Need battery back-up for a portable repeater (GM300 with RICK) that would fit inside a 1650 series pelican case.
Max draw would be 12amps provided by a lightweight switching supply.
Obviously AC is the primary power to the supply but I'd like something to kick in if the power barfs.
Was thinking of a small PC UPS.
battery back-up for a portable repeater?
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apco25
- Posts: 2685
- Joined: Tue Oct 30, 2001 4:00 pm
- What radios do you own?: APX / Astro 25 / Harris
battery back-up for a portable repeater?
"Some men just don't know their limitations"
How long are you wanting to operate on backup power?
Are planning on preserving the integrity of the case? (gonna run with the case open or closed?)
I would remove the guts from an ups and use a coupla of 12 volt gel cells wired in parrallel. Would also consider a external power coupler for 12 volts to be able to hook up to batteries or a running vehicle.
Strap the batteries down on each end of the case and put the repeater in the middle.
Are planning on preserving the integrity of the case? (gonna run with the case open or closed?)
I would remove the guts from an ups and use a coupla of 12 volt gel cells wired in parrallel. Would also consider a external power coupler for 12 volts to be able to hook up to batteries or a running vehicle.
Strap the batteries down on each end of the case and put the repeater in the middle.
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apco25
- Posts: 2685
- Joined: Tue Oct 30, 2001 4:00 pm
- What radios do you own?: APX / Astro 25 / Harris
I'd like to run the case closed if the need came up such as tossing on top of a tall building in pinch.
Length of operation on batteries is directly related to how heavy its going to be. Not sure on that one.
I was thinking gell cells - already got a nice trickler charger that swaps over to battery when AC power is lost.
Length of operation on batteries is directly related to how heavy its going to be. Not sure on that one.
I was thinking gell cells - already got a nice trickler charger that swaps over to battery when AC power is lost.
"Some men just don't know their limitations"
Here is an article that a Motorola tech passed on to me when I was trying to figure out run times and battery size. I hope this helps
The Amateur Engineer…...Battery Backup
Radio communication equipment is dependent on commercial power. If this power is interrupted, the customer’s communication system goes down right along with it. For many users, such as police and public utilities, this is an unacceptable situation. It is, however, an easily avoidable one. By providing battery backup for a radio system you enable the user to communicate during temporary power outages. To supply your customer with a back up power source, follow the steps below.
First determine the average current drawn by all equipment to be provided with emergency power. To do this you will need to find the DC current drain during transmit, receive, and stand-by operation. This information is typically supplied on the product’s R3 sheet.
Next you will need to determine the equipment’s duty cycle, i.e. the percentage of time the equipment spends in each mode of operation. Duty cycle is expressed as a series of three percentages: % Transmit, % Receive, % Stand-By. Most base station applications have a duty cycle of 5%, 5%, and 90%. Since some users have different requirements (e.g. police departments, ambulance services, and others) you should discuss your customer’s usage habits before making any assumptions.
With the information above you can calculate the average DC current required by your equipment.
IAVE = (ITX) (.05) + (IRX) (.05) + (ISB) (.90)
Where I is the DC current required during transmit (TX), receive (RX), and Stand-BY (SB) operation. The above is for a 5%, 5%, 90% duty cycle. If your customer requires a different duty cycle, remember to change the percentages in the above equation.
To determine the battery size required multiply the average current by the number of hours of back up power required.
Battery Size+ (IAVE) (Hours of back up power required)
Nicad batteries for use as emergency back up power supplies are in Sec 2.2, Pg 2 of the price book. The size of the batteries is given in amp hours, the same units as the battery size you have just calculated. Select a battery from the price book that has at least the same amp hour rating as your system requires. As the batteries are made of individual cells, a rack must be provided to hold them. Appropriately sized racks are grouped with each size range of batteries. The length of each rack is indicated next to its part number. The other dimensions are 7” wide by 22” high for the single step configuration and 14” wide by 28” high for the double step configuration.
The battery back up supply you have just developed may be used with any station equipped with the battery revert option. This option provides the power supply to charge the batteries and a circuit that will automatically switch the radio from commercial power to battery power when it senses an interruption in the commercial supply. If your customer’s radio is not equipped with the battery revert option, the option can often be added in the field. If your station does not list a battery revert option, please call us and we’ll help you find a solution.
The Amateur Engineer…...Battery Backup
Radio communication equipment is dependent on commercial power. If this power is interrupted, the customer’s communication system goes down right along with it. For many users, such as police and public utilities, this is an unacceptable situation. It is, however, an easily avoidable one. By providing battery backup for a radio system you enable the user to communicate during temporary power outages. To supply your customer with a back up power source, follow the steps below.
First determine the average current drawn by all equipment to be provided with emergency power. To do this you will need to find the DC current drain during transmit, receive, and stand-by operation. This information is typically supplied on the product’s R3 sheet.
Next you will need to determine the equipment’s duty cycle, i.e. the percentage of time the equipment spends in each mode of operation. Duty cycle is expressed as a series of three percentages: % Transmit, % Receive, % Stand-By. Most base station applications have a duty cycle of 5%, 5%, and 90%. Since some users have different requirements (e.g. police departments, ambulance services, and others) you should discuss your customer’s usage habits before making any assumptions.
With the information above you can calculate the average DC current required by your equipment.
IAVE = (ITX) (.05) + (IRX) (.05) + (ISB) (.90)
Where I is the DC current required during transmit (TX), receive (RX), and Stand-BY (SB) operation. The above is for a 5%, 5%, 90% duty cycle. If your customer requires a different duty cycle, remember to change the percentages in the above equation.
To determine the battery size required multiply the average current by the number of hours of back up power required.
Battery Size+ (IAVE) (Hours of back up power required)
Nicad batteries for use as emergency back up power supplies are in Sec 2.2, Pg 2 of the price book. The size of the batteries is given in amp hours, the same units as the battery size you have just calculated. Select a battery from the price book that has at least the same amp hour rating as your system requires. As the batteries are made of individual cells, a rack must be provided to hold them. Appropriately sized racks are grouped with each size range of batteries. The length of each rack is indicated next to its part number. The other dimensions are 7” wide by 22” high for the single step configuration and 14” wide by 28” high for the double step configuration.
The battery back up supply you have just developed may be used with any station equipped with the battery revert option. This option provides the power supply to charge the batteries and a circuit that will automatically switch the radio from commercial power to battery power when it senses an interruption in the commercial supply. If your customer’s radio is not equipped with the battery revert option, the option can often be added in the field. If your station does not list a battery revert option, please call us and we’ll help you find a solution.
How long was power out last week? That should be a max hint!
Ours are setup for at least 8 hrs at 50% duty cycle, but have a reduced current on standby to less than .4 amps. On a 7 watt R1225 chassis only, (no display or control "head) a 37 ahr battery goes the distance. Use a flodded gell cell with safety valving so it wont get fumes in the case.
Two radios and a RICK will draw quite a bit more on standby. You can disable the audio output stages in each radio and disable the displays to help get the current down. The RICK draws a bit too.
Ours are setup for at least 8 hrs at 50% duty cycle, but have a reduced current on standby to less than .4 amps. On a 7 watt R1225 chassis only, (no display or control "head) a 37 ahr battery goes the distance. Use a flodded gell cell with safety valving so it wont get fumes in the case.
Two radios and a RICK will draw quite a bit more on standby. You can disable the audio output stages in each radio and disable the displays to help get the current down. The RICK draws a bit too.
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RapidCharger
- Posts: 611
- Joined: Thu Apr 10, 2003 5:11 pm
A well established ham / retired RF engineer in my area uses a vehicle jumpstarter rechargable battery pack that you find in discount stores for $29. He uses this as his PRIMARY power! He claims to get 6 hours from it running his 2m radio at 60 watts. Simply plugs it in every now and then for a charge with the AC. I suppose everyone is going to have their own preferences but he has good luck with it.
Obviously, if you buy an extra one and keep it charged for the next blackout and you got 12 hours of power for $60 and a handy vehicle jumpstarter kit when not in use! Sounds pretty clever if you ask me. Especially since you can get 18 hours of power for under $100.
And, it eliminates the need for that powersupply with the 2 sets of connectors on it to plug your gm300's into... That is if you use it as a primary.
Obviously, if you buy an extra one and keep it charged for the next blackout and you got 12 hours of power for $60 and a handy vehicle jumpstarter kit when not in use! Sounds pretty clever if you ask me. Especially since you can get 18 hours of power for under $100.
And, it eliminates the need for that powersupply with the 2 sets of connectors on it to plug your gm300's into... That is if you use it as a primary.
Key Word Is Portable
Well without knowing the Duty cycle then
It is a bit harder to do the math.
Most "Jump Start"units are 17AH
Batteries.We Like the 70AH Battery.
( Most Important -Deep Cycle Only)
A Radio At 13.8 Volts and 40 watts tx
is about 27 Watts At 12 volts with a
stand-alone Battery.
We call a gm300 40 watt repeater
a back-up or mobile "BUT"
( I do remember someone saying
portable.)
Good luck with the project.
I am glad that I will not be carrying
the portable battery to the rooftop.
With the recent power outage in the NE here, I had to revert to battery back-up for both my 800 mhz mSF5K's. Since we lease out tower facilities
they do not provide any generator service, and all of our city generators were hard at work, I had the option of grabbing two 1400 amp Bus/Firetruck batteries, making a quick disconnect from a jump start kit, and with the help of one master mechanic, drag the two batts. to the tower and connect them to the two rptrs. The antenna system uses tower top rx preamps, and multicoupler preamps, so had to drag a power line to the duplexer shack and make power connection to the preamps from the batts.
We were back on the air in less than 1/2hour. Although dispatch had to work by portable, due to the power of the phone line going out, each batt ran the system for 53 hours without a glitch. I still had over 600 amps reserve left in each batt, and a voltage drop of only .14 volts when we returned to comercial power on Saturday.
Should this happen again, it will be a "plug and Play" system .
Jimmy
they do not provide any generator service, and all of our city generators were hard at work, I had the option of grabbing two 1400 amp Bus/Firetruck batteries, making a quick disconnect from a jump start kit, and with the help of one master mechanic, drag the two batts. to the tower and connect them to the two rptrs. The antenna system uses tower top rx preamps, and multicoupler preamps, so had to drag a power line to the duplexer shack and make power connection to the preamps from the batts.
We were back on the air in less than 1/2hour. Although dispatch had to work by portable, due to the power of the phone line going out, each batt ran the system for 53 hours without a glitch. I still had over 600 amps reserve left in each batt, and a voltage drop of only .14 volts when we returned to comercial power on Saturday.
Should this happen again, it will be a "plug and Play" system .
Jimmy
Best thing I ever did was add a battery backup to all my systems. I use a GR500 repeater - added a car battery as battery backup - lasted the 24 hrs I was without power! Not even a slight decrease in power!
Jay Goldmark, EMT
Ex-Captain, Woodmere Vol. Fire Dept.
Fire District Communications Supv.
KC2ZHI Amateur Radio Operator
Licensed Master Electrician
Owner, Top Class Electric, LLC.
Woodmere, Long Island, NY
"Enjoy Life, it's not a dress rehearsal !!!"
************************************************************
Ex-Captain, Woodmere Vol. Fire Dept.
Fire District Communications Supv.
KC2ZHI Amateur Radio Operator
Licensed Master Electrician
Owner, Top Class Electric, LLC.
Woodmere, Long Island, NY
"Enjoy Life, it's not a dress rehearsal !!!"
************************************************************
I vote for the yellow-top Optima battery. I don't know how large the case is that you are using, but the Optima is the size of the average American car battery.
These things are indestructable. They also "come back" if run dead then the load is removed. They are deep-cycle rated, so they can cycle LOW without harm.
These things are indestructable. They also "come back" if run dead then the load is removed. They are deep-cycle rated, so they can cycle LOW without harm.
Deep Cycle For The Long Haul
For the long haul you should compare deep cycle batteries
to lead acid batteries. We were sold on deep cycle.
From The Great White North (Canada I Mean)
Susan157