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Author Topic: Which 12 VDC Heavy Duty Battery To Buy?  (Read 1279 times)
N3BQA
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Posts: 9




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« on: March 22, 2013, 12:51:45 PM »

I plan on purchasing a Kenwood TM-281 2 meter mobile rig. I would like to use this rig at home with a heavy duty battery. I was told to get a deep cycle marine battery. I just don't know what size battery in amps to get? Kenwood advises to use a power supply at 13.8 vdc at 14 amps if one is going to use the rig at the maximum output of 65 watts. I'm only going to use 25 watts at maximum.
Any suggestions on the type or make of battery to purchase? Should i purchase a battery with maximum amps?
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KE3WD
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« Reply #1 on: March 22, 2013, 02:56:21 PM »

You should also take into account what type of Battery Charging System you will be using, as that often will have a lot of impact on the size and type of battery used. 
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WB2WIK
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« Reply #2 on: March 22, 2013, 03:20:23 PM »

I'd want to know:

Do you intend to use a battery because you want to be "off grid" (so to speak) and not reliant on the AC mains?

Or, will the battery be charged daily, or continuously float charged by the AC mains?

That information is really required to make an informed decision about the battery.
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N7BMW
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« Reply #3 on: March 22, 2013, 05:10:57 PM »

There are three basic lead-acid battery types.  Liquid electrolyte, gelled electrolyte and absorbed glass mat.  LA, Gel and AGM.

Liquid acid is the most common, oldest and can take the most abuse. 

GELs and AGMs are sealed, valve regulated batteries meaning that they do not vent any gasses unless they are abused by overcharging.  Supposedly they can be discharged further than LA.  They are more expensive and are claimed to last longer than LA. 

I was a long time live aboard sailor. Among the sailing community many had disappointing results with GELs and AGMs.  I always went with LA and usually got 5-6 years out of a set.  That said, if you are planning to use this battery inside your home I suggest that you check with your insurance company or your building codes. 

If you get a LA battery get a marine battery box to go with it.  They are not expensive and have liquid tight bottoms in case of spills.  The most common deep cyccle batteries come by physical size.  Group 24 is the smallest, group 27 is next,  after those two sizes they get very large - too large to lift without help.  I suggest a LA group 27 deep cycle as the best alternative.  BUT be sure to be safe with it.  There is a lot of power, even in a "dead" battery if it is shorted.  Charging a LA causes hydrogen gas to be vented and hydrogen can explode if concentrated and triggered by a spark.  Charging AGMs and GELs require chargers specifically designed to prevent overcharging (and venting). 

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W5FYI
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« Reply #4 on: March 22, 2013, 10:42:01 PM »

Your question is like asking how much gasoline should you put in the tank of a new car; it depends. If the car is just going to sit in the driveway, you don't need any, but if you're planning a long trip, you'd probably want the tank full.

The battery depends on how you intend to use the radio. Will it be on all day and night, or just during the evening nets, or just for emergency use when the power goes out? You also need to figure out your talk-to-listen ratio, since talking will require around 3 amps while listening should require a lot less. It takes a lot of calculating.

From the practical standpoint, I'd go for the highest amperage I could afford for a home installation, and work down from there. For field use, I'd consider a lithium battery because of its weight advantage. For emergency power-outage duty, I'd go for the highest amperage again, because I know I'd be running a BC band radio or small TV off it as well, and maybe a small electric fan if needed. Like the car analogy, you're probably better prepared for anything if you had the gas tank full. GL
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K1CJS
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« Reply #5 on: March 23, 2013, 05:04:58 AM »

I plan on purchasing a Kenwood TM-281 2 meter mobile rig. I would like to use this rig at home with a heavy duty battery. I was told to get a deep cycle marine battery. I just don't know what size battery in amps to get? Kenwood advises to use a power supply at 13.8 vdc at 14 amps if one is going to use the rig at the maximum output of 65 watts. I'm only going to use 25 watts at maximum.
Any suggestions on the type or make of battery to purchase? Should i purchase a battery with maximum amps?

A battery will not power the rig to it's maximum advantage, since it will supply only about 12.5 volts.  It won't do so even if you're not going to use full output power.  What you really want is a good power supply which will cost you about the same and will supply 13.6 volts continuously.

Is it that you want to be able to use the rig if the power fails?  A small garden tractor battery would do fine to do that--if it were topped off regularly.  Or do you want to do emergency communications with a group for a longer time period?  To do that you will need a larger battery.

We need to know what the purpose and the expected duration of use is to be able to give you any sort of a useful answer.  Please respond and provide that.  73!
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NA0AA
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Posts: 1042




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« Reply #6 on: March 23, 2013, 08:01:37 PM »

Well, at one shack, I have a 100 amp/hour AGM deep cycle battery, at this one, I have two 33 amp hour AGM's in parallel - mine run connected to a 13.8 volt regulated power supply so provide 100% backup power to the 12 volt bus.

The 100 amp hour battery ran an all 12 volt shack for a good 8 hours unless you are a real big talker - that included dual band FM, 220 FM, HF radio, audio mixing box, and desk LED illumination, scanner, tuners, and other misc. accessories.


Here, my primary radio is 120 VAC only, so this 66 amp/hour battery runs a couple of scanners, and a dual band FM radio.  Should work for days, but our power almost never goes off out here.

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