I just put led landing and taxi lights in. They work well. But as you say I wouldn't be using if an alternator failed.
How do you do that load test? My Concorde is ca. 6 years old (the replacement Gill has been sitting on my shelf for some time) and while it appears to be strong, I would like to determine its capacity. Maybe you have a clever setup?
It was done by the maint. shop.
Actually I would not be entirely suprised if an incorrect procedure was used, because the test involved doing some calculations and the battery appears fine.
They are not cheap - about £400 for that size.
I would never replace a Concorde with a Gill. It's like replacing a VW Golf with a Vauxhall Viva 
And the Gill needs topping up, and you can get acid spills.
You can easily measure the capacity of a battery by loading it up and plotting the voltage over time. But the official test involves quite a high current, AFAIK. The capacity at a high load is less than at a low load.
I would never replace a Concorde with a Gill. It's like replacing a VW Golf with a Vauxhall Viva
That's a nice topic for discussions, just like Lycoming vs Continental and which oil to use. A lot of opinions out there. Both sealed and flooded batteries have pros and cons and there are people that prefer Concorde and people that prefer Gill. I've come to the conclusion that the sealed Concordes are probably better than the sealed Gills but the flooded Gills beat the flooded Concordes. I think the flooded lead acid batteries are well proven and and topping off is part of the annual (only need distilled water). Acid spills are rare.
You can easily measure the capacity of a battery by loading it up and plotting the voltage over time.
The official test involves a known load and measuring the time until the voltage drops below a certain threshold. It's detailed in the owner manuals from Gill and Concorde. I was planning to build a test set using two landing lights but hoping that somebody else might have some good tips on how to do it.
That's a nice topic for discussions, just like Lycoming vs Continental and which oil to use
The Concorde has a ~30% advantage in mAh (TB20: Gill 242 v. Concorde 24-15) but the Concorde has a ~ 2x lower internal resistance i.e. the ability to deliver current which really shows up in operation.
This is immediately evident post-installation, when you see about 2x a higher charging current after the engine starts up, and it's evident in the way the voltage holds up when sitting on the ground doing e.g. avionics tests (no engine).
The impression is of a battery which is twice the size.
I now also have a Skytec high speed starter (not the top-power model which knackers the starter relay, and any other relays the starting current passes through, but the 149NL 12/24 switchable) and together with the Concorde battery the old business of hot starts / warm starts etc has totally vanished. The engine spins at least 2x faster. These starters are brilliant. Every time I fly I see people struggling to start their engines... But one has to be careful with relay ratings; Socata made a design error in using a N/C contact of a "ground power" relay which is rated at only about 50A, which is stupid.
Sorry, but all this talk of people using Concorde parts reminded me of the time I put a Concorde Olympus 593 on my plane
I had an amazing discussion with both the Concorde and Gill tech reps last week for one of my projects. Though both fellows were great, the Concorde fellow directed me to this page.
Find the batter you're dealing with, and everything you need to know will be in the ICA or other technical paper for that battery.
I've done several second alternator approvals. One was a highly modified Cessna 207, with a primary alternator of 180 amps, and a standby 20 amp on a spare drive pad on the engine. The challenge is the need for a system to assure that if you're drawing the big power, and you loose the big alternator, the whole load does not move to the little one. you have to shed most of it before the switch. This can be done as a completely manual system which prevents both alternators being on at the same time, but then you still have to assure that the second smaller one is only turned on when most of the consumers are off. After some real head scratching, we came up with a circuit which did this automatically, and it worked. I did something similar on the Basler turbine DC-3, because the mission system drew more than either one engine driven generator could produce.
If an approval quality electrical load analysis is required for such a mod, let me know, I have some pointers and references. In short, know that for the 30 minutes running on the battery part of the demonstration of compliance, it may be required that you allow ten minutes at the full consumption to allow for the pilot to not notice the alternator failure right away, and it will be required that you only take credit for 72% of the amp hour rating for the battery, as your battery only system capacity. I have just been through on of these on a 172.
Although be aware that the Concorde website is not always right. They list a battery as approved for the PA-46 which isn't. This meant the previous owner of my plane had to change it to a legal one before they could fly it to me.
Was the battery the same (or almost same) size as the factory one?
If so, it is a Minor Mod and an A&P can install it with just a logbook entry.
Ref FAR 43 Appendix A.
The list on a mfg's website is usually non-exhaustive.
Take e.g. the change from the Gill to the Concorde that I did. I had three IAs, one DAR in Europe and one DER in the USA agree that is fine. Several people in the USA have letters from their FSDOs saying it is fine - for this aircraft too. But this is still not good enough for some people.
And it has to be said that if you ask enough FAA inspectors at enough FSDOs you will eventually find one who says it's not OK. A bit like when I phoned the NY IFU and they were adamant an EHSI was "EFIS" and thus needed an STC, which is complete rubbish. Or the one at Oakland who insisted that a KLN94 is not an IFR approved GPS and the time it takes to debunk that is what it takes to email somebody a PDF.
I spoke to the chiefs of Concorde at Friedrichshafen and they said one of their biggest problems is the disinformation which is circulating around this area.
In the USA (and more or less everywhere else) it is fairly normal for maintenance engineers to adopt a position that nothing can be done unless the mod is covered by an STC.
This is obviously a misunderstanding of the position but they just want an easy life and don't want to (or in my frequent experience can't) read the regs. And most of their customer know no better.
So one finds that loads of manufacturers have obtained STCs for stuff which is unquestionably a minor mod - as a marketing exercise. A bit like getting ISO9000
I personally would have no problem installing another battery that fits, has the right specs, is used by other aircraft owners, etc. Neither would my IA.
If some pointy-headed official at some point thinks it is against the regulations, the worst I can imagine is that my plane is grounded until I put in another battery. A risk I would take although I am sure it would never be a problem.
Aviation seems to attract regulation-loving people that want papal blessings with three carbon copies for everything. Probably because of some legal cases in the US that ended up badly for mechanics, people are afraid of using common sense and making judgement calls. Luckily all maintenance people I deal with are rather pragmatic (but not anarchic).
Aviation seems to attract regulation-loving people that want papal blessings with three carbon copies for everything. Probably because of some legal cases in the US that ended up badly for mechanics, people are afraid of using common sense and making judgement calls.
Truer words were never written!
