Battery Voltage Readings When Fully Charged

[Rolex888]

How do you calculate what the voltage reading should appear as when your battery is connected to your charger?

For example, if I run a 7 cell 1100mah GP Battery Pack, then what would a fully charged pack give as a voltage reading?

Sometimes if I run 8 alkaline AA cells for my transmitter it gives me a higher voltage reading than if I stuck in 8 2200mah nimh AA cells.

I have a Triton charger and sometimes my batteries finish off with a high and sometimes low voltage reading (after all, this is what the charger displays). And also I'm trying to figure out when my batteries are almost done and need to be replaced because of too much re-charging.

 

[FastEddy]

For RX and TX peak voltage isn't a big issue. The issue is how long will they last at operating voltage before they dump. Alkaline batterys / packs, will slowly decrease in voltage close to a strait line from full to empty. Not quite a strait line but a lot more so then a rechargeable.

A rechargeable battery / pack will have a curve. your pack may peak at 10 volts but go to 9 volts right away when you put a load on them. At that point they may stay at 9 for a long time and gradually drop on a small curve to 6 volts then within minutes dump.

My 2200 AA 8 cells peak out around 11v or so drop to 10 then stay there for hours in my TX when they drop 9 I know my day will soon be over.

 

[FastEddy]

If accurate numbers are important to you, I can run some tests and give you exact data. My charger will display the charge curves and discharge curves on my computer.

Let me know what cells, how many, and what charge and discharge rates you want me to use and I can be a lot more accurate using the cells I have on hand. All cells and packs will differ but it will get you close.

Rechargeable batterys will last for about 200-300 charges then they will fall to about 80% efficiency for another 2000 charges or so.

 

[Rolex888]

Thanks for the info once again, Eddy. Hmm, so I guess you're telling me that I should just monitor my battery voltage as I charge and use each pack because there's no set formula for these things?

I just have too many battery packs and I can't remember what the voltage reading is when it usually peaks out when fully charged and I keep forgetting the voltage reading at which the stuff is drained out for the day (when I'm using them).

Well, Eddy if it's not too much trouble, the next time you run your equipment and you happen to have some of the similar packs or battery setup as mine - it would be cool if you could share with me some of your own findings.

Here's what I have and what I'm curious about finding out the fully charged and practically drained voltage readings (basically having a better idea of when the battery is fully charged and when it's dead) :

5 cell - 1400mah nimh receiver pack
7 cell - 1100mah nimh battery pack
8 cell - 2200mah nimh transmitter pack
8 cell - 700mAh nicad transmitter pack
6 cell - 1500mah nicad battery pack
7ah lead acid battery (for starter box)
1 cell - nicad glow plug igniter

Usually, I just charge everything at double whatever the mah rating is. Let me know if this is what you were asking me for.

Thanks!