Battery Calc for fire alarm wheelock sp40 and booster panel 162 total speakers @ 1/4w

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Ive been looking online for a battery calculator specific to the devices im installing. i have two dorms one with 96 speakers at 1/4watt and one with 66 speakers at 1/4 watt. i have a wheelock sp40 feeding audio signal to a wheelock booster that has two 80watt channels. i have the system set for 25v NOT 75v. i just failed my first inspection... i had 4x 12v 12amp/hr batteries in paralell series for the booster and only 2x 12v 12amp/hr batteries for my sp40 i was only getting 3.4dcv from my audio out on my sp40 and 8.6dcv to each of my audio cards on the booster panel. needless to say it was insufficent to produce any voice messages from any speaker in the system. i still had 24dcv powering each audio card and 24vdc to the sp40. so im confused as to why the output signal was so low and need help to figure out what i need to do to make these speakers work for 15min on battery power after 24hrs in standby on battery power.
 

jewellfish

Member
Location
Indiana
Battery calc spreadsheet for Wheelock can be found here: www.cooperindustries.com/content/dam/.../[FONT=arial, sans-serif]batterycalcs.xls[/FONT]

[FONT=arial, sans-serif]But you should have gotten some run time with the set up you describe. You would have to provide more info. Make sure you read the install manual thoroughly for those panels. They have many jumpers and dip switches that have to be set properly. Wheelock tech support is knowledgeable and will help troubleshoot your install.[/FONT]
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Ive been looking online for a battery calculator specific to the devices im installing. i have two dorms one with 96 speakers at 1/4watt and one with 66 speakers at 1/4 watt. i have a wheelock sp40 feeding audio signal to a wheelock booster that has two 80watt channels. i have the system set for 25v NOT 75v. i just failed my first inspection... i had 4x 12v 12amp/hr batteries in paralell series for the booster and only 2x 12v 12amp/hr batteries for my sp40 i was only getting 3.4dcv from my audio out on my sp40 and 8.6dcv to each of my audio cards on the booster panel. needless to say it was insufficent to produce any voice messages from any speaker in the system. i still had 24dcv powering each audio card and 24vdc to the sp40. so im confused as to why the output signal was so low and need help to figure out what i need to do to make these speakers work for 15min on battery power after 24hrs in standby on battery power.

jewelfish has a handle on the calcs, but why are you running at 25v instead of 70.7? That's gonna suck amps like crazy, not to mention limiting your distance due to voltage drop.
 

JohnCA

Member
Location
California
Your 96 speakers should draw on average (96 * 0.25 wat/peaker * 0.045Ma per watt) = 1.08 Amps
Then calculate your standby current and multiply by 24 hours
Then calculate your alarm current by adding the speaker draw and any power booster draw and multiply by 15 min (15/60)

Add both standby and alarm and you will have your your Ahr required.
Multiply that number by (1.2) derating factor and that would be the minimum battery size you should use.

This is the general idea, however like jewefish stated always follow the manufaturer instructions, they should have this in their manual or on their website.

John.

My journey towards NICET and PE certification
 
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