, or the cell passes current into the induction coil till the voltages balance, then the whole process starts again.
These units do not turn on until they see a 150millivoltage difference between the highest and lowest and turn off again at 15 millivolts so they are not a constant drain across the cell like the balance boards are, they have to stay active constantly.

Next thing to consider, the Australian Dollar (AUD) is worth about 69cents US at the moment and all products out of China are price in USD. Wages are continually climbing in China as they become westernised and the factory need to hold on to their trained workers. The result is the costs must rise, we were just hit with a 10% price increase for our cells. Now look at these drop in battery sellers, aren't they dropping their prices? If the replacement product is going to be more expensive, where will they find the money if they selling off what they have cheap? Are they just clearing the shelves so they can shut up shop? What happens to the 2yr or 3 yr warranty then? You already know what will happen don't you, the failed product is yours now to do what ever you want with it, the reseller is no more and the manufacturer never offered that warranty and is in China anyway, so forget about any honouring of the warranty, you now have a rather expensive door stop.

Now what do you do, you have had 12mths or 2 yrs to appreciate just how much better lithium batteries perform, so you can't go back to lead acid without the minister for war and finance being a tad upset with you .... It is going to be a rather painful sell to now convince the same person who is rather upset with you that you either have to spend more on an unknown product, or get the job done properly like you should have done the first time .......

Benjamin Franklin once said "The bitterness of poor quality remains long after the sweetness of low price is forgotten" wise words.

T1 Terry

[BernieQ2]

Do you sell drop ins Terry ?
BernieQ .

[T1 Terry]

Do you sell drop ins Terry ?
BernieQ .

We do sell a single 100Ah battery and could probably build a 200Ah battery for light current duty, less than a 100 amp draw, it has a lift off lid to protect the cell connections from anything being dropped on them but all the cells can be accessed if required. The actual battery management bit is separate to the battery. This is a cheaper option to the full battery management system, designed for those that only want a low power draw replacement for their lead acid battery. You could run a small inverter from it to charge phones, power the electric blanket or a 240vac household fridge, as long as the total load did not exceed 100 amps. The full control system is required for an inverter that could power the microwave, air conditioner, washing machine, coffee maker, air fryer toaster, kettle .... what ever you use at home basically can be powered from a lithium battery system that was properly designed.
The catch with the drop in batteries, they say they can be parallel connected, they do not say the battery discharge capacity increases by the number of batteries in parallel, they just let you think that is what they said. The limit for any single battery in the system is the limit for the whole system, they do not add together, if a battery fails and you have been drawing more than the continuous rated output current for any single battery, the warranty is null and void on all the batteries in that parallel string.

T1 Terry

[BernieQ2]

Just after one for the 240v fridge , don't use any other 240v appliance .
BernieQ