I have 8 batteries with a 12 volt output. The device they are powering draws 57 ma. How do I figure out how long the device will run?
Battery life
Collapse
X
-
Tags: None
-
Re: Battery life
you need to know the capacity of the battery/s
Divide the energy storage capacity of the battery (watthours) by the battery voltage (volts) to get Ah (Amphours). Multiply by 1000 to get mAh.
then divide by 57
I think.Please upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740 -
Re: Battery life
Pretty much as selldoor says.
However, also consider the following.
It depends on the battery... if you mean car/motorbike batteries, those are about 13.5-14v when charge, and they're discharged completely at about 10v.
The device may need more current as the voltage drops and may use less current when the voltage is about 12v so it may not be a constant, linear discharge... just dividing the mAh by the device consumption won't give you the exact time.
This site: http://www.batteryshowdown.com/ has graphs with AA batteries discharging at 100mA and 1000mA
100mA : http://www.batteryshowdown.com/results-lo.html
1000mA : http://www.batteryshowdown.com/results-hi.html
If you scroll down to the table, you can click on whatever battery you want and see the discharge graph, and you can see the 1.2v battery is 1.4v new and discharges pretty much completely at 0.8vComment
-
Related Topics
Collapse
-
by sam_sam_samI have had with regular AA batteries that leak this meter is expensive new I already replaced the battery battery clips once and the same thing happened again and I am tried of so it is getting modified to accommodate lithium ion batteries that are the same size excluding the positive terminal and removing the battery clips I will have enough room for the BMS protection board
I going to put 3 lithium ion battery in parallel with the BMS protection board and a way to charge the battery externally and heat shrink the battery pack and use a JST connector so I easily remove the battery... -
by flat-eartherI have a cheap action camera with an annoying trait, every time I change batteries the date & time gets reset and I have to set it again.
To solve this problem I want to add a small internal battery inside it which will keep supplying power to the camera for a while while I change batteries so the date & time is retained.
I have opened the camera and I think there is enough room to add something inside to accomplish this:
The camera is powered by a 3.7V nominal single cell lithium ion battery.
So I need to connect another battery in... -
by huzoHi, so the old battery was getting error stated it's capacity is starting too get low and should be replaced, so the customer bought a new one and replaced it, but the new battery was also getting this notice that it's capacity is getting low and should be replaced, so i took the laptop for testing and the battery is charging at the terminal at 8.03V , the voltage of the battery is 7.7V, and drawing around 600mA when charger is put and the laptop is off...so that should be ok... but the bios system test doesn't recognize the battery and can't do the battery test and so is the hp battery manager,...
-
by trepachkaThis iPad was working fine except the battery was not holding charge for more than 40 minutes. I replaced it with a new battery. I haven't glued the battery yet, just inserted it into the slot and held it with battery screw.
The iPad was powered on with the new battery and I am getting white screen with Apple logo for about 10 seconds, then the screen turns dark. It then cycles like this forever.
I know the battery is working because the iPad continues to boot loop without the charger until it depletes to 0% and the message displays I need to plug in the charger.
... -
by sam_sam_samI bought a case of them the battery cells are made in China the charge curve looks decent for 1 amp charging rate there is also a BMS protection board which here is the website link to them
https://batteryhookup.com/collection...-lifepo4-cells
Here are more of the same but the difference is that they do not have the BMS protection boards but have the tabbing on them
https://batteryhookup.com/collection...o4-power-cells this is... - Loading...
- No more items.
Comment