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Author Topic: battery and charger or PSU with battery backup?  (Read 746 times)
NEVBEN
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Posts: 104




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« on: November 27, 2017, 09:35:47 AM »

I have a 2 meter base station that needs 12A to 14A (12 is measured, 14 is spec max.) for the transceiver when transmitting, and as much as 8A for an audio amplifier when receiving.  I want battery-backup operation in the event of AC power failure.  Which of the following should I use or is there a better alternative?

A. Astron R20A-BB, 12V 92Ah battery, MFJ4416B voltage booster
$139 + $179 + $169

or

B. Deltran Battery Tender, 12V 92Ah battery, MFJ4416B voltage booster,
$49 + $179 + $169


The difference is system A uses the Astron unless power fails, and the Astron trickle-charges the battery.  I have not been able to find if the Astron will go into float mode once the battery is charged.  Astron literature also indicates their standalone "BB" module will combine current from PSU and battery at peak demand, but I could not find an indication of whether their "BB" model PSU's do the same.

System B uses the battery's current supply for operations and the battery tender trickles and floats the battery in the background.  The advantage I see with this is much higher current for peak demand.  The battery could easily provide 40A for a time, whereas an Astron that can do that is too expensive.

Keep in mind this is 2 meter FM with very intermittent load.  This system runs 24/7 but on a typical day the squelch is only opened for a few minutes, and transmit is also measured in minutes.
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W9FIB
Member

Posts: 2103




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« Reply #1 on: November 29, 2017, 06:28:56 PM »

The battery booster is pretty much useless when you have a battery that is kept charged. That only helps if you run a battery low on voltage. But the trade off is to boost the voltage, it draws more current, which drains what's left in the battery even faster.

I run battery 24/7 on my station. Have 2 large AGM batteries in parallel. I can unplug the smart charger and receive with 2 radios (Icom 706mkII and a Yaesu FT-897) on all the time for a minimum of a week. Time varies depending on how much transmitting I do. No transmitting will give me almost 3 weeks of just receive.

Also note that chargers can be very noisy. You may need to put some bypass capacitors on the output. I use a combination of 0.1, 0.01, and 0.001 uF across the power leads to kill a lot of the noise.

I also have a large 12V power supply that I can use and bypass the batteries. Mostly if I am in a contest and want to maintain a full 13.8V to the rigs when doing a lot of transmitting. Plus I can always switch to the batteries with a flip of a switch if there were a power failure during the contest.

I would also note that I use a 4 Farad supercap to keep any current spikes from hitting my power supply output too hard. Have the same bypass caps like on the battery charger. The output to the rigs is also MOV protected. Same with the 120VAC input for the charger and power supply. Overkill? Yea. But I had the stuff to build it already, so I used it.

Long story short...invest in battery capacity, not boosters. Shop around for the battery. There are good deals to be had. I pay less for larger Ah batteries for my electric wheelchair which requires 2 12V AGMs.
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Happy being an Amateur Extra!
Nothing says CB on my printed license.
Ares/Races but no lights or crown vic.
NA4IT
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Posts: 51


WWW

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« Reply #2 on: November 30, 2017, 04:01:42 AM »

See http://www.qsl.net/na4it/ about halfway down the page... look for this...



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KD8IIC
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Posts: 667




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« Reply #3 on: November 30, 2017, 05:07:20 AM »

A) But minus the MFJ device. The battery is wired in parallel with the PS keeping it topped off.
The power supply will re-charge but not overcharge your battery.
I'm doing same but using a Samelex 1235m and Deep Cycle 35ah Life Line U1.
Will add a 2nd U1 battery later or a single group 24 Life Line deep cycle.
Obviously with the limitations of battery current vs time I'm restricted to QRP or a bit more.
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W9FIB
Member

Posts: 2103




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« Reply #4 on: November 30, 2017, 06:25:40 AM »

See http://www.qsl.net/na4it/ about halfway down the page... look for this...

Nice set up. Clean and easy!
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Happy being an Amateur Extra!
Nothing says CB on my printed license.
Ares/Races but no lights or crown vic.
N8FVJ
Member

Posts: 374




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« Reply #5 on: November 30, 2017, 08:07:37 AM »

I would prefer the Astron with battery backup.
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NEVBEN
Member

Posts: 104




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« Reply #6 on: November 30, 2017, 09:05:47 AM »

I bought the RS20A-BB for now.  I will add battery backup later.  The reason I thought of the MFJ booster is my familiarity with them from portable ops, but I see the point of them being unnecessary until the battery voltage drops considerably.  With the latest version of the booster, it is bypassed until the voltage drops sufficiently to need it.  Therefore, the loss of efficiency isn't a drawback until it is necessary.  So the only drawback with that version is the cost.  For the price of the booster, one could acquire significantly more battery capacity.

I considered using solar panels to maintain my battery voltage, I would probably only need a couple of "100W" panels that are more likely to deliver around 3A.  The AGM batteries can easily take a higher charge rate.  But I'm not willing to spend on solar immediately given how unlikely it is to have an extended power outage.  I'm on a reliable and also low demand part of the grid.  In the last 10 years, there have been fewer than as many outages.  Most are only an hour or two and the longest was only about 10 hours.

My next priority is to acquire battery capacity.  Presently I have three aged (4-7 yo) Group 34 AGM car batteries, and a broken Group 49.  I was using Die Hard Platinum/Odyssey (they had dual purpose in vehicles).  I will check out the Life Line.  I'm also looking at Mighty Max, NPP, Keyko and Trojan.  I'm not really familiar with this type of battery product yet where they are not also intended for high current demand (starting).  I'm really only familiar with Trojan but doubtful I want to pay as much as they cost.
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AC7CW
Member

Posts: 1004




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« Reply #7 on: December 02, 2017, 09:56:07 AM »

Solar backup, even at 100Watt panel, is comforting. I have that and a charge controller with even a usb output for charging various things. In an extended outage even if there is no gas for the car I can have minimal lighting, radio, AA battery charging, etc... It's fun to operate QRP solar powered anyhow, I can take the whole thing to the beach maybe next year, the battery is lightweight, 23Amps with a carry handle...

I've always operated from a battery and charger. The advantage is instant, simple, failproof, idiotproof switchover to battery power if the mains fail. The newer lipo batteries require charge management boards and all, less reliable because of all the extra electronics but lighter in weight.
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Novice 1958, 20WPM Extra now... (and get off my lawn)
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