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Batteries (again) - 2 Main Batts plus Tail Fin Batt wiring/switching
Hi,
Time to dust off a perennial topic I looked through the archives and read Darryl Ramm's battery presentation. Not an exhaustive search but I didn't find an answer to my question. At present we have two (fused) 12V 7Ah "main batteries" connected to the Master switch via an SPDT "changeover" switch. We are adding a smaller capacity tail fin battery as a "reserve". Without using diode switching and keeping it as simple as possible for multiple club pilots, I can see 3 possibilities that I've illustrated he http://www.avon-tech-solutions.co.nz...derBattery.pdf - select 1 of the three batteries using two SPDT "changeover" switches in "series" - separately isolate the tail battery in parallel to the currently selected master - separately isolate the tail battery in parallel to the master switch Each has its advantages and disadvantages. No doubt there are more possibilities. I expect to add the recommended Volkslogger "hold up" circuit separately (or power the logger and possibly a PDA from a dedicated battery, much like the self contained battery/logger systems previously discussed here on r.a.s.). What wiring / switching schemes are you using for this 3 battery arrangement? Thanks for your suggestions. Neil |
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Batteries (again) - 2 Main Batts plus Tail Fin Batt wiring/switching
Schleicher uses a rotary switch
Batt 1, Batt 2, Batt 3, Off. If you can get one of these, it reduces to one switch. -- Hartley Falbaum "Neil Allison" wrote in message ... Hi, Time to dust off a perennial topic I looked through the archives and read Darryl Ramm's battery presentation. Not an exhaustive search but I didn't find an answer to my question. At present we have two (fused) 12V 7Ah "main batteries" connected to the Master switch via an SPDT "changeover" switch. We are adding a smaller capacity tail fin battery as a "reserve". Without using diode switching and keeping it as simple as possible for multiple club pilots, I can see 3 possibilities that I've illustrated he http://www.avon-tech-solutions.co.nz...derBattery.pdf - select 1 of the three batteries using two SPDT "changeover" switches in "series" - separately isolate the tail battery in parallel to the currently selected master - separately isolate the tail battery in parallel to the master switch Each has its advantages and disadvantages. No doubt there are more possibilities. I expect to add the recommended Volkslogger "hold up" circuit separately (or power the logger and possibly a PDA from a dedicated battery, much like the self contained battery/logger systems previously discussed here on r.a.s.). What wiring / switching schemes are you using for this 3 battery arrangement? Thanks for your suggestions. Neil |
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Batteries (again) - 2 Main Batts plus Tail Fin Battwiring/switching
Paralleling batteries is Bad Bad Bad. Its OK to parallel 2 batteries for the brief moment it takes to turn on battery 2, just before turning off battery 1 (or tail battery on/ off) This way you don't interrupt current flow to your flight recorder. I have used this method for 30 years. Please don't tell me it will cause a voltage spike. I have tested it by hooking a dead battery directly to a freshly charged one...........................no spike, didn't blow a 3A fuse all that happened was 220 m/a current flow as the good battery tried to charge the dead battery. While we're speaking of voltage spikes, you can get one coming out of your radio when the power is interupted and this can cause trouble with other units in the system ....................see Ilec manual warning about this. JJ |
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Batteries (again) - 2 Main Batts plus Tail Fin Batt wiring/switching
HL Falbaum wrote:
Schleicher uses a rotary switch Batt 1, Batt 2, Batt 3, Off. If you can get one of these, it reduces to one switch. I just checked the Maplins online catalog (Maplins is the UK equivalent of Radio Shack) for their standard range of panel mount rotary switches. These are 1,2,3 and 4 pole types (12,6,4 and 3 positions). They have a movable stop so you can blank off unwanted positions. Something like these is available pretty much anywhere. They are rated at up to 5 amps, so should be OK in a glider panel. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
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Batteries (again) - 2 Main Batts plus Tail Fin Battwiring/switching
On Mon, 19 Nov 2007 12:45:57 +0000, Tim Newport-Peace wrote:
Not using diodes is good. I use two diodes to provide a "fail safe" supply to the equipment that draws low current but requires high availability, like the Volkslogger. Two very small cheap rectifying diodes do a very effective job with negligible voltage drop (about 0.1V), no heat sinks etc. The high current equipment (radio, transponder etc) is powered directly from alternate batteries via change over switches. But these normally don't mind a short duration interruption. Ian |
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