max. amount of Lithium batt. in parallel

[parachute]

Lithiumm batteries have caughfire in planes and and cars and everything else with a Lithium battery including phones.

Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. ... "If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire

List of UK Lithium battery fires: https://resource.co/article/lithium-...llion-annually

[T1 Terry]

Originally Posted by Pete7

That is very location dependent. The costs of import duties and transport costs for an individual could easily strip away the benefits of importing and building your own system over a drop in. Buy it in your own country with and there are likely consumer rights if it doesn't work. What sort of warranty do you offer on your batteries?

Pete

3 yr renewable with a battery service to verify the cells are still in good condition. The oldest sets we have still out on the road are on their 4th renewed 3 yr warranty and still going strong.
We are already seeing the drop in batteries fail over here, we have tested and reported for 3 different brand single lithium batteries that didn't live up to the claims, all of these dropped their bundle in less than 12 mths and it was only because we had written the report for each failed battery that consumer law over here would look at the claim. Those who have fitted multiple drop in batteries don't have a legal leg to stand on because if you read what is actually written in the specs, the max capability of any single battery had been exceeded. Just because they say you can connect them in parallel, they do not say that the maximum output current is multiplied by the number of batteries .... they just make it look like that is what they are saying .....

T1 Terry

[T1 Terry]

Originally Posted by parachute

Lithiumm batteries have caughfire in planes and and cars and everything else with a Lithium battery including phones.

Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. ... "If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire

List of UK Lithium battery fires: https://resource.co/article/lithium-...llion-annually

You need to understand that not all lithium chemistries are the same. The LTO chemistry for instance, is used inside human bodies to power muscle stimulators, nerve blocking pain relief units and pacemakers for heart conditions .... do you really think they could put a battery inside a human body that had the potential to explode or burst into flames?
There is a lot of nonsense out there on the interweb, posted by people who really don't have a clue but want their 5 secs of glory spreading nonsense as a scare campaign .....

T1 Terry

[more]

Originally Posted by parachute

Lithiumm batteries have caughfire in planes and and cars and everything else with a Lithium battery including phones.

Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. ... "If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire

List of UK Lithium battery fires: https://resource.co/article/lithium-...llion-annually

i suggest to you before write educate self.

Dangerous vs. Safe batteries, Explosion and fire test

https://youtu.be/Qzt9RZ0FQyM

[Alistair242]

Originally Posted by parachute

Lithiumm batteries have caughfire in planes and and cars and everything else with a Lithium battery including phones.

Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. ... "If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire

List of UK Lithium battery fires: https://resource.co/article/lithium-...llion-annually

Faulty link and nothing to do with the thread subject?

[Philtao]

Back to the original question:

Originally Posted by henryk

If I will get 6 batteries, 12 V, 100 AH each and connect them in parallel,would BMS take care of even charging distribution ?

The short answer is NO.
BMS in built in batteries are most often designed just to protect against very low and very high voltage. They cannot distribute current across different batteries.

Each battery you buy will have a different internal resistance. So when you connect them in parallel, they all see the same voltage, but the battery with the lowest internal resistance will suck all the current (simplified)... creating an unbalance... some batteries will age faster and you are in trouble with a set of batteries that may not last very long.

To help you understand the choices when buying a lithium battery and the implications of those choices, an article I wrote recently might help you. It's title is "Which lithium battery to buy?" (note: I do not sell batteries ). You should find it in Google if you enter that title with my CF user name. And keep posting questions on this forum until you feel confortable you understand what you buy.

[hzcruiser]

Originally Posted by more

yes. also all this post up is mubo jambo for you. don't worry. normally be better if you build 1 baterry 600A

If _any_ of this is "mumbo jumbo" for him I would be rather worried that something goes horribly wrong in the long term.
And just to throw in a different opinion, I would rather have slightly smaller batts placed in different places on the boat, than having one big central bank and rely on heavy gauge wire to get the real power to where it's needed: the windlass, bow thruster and inverter. Everything else is small pittens.

[SailRN]

Originally Posted by parachute

Lithiumm batteries have caughfire in planes and and cars and everything else with a Lithium battery including phones.

Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. ... "If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire

List of UK Lithium battery fires: https://resource.co/article/lithium-...llion-annually

LFP Sinopoly cells:

[Anders]

Originally Posted by parachute

Lithiumm batteries have caughfire in planes and and cars and everything else with a Lithium battery including phones.

Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. ... "If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire

List of UK Lithium battery fires: https://resource.co/article/lithium-...llion-annually

Every time you posted this you have been told that boats use LiFePO4 batteries and NOT lithium ion.

[CarlF]

There's nothing wrong with putting several drop-in's in parallel. It's done every day. While a single BMS driving individual cells has some advantages, I think in the last year or so the boat market has mostly shifted to drop-ins. Of course, you need to do a safe installation but that wasn't really the OP's question. There are two reasons I know for the parallel limit that manufacturer's put in their spec -

1) If the batteries are wired in the usual way with a positive lead at one end of the bank and the other lead at the end, the batteries will not charge and discharge equally depending on where they are in the bank. Equal length cables can avoid this problem.

2) Some drop in BMS designs will shut off the battery if they don't see enough load. In a bank with many batteries the least loaded might turn off.

But in general, if you are going the drop-in route you should stick exactly to the manufacturer's spec or you'll just end up voiding your warranty. I would certainly contact the manufacturer - they may tell you it's fine to use more in parallel given other elements of your design (get that in writing).

[more]

Originally Posted by hzcruiser

"mumbo jumbo" I would rather have slightly smaller batts placed in different places on the boat, than having one big central bank and rely on heavy gauge wire to get the real power to where it's needed: the windlass, bow thruster and inverter. Everything else is small pittens.

Do you want thru

While it may seem that paralleling multiple strings would increase the overall reliability of a battery pack
design, in reality, the opposite is usually true. Unlike lead-acid cells which are commonly assembled in
parallel strings, lithium cells are very intolerant of over charge and over discharge. Since lithium cells must be managed on a cell level, parallel lithium strings dramatically increase the complexity and cost
of the battery management and introduce many additional points of failure and failure modes not found
with a single string. A parallel string topology almost always leads to a lower overall usable capacity and
lower maximum power output. A single weak or bad cell can exponentially lower the capacity of the entire battery pack. Whenever possible, a single string set-up should be considered.When two or more strings are paralleled together, currents will flow between the
strings. These currents form due to differences in the total pack voltage between strings. The amount of
current that flows is determined by the difference in total string voltages, resistance of each string, and
the characteristics of the cells. With these currents, it is possible for one string to force charge a second
string, which can lead to over-charging or over-discharging individual cells. A low capacity cell or a
faulty cell can cause the force charging of an entire string which may result in over-charge and/or overdischarge. While it seems counter-intuitive, it is possible (in fact, likely) when the charger shuts off due
to a fully charged cell in one string, that string may continue to be charged by another parallel string
(the same principal applies to discharge). For example, if string A contains a cell which is fully charged,
it is possible that current could flow from a second paralleled string B into string A. This would happen
every time the average cell voltage in string B was higher than the average cell voltage in string A, even
though string A has a cell which has become fully charged (or fully discharged.) This can be
compounded by the characteristics of the cells. Most cells have some “surface charge” which causes
the cell voltages to artificially rise and drop depending on the recent history of the cell. For example, if it
was charged, the voltage will be temporarily raised. Common sense would suggest that these currents
would form only when the packs are first paralleled together and then dissipate over time. However,
because different currents flow through each string during charge or discharge and due to the surface
charge phenomenon, these currents end up being present any time a pack has been charged or
discharged. These currents present a significant challenge for managing paralleled strings. Because of
the possibility of these currents, it is absolutely essential that each string MUST have a
contactor, shunt trip breaker, or other automatic and redundant means of isolating the string
from any other strings if a critical fault occurs. This is in addition to the standard over-current
protection for the string. The designer must consider and ensure safe behavior in the event of a
failure of any single component, including diodes, contactors, and BMS units.Lower maximum usable capacity) Due to the eddy currents mentioned above, headroom must be left
at the top and bottom of each cell’s voltage and state of charge windows in order to allow for additional
charging / discharging after the BMS turns off charging or discharging. This reduces the maximum
usable capacity of the pack. The headroom that must be left depends significantly on the cell types,
operating temperature range, and quality of the cells.

read more

https://www.orionbms.com/manuals/pdf...el_strings.pdf

[T1 Terry]

Good information, but I'm afraid it will go straight over the heads of most. It is not helpful when those with zero hands on experience make statements that are completely wrong on just about every level.

"There's nothing wrong with putting several drop-in's in parallel. It's done every day." Dumb things are done every day, but it doesn't stop them being dumb things all the same. Unless you can provide actual testing with the backing of test equipment print outs, you should add "In my opinion" before such statements, just so those who don't know better believe you have some sort of credibility backing up such a statement.

There seems to be no understanding about just what a proper BMS should do, so simply using the the letters "BMS" in a sales pitch doesn't mean it is a properly designed Battery Management System installed. Lithium batteries are vulnerable at cell level because they don't have the advantages flood cell lead acid batteries have of wasting energy to electrolysis seperating water into hydrogen and oxygen and venting that to the atmosphere. A proper quality BMS monitors and is driven by cell voltage, not by battery voltage and relying on some form of balancer to have all the cells at the same voltage.

When a lithium cell can no longer move lithium ions through the electrolyte because either:
The carbon coated plate is saturated with lithium ions and can not accept any more (fully charged)
or
The lithium compound coated plate can no longer contain any more lithium ions (full discharged)
the only path for the trapped energy is to convert the electrical energy to heat energy ..... this is where the problems begin. When the electrolyte is heated above its safe level (different between chemistries and the actual make up of the electrolyte), it either starts to release oxygen bubbles in the lithium chemistries that explode, or in the safer chemistries, the lighter hydrocarbons boil off and can not be recombined with the electrolyte.

This hydrocarbon vapour is what creates the pressure that causes the cell to balloon out because the plastic case is softened by the heat so the pressure expands the case rather than escaping through the pressure relief valve.

Now the electrolyte is reduced in volume, there wasn't much in there to start with, so any loss means the whole surface of the plates can no longer remain saturated ... no contact with the electrolyte means no lithium ion transfer so the capacity is reduced. If the cases swell the electrolyte has an even bigger area to pool in so even less of the plates are saturated so even more capacity is lost.

The result, a 100Ah 4 cell in series 12v lithium battery is made up from 4 x 100Ah cells, if the capacity is reduced in one of those cells by even 5Ah, that cell will reach saturation charge before the other three cells and more electrolyte heating occurs and more capacity is lost.

At the other end of the scale, the cell with a reduced capacity will be the first fully discharged, now the really serious damage happens. Because the other 3 cells still have capacity and current to deliver to the load, the current is forced through the fully discharged cell.
From zero volts the negative becomes the entry path for the current turning it into a positive and the current discharges via the positive terminal turning it into a negative ... reverse current flow, this almost instantly destroys the cell.

Now there is a cell that can no longer hold any capacity so can not hold a voltage stable when charging or discharging. The 12v 4 cell battery become a 3 cell 9v battery with a cell that can swing for minus voltage when discharging to high positive voltage when charging.

This creates a serious problem if the BMS is only measuring the total of all 4 cells, three cells @ 3v plus one cell showing 5v = 14v, the poor quality BMS sees 14v and deems the battery fully charged maybe disconnects. Now the failed cell drops to 0V and the balancing elements in the BMS try to drain from the 3 volt cells to charge up the 0v cell. At 3v, the 3 remaining cells are already very deeply discharged so draining them further will damage those cells as well.

A parallel string of healthy 4 cell 12v batteries linked to the 3 cell battery will create pulse charging from the healthy batteries into the damaged battery.

An example of what I'm saying. The dead cell drops voltage because it is no longer being charged, the 3 cell battery is now a 9v battery while the other batteries in the parallel string are charged and holding 14v. The 5 volt differential will cause huge currents to flow into the 9v battery.

Deeply discharged LFP cells need to be trickle charged to get them up to a point where they can handle big charge current, but the opposite would happen in this case. The huge current must pass through all 4 cells because they are in series, the damaged cell now has huge reverse current flowing through it and it will start to separate the most volatile elements first, the cell will transfer lithium onto the carbon plate .... until it finally build up enough to bridge the gap through the plate separator sheet. Now it is no longer just a cell that can not hold any capacity, it is now a dead short so the voltage remains zero because the current can flow straight through this lithium bridge that has formed. The cell virtually no longer exists, it would be just like removing thiscell completely and just linking the 3 cells together.

The 3 cell battery is now being charged by multiple 4 cell batteries trying to get the voltage even across all the batteries.
Remember that 14v in the fully charged 4 cell batteries, 14v across a 3 cell battery is 4.66v per cell, seriously over voltage charging and the electrolyte loss occurs in these 3 cells as well and the whole scenario that happened with the first damaged cell now happens with the other three cells ......

What effect do you thing a dead shorted 4 cell battery connected in parallel with a bank of good 4 cell batteries would have .... a very high discharge from all the paralleled batteries into the shorted battery? .... if the cables didn't catch fire that connected the batteries together, then the end result would be a completely flat battery bank .....

I know it is a very long post that many will not both reading, but for those that battle through it, I hope you get a better understanding of why lithium batteries should not be linked in parallel.

T1 Terry

[CruiseN]

I did years of engineering electrical and electronic studying.
I also did years of sailing.

Keep it simple because you need to understand how to use.

I can't get my head around lithium ion. Like comparing a skiff to a displacement hull. Yes better performance but the old girl will plough through the slop.
Someone mentioned big singular batteries therefore less units in bank. That's logical. I don't know how to balance, better off just having a decent low ballast keel.

At home I built a blackout power to keep fridge, lights, cctv and idiot box going in event of mains failure. 20 seconds post mains return, avoiding spike loads of common system, switches back to charging bank whilst running on mains.

Instead of parallel bank, bank is in series. Allows cell failure with controlled use of system, eg instead of failed cell dragging other battery down, a failed will reduce the output but keep the flow at a much lesser loss.

I'll look into batteries in a few years.. later lithium that doesn't explode with salt water contact probably look okay. Much better performance . Will be recycling soon enough because we can't afford to throw away valuable minerals and they're toxic.
Although ignorant some Watt, I can't help at moment, I do not know.. yet surely there is switches that would allow multiple bank isolation and triggers could be set to open circuit at the low side of the longactivity storage within. Thus allowing each bank to withdraw separately, recharge separately yet one at a time and soak charging could be obtained via a timed delay when all full . Eg after a couple of hours, a day, a few days, whatever delay is, banks would switch.
Hence with performance aimed at long activity via staging usage in a controlled manner.

I'm headached, but if useful. Maybe query bank switching rather than bank balancing.

Edit: switching Watt I do..
Happens so fast even modern electronic devices don't notice bank change.
My banks being; mains electricity, batteries.
Switching back in my case is a timed delay to avoid mains spike, another moment to settle batteries prior to engaging recharge.

On a boat this could mean that you could recharge one bank whilst withdrawing from another and effiently saw through the slop like a plough.
Look into switches.. low cost and robust. Like stays on a rigging sorta.

[T1 Terry]

By building one single battery using multiple smaller capacity cells linked in parallel to build capacity referred to as P) and these groups linked in series (referred to as S) to build voltage, you could have a 400Ah 12v battery built 4P4S using 16 x 100Ah cells.
Because the P groups are in series, the maximum voltage differential within the parallel group is only cell voltage, 3.2v nom. so the huge current flow would not happen and the cell with slightly less capacity would be carried by the cells with slightly more capacity. The whole group would go down if there was a problem and this becomes obvious when cell voltage monitoring is used, so you have an indication well before it becomes a problem. Even if the whole parallel group went down, 4 cells, one cell from each of the other groups can be used to build a 3P4S 300Ah battery and you have a spare cell, redundancy to get you to somewhere you can source replacement cells for the failed ones. You can add new cells to an old battery, just one new one to each P group, the balance is the same because all 4 series groups have a new cell along with the older cells. You can even replace a single cell in one P group, just bring it up to the voltage of the other cells and away it goes ... yes, that P group might have slightly more capacity than the other 3 P groups, but as long as the voltages remain within the damage free range, it simply doesn't matter.

T1 Terry

[more]

Originally Posted by T1 Terry

By building one single battery using multiple smaller capacity cells linked in parallel to build capacity referred to as P) and these groups linked in series (referred to as S) to build voltage, you could have a 400Ah 12v battery built 4P4S using 16 x 100Ah cells.
Because the P groups are in series, the maximum voltage differential within the parallel group is only cell voltage, 3.2v nom. so the huge current flow would not happen and the cell with slightly less capacity would be carried by the cells with slightly more capacity. The whole group would go down if there was a problem and this becomes obvious when cell voltage monitoring is used, so you have an indication well before it becomes a problem. Even if the whole parallel group went down, 4 cells, one cell from each of the other groups can be used to build a 3P4S 300Ah battery and you have a spare cell, redundancy to get you to somewhere you can source replacement cells for the failed ones. You can add new cells to an old battery, just one new one to each P group, the balance is the same because all 4 series groups have a new cell along with the older cells. You can even replace a single cell in one P group, just bring it up to the voltage of the other cells and away it goes ... yes, that P group might have slightly more capacity than the other 3 P groups, but as long as the voltages remain within the damage free range, it simply doesn't matter.

T1 Terry

2P4S,3P4S ,4P4S,100P4S this is only path for small user and medium company go. also forget 1C charging minimum 2C better 3-5C CC charge.
Forget also 100 Charge better 95% 80-90% is ideal (this is not possible or very hard to achieve ) Fast charging is for car industry her is hundred to thousand million € spend for simple battery. VW,Hyundai,Kia an other pay small company Rimac car to help develop car battery all this battery up is like 50-100p 70-140S , couple of world class company developed chips and other electronic for BMS. evry piece is of components is not paid in gold but with Diamonds(lot,lot green paper) But I am hard in KISS principle.