Lithium Ion Battery help please

[K1ng]

Hello
Question 1 : I have a rechargeable Li-ion battery pack and it has a standard voltage of DC25.2V is that how much each battery outputs or all up because i am looking into making my own battery pack and dont want to fry anything or under power.

Question 2 : I am looking into buying alot of Li-ion batterys to make a very powerful rechargeable Li-ion battery pack and on stuff like ebay people are selling 18650 Rechargeable Li-Ion Battery 2600mAh 3.7V is that per battery or all up because they dont specify very well.

Question 3 : The battery pack says the standard voltage is DC25.2V but Li-ion batterys online say stuff like 3.7v so is the DC25.2V mean its 2.5v?

Question 4 : if i am correct in question 3 is there any way i can buy 3.7V batterys and not fry the curcuit board it powers or have something to knock it down to 2.5v?

Thanks

 

[billvon]

Question 1 : I have a rechargeable Li-ion battery pack and it has a standard voltage of DC25.2V is that how much each battery outputs or all up because i am looking into making my own battery pack and dont want to fry anything or under power.

That is most likely a 7S (7 cells in series) pack. That means voltages will range from about 21 volt to 29.4 volts.

Question 2 : I am looking into buying alot of Li-ion batterys to make a very powerful rechargeable Li-ion battery pack and on stuff like ebay people are selling 18650 Rechargeable Li-Ion Battery 2600mAh 3.7V is that per battery or all up because they dont specify very well.

That sounds like a single cell (not a single battery.) Batteries are made of cells.

Question 3 : The battery pack says the standard voltage is DC25.2V but Li-ion batterys online say stuff like 3.7v so is the DC25.2V mean its 2.5v?

No. (See above.)

 

[john61ct]

Each LI cell (other than outliers like LFP or LTO) is "nominally" rated as 3.7V.

Connecting them in parallel increases Ah capacity, leaves voltage the same.

Connecting them in series increases voltage, leaves Ah alone.

So 3.7V 1800mAh x70 cells, laid out as a pack of 10P7S, makes

18Ah capacity total, at

26V nominal, resting full about that, terminate charge to around 29V, in use don't let them go much below 23V, maybe 21V occasionally in a pinch.