A decent battery (Concorde) will be fine. If the bus voltage is adjusted right (28.0V) you get a high charging current for some seconds but it will be fine. After all, these can deliver say 300A to a Skytec starter motor, without buckling the plates.
On the TB20 there is the overhead cockpit light which can run the battery down.
There is also a long procedure for starting with an external power source, if you don’t want to blow some fuse… I think I posted it here before. Not sure what it tries to achieve, and may be airframe S/N dependent. On some, the external power pack would attempt to charge the battery. On later ones, there is a “ground power relay” which disconnects the battery the moment the external power plug is inserted.
Brakes: ON
Battery Master: Off
Alternator: Off
Avionics & Autopilots Masters: Off
All other Electrics: Off
Connect External power cable
Note: NEVER turn on the avionics master switch with the engine running unless the external power cable is removed and the battery master is on.
Battery Master: On
Start Engine allow it to stabilize
Battery Master: Off
Remove External power cable
Battery Master: On
Alternator Master: On
Allow engine to warm long enough so it will idle correctly
Battery Master: Off
Landing Light: On
Taxi Light: On
Engine RPM: Idle
Battery Master: ON
Bring Engine RPM up to 1500 RPM
Check that the indication of the factory voltmeter stabilizes inside the green sector. If the voltmeter is in the lower red sector, shutdown, remove and charge the battery before flight.
Landing Light: Off
Taxi Light: Off
Proceed as per normal checklist
Michael
You are suggesting doing exactly the same as me………. loading the battery to see if it is not producing enough power, the fact is the pitot heat is doing exactly the same as a capacity tester in that It is putting a load on the battery………… it’s just the indication that is rather subjective.
Using a voltage indication without a load on the battery tells you nothing about capacity but it may tell you if you have a cell that has failed.
While not being very precise way of checking battery condition over the last twenty years of running a fleet of aircraft a report of “pitot heat is not working” from the pilots is a clue that the battery condition is less than optimum in abcense of reports of starting problems or charging problems.
The pitot heat is checked on each pre flight check and so it is usually the first clue to fast approaching battery problems, I’m sorry that you choose to dismiss the experience gained from thirty five years of maintaining light aircraft but in that time I have found that if anything out of the ordinary is reported the aircraft is trying to tell you something, these clues are never definitive but tell the astute aircraft maintainer that further investigation is required.
120 watt for the common ones I know.
Aviation Consumer battery comparison – Concorde v. Gill
A really interesting comparison here [ local copy ]
To people who switched from Gill to Concorde (usually for a good reason) it won’t come as a surprise that the Concorde comes out much better. I have had Gills fail suddenly, failing to drive the old Lyco (low current) starter only months after they passed the load test, but never had a Concorde (on my 2nd one, which is now at 5 years and just passed the load test) fail and that was with the Skytec starter which draws about 2x more current.
But still some of it is pretty amazing e.g.
That comparison includes the sealed Gill also but AFAIK the above 2007 early-failure figures can apply only to the (sealed) Concorde versus the standard (flooded) Gill.
And since I have found Concorde batteries to be perfectly usable even when they fail the load test, here is one working to power a UPS (which conveniently used a 24V battery):
Most UPSs on the retail market come with poor quality batteries so in this way you get a real improvement.
My batteries were shot on the 680V. So my mechanic ordered two new Gill’s. He’s old school and thinks lead acid is more resilient and cost effective, but in hindsight I wish I bought Concorde’s as most people I’ve talked to have had great experiences. Another thing the clouded the decision at the time was that I don’t have a hangar, and I’ve heard the C’s really benefit from some Battery Minder trickle charging. The Gills are kinda easier to drain more out of and also revive with a little GPU action, was the conclusion. But next time I’m going for Concorde’s. Just hope I have a hangar for it by then.
I am sure a reconditioning charger helps all lead acid batteries, but the one above is about 11 years old and still going strong and it has never seen one.
BTW Concorde are still lead-acid and have same cell voltage as all the others. They are merely a gel electrolyte instead of liquid and I guess the plate construction is different because – looking at things like the charging current at a given voltage – their internal resistance is lower. I reckon an RG24-15 has half the internal resistance of a Gill 242 and this translates to an ability to deliver more starting current etc.
But still a lot of people are afraid of changing out a Gill 242 due to the Concorde not having an STC for their plane, and almost never appearing on any TC. Especially here in Europe on the EASA scene… most I know are told by their maintenance company they can’t do it. It’s a problem in the USA too but much smaller because most A&P/IAs view this as a Minor Alteration.
Peter wrote:
But still a lot of people are afraid of changing out a Gill 242 due to the Concorde not having an STC for their plane, and almost never appearing on any TC.There are not so few approvals, I would say… http://www.concordebattery.com/otherpdf/finalfaapma.pdf
My club swapped an original Gill battery for a Concorde and the CAMO said “no problem”.
