Building and managing 4S66P 18650 pack

[Znourf]

Hi,
so here is my project.
I have 264 18650 pana in 3400 mah .
I wish to build a 4S battery with them.
My idea is to be able to use it on loads up to 50 amps with a peak of 75 amps.
It will be used for camping and on a trolling motor .

I'm looking for a BMS or an assembly of system that can manage this.
Manage each cell individually.
Charge cell from a 24V 100 amps source
balance each cells.
Cut off at desired voltage.

Thanks for any views .

 

[wesnewell]

Any time you put 2 or more cells in parallel, they then act as 1 cell, so all you really need is a 4s bms. That's a 225ah 3.3Kwh pack. Just be sure the devices can operate at 16.8V. Maybe one of these 100A or 200A bms's.
http://bestekpower.com/148v4spcmbmspcbforli-ionli-polymerbatterypack/
But you'll need a 16.8vdc charger or have to find some way to lower the voltage on your 24VDC 100A source.

 

[Samd]

Intriguing project - what are you making?
What are the discharge amps?

 

[Znourf]

I did a mistype i mean't 12v not 24volt :/

Thanks Samd.
for the charging shoundn't i need a CC CV charger ?
Do these BMS charge the battery this way if i send out to them 16.8V ?

My project is to have a battery with maximum reserve.
It will power a small 12volt 55lbs trolling motor,a 12V led light at the camp site (24 watts), a small cooler 72w/h , usb for the phones, a 12V radio and sonar, and a toughbook.

I will recharge it with.
A / the engine of the outboard that gives out 12v 20Amps max through a rectifier it will be used 2 hours a day max
B/ a small silenced petrol generator 1500 w 220v that i can use when needed.
C/ 2 foldable solar panels of 120w each.
D/ not bought yet a small wind turbine but have to get some research done.
E/ The after market alternator of the 4X4 that give out around 110 amps .

the idea is to be autonomous for a few days while going round fishing and camping within the swedish baltic archipelago south of stockholm.
The trolling motor will be used at maximum 48 amps for a few minites else it will be used at a 10 to 18 amps setting for most of the day.
So that should draw at maximum setting on the engine 0.72 amps per cell. So all in all if i used it with maximum power, cooler, usb charging, radio and sonar and a few led lights i wouldn't go over 1 Amps / cell.

Everything will be packed in a pelicase. cells, bms ad if needed a battery charger and 220v to 16.8volt and 12v to 16.8 transformers.
I haven't the pelicase yet since i need to size everything up.
AS for the heat i plan on using a peltier cooler to that the inside keeps cool and dry.
To keep the air dry i will use silicates thus preventing condensation from building up.

So any help would be appreciated.
Thanks

 

[Samd]

Lots of us on ES Facebook using these to charge 36v and higher batteries with solar or 12v PSU units.

https://youtu.be/-kWps5Wpbzo

I really like these analog ones just tune them up with a multimeter.
https://www.ebay.com.au/itm/281957104828

But I think you are charging via similar voltages?


Sent from my iPhone using Tapatalk

 

[Punx0r]

I bought a couple of those but with the LED display and my advice would be: don't... The output voltage is around 2V lower than the displayed voltage and you have to set the voltage and current each time you power it up. I will be replacing them with the ones Samd linked to, set once with a multimeter and use a separate volt/ammeter for display

 

[wesnewell]

With a 12VDC source, the easiest solution would be to use an RC balance charger and forget about a bms. The problem is finding an rc charger that will charge your pack fast enough. To charge in 12 hours you'd need a 300W charger.

 

[redilast]

I think you are going to find it difficult or impossible to find an off the shelf BMS that is for 4S that can do the 50-100A continuous that you need.

What you could so as the previous poster mentioned is not use a BMS and charge it with a hobby charger. There are many hobby chargers in the 300W-1Kw range, you'll also need a 12-36v or so power supply to power the chargers.

If you don't run a BMS you'll want a balancing plug and also a fuse, perhaps an ANL type fuse of 100-150A or so. Then you'd probably want to put a small volt meter which can show each individual paralleled group of cells to insure that everything is in order. Lots of RC volt meters out there for cheap.

Lastly, you'd want to be sure that you can actually run your motor and other devices at up to 16.8v. Alternately if tha'ts just a little too high, you could probably just charge them to 4v (around 80% capacity) per cell for 16v or even 3.9 (around 70%) for 15.6v.

4S LiFePo4 is a much better fit for replacing a 12v lead battery.

 

[Samd]

Any reason why there couldn't be say four or five of these BMS units in parallel?
http://www.aliexpress.com/item/4S-20A-11-1V-li-ion-BMS-PCM-battery-protection-board-bms-pcm-for-lithium-LicoO2/32388217872.html?spm=2114.01010208.3.2.sTK1fb&ws_ab_test=searchweb201556_10,searchweb201602_2_10017_301_407_406,searchweb201603_3&btsid=0f3ed6fb-1bb9-4554-8a4f-fd8e1e70f9d9

 

[wesnewell]

4s bms rated for 200A continuous. They also have ones rated for 100A. Most 18650 cells don't like more than a 0.5C charge rate though, so I wouldn't go with more than a 100A 16.8VDC charger.
http://bestekpower.com/148v4spcmbmspcbforli-ionli-polymerbatterypack/BMS-D170.html

 

[Znourf]

Samd thanks for the link.
So if i get this right.
I could use 4 of these dc dc analog boost converters to charge my packs. Each one charging 1 set of 66 cells in parallel
Now the question might have been asked. I will charge my cell up to 4.15 volts to maximize life cycles. Is CC ok for charging to 4.15 or should i consider less voltage per cell. In fact up to what voltage should i use CC ?
Over question Since i would be charging each set to 4.15 the battery as a whole should balance it s tension but how could i stop the charging process once it get s to 4.15 volts. ? Else wouldn t it just continuesly send out a current and have that disipate ? Or would the BMS just cut of the charge untils the tension goes back down a certain amount ?

 

[Samd]

No you would only be using one of the DC DC chargers to charge the whole pack at 16.8Volts (open voltage with a multimeter). When you connect a less-than-full pack the voltage would dive down until it charges up slowly.

The 4 units referred to the BMS.

There are two different items here. The DC DC converter and the BMS units.

Do not put four of the DC DC units in series. They cannot be connected in series.

 

[Znourf]

okay , so the pack is finished.
i tested the pack with the trollingmotor.
the voltage stays put at 16.8 volts even at 50 amps draw.
now the motor is heating but i only gained 0.5 km/h even with a ultra light boat i mean 150 kg with me battery and engine on board i go the same speed (6km/h) than with a 750kg boat.

it's a 54 lbs watersnake venom motor. 5 speeds foward 3 reverse.
Note there are 4 cables going to the motor red black +/- blue and yellow /

i then used only 3S and the speed went down to 5.5 km/h with 12.6volts that matches the 105 ah pb brick i use.
before taking the motor a part is there a resistance inside that limits the rpm / power
edit
opened the motor casing and found a extra coil that acts like a resistance for slow speeds.
for fast speed it goes straight to the battery.
at 16.8volt the brushes started burning up and the collector started to have spark damage.
I'm going for the 3s with that li ion battery and i'l have a propeller with a slighty improved pitch to catch up the lower voltage.

 

[redilast]

I'm not surprised it started burning out a 12v motor @ 16v.

Keep in mind though that 3s Li-ion is 11.1v on average, which is lower than a 12v SLA, but it will be much more gentle on the motor.

 

[wesnewell]

Put a 12v buck converter on the pack to limit voltage to whatever you want.
http://www.ebay.com/itm/New-DC-Converter-24V-to-12V-40A-480W-Step-Down-Buck-Power-Supply-Module-Car-/221866499227

 

[Znourf]

if i use 16.8V on a brushless 12v motor would the motor have the same problems heating and or burning up ?

does any one know of a li ion automatic charger with balancing that give out 40 amps and that can charge a 3s battery ?

wesnewell : do you know of one with say 80 amps ?

 

[redilast]

My guess is most 12v motors won't be able to handle 16v+ continuously regardless of if they are brushed or not.

But as for the charger, the iCharger 3010B can do 30A and has balancing.

 

[wesnewell]

https://www.google.com/search?q=80A+converter&oq=80A+converter

 

[Znourf]

Ok 3s88p
I use it right now as a 3s88p but i can rewire it as a 4s66p
This powers my 54lbs trolling motor ,sonar , mobil phone charger ect.
Now.
I would like to have a regulated 13.5 volts coming out.
And the question i asked my self can i connect in parallel 2 1500w power up / down dc/dc regulators so as to have a 60amp 13.5v regulated power source.
My question was then ok which is more efficient taking the voltage down or picking it up ? Should i regulate a 3s or a 4s pack. ?


Though i use a 3s bms.i would lke to have some guidance for my personal kwnoledge.
I have ordered a chargery s1500. I m looking to charge the pack up to 4.1 v or if only needed for a day to 4 volts .
I am simply plannng of sending in only 4v or 4.1 v to the bms.
Since I can charge the pack at 60 amps continous which is like 0,2C i have a slow rate of charge. Is it better to take that C down since i have plenty of time to recharge the pack ? Capacity wise and regarding the battery life wise?
I use 3400 panas.
. Now the cut of amp per cell is 100mA in CV. if i charge it in a 3s config i should have 8.8 amps of draw then i should shut the power source off. At what point should go from CC to CV ? 4,1 ? What would be the lowering of the tension at intensity be like ?
Thanks for reading.

 

[999zip999]

Can you use a 4s jst sense wire and connector just use 3s for a cellog or charger. Then later if 4s needed hook up the fourth wire. The charger reads 3s ? Right. Same with some bms's use 3 channels not 4. But 200 amp. Wow. Water and a prop.
A little off topic.