If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Battery Chargers
I have recently converted from NiCad to lead acid batteries which are supped
to have a life of 2-3 yrs. The batteries cost about $1500 for the pair and I am interested in maximizing their life the extent practical. I have heard about "pulse chargers" that reportedly reduce sulfate on the battery plates. Would using one of these make a meaningful difference in battery life? I plan to connect the charger through the external power recepticle. Any thoughts/ideas/sources? I am also interested in a larger source of DC power so that I can use the cabin lights and have things turned on while cleaning/troubleshooting ect. Again I plan to connect through the external power recepticle. I ahve 120V and 240V availible. I am not looking to spend $000s on a GPU type cart. Thanks for any input! Mike MU-2 |
#2
|
|||
|
|||
I am also interested in a larger source of DC power so that I can use the
cabin lights and have things turned on while cleaning/troubleshooting ect. Why not make a battery cart with large truck or tractor batteries? I have used several of those over the years most home made. One even used a marine rotary switch that when wired correctly allowed the user to select either 12 or 24 volts. That one used just two batteries mounted on a welding bottle cart. It also had a battery charger permanently mounted and connected. When not in use we kept it plugged in. John Dupre' |
#3
|
|||
|
|||
Mike,
Here is something I recently wrote on this topic on the SWPC email list: From: "Adolph . . ." As I looked at the latest Popular Mechanics, there was an ad for a company that makes a "smart" battery charger. One claim is "Reconditions sulfted batteries using electronic pulse technology that reverses sulfate buld-up on battery plates, improving charge-carrying capability." Will it "float" a lead acid battery and keep it from self-discharging? Yes. Will it recharge a run down battery that just needs to recharged? Yes, if you are willing to wait long enough. A 10A Sears model will do it a lot faster and cheaper Will it substantially increase the AH capacity of an old battery which has already lost capacity? No. Not that I'm in the market for a charger, but if it can do that, it would be a significant improvement. Anyone have one, or know anything about these? I built a computer-controlled battery charger/discharger which acurately measures the AH capacity of batteries. The device is used routinely by my AP/IA to evaluate aircraft batteries for continuing airworthiness. I researched the "pulse charging" desulphating techniques, read the patents, built a prototype, and did some carefully controlled experiments where I measured the before and after Amp-Hour capacity of some flooded cell SLA, automotive, marine, and aircraft batteries. I found no improvement in AH capacity that lasted. There was no difference in the capacity of the battery if it was charged with pure DC, or with "pulses"!!! That said, can a case be made for sophisticated chargers which have several operating modes? Certainly. A good example of what is out there is at http://batterytender.com/technical.php (I have no connection with them, but they explain the fundamentals well). Read "battery charging basics". IMHO, the "pulse charging" stuff is snake oil... MikeM (PhD EE) Pacer '00Z Skylane '1MM Mike Rapoport wrote: I have recently converted from NiCad to lead acid batteries which are supped to have a life of 2-3 yrs. The batteries cost about $1500 for the pair and I am interested in maximizing their life the extent practical. I have heard about "pulse chargers" that reportedly reduce sulfate on the battery plates. Would using one of these make a meaningful difference in battery life? I plan to connect the charger through the external power recepticle. Any thoughts/ideas/sources? I am also interested in a larger source of DC power so that I can use the cabin lights and have things turned on while cleaning/troubleshooting ect. Again I plan to connect through the external power recepticle. I ahve 120V and 240V availible. I am not looking to spend $000s on a GPU type cart. Thanks for any input! Mike MU-2 |
#4
|
|||
|
|||
Here is yet another (I hope) relevant posting from the other list:
Subject: Battery Chargers What charger, amp size, etc., would you recommend to slightly charge or maintain a std lead acid 35 series aircraft battery? By "maintain", I assume you are concerned about what happens to the typical G35 aircraft battery during times when the aircraft is not flown regularly (say bi-weekly). The answer is complicated. As long as the aircraft is flown once every couple of weeks, assuming that the generating capacity in the aircraft exceeds the current being drawn by the instruments, avionics and lights, (so that the reserve capacity is available for charging the battery), and that the voltage regulator gets the battery voltage up to 14.2+ Volts for the duration of a flight, then you dont need to do anything involving external chargers. If the aircraft generation capacity or regulation is suspect, then instead of tinkering with chargers, you really should fix the root cause (which is install enough generating capacity, adjust the voltage regulator to produce said 14.2+ V, fly the airplane an hour or two every two weeks, etc.) The reason for the "every two weeks" statements above are based on the physics of flooded-cell batteries. There are two parts to prevent degradation of a battery which is sitting unused for periods of weeks to months. Lets call this "battery maintenance". Note that "maintenence" only needs to be done when the aircraft is not regularly flown, as in the winter months. First, you need to keep the battery from discharging itself even after disconnecting anything that draws current, which should be the case if you turn off your Master. Second, you need to periodically stir the acid in battery to prevent the acid from stratifying with the lowest specific gravity on top. All lead acid batteries loose charge just by sitting around. at 100 deg F, a G35 will loose 10%-20% of its capacity per month. In cold weather, the self discharge rate is much lower. So if you want to maintain a battery near full capacity, you have to replace the charge lost due to self discharge. It requires only ~ 0.25A to make up for the leakage. Preventing self discharge is usually accomplished by "floating" the battery using a voltage-limited charger, which puts out 13.5 +-0.1 V open-circuit. Most commercial automotive chargers such as you would get at Sears or Checker are not voltage limited accurately enough to leave them connected to a battery for more than 24 hours!!! They are suitable for recharging a run-down battery, but they must be manually disconnected after a few hours. The better models of the automotive chargers have a time clock shutoff which means you dont have to drive back to the airport to shut off the charger. If you have the disipline, you can "maintain" an unused battery through the winter months by giving it an 4-6 hour charge every 30 days or so, relying on the clock in the charger to shut it off, otherwise you have to drive back to airport to disconnect the charger. One of the primary causes of loss of capacity of batteries is sulfation of the lead plates; Sulfation happens when the battery is allowed to sit around in a partially or totally discharged state for long periods; sulfation is minimised by keeping the Specific Gravity of the acid high (fully charged) see: http://www.sierrasolar.com/design/b_leadbattery.htm The acid in a stationary battery (not being sloshed around in a car, boat, motorhome, airplane) will stratify, meaning that the Specific gravity at the top of the battery will be much less that at the bottom. Due to low SG at the top, the top parts of the plates will sulfate first, reducing the capacity and cold cranking amperage of the battery. The solution to stratification is to mechanically stir the acid, which happens normally if you take your battery for a ride in the car, or for a flight in the airplane. However, if the airplane/car is parked for six months, what then? A good substitute for mechanical agitation is to periodically (once every two weeks or so) connect the battery to a charger whose voltage is set to 14.4+ V for a few hours. In the industry this is sometimes called "equalization", but the primary benefit comes from charging the battery hard enough to evolve gas (hydrogen at one plate, oxygen at the other). The bubbles rise through the acid, stirring it as they go, mixing the weaker acid with the stronger. So, for total automatic unattended maintenance of batteries, the charger has to float at 13.5V continuously, and every two weeks or so, it needs to bump up the voltage to about 14.4V while delivering a few amps for a few hours, and then revert back to the float mode. If the aircraft is flown regularly, then you dont have to bother with equalization. Is it feasible to leave the master switch "on" to activate the solenoid and charge/maintain the battery thru the cigar lighter circuit? Do you think this might create any unforeseen problems such as overheating the solenoid if left unattended for several days at a time etc. Or is this just a plain bad idea? Its just a bad idea. Overheating of the solenoid shouldn't be a problem, because the solenoid is rated for it. However, your charger has to deliver approximately 1.5A to the coil in the solenoid, plus whatever unswitched loads there are in the aircraft (like the fuel gauges) Suppose someone unplugs your charger? Now the solenoid/gauges will kill your battery. Its not hard to wire in a fused connector which will allow direct access to the battery with the master off. Is it possible to overcharge a battery with today's low amp chargers? Yes. You have to buy a charger specifically made for "float charging", like the BatteryTender http://www.batterytender.com/ If in doubt, connect your charger to a battery for 6 to 12 hours. Use an accurate digital voltmeter to measure the voltage between the battery terminals with the charger still charging. If the measured battery voltage after a few hours exceeds 13.6V, the charger is not suitable for long term float charging. In summary, if all you own is the typical Sears 10A charger with the time clock, then while the aircraft/motor home/boat is not being used, hook the charger to the battery with the time clock set to 6 hours. Go back and do it each month. That is the best you can do to prevent the battery from loosing capacity while inactive. During the six hours, the charger will put back the self discharge, and then it will bubble the battery just enough to stir the acid. This regemin is way better than just letting the battery sit idle for six months. MikeM (Batteries r us) Pacer '00Z Skylane '1MM |
#5
|
|||
|
|||
Thanks that is a great idea.
Mike MU-2 "JDupre5762" wrote in message ... I am also interested in a larger source of DC power so that I can use the cabin lights and have things turned on while cleaning/troubleshooting ect. Why not make a battery cart with large truck or tractor batteries? I have used several of those over the years most home made. One even used a marine rotary switch that when wired correctly allowed the user to select either 12 or 24 volts. That one used just two batteries mounted on a welding bottle cart. It also had a battery charger permanently mounted and connected. When not in use we kept it plugged in. John Dupre' |
#6
|
|||
|
|||
Thanks, it will be a lot easier to choose a charger without considering the
pulse types. Mike MU-2 "mikem" wrote in message ... Mike, Here is something I recently wrote on this topic on the SWPC email list: From: "Adolph . . ." As I looked at the latest Popular Mechanics, there was an ad for a company that makes a "smart" battery charger. One claim is "Reconditions sulfted batteries using electronic pulse technology that reverses sulfate buld-up on battery plates, improving charge-carrying capability." Will it "float" a lead acid battery and keep it from self-discharging? Yes. Will it recharge a run down battery that just needs to recharged? Yes, if you are willing to wait long enough. A 10A Sears model will do it a lot faster and cheaper Will it substantially increase the AH capacity of an old battery which has already lost capacity? No. Not that I'm in the market for a charger, but if it can do that, it would be a significant improvement. Anyone have one, or know anything about these? I built a computer-controlled battery charger/discharger which acurately measures the AH capacity of batteries. The device is used routinely by my AP/IA to evaluate aircraft batteries for continuing airworthiness. I researched the "pulse charging" desulphating techniques, read the patents, built a prototype, and did some carefully controlled experiments where I measured the before and after Amp-Hour capacity of some flooded cell SLA, automotive, marine, and aircraft batteries. I found no improvement in AH capacity that lasted. There was no difference in the capacity of the battery if it was charged with pure DC, or with "pulses"!!! That said, can a case be made for sophisticated chargers which have several operating modes? Certainly. A good example of what is out there is at http://batterytender.com/technical.php (I have no connection with them, but they explain the fundamentals well). Read "battery charging basics". IMHO, the "pulse charging" stuff is snake oil... MikeM (PhD EE) Pacer '00Z Skylane '1MM Mike Rapoport wrote: I have recently converted from NiCad to lead acid batteries which are supped to have a life of 2-3 yrs. The batteries cost about $1500 for the pair and I am interested in maximizing their life the extent practical. I have heard about "pulse chargers" that reportedly reduce sulfate on the battery plates. Would using one of these make a meaningful difference in battery life? I plan to connect the charger through the external power recepticle. Any thoughts/ideas/sources? I am also interested in a larger source of DC power so that I can use the cabin lights and have things turned on while cleaning/troubleshooting ect. Again I plan to connect through the external power recepticle. I ahve 120V and 240V availible. I am not looking to spend $000s on a GPU type cart. Thanks for any input! Mike MU-2 |
#7
|
|||
|
|||
Jim Weir had a design to bring sulphated batteries back to life.
I would guess that you don't need to do it if the battery is ok in the first place. I've got a 300mA 13.5V top-up thing I bought, just a constant trickle charge, and I've actually found that I've brought a couple of "dead" batteries back to serviceable condition by leaving that on for a couple of weeks (car batteries). Paulu "Mike Rapoport" wrote in message news I have heard about "pulse chargers" that reportedly reduce sulfate on the battery plates. Would using one of these make a meaningful difference in battery life? |
#8
|
|||
|
|||
http://www.rst-engr.com/kitplanes/KP0204/KP0204.htm
I read it in Kitplanes. "Paul Sengupta" wrote in message ... Jim Weir had a design to bring sulphated batteries back to life. |
#9
|
|||
|
|||
"Paul Sengupta"
shared these priceless pearls of wisdom: -http://www.rst-engr.com/kitplanes/KP0204/KP0204.htm - -I read it in Kitplanes. So of course it HAS to be true. {;-) Jim Jim Weir (A&P/IA, CFI, & other good alphabet soup) VP Eng RST Pres. Cyberchapter EAA Tech. Counselor http://www.rst-engr.com |
#10
|
|||
|
|||
On Thu, 20 Nov 2003 21:05:24 GMT, "Mike Rapoport"
wrote: I have recently converted from NiCad to lead acid batteries which are supped to have a life of 2-3 yrs. The batteries cost about $1500 for the pair and I am interested in maximizing their life the extent practical. I have heard about "pulse chargers" that reportedly reduce sulfate on the battery plates. Would using one of these make a meaningful difference in battery life? I plan to connect the charger through the external power recepticle. Any thoughts/ideas/sources? I am also interested in a larger source of DC power so that I can use the cabin lights and have things turned on while cleaning/troubleshooting ect. Again I plan to connect through the external power recepticle. I ahve 120V and 240V availible. I am not looking to spend $000s on a GPU type cart. Thanks for any input! Mike MU-2 I read this and thought I was on the Homepower NG g. I don't know how well the pulse chargers will work on starting type batteries. They are helpful for deep discharge cells, though. For the type of battery you have, they are designed for starting. They can produce a large amount of current for a short period of time. However, they are NOT designed to be deep discharged. So you should take care not to discharge them to any lower than about 20%. In other words, they should always retain at least 80% of their full state of charge, and be maintained at full charge as often as practical -- certainly at least every two weeks. If you are going to run cabin lights and other appliances for any length of time, you really should be using deep discharge batteries. These can tolerate repeated 80% depth of discharge (DOD). Depending on your power requirements (which can be calculated), you may be able to use second hand fork lift or golf cart batteries. These are available inexpensively through Sam's and other discount places, as well as at battery dealers. Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA) |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
RG Battery Charger by Jim Weir in Kitplanes | Kevin O'Brien | Home Built | 4 | January 6th 05 01:19 AM |
Handheld battery question | RobsSanta | General Aviation | 8 | September 19th 04 03:07 PM |
Battery Requirements | jgarner | Home Built | 3 | March 28th 04 06:32 AM |
FS: Yaesu VXA-100 "Aviator Pilot" Alkaline Battery Case, $20 obo | Jaysen Underhill | General Aviation | 0 | September 3rd 03 05:35 AM |
WX1000 Stormscope battery | D. J. Gooding | Owning | 2 | August 9th 03 02:25 AM |