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Author Topic: Shack Battery  (Read 411 times)

KD8KCH

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Shack Battery
« on: February 18, 2020, 07:57:13 PM »

Wwhat are people's thoughts on using a pair of 6 volt battery for powering the shack radios. For some reason I am only getting about 2 years out of deep cycle batteries.

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K5LXP

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Re: Shack Battery
« Reply #1 on: February 18, 2020, 08:41:26 PM »

Wwhat are people's thoughts on using a pair of 6 volt battery for powering the shack radios.
It will work just fine electrically.  If they're flooded you will want to vent them somehow, if AGM they're OK indoors.

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For some reason I am only getting about 2 years out of deep cycle batteries.
That can be from self discharge, undercharging, to overcharging.  Generally you should be getting at least double that so I'd be reviewing how they're being charged and stored.

Mark K5LXP
Albuquerque, NM

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K6AER

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Re: Shack Battery
« Reply #2 on: February 18, 2020, 08:50:20 PM »

What kind of operation you place upon the batteries has a great deal to do with their life cycles.
A wet cell or a gel cell should not be discharged below 50% of their amp/hour rating. These batteries are made for high demand (car starting)  but have a limited charge cycle life expectancy.

Lithium batterie have a greater number of discharge cycles and will provide up to 2000 deep discharges down to 10% charge levels. The batteries are not cheap though. A 100 amp 12 volt lithium battery will run a bit north of $850. The good news are they are light as compared to a standard lead acid wet cell bqatttery.

I have witnessed new wet cell batteries that got completely discharge 3-5 times and no longer able to be recharged to specification. The plates sulfate and will not take a charge.

A good heavy duty wet cell is the 6 volt golf batteries. They still need proper care to last. Another good battery is the marine 12 volt trolling wet cells that have a 150 amp hour rating. You can buy these batteries at NAPA for about $95 each. I use four of them for my Solar station.

Don’t forget to use a good battery maintenance charger. One the provides an initial charge, maintanace  charge and a float charge. These chargers are available for under $50 depending how much charge time you can tolerate.
« Last Edit: February 18, 2020, 08:57:00 PM by K6AER »
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K2CMH

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Re: Shack Battery
« Reply #3 on: February 19, 2020, 04:09:22 AM »

>Don’t forget to use a good battery maintenance charger.

Would you happen to have some recommendations?
I have not been able to find any that are not RF noisy as heck.
One of the top recommended brands (Noco) pretty much wipes out the HF bands.
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K5LXP

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Re: Shack Battery
« Reply #4 on: February 19, 2020, 04:12:36 AM »

What kind of operation you place upon the batteries has a great deal to do with their life cycles.
True, but cycles don't run your stuff, amp hours do.  The cycles are secondary to Ah delivered.  The amp hours a given battery can potentially give over those life cycles the depth of discharge doesn't impact it as much as many believe.  A battery cycled to 80% DOD over its' life has less than a 10% difference in delivered Ah than one discharged to only 50% DOD.  It does mean you cross the finish line sooner but that comes down to a choice between twice as long or twice as fast.  The "50% Rule" is mostly a myth since even if you're only going by cycle life, you would have to be cycling your battery nearly every day, for years, before you'd come close to using up the cycle life even to 80% DOD.  Then, even if you managed to do that you just realized all the capacity the battery was able to give making it the most cost effective you can get.  Since there's a calendar life consideration and numerous other factors like stratification, partial state of discharge and various other impacts to service life you'd be doing well to use cycle life and delivered Ah up before the other effects take their toll.

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A wet cell or a gel cell should not be discharged below 50% of their amp/hour rating.
"Wet" implies several topologies.  The one that wouldn't deal with cyclic use is an automotive starting battery ("SLI") that you referenced.  Gel cells usually have pretty good cycle life but are more for standby service like UPS and emergency lighting applications.  Pretty good for ham radio too, since most hams don't cycle batteries very hard or very often.  Over the years I've always run the calendar out on the gel cells I end up with before I use them up. 

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A good heavy duty wet cell is the 6 volt golf batteries.
These are the best value in lead acid storage.  There are "better" batteries but they cost 2 or more times as much, so dollar per Ah they are a good deal.  Just need to pay attention to water levels but for the first few years they're pretty easy to keep up with.

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Don’t forget to use a good battery maintenance charger. One the provides an initial charge, maintanace  charge and a float charge.
Can't agree more.  One with a thermal sensor is even better, but having the proper finish and float voltages are very important to fully recovering the charge and maintaining it.  I have several here that I use but not at the same time I run the radios so at some point I'll have to see which ones are radio friendly.

Mark K5LXP
Albuquerque, NM
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DL4NO

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Re: Shack Battery
« Reply #5 on: February 19, 2020, 04:47:44 AM »

Wwhat are people's thoughts on using a pair of 6 volt battery for powering the shack radios. For some reason I am only getting about 2 years out of deep cycle batteries.

I have been quite happy with used AGM or other lead-gel batteries. But you need to take some measures to get 5 or more years of service from them:

  • The batteries should be fully charged nearly all of the time. Otherwise lead sulfate crystals grow that isolate the surfaces and crack the lead plates. Lead sulfate needs more space than the lead or lead oxide it is made from.
  • Under normal circumstances, only use 30% of the rated capacity or less. This also has to do with the space lead sulfate needs: The lead foam of the plates crumbles.
  • Get a charger that handles the batteries correctly. It must limit the charging current, have a correctly calculated absorption voltage (about 14.6 V) for a defined time (up to a few hours) and the reduce the maintaining voltage (about 13.8 V).
  • If your lead gel batteries are at least 3 years old, you should check the acid level. For a 7 Ah battery some 20 ml per cell of demineralised water should "disappear" in the gel. This often helps a lot! It is quite easy to open the cells. Beware of the acid!
  • You must definitely avoid any deep discharge. With quite light loads I normally stop at 11.8 V.

Avoid car batteries: They are intended to provide high currents for a few seconds, which translates to 2 Ah or so. Then they are recharged within minutes. If you use them this way they might last for 10 years or so. But they do not survive any other use cases.

BTW: I mostly use lead gel or ACM batteries I get more or less for free. In alarm systems, computer UPSs and so on they are replaced after 3 years of service. Especially if you use them in relatively low-current situations like a 100 W station with mostly reception, they are good for several more years of service.

I have nominally more that 300 Ah/12 V capacity that cost me about US$ 100. Let still have them half of the nominal capacity: For my batteries, 20 A is definitely a low-current application. It must be if I want to operate in an emergency.
« Last Edit: February 19, 2020, 04:49:57 AM by DL4NO »
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KD8KCH

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Re: Shack Battery
« Reply #6 on: February 19, 2020, 05:26:24 AM »

I ment to say Golf Cart battery, ( shouldn't try to type when tired) I had a Deltran battery tender + on the 1st one till it went bad then I got a Battery Minder that also de-sulfates and now 2 years and 1 month later 25 watt radio voltage drops to 12.4 volts on transmit. Guess I will give them a try.
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N2AYM

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Re: Shack Battery
« Reply #7 on: February 19, 2020, 05:42:32 AM »

>Don’t forget to use a good battery maintenance charger.

Would you happen to have some recommendations?
I have not been able to find any that are not RF noisy as heck.
One of the top recommended brands (Noco) pretty much wipes out the HF bands.

These are by far the very best battery chargers i have ever dealt with as far as
intelligent charging is concerned.

https://www.iotaengineering.com/dlsx.htm
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K7AAT

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Re: Shack Battery
« Reply #8 on: February 19, 2020, 07:34:49 AM »


I have two 50AH AGM batteries that are 10 years old.   They are float charged at 13.6V  24/7 by a MFJ 4225mv power supply.  I know my batteries are overdue for replacement but they still have most of their capacity.    Original Poster has something going on if he is only getting 2 years out of his batteries.
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KD8KCH

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Re: Shack Battery
« Reply #9 on: February 20, 2020, 12:35:18 PM »

Well it turned out to be a bad cell so a new battery and all is well.
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