++++++++++++++++++++++ See Also K2_Battery_Charging ++++++++++++++++++++++ Date: Thu, 12 Apr 2001 23:44:46 -0600 From: Kevin Ferguson Subject: Re:[Elecraft] NiMh Batteries > > > NiMH cells get extremely hot if > you continue charging at rates above C/10 {rated capacity in Ma divided by >10} after they have peaked. Safe if solar cell capacity does not exceed this [Kevin Ferguson] The same is true of NiCads. BTW, both NiMH and NiCad may be routinely discharged to near 0% capacity without degradation. Any type (even deep discharge) of lead acid has trouble if routinely discharged below 50%. So if you routinely run your batteries down, then SLA weighs about 2X NiCad, and 3X NiMH for same "long term useful capacity". A _single_ NiMH or NiCad cell may be safely sischarged to zero volts. The problem comes with series strings, where the first cell to discharge may be _reverse_ charged by the others in the string...that can be bad, and is the reason that cells are matched for capacity in high performance applications (much as elecraft sorts the xtals for our rigs). I actually had to take large amounts of experimental data on SLA batteries at a previous job. The manufacturers say that discharge should not proceed below 10.5 V (for a 12 nominal Volt battery). According to my measurements, the battery was about 95% discharged when it got down that far. If you routinely discharge to such low voltage, you should anticipate that the battery will have reduced life. The downside is that Neither NiMH nor NiCAD likes "float" service (continual charge) Also, Lead-acid is better suited to Solar applications as its power-out/power-in effiency is much higher than other common types. NiMH are great if you can charge them from AC line just before use (or a day or two)...but they have an even higher self-discharge than LA If you like SLA batterys, you can do much better than the commonly available Power-Sonic gell cells. (Sonnenschein are nearly as bad a P-S, but venting is more reliable, IME)Panasonic, and Eagle-Pitcher both make "starved electrolyte" versions of the popular gell-cell batteries. These offer a lot of advantages....higher permissable charge& discharge rates, No "break in" needed. ~20% more capacity, Less likely to leak acid on over-charge (not theory, but personal experience talking here) The Gates cells, and large (car sized) Optima & Concord batteries are other examples of starved-electrolyte technology. Starved electrolyte is still Lead-acid chemestry, but with a couple of twists in the way it is done...especially WRT gelled-electrolyte construction. If there is interest, I can eleaborate on this. 73-ko0b ++++++++++++++++++++++++++++++++++++++++++++++++ Date: Wed, 16 May 2001 21:35:17 -0100 From: "Julian" Subject: Re: [Elecraft] Automatic charger for SLA's I doubt if that product is available to me. However, Maplin has a "12V Constant Voltage SLA Battery Charger" which has an output voltage quoted as "Float 13.8V +/- 0.2V". I presume, though, that it is intended to be connected directly to the battery and that the current limiting resistor and reverse polarity protection that the charge current would encounter if it were connected to the normal K2 DC socket would interfere with operation. I suppose I could do as you have done and find a suitable socket that fits one of the transverter interface holes and make a direct connection to the battery. I always held out the hope that one day those holes would be used for their intended purpose... - -- Julian, G4ILO http://www.qsl.net/g4ilo ==== Original message ==== > Power Sonic manufactures an automatic wall charger, the PS12500A you can > buy from Mouser and others. Just don't keep the battery on charge with > the > K2 in receive, because the K2 receive current fools the automatic > charger > into thinking the battery is not fully charges and will ultimately > overcharge it. Also, it has some hum if you connect it to the K2 power > input, so I used a spare hole in the top cover and mounted a DC > connector > connected to the battery through a fuse. Works fine. > > > > 73, Chas, W1CG ++++++++++++++++++++++++++++++++++++++++++ Date: Fri, 25 May 2001 06:36:45 -0000 From: "Marinos Markomanolakis, M.D." Subject: Re: [Elecraft] Cost of AA4PB Battery Charger Jeff, I am glad to report my completion of the QST charger project which works FB... Pulse, voltage controlled charging of SLA batteries, including but not restricted to the internal K2 battery, is probably the best way of keeping them alive for long time. Not to mention that you could feed your K2 with the charger only, povided that you do not exceed a 9% transmit time on it. Calculated parts cost from the recommended supplier is ~$59 without an enclosure. I bought all the parts,PCB included, from All Electronics and built the charger on a utility perforated PCB for $13 !! I only could not find a LM 336 regulator IC, which I replaced with a 2.5V zener diode in series with a 240 Ohm resistor which worked fine. Hope that information helps. 73, Marinos sv9dru/w6 >From: Jeff Burns >Reply-To: Jeff Burns >To: elecraft list >Subject: [Elecraft] Cost of AA4PB Battery Charger >Date: Thu, 24 May 2001 20:40:49 -0700 (PDT) > >Has anyone costed out the parts to build the battery charger that AA4PB >described in the May QST? I am contemplating the internal battery for >my K2 and will need a charger. Before I look up the price for all those >parts, I thought I would ask if anyone else has done that already. > >AD9T >Jeff Burns +++++++++++++++++++++++++++++++++++++++++ Date: Sun, 18 Nov 2001 15:18:39 -0500 From: "Bob Lewis \(AA4PB\)" Subject: Re: [Elecraft] KB7OEX: battery charger question Here's a link that provides some info on the AGM batteries: http://www.windsun.com/Batteries/Battery_FAQ.htm#AGM,%20or%20Absorbed% 20Glass%20Mat%20Batteries Basically, once charged they should be maintained on a standard "float" charge (13.8 VDC). ++++++++++++++++++++++ Date: Sun, 18 Nov 2001 15:19:20 -0500 From: "David A. Belsley" Subject: Re: [Elecraft] KB7OEX: battery charger question Tim: You definitely want to use a "smart" charger: one that allows bulk charging to replenish the battery charge, then goes to a slightly higher voltage for a short "top off" to provide a full charge, and then backs off to an appropriate trickle level that can be left on the battery indefinitely. A & A Engineering (714-952-2114) makes a nice little kit for about $60 that does the job very well. You can wire it for either a .5 or 1 amp charging level (or, you can add a switch in an obvious fashion to allow changing without rewiring). For the record, I have nothing to do with A&A Engineering except to use their product with considerable satisfaction. best wishes, dave belsley, w1euy - --On Sunday, November 18, 2001 10:47 AM -0700 Tim and Nancy Logan wrote: > Hi folks - > > I have a Concorde AGM sealed 105 amp/hr 12 volt battery that is part of > a solar communications power center I am making. While not in use I need > to keep the battery topped off. I know that it will ruin such a battery > if it gets below a certain charge level but seem to get conflicting > recommendations regarding a trickle charger that will be plugged into my > normal AC house current.. Can a battery guru give me the straight > skinny? Thanks again. 73/Tim +++++++++++++++++++++ Date: Sun, 18 Nov 2001 16:57:07 -0500 From: "Francis Belliveau" Subject: Re: [Elecraft] KB7OEX: battery charger question Okay Tim, you have two answers already, let me see if I can help a bit more. As you can see looking at the web site Bob pointed you to the manufacturers specify everything on a "per cell" basis. Lead-Acid cells run at a 2 volt nominal so your 12 volt battery has 6 cells. A 105 amp-hr battery will draw a lot of current if you connect it to a supply when discharged. I hope that your setup will handle that when it is finished. Otherwise it will draw enough current to destroy itself. As far as keeping the battery alive, lead-acid technology does not lose charge nearly as fast as the lighter weight technologies like NiCad. You can let a fully charged battery sit for a few weeks and it will be ready to give nearly full service. Keeping it hooked to 13.8 volts while waiting to be used is exactly what you want to do to ensure that it is always topped off and ready to go. The only caution is to make sure that your voltage source will survive a power failure. Not all power supplies can handle 12 volts at their output when they are without a power source. Also you do not want the battery discharging back into the supply during these periods either. The smart-charger that David suggests will definitely handle your charging needs to bring the battery back after heavy use. In my opinion the Smart-Charger is well suited for use when connecting to power mains. However, for solar use I would suggest you try a circuit like the Micro-M+. Bob suggested that to me a while back and it looks like it will do exactly what I needed. Check it out at http://www.seslogic.com/microm.html and see which you think is best. Good Luck and 73, Fran, KA4FRH ++++++++++++++++++++ Date: Sun, 18 Nov 2001 17:07:09 -0500 From: "Francis Belliveau" Subject: Re: [Elecraft] KB7OEX: battery charger question - ----- Original Message ----- From: "Bob Lewis (AA4PB)" To: Sent: Sunday, November 18, 2001 4:00 PM Subject: Re: [Elecraft] KB7OEX: battery charger question > David, for his 105 AH battery that AA smartcharger (even if set for > 1A) represents a pretty small charge rate even when it's in bulk mode. > He needs a much bigger charger IMHO. > Bob is absolutely correct, at 105AH you would want at least 10 if not 20 amps at the start to bring the battery back from full discharge. The maximum allowed current is manufacturer specific but C/10 should be safe. One important thing to note. Full discharge DOES NOT mean zero volts. The full discharge voltage of a 12 volt lead-acid battery is between 10 and 11 volts. Using 11 volts is a good rule of thumb that will provide maximum protection for battery life. Fran ++++++++++++++++++++ Date: Sun, 18 Nov 2001 23:15:02 +0000 From: Larry Cahoon Subject: Re: [Elecraft] KB7OEX: battery charger question At 05:07 PM 11/18/2001 -0500, Francis Belliveau wrote: >One important thing to note. Full discharge DOES NOT mean zero volts. The >full discharge voltage of a 12 volt lead-acid battery is between 10 and 11 >volts. Using 11 volts is a good rule of thumb that will provide maximum >protection for battery life. The spec at the solar power sites usually specify 10.5 as full discharge, but don't like you to take them below 11.5. Check 0ut http://www.windsun.com/Batteries/Battery_FAQ.htm#Cycles%20vs%20Life for some detail. 73 de Larry..........WD3P in MD http://www.qsl.net/wd3p/ ++++++++++++++++++ Date: Sun, 18 Nov 2001 20:50:57 -0500 From: "Bob Lewis \(AA4PB\)" Subject: Re: [Elecraft] KB7OEX: battery charger question I agree that a 1 amp charge rate will eventually bring the battery to full charge. I'm not sure about "overnight" unless of course the battery not fully (to 10V) discharged. At 1 amp it would take 100 hours or 4 days to fully charge a 100 AH battery. That assumes that you have no load on the battery during charging. A 1/10C (10 amps for a 100 amp capacity battery) will generally fully charge a battery in about 12-16 hours. The bottom line is it depends on what you plan to do. If you are using the battery for back up power and you want it to charge as quickly as possible after a power outage or you want it to be recharged while a load such as a receiver (taking pehaps 1 amp) is connected then you'll require a much larger charger. If you just want to charge the battery over several days after use and then leave it on float until you carry it out to the field for use then the 1 amp charger will likely suffice. ++++++++++++++++++ Date: Sun, 18 Nov 2001 21:25:08 -0700 From: Tim and Nancy Logan Subject: Re: [Elecraft] KB7OEX: battery charger question Hi folks - The info that you are sending out is excellent and appreciated. As you all probably already know, the Wind & Sun website info was invaluable and sets me on the right track. You bring up a good point which when I think about it, I have not quite answered for myself: what exactly is it I want? When I asked the question, I was focusing on a charger to top of batteries when I am not using a solar system. When using the solar system I will have a Morningstar 30A charge controller (actually will have two 105 ah batteries in the setup) and a Tri-Metric Monitor. I presumed outside the system that the issue was simply to keep batteries topped off. However, there could be situations where you might want to charge at a faster rate - and I think Bob's point re bulk mode merits more study. I suspect that when I decide I may go for a slightly more heavy duty smart-charger - tho some can get pretty expensive. I will say one thing for sure - after your discussion and info, there is no doubt in my mind what the issues are - now it's just a matter of deciding which charger....so thank you all VERY MUCH for the help!!! BTW, I'm surprized no one said, "What's this crazy fool doing with 105 AH batteries when he likes QRP?" Well, ya' gotta power the beer cooler somehow :-) thanks all and 73! Tim Logan KB7OEX "Bob Lewis (AA4PB)" wrote: > > One other potential issue with the 1A three-state charger. The charger > senses a drop in charging current to some pre-determined low level in > order to know when to switch from bulk charge to float mode. The > proper switch point for a 100 AH battery is much higher than it is for > a 10 AH battery (normal for a 1 amp charge rate). The charger will > likely remain in bulk mode much longer than you would normally like. > It is not likely to do any damage to a 100 AH battery since the bulk > charge rate for this charger is only 1/100 C. It could become a > problem if one were to use a charger with a larger bulk charge rate > without considering the switch point. +++++++++++++++++ Date: Mon, 19 Nov 2001 22:36:16 -0800 From: Jay Hanawalt Subject: Re: [Elecraft] Battery charger Michael- The Maha charger is a constant current charger and switches to trickle charge when it senses the terminal voltage begin to drop from the peak value (-Delta V) as the battery approaches 100% charge, a characteristic of NiCad and NiMH batteries. Temperature rise (Delta T) is an alternate method of charge termination. Some chargers of this type also have timer as a failsafe. Assuming that the Maha could even reach 13.8 VDC, the SLA battery would have to be constantly monitored with a DVM and the charge manually terminated at about 13.8 VDC, since the SLA would probably have to suffer damage before either -Delta V or Delta T was sufficient to satisfy the Maha charger. Different chemistry. A simple constant voltage charger, perhaps using a 3-terminal regulator, would be a lot easier to use and much less likely to damage the battery. "Why?," "Why Not?," and "Is it possible...?" are good questions anywhere, any time. Otherwise, we might as well be sheep. - -Jay, WB6SZE K2 #2322 Michael wrote: > > As long as the battery charger topic is back again I have a question. I have > a Maha universal charger that is made for Ni cads and metal hydrides. It > charges at a rate of 650 mah and when it senses the battery is charged it > goes to trickle charge of 40 mah. Can I use this charger for SLA batteries? > I have 2.9, 4 and 7 amp/hr batteries. Oh yeah, also a 17 amp/hr. It does > have a heat sensor to turn off the charger if the battery gets too hot. > This charger works great for my HT. It is adjustable to fit almost any > pack, pretty cool. > Thanks for any help and 73, > Michael > kc2fnl ++++++++++++++++++ Date: Tue, 20 Nov 2001 16:44:41 -0500 From: "Francis Belliveau" Subject: Re: [Elecraft] Battery charger Michael, Jay was correct to advise against using that type of charger on SLA technology. Please note that one thing that makes SLA technology easy to use is the minimal charging requirements. If you are not in a hurry to recharge the battery, just connect it to any power supply that will deliver 13.8 volts with current limiting capability. As long as the supply will not deliver enough current to destroy either itself or the battery, you will be fine. A series resister (Elecraft uses 6.2 ohms) will protect the battery if the supply is able to deliver too much current. More complex SLA chargers monitor the current so they can start out at a higher charging voltage and then switch to the 13.8 float charge when the current being drawn indicates full charge. 12 volt SLA batteries can be connected to 13.8 volts forever without damage. I would recommend exercising the battery by discharging it 90% at least once a year when seldom used. Fran +++++++++++++++++++++ Date: Mon, 15 Apr 2002 16:38:20 -0700 From: "Dan Hogan" To: "Low Power Amateur Radio Discussion" Subject: [124832] Re: questions on HB gel cell charger I have the Jade Products Gel-Cel charger with the same Chip. If I remember right it too several dats to charge a 7 AHR battery. More than a week end. On 15 Apr 2002, at 15:35, John_Evans wrote: [Snip} > Charging seems to take forever, on the order if 3-4 > days, and I have never seen it go into the final > overcharge portion of the cycle. > > I replaced the TIP42s, thinking I had obtained some > bad parts, but the behavior hasn't changed. > > tnx es 73/72 - john - n0hj > Dan Hogan WA6PBY dhhogan1 at earthlink.net West Covina,CA QRP-L #558 +++++++++++++++++++ To: elecraft at mailman.qth.net Date: Fri, 10 May 2002 08:56:04 -0500 From: n4so at juno.com Subject: [Elecraft] Supervisory Microcircuits The idea of charging the NiCd or NiMH 8-pack needs to be looked into further. What is required is a small supervisory microcircuit or charge controller on a tiny PC board that performs all charging functions. It needs to have all the parts and attach with just a couple of source voltage wires. There are several companies that sell the microcircuits that perform the charging functions. Some have modules with all the parts ready to attach to a battery pack. Maxim www.maxim-ic.com Linear Technology www.linear.com Benchmarq www.benchmarq.com bq2054 and bq2058 for 3 or 4 cells Temic (Siliconix) www.temic.com National Semiconductor www.nsc.com For example, Benchmarq offers a complete supervisory module for Lithium-Ion cells with everything but the batteries on a PC board measuring 2.6X0.7 inch (bq2158) and fully assembled. This idea from QST is for a Lithium-Ion type battery, but similar modules should be available for Nickel-Metal Hydride and Nickel Cadmium batteries. Perhaps someone with time and access to the Web can check out supervisory modules for 8-packs. Ref> Don Gagnon, Which Battery Should You Use in Your Equipment?, QST, April, 1999, p. 40. Ken Brown-N4SO Mobile, AL EM50tk Elecraft K-1 4 ele. monoband yagi N4SO at juno.com ++++++++++++++++ Date: Tue, 14 May 2002 12:42:13 +0200 From: "Ingo, DK3RED" To: Elecraft Subject: [Elecraft] Re: SLA charger internal needed Hello Daniel, > I need to know a direct link URL, so that I can get the schematics to > building a gel-cell charger. I would like to mount it in my K2 and just > be able to hook up my Power supply. To charge the internal battery. 14V > at 560mA. No, I have not a schematic. But look at the PDF for the L200 at http://us.st.com/stonline/books/pdf/docs/1318.pdf (about 165KB) and there at figure 1 in these data sheet. The L200 is an ajustable voltage and current regulator from ST Microelectronis (http://www.st.com). So you can EASY (!) built a programmable voltage regulator with current limiting with this IC. The IC with only 3 resistors and 2 capacitors and you have a gel-cell charger. -- 72/73 de Ingo, DK3RED Don't forget: the fun is the power! dk3red at t-online.de http://www.qsl.net/dk3red ++++++++++++++++++