Nominal Capacity : 100Ah ?

[johninscotland]

Hi All
NEW 3.2V LIFEPO4 Product Lithium iron phosphate cells i got 8 of these my question is are they 100ah each or are they 100ah x 8 = 800ah as the DALY bms i got is 4 x 12v 100a should i have purchased an 800ah ?
i am a newbie !
John
▲Specification
Material system : Lithium iron phosphate
Nominal Capacity : 100Ah
Minimum Capacity : 100Ah
Nominal Voltage : 3.2V
Charge Voltage : 3.65V
Internal Impedance : 0.4~0.6mΩ
Weight : 2.2±0.03Kg
Dimensions: 36-135-197mm
Cycle life (80%DOD):4000 cycles
Charging Temperature：0~45°C
Discharging Temperature：-20~55°C

 

[MisterSandals]

100ah x 8 = 800ah

They are 800Ah at 3.2V. (all 8 cells in parallel)
If you put the 8 cells in series to make a “24V” battery, it is 100Ah at 25.6V.

In both cases, the watt hours are 2560Wh.

8 x 100Ah x 3.2V = 2560Wh
1 x 100Ah x 25.6V = 2560Wh

 

[Tim Tim]

Hi All
NEW 3.2V LIFEPO4 Product Lithium iron phosphate cells i got 8 of these my question is are they 100ah each or are they 100ah x 8 = 800ah as the DALY bms i got is 4 x 12v 100a should i have purchased an 800ah ?
i am a newbie !
John
▲Specification
Material system : Lithium iron phosphate
Nominal Capacity : 100Ah
Minimum Capacity : 100Ah
Nominal Voltage : 3.2V
Charge Voltage : 3.65V
Internal Impedance : 0.4~0.6mΩ
Weight : 2.2±0.03Kg
Dimensions: 36-135-197mm
Cycle life (80%DOD):4000 cycles
Charging Temperature：0~45°C
Discharging Temperature：-20~55°C

Hi John,

What you have is 8 cells at 100Ah each so if you put 4 of these in series you then get 100Ah @ 12.8volts. If you do the same with the other 4 cells then connect them in parallel to the first pack you get 200Ah @ 12.8 volts.

As per MisterSandel‘s post if you put the 8 in series you get 100Ah @ 25.6 volts.

Firtsly, what voltage system do you require 12v or 24v.

Your BMS is 12v so that is only suitable for a 12v system. If you only have one BMS then you will need another for the other 12v pack.

If you are building a 24v system the you need an 8S x 24v BMS.

The size of your BMS is governed by the amps or current that you want to draw from the battery and not necessarily the size of the battery although there are other limitations. So no you did not require a 800A BMS.

Ok so lets start at the beginning so we can help you. What is your system for? Is it to run a 12v lighting etc or is it to run an inverter and run 240v appliances?

Welcome from a Taffy in Australia.

Tim

 

[rmaddy]

If you are building a 24v system the you need an 8 x 12v BMS.

I believe you meant "8 x 24V BMS".

 

[Dzl]

Hi All
NEW 3.2V LIFEPO4 Product Lithium iron phosphate cells i got 8 of these my question is are they 100ah each or are they 100ah x 8 = 800ah as the DALY bms i got is 4 x 12v 100a should i have purchased an 800ah ?
i am a newbie !

Both or either. Each cells is 100Ah at 3.2V. As a general principle. connecting cells in series increases the voltage but amp-hours stay the same, so 8 x 100Ah 3.2V in series is 100Ah and 25.6V ('24V') Connect the same 8 cells in parallel and voltage stays the same but amp-hours increase (so you would have an 800Ah 3.2V battery which is not usuable for your/our purposes). In either case you have the same amount of stored energy, its just a matter of what voltage and amp-hour rating.

Also, it looks like you may be confusing amp-hours and amps, they are not the same thing. Just because you have xxx amp-hour battery does not mean you need a BMS with the same amp rating. The two things you need to know to choose the proper BMS is the max current you will use (amps not amp-hours) and the number of cells in series (4S = 12V, 8S = 24V, 16S = 48V).

IF you have 8 100Ah cells, and build a 24V battery, you will need an "8S" BMS, if you build a 12V battery you will need 1 or 2 "4S" BMS's depending on how you build it. And the current rating is not related to your cells, its related to your max planned current (usually inverter size is used to ballpark this).

 

[Tim Tim]

I believe you meant "8 x 24V BMS".

Oooops ty will correct now

 

[Dzl]

I believe you meant "8 x 24V BMS".

Unless I'm confused (my natural state of being ), shouldn't we be saying 1 x 24V BMS (or an 8S BMS). Not 8 x 24V
OP says they have 8 x 3.2V cells.

 

[MisterSandals]

shouldn't we be saying 1 x 24V BMS (or an 8S BMS). Not 8 x 24V

That’s what I was thinking… I actually typed the following but didn’t post…

I believe you meant "8 x 24V BMS".

8 x 3.2V BMS?
8S 24V BMS?
8S BMS?

 

[Tim Tim]

Unless I'm confused (my natural state of being ), shouldn't we be saying 1 x 24V BMS (or an 8S BMS). Not 8 x 24V
OP says they have 8 x 3.2V cells.

Lol yep…thank goodness I have proof readers to keep me on the straight and narrow ?

 

[rmaddy]

I guess 8S BMS is the proper term. I figured 24V was more correct than 12V.

 

[Dzl]

Lol yep…thank goodness I have proof readers to keep me on the straight and narrow ?

One thing you can always rely on the internet for is nit-picking and corrections ?

 

[Dzl]

I guess 8S BMS is the proper term. I figured 24V was more correct than 12V.

Either 24v or 8S are correct in my book, just not 8 x 24V (unless you mean 8, 24V BMS's)

 

[Tim Tim]

I did correct it and it didn't save the first time . Anyway I think you will find that John is building a 12v system and if he returns we can hopefully help him out.

 

[johninscotland]

sorry to all i didn't know how to reply....... im learning ?

 

[Tim Tim]

sorry to all i didn't know how to reply....... im learning ?

No a problem John as we were all at that stage at one time. To reply to an individual post just click reply at the bottom right of the post.

Did you mange to work out what you need from our mumble jumble?

 

[johninscotland]

Thanks Tim Tim
Yes i took the advice offered and arranged them into 2 sets of 4 and joined them for the 12v i need ... unfortunately a storm which knocked out main power happen before i was ready.
Perhaps you can help me ?
i would like to use my new ISDT BattGo BG-8S Battery Meter to monitor all 8 cells but i can only get all 4 in the first group and 3 in the second group, i can connect to either set and get a reading but not to all 8 ?
i do like the ISDT BattGo BG-8S as it shows me all cells at once (well it would if it could) i would like to top ballance all 8 cells and see what is happening is this possible ? Am i getting a confused reading..... due to my positive and negative outputs being joined ?
Any advice would be appreciated.
John

 

[Tim Tim]

Thanks Tim Tim
Yes i took the advice offered and arranged them into 2 sets of 4 and joined them for the 12v i need ... unfortunately a storm which knocked out main power happen before i was ready.
Perhaps you can help me ?
i would like to use my new ISDT BattGo BG-8S Battery Meter to monitor all 8 cells but i can only get all 4 in the first group and 3 in the second group, i can connect to either set and get a reading but not to all 8 ?
i do like the ISDT BattGo BG-8S as it shows me all cells at once (well it would if it could) i would like to top ballance all 8 cells and see what is happening is this possible ? Am i getting a confused reading..... due to my positive and negative outputs being joined ?
Any advice would be appreciated.
John

Hi John, happy to helip but just got back from a 800km drive so will follow up with a post in my morning.

Tim

 

[johninscotland]

Thanks Tim enjoy your rest. There is absolutely no hurry please feel free to not reply until after the festivities.
John

 

[MisterSandals]

arranged them into 2 sets of 4 and joined them for the 12v

Okay that's referred to as 2P4S, i have a battery configured this way with 8 cells.

i would like to use my new ISDT BattGo BG-8S Battery Meter to monitor all 8 cells but i can only get all 4 in the first group and 3 in the second group, i can connect to either set and get a reading but not to all 8 ?

I also have this BattGo. You can only monitor the pairs, not the individual cells. However the pairs will equalize and have the same voltage even if their capacities or condition is different.
Your balance leads (5 wires for 4S) need to be pin 1 to battery negative (known as cell 1 which is a pair of cells physically). Pin 2 goes to cell 1 positive. Pin 3 goes to cell 2 (pair) positive. Pin 4 goes to cell 3 (pair). Pin 5 goes to cell 4 (pair).

i would like to top ballance all 8 cells and see what is happening is this possible ?

I consider a top balance to be all cells connected in parallel and charged together to 3.65V.
The BattGo will charge an assembled battery in a balanced manner very nicely if you have the balance wires connected as described in my previous paragraph. It should detect 4 cells and you can set the per cell voltage. I think the lowest it goes is 3.60V, which is what i use, especially if i let it go unattended for many hours.
What do you intend to use as a DC power source for your BattGo?

Here is a pic of a 2P4S battery with balance wires (not my battery but just like mine):

 

[johninscotland]

Hi Tim
The photograph i think shows 8 cells into 4 12v out ... i was advised not to do this by someone in the forum as it might miss a cell not performing like the rest... so i have 2 banks of 4cells 12v out.... which i then connected in parallel to give me 12v in total to this i connected my nine wires 1 neg and 8 to the cells pos ... you ask "What do you intend to use as a DC power source for your BattGo?" my answer is nothing as it lights up when connected to the cells ........ so are you saying i need to add a separate DC power source ? if yes what would you recommend ?
I am 75 with a decreasing memory and wishing i had never started this project ....
So thanks for your help its much appreciated.
John

 

[MisterSandals]

The photograph i think shows 8 cells into 4 12v out ...

Yes, sorry different from what you specified sorry. But, i have this battery setup and its been flawless in my RV for 2 years now. There are a bunch of us here that do it this way. It lets you us a single BMS but you are limited by the current of a single BMS. With 4S2P (2 batteries in parallel, each with a BMS), the amperage is the sum of them (and presumably they are the same).

What do you intend to use as a DC power source for your BattGo?

Oops, another swing and a miss. Sorry, i thought this was the model that was also a charger and therefore needed a power source. You're good to go as yours does not need anything other than balance lead and +/- connections.
That is a nice little meter. It will do balancing but very slowly. I think the most powerful feature are the alarms when you can have it beep if it gets over or under charged, even at the cell level. Handy if you are doing something without a BMS (i was my own BMS for several months before i found one i liked. its a tough job that requires attentiveness and some alarms to keep from catastrophic results).

 

[Tim Tim]

Hi Tim
The photograph i think shows 8 cells into 4 12v out ... i was advised not to do this by someone in the forum as it might miss a cell not performing like the rest... so i have 2 banks of 4cells 12v out.... which i then connected in parallel to give me 12v in total to this i connected my nine wires 1 neg and 8 to the cells pos ... you ask "What do you intend to use as a DC power source for your BattGo?" my answer is nothing as it lights up when connected to the cells ........ so are you saying i need to add a separate DC power source ? if yes what would you recommend ?
I am 75 with a decreasing memory and wishing i had never started this project ....
So thanks for your help its much appreciated.
John

Hi John,

You werent replying to me but MisterSandals was trying to help you. I will have a read through tomorrow and get back to you as soon as I can. Don’t give up as we are all here to help and once I have read through I will try and help you. You said that you are not getting a reading on one cell but you know it has voltage. In all probability it will be the wire connection which is faulty

Tim

 

[Tim Tim]

Ok John, you said you have a Daly 4S 12 volt, do you have two of these now or are you using a different BMS. we need to start back at the beginning. I now understand you want a 12 volt system so as i said previously you need another 4S 12 volt Daly BMS.

I currently have one bank of cells and another on the way so my system will be exactly like yours. I have plenty of patience and will help you through this.

In regards to your battery monitor it sounds like you have a faulty lead to one of the cells. Do you have a multimeter? If so just unplug the lead from your monitor and test between the end of the wire on the plug for that particular cell and the the negative terminal. If you have no reading then check the crimp at the terminal and also the wire going into the connector. Hopefully it is just the connector and if you cant repair the connection they are easily available online from a toy hobby store.

Ok the next question is whether you bought the Daly smart BMS because if you did it can monitor and balance each cell and you do not need you little battery monitor.

Tim