What battery to use?
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Hi guys,
I am gearing up for a portable station for emergency communications and have decided to use my K2/100 and KAT100 combo. I want to be able to power it with batteries, if the need arises. Have any of you "high tech" Elecrafters used a battery to power a K2/100? I don't know whether to chose a deep-discharge marine, an SLA/gel cell or AGM battery. Let's not beat this horse to death, but I would like some help on what the best choice would be. I've been thinking about using something on the order of a 50-60 Ahr size. 73, Mark Baugh W5EZY Grenada MS ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Mark wrote:
>I am gearing up for a portable station for emergency >communications and have decided to use my K2/100 and >KAT100 combo. I want to be able to power it with >batteries, if the need arises...I've been thinking about using >something on the order of a 50-60 Ahr size. I've been playing around with portable HF gear at campsites for 25 years. My only QRO rig for such use is a TS-50S running about the same power as the K2/100. I won't speculate on other battery technologies, but I'll just say I've found deep-discharge batteries to work fine as long as they are periodically well discharged and re-charged (about every 90 days or so). At the very least, they need to be put on charge once or more during the same interval even if they've been sitting unconnected. Even for short camping trips less than a week long with casual HF operations, I've found it best to choose the highest amp-hour capacity battery that you can find and easily move around (something about 100 amp-hours or better). I think you'll find the 50 to 60 amp-hour capacity you mention to be too low, even for short trips portable, but especially for stationary emergency use. I don't know how the K2 is, but for many solid state QRO rigs the various bandswitch and control relay switching circuits are the first things to falter as the battery voltage drops from the 12.6 vdc max that you'll have when the battery is at full charge. Low source voltage combined with voltage drop in the solid-state relay coil switching circuits (at least 0.7 vdc) can result in coil voltage that is too low to reliably operate the relays. I had one rig that wouldn't function much below about 11.0 volts due to that effect. Under transmit loads on the battery and with the voltage drop in the power cables, 11 vdc at the rig happens a lot sooner than you'd think for a QRO rig. Since you'll be starting with a relatively low 12.6 vdc, you'll want to use the shortest and heaviest wire that's practical for the power cables. I think you've got a great idea about preparing your station to operate at a power output level that is conducive to reliable communications. Any HF station truely intended to function for emergency communications should be capable of 100 watts output at least. QRP is a great hobby mode that tests the proficiency and equipment of the operator at the other end, but it has no place in serious emergency communications planning except as a very last resort. BTW, I've been able to operate for a week a 100 watt HF rig (SSB and CW) a few hours a day, and as a shortwave receiver for several times that, while camping in the boonies. I still had plenty of energy left in the deep-discharge battery I took, which was rated for 105 amp-hours. I also was using that battery to feed a 50 watt 2m FM rig and a scanner radio, and to feed a small electric light. It's really surprising how much service can be gotten from one charge from a decent-sized battery. I've had a 400 watt 12vdc/120vac portable gas-powered generator for 20 years but I've never needed to run it to re-charge the battery on any trip. The nice thing about these high capacity deep discharge batteries is that, compared to the price of typical handy-talkie battery packs, they are dirt cheap. I keep a couple charged at all times. 73, Mike / KK5F _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Mark - W5EZY
Something to keep in mind when you desire your battery to have a
relatively long life. Taking out 50% of the capacity will, in general, seriously shorten a battery's life as compared to only drawing it down to 80%. Most renewable energy systems shoot for the 70 - 80% mark. Since we're talking emergency battery operation here, it can be assumed that you'll likely be drawing the batteries down quite a bit before a recharge. Higher capacity batteries are always better - other than in size & weight. My suggestion is to do this right. Don't use any kind of flooded battery (with removable caps to add water), or "maintenance-free" flooded batteries - same internally but you can't add water. True maintenance-free batteries are either gel or AGM. Gel batteries can supposedly handle really deep discharges better, but I wouldn't worry about that. Good AGM batteries beat gel in every other respect. Some manufacturer's charts show more discharge-charge cycles for their gel than competitor's AGMs, but from what I've heard in real-world scenarios, AGMs are more robust and actually hold up longer. Concorde AGM batteries came out clearly as the best AGM in the months of on-line research I did when recommending new batteries for work, and their price was comparable to anything else out there. No relation, but http://thesolar.biz/Concorde_Battery.htm has one of the best prices out there for the 100 and 105 Ah Concorde batteries. Hope this helps a little. -- 73, Mike Boice, KW1ND Karns, TN Behold the power of the penguin Reclaim Your Inbox! http://www.mozilla.org/products/thunderbird/ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Mark - W5EZY
In a message dated 15/07/05 15:37:09 GMT Daylight Time, [hidden email] writes: I had one rig that wouldn't function much below about 11.0 volts due to that effect. Under transmit loads on the battery and with the voltage drop in the power cables, 11 vdc at the rig happens a lot sooner than you'd think for a QRO rig. Reply: ---------------------------------------- The basic K2 at least seems a lot more tolerant than most radios with an operating voltage range quoted in the specifications from 9 to 15VDC. An Icom IC-706 mkII I have will not work below 11.75VDC as the PLL section voltage regulator goes out of regulation below this point causing severe FM on the TX signal. With a 12V lead acid type battery it is unwise to expect too much life left available when the voltage measured directly at the battery is approaching 11V as the droop in voltage starts to accelerate at that point. Most comm systems that I worked on with lead acid battery plant are usually set to disconnect the batteries at 1.75V per cell or 10.75V with a 12V system to prevent permanent damage to the batteries. Even if they did not take this action the available battery charge would not last too long in any case. Bob, G3VVT _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Mike Morrow-3
i also used a 84 ah,,,, for field day k2/100... with a 50 watt solar panel...
at night it dropped to 11.4 before the panel brought it back to 12.4 the next morning after the sun hit the panel for a few hours... it was slowing climbing up.... this was a gota station,.,,,so xmt duty cycle was slow... bill. At 09:19 AM 7/15/2005, Mike Morrow wrote: >Mark wrote: > > >I am gearing up for a portable station for emergency > >communications and have decided to use my K2/100 and > >KAT100 combo. I want to be able to power it with > >batteries, if the need arises...I've been thinking about using > >something on the order of a 50-60 Ahr size. > > >I've been playing around with portable HF gear at campsites for 25 years. >My only QRO rig for such use is a TS-50S running about the same power as the >K2/100. > >I won't speculate on other battery technologies, but I'll just say I've >found deep-discharge batteries to work fine as long as they are periodically >well discharged and re-charged (about every 90 days or so). At the very >least, they need to be put on charge once or more during the same interval >even if they've been sitting unconnected. > >Even for short camping trips less than a week long with casual HF >operations, I've found it best to choose the highest amp-hour capacity >battery that you can find and easily move around (something about 100 >amp-hours or better). I think you'll find the 50 to 60 amp-hour capacity >you mention to be too low, even for short trips portable, but especially for >stationary emergency use. > >I don't know how the K2 is, but for many solid state QRO rigs the various >bandswitch and control relay switching circuits are the first things to >falter as the battery voltage drops from the 12.6 vdc max that you'll have >when the battery is at full charge. Low source voltage combined with >voltage drop in the solid-state relay coil switching circuits (at least 0.7 >vdc) can result in coil voltage that is too low to reliably operate the >relays. I had one rig that wouldn't function much below about 11.0 volts >due to that effect. Under transmit loads on the battery and with the >voltage drop in the power cables, 11 vdc at the rig happens a lot sooner >than you'd think for a QRO rig. Since you'll be starting with a relatively >low 12.6 vdc, you'll want to use the shortest and heaviest wire that's >practical for the power cables. > >I think you've got a great idea about preparing your station to operate at a >power output level that is conducive to reliable communications. Any HF >station truely intended to function for emergency communications should be >capable of 100 watts output at least. QRP is a great hobby mode that tests >the proficiency and equipment of the operator at the other end, but it has >no place in serious emergency communications planning except as a very last >resort. > >BTW, I've been able to operate for a week a 100 watt HF rig (SSB and CW) a >few hours a day, and as a shortwave receiver for several times that, while >camping in the boonies. I still had plenty of energy left in the >deep-discharge battery I took, which was rated for 105 amp-hours. I also >was using that battery to feed a 50 watt 2m FM rig and a scanner radio, and >to feed a small electric light. It's really surprising how much service can >be gotten from one charge from a decent-sized battery. I've had a 400 watt >12vdc/120vac portable gas-powered generator for 20 years but I've never >needed to run it to re-charge the battery on any trip. > >The nice thing about these high capacity deep discharge batteries is that, >compared to the price of typical handy-talkie battery packs, they are dirt >cheap. I keep a couple charged at all times. > >73, >Mike / KK5F > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Mark - W5EZY
Mark,
I used the batteries from my boat for field for my K2/100. They are deep discharge marine/RV batteries, one about 60 AH and the other about 80 AH. I also use an old car battery in the shack which I keep on float at 13.8 volts. Some comments. The K2 which will work at lower voltages, down to 10.5 volts. Don't try it with some other rigs, which do not work well at the lower voltages. The AH capacity is less at a higher load, so a battery nearly discharged will work well on receive, but will not support transmit. I removed the car battery from my car as it wouldn't start it. I cleaned it up and it has a lot of life left as a battery for ham radio use. Car batteries are designed for high starting current and are nrmally kept fully charged by the car alternator, as opposed to operating at long periods at partial charge like the deep discharge batteries. Look around for a used car battery, clean it up, and it will probably last another few years powering your K2/100. Just keep it floating when you have power available. Being old, it will self discharge faster than a new one, but you won't notice that effect during a few hours of operation powering the K2/100. In the emergency communication use, a new deep discharge battery is best. Keep it floating with a small charger or place it in parallel with a 13.8 v low current power supply. I use a 6 amp 13.8 volt power supply in parallel with the old car battery with the rig connected directly to the battery. When the rig wants more current on transmitt, it takes it from the battery. I use a 20 amp fuse between the power supply and battery, and have never blown it. Some recommend a low ohm resistor in addition to the fuse. A 40 watt 115 volt light bulb would work. I just never found it necessary. GL 73, Chas, W1CG At 09:32 AM 7/15/2005, Mark Baugh wrote: >Hi guys, >I am gearing up for a portable station for emergency >communications and have decided to use my K2/100 and >KAT100 combo. I want to be able to power it with >batteries, if the need arises. Have any of you "high >tech" Elecrafters used a battery to power a K2/100? I >don't know whether to chose a deep-discharge marine, >an SLA/gel cell or AGM battery. Let's not beat this >horse to death, but I would like some help on what the >best choice would be. I've been thinking about using >something on the order of a 50-60 Ahr size. > >73, >Mark Baugh >W5EZY >Grenada MS > > > >____________________________________________________ >Start your day with Yahoo! - make it your home page >http://www.yahoo.com/r/hs > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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