How does ohms law work with 2 batteries

[Mden89]

so when you are running two 18650 batteries in an unregulated box mod that have a CD of 25A does this mean when running them parallel you have 50A CD? Or is the CD still 25a and you just increased your battery life twofold?

 

[Thrasher]

The mah and amp rating doubles, voltage stays the same

 

[Matty316]

Heres some good info on series and parallel battery configurations.

Serial and Parallel Battery Configurations and Information

 

[IMFire3605]

In series (the whole circuit load runs through both batteries like in a maglight flashlight config), the voltage is double, but the amp limit is the same 25a would be 25a
In parallel (load is balanced across both batteries (side by side box mod, both negative and positive connections are in the same direction negative bottom, positive top) the voltage is the same 4.2v but the amp drain load is balanced across both, technically still 25a but calculations can be done as 50a.)

And yes, battery life in both configs is generally double per charge cycle due to 2 batteries supplying power

 

[edyle]

so when you are running two 18650 batteries in an unregulated box mod that have a CD of 25A does this mean when running them parallel you have 50A CD? Or is the CD still 25a and you just increased your battery life twofold?

2 25A 18650 batteries in parallel have a potential CRR of of 50A

But if you get drunk once a year on a Friday night and happen to put your batteries in the wrong way 1 time out of two, you get a battery accident problem every two years.


I fried a dual bay charger last year; and now I happen to still use dual bay chargers but I got and confirmed electrically that they are independent bay chargers;
The dual bay regulated mods have the battery bays mechanically connected, so if you put one battery upside down to the other one, you get instant................. YIKES!

 

[Mden89]

In series (the whole circuit load runs through both batteries like in a maglight flashlight config), the voltage is double, but the amp limit is the same 25a would be 25a
In parallel (load is balanced across both batteries (side by side box mod, both negative and positive connections are in the same direction negative bottom, positive top) the voltage is the same 4.2v but the amp drain load is balanced across both, technically still 25a but calculations can be done as 50a.)

So when building coils I can calculate at 50A when using the parallel batteries? Why do you say "technically still 25a"?

 

[IMFire3605]

Each battery is still 25a cdr, if one fails, the load falls on the second. IE both batteries start at 4.2v, but if one is weak or older it will drain or not hold the charge as long, its amp draw will increase compared to its mate battery that is draining slower. A lot of physics, electrical engineering and such goes into consideration, so in parallel the true CDR of the circuit is higher than the 25a baseline as both batteries share the load. Thus why when in dual battery or multibattery configs we suggest buying the set of batteries together, charge and use them together, called marrying or mating a set to decrease the occurence of a weak cell nerfing the circuit.

 

[Mden89]

Ok it seems like im not getting a really concise answer here. Will the max load on the box be 50A or 25A? I want to know what builds the box will be able to handle.

 

[Dampmaskin]

Ok it seems like im not getting a really concise answer here. Will the max load on the box be 50A or 25A?

Yes.

I want to know what builds the box will be able to handle.

It depends.

 

[Mden89]

Yes.


It depends.

... Thank you for your incredibly helpful contribution

 

[Mden89]

In series (the whole circuit load runs through both batteries like in a maglight flashlight config), the voltage is double, but the amp limit is the same 25a would be 25a
In parallel (load is balanced across both batteries (side by side box mod, both negative and positive connections are in the same direction negative bottom, positive top) the voltage is the same 4.2v but the amp drain load is balanced across both, technically still 25a but calculations can be done as 50a.)

And yes, battery life in both configs is generally double per charge cycle due to 2 batteries supplying power

So the amp load is taken from both simultaneously? AKA if im pulling 15A from a box with 2 18650 batteries, it will be pulling roughly 7.5A from each battery. Give or take depending on how similarly they are charged?

 

[Asbestos4004]

... Thank you for your incredibly helpful contribution

You've gotten many "concise" answers. 2- 25amp batteries in parallel will give you 50 amp. However, it's not the best idea to try and build a coil that requires 50 amps.

 

[Mden89]

You've gotten many "concise" answers. 2- 25amp batteries in parallel will give you 50 amp. However, it's not the best idea to try and build a coil that requires 50 amps.

Honestly, i had to go back and re-read the previous posts. They had other information smushed in their responses that confused me. After reading them over about 6 more times i think i understand. Im more of a kinesthetic learner. So reading is the worse way for me to learn new information. Pair that with early morning and late night posting... [HASHTAG]#fail[/HASHTAG]. Sorry

 

[Froth]

So the amp load is taken from both simultaneously? AKA if im pulling 15A from a box with 2 18650 batteries, it will be pulling roughly 7.5A from each battery. Give or take depending on how similarly they are charged?

If the batteries are in parallel and of the same make, age and condition then yes. Each battery will only supply half of the output regardless of what amperage the box is used at. At 2A, each battery supplies 1A...at 40A, each battery supplies 20A. Quite simple.

 

[Mden89]

If the batteries are in parallel and of the same make, age and condition then yes. Each battery will only supply half of the output regardless of what amperage the box is used at. At 2A, each battery supplies 1A...at 40A, each battery supplies 20A. Quite simple.

Thank you for dumbing it down for my tiny brain

 

[Froth]

Thank you for dumbing it down for my tiny brain

I could get deep in to pulse drain discharge limits and post a bunch of graphs that will further confuse you, if you would like.

 

[Mden89]

I could get deep in to pulse drain discharge limits and post a bunch of graphs that will further confuse you, if you would like.

No, i sincerely appreciate your blunt answer. Like i was saying, im more of a hands on learner. I have the WORSE A.D.D. in the world so i generally have to read the same sentence about 4 times before i can comprehend.

 

[Bunnykiller]

you should try ADD and dyslexia.... now that makes reading fun

 

[Mden89]

you should try ADD and dyslexia.... now that makes reading fun

ACTUALLY! I often mix up number sequences. I bet part of the reason i have to go back and read things over again so many times is a side effect of mild dyslexia

 

[Asbestos4004]

How many people with A.D.D. does it take to change a lightbulb?


So, I got this really great new rda today ......