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Guest

Mon Jul 30, 2018 10:45 pm

I am looking for a formula for calculating the run time of my APC battery system.

I did a search but what I found required a particular model of apc.

Total watts of computer and monitor is about 120 watts.

Battery in my apc is 12V 18 Ah

Thanks,

Andy

Guest

Tue Jul 31, 2018 12:45 am

In article <40ce16a5-b9e3-41ff-8be5-b2b8aa861b42_at_googlegroups.com>,

andrewkennedy775_at_gmail.com says...

I am looking for a formula for calculating the run time of my APC battery system.

I did a search but what I found required a particular model of apc.

Total watts of computer and monitor is about 120 watts.

Battery in my apc is 12V 18 Ah

Thanks,

Andy

Simple except for one missing piece of info. How efficent is the system

?

The Ah (amps the battery can put out for one hour). As Amps and voltage

equals watts, your battery is rated for 12 times 18 or 216 watts for one

hour. So you get 216 devided by 120 or 1.8 hours. Then multiply by the

efficency (loss of the system) that is unknown, but 50 to 80 percent

would be inthe ball park. So at 50 % you get half of the 1.8 hours or

..9 hour.

All that is provided the battery can put out enough current to last that

long. Often the more current the battery is required to put out, the

less time it will last.

Guest

Tue Jul 31, 2018 3:45 am

On Monday, July 30, 2018 at 6:41:01 PM UTC-5, Ralph Mowery wrote:

In article <40ce16a5-b9e3-41ff-8be5-b2b8aa861b42_at_googlegroups.com>,

andrewkennedy775_at_gmail.com says...

I am looking for a formula for calculating the run time of my APC battery system.

I did a search but what I found required a particular model of apc.

Total watts of computer and monitor is about 120 watts.

Battery in my apc is 12V 18 Ah

Thanks,

Andy

Simple except for one missing piece of info. How efficent is the system

?

The Ah (amps the battery can put out for one hour). As Amps and voltage

equals watts, your battery is rated for 12 times 18 or 216 watts for one

hour. So you get 216 devided by 120 or 1.8 hours. Then multiply by the

efficency (loss of the system) that is unknown, but 50 to 80 percent

would be inthe ball park. So at 50 % you get half of the 1.8 hours or

.9 hour.

All that is provided the battery can put out enough current to last that

long. Often the more current the battery is required to put out, the

less time it will last.

andrewkennedy775_at_gmail.com says...

I am looking for a formula for calculating the run time of my APC battery system.

I did a search but what I found required a particular model of apc.

Total watts of computer and monitor is about 120 watts.

Battery in my apc is 12V 18 Ah

Thanks,

Andy

Simple except for one missing piece of info. How efficent is the system

?

The Ah (amps the battery can put out for one hour). As Amps and voltage

equals watts, your battery is rated for 12 times 18 or 216 watts for one

hour. So you get 216 devided by 120 or 1.8 hours. Then multiply by the

efficency (loss of the system) that is unknown, but 50 to 80 percent

would be inthe ball park. So at 50 % you get half of the 1.8 hours or

.9 hour.

All that is provided the battery can put out enough current to last that

long. Often the more current the battery is required to put out, the

less time it will last.

Thanks.

It ran for an hour just on the battery backup.

It said I had around 15 mins left when I went back to A.C. power.

Andy

Guest

Tue Jul 31, 2018 12:45 pm

On 07/30/2018 07:40 PM, Ralph Mowery wrote:

In article <40ce16a5-b9e3-41ff-8be5-b2b8aa861b42_at_googlegroups.com>,

andrewkennedy775_at_gmail.com says...

I am looking for a formula for calculating the run time of my APC battery system.

I did a search but what I found required a particular model of apc.

Total watts of computer and monitor is about 120 watts.

Battery in my apc is 12V 18 Ah

Thanks,

Andy

Simple except for one missing piece of info. How efficent is the system

?

The Ah (amps the battery can put out for one hour). As Amps and voltage

equals watts, your battery is rated for 12 times 18 or 216 watts for one

hour. So you get 216 devided by 120 or 1.8 hours. Then multiply by the

efficency (loss of the system) that is unknown, but 50 to 80 percent

would be inthe ball park. So at 50 % you get half of the 1.8 hours or

..9 hour.

All that is provided the battery can put out enough current to last that

long. Often the more current the battery is required to put out, the

less time it will last.

andrewkennedy775_at_gmail.com says...

I am looking for a formula for calculating the run time of my APC battery system.

I did a search but what I found required a particular model of apc.

Total watts of computer and monitor is about 120 watts.

Battery in my apc is 12V 18 Ah

Thanks,

Andy

Simple except for one missing piece of info. How efficent is the system

?

The Ah (amps the battery can put out for one hour). As Amps and voltage

equals watts, your battery is rated for 12 times 18 or 216 watts for one

hour. So you get 216 devided by 120 or 1.8 hours. Then multiply by the

efficency (loss of the system) that is unknown, but 50 to 80 percent

would be inthe ball park. So at 50 % you get half of the 1.8 hours or

..9 hour.

All that is provided the battery can put out enough current to last that

long. Often the more current the battery is required to put out, the

less time it will last.

UPS batteries have to provide the magnetizing current for the big iron

transformer, so battery life is disappointing at light loads. Nowhere

near as good as a DC-DC converter.

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal Consultant

ElectroOptical Innovations LLC

Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203

Briarcliff Manor NY 10510

hobbs at electrooptical dot net

http://electrooptical.net

elektroda.net NewsGroups Forum Index - Electronic for beginners - **Formula for calculating run time of apc ?**