What are the attributes of batteries in series, or in parallel?
How do they differ in relationship to delivering power to the Flashlight?
how would you classify a four battery carrier that has all the cells facing the same way as compared to two up and two down?
just asking.
In Series, Current and AmpHours remain the same while Voltage Doubles
In Parallel, Current and AmpHours Double while Voltage remains the same
The raw amount of power they can deliver to the flashlight is the same. Watts is calculated as Volts * Current, so watts doubles when you double either Voltage or Current. Which is best depends on the particular flashlight and whether it is in need of more volts or more amps.
The is VERY generalized, but FOR THE MOST PART
Two up and two down = Series
All the same way = Parallel
There are exceptions to this rule, however, so don’t make assumptions!
PPtk
I'm sure someone will provide a concise answer for this. But if you want the long answer, here it is:
Is one of these options safer for running unprotected batteries?
i would say parallel would be safer. but, i may be wrong.
I hate to even answer a question like this… I really do… But again IN GENERAL unprotected cells will be safer in parallel.
If you’re not familiar with LiIon battery safety - get familiar before you run multi cells in either configuration.
PPtk
running batteries in series, you have the chance of reverse charging, but im not sure if you have that chance with parallel…?
edit: just a thought came to mind… might be useless though. couldnt you use a battery carrier to run batteries in series, but have a diode between each battery? in theory, it would eliminate the chance of reverse charging…
my electronics engineering skills is nill, so go easy on me if theres a HUGE flaw in my thinking…
I’m assuming that reverse charging would be most likely to happen when using unevenly matched cells.
yeah, but i just remembered about the function of a diode basically works like check valve, allowing flow in one direction and blocking reverse flow. like i said there may be a huge flaw in my theory, but i would think that this could help add an extra layer of protection… but im sure it would have been done by now
I’ll have to think about that for a minute to come to a conclusion on whether it would even actually ‘do’ anything…
One thing it would definitely do, however, is generate a whole lot of heat. At 3A, for instance, even a good schottky diode is going to drop about .4V… That’s 1.2 Watts of heat between each battery… Bad… In a 3 Battery series configuration, it’s also 1.2V of drop… Quite huge…
PPtk
Using diodes on battery carriers:
meaning it charges backward. Instead of pushing current, due to depleted battery, it now accept charge the other way around. This current still moves forward the same way as before, meaning diode will still happily let it through.Anodes and cathodes and diodes. Oh, my!
The direction of flow is what determines when a cell is being charged or discharged normally. Consequently, the diode will prevent a normal “forward” charge but allow reverse charging.
In Parallel, if there are three cells and one of them is slightly weaker than the other two, would the voltage of all three cells even out in time (ie, would the weaker cell be charged at the expense of the other two cells?)
Yes, current would flow from the two charged cells to the weaker one until the voltage of all of the cells is equal.
I do have a question for someone else on here, it isn't strictly related to flashlights though. If a 12 volt line is wired in parallel with a 5 volt line what would happen and what would the measured voltage be?
Assuming you've got a 12v source and a 5v source coming together before the load I believe you would measure 12v. I'm also assuming transformers and not batteries.
Can you give more info?
(Not an E-Eng or electrician but do a lot of electrical testing as diagnostics)
Yes coming together before the load, and yes again it is transformers (a power supply) not sure what other info you need.
That's good.
In your situation I'm 90% sure you'd just end up with 12v at the load.
Some information I've found doesnt agree on whether you'd damage the PSU or not.
or
"Batteries != power supplies. Energy going into a battery charges it. Energy going into the output of a power supply usually smokes it."
More:
Gets more relevant further down I think.
http://electronics.stackexchange.com/questions/23943/what-happens-if-i-connect-two-different-dc-voltage-sources-in-parallel
computer issues ?
step 13 to be exact
also this one mentions as long as all outputs dont use the same ground it will work, but if they do it will not
ive read other places on linking different voltage outputs on a psu to get a voltage you want. i believe it was on ECF modding forum…
I have always thought that too. Although there have been multiple times where I have taken my batteries out of 2x18650 and 3x18650 flashlights and they were uneven. I am talking a significant difference. (3.6v and 3.2v)