some light on odd electric issue

[GMAs]

As to the Sulfating of the ships batt from setting... to answer the other question I got... you can go to the internet and look up why they do it better than we can re-write the issue here.

We did a extensive study on the problem and what can be done to keep the ships battery from having it happen.
We tested several pieces of manufactured equipment to find out if they really did what they claimed. We got down to just 3 manufactures. One even improved their product further after he reviewed our testing data. The currently are the No. 1 aircraft battery charger/desulfator and highly recommended to the members of the Skymaster groups.

This charger/de-sulfiator can be left on the ships battery indefinately. It uses a microprocessor to sense the battery and keep it peaked.

Here is the best of the best that we tested... and their new aircraft specific appliance

BatteryMINDer
AviationSpecific Battery Charger

12-24 Volt 2,4,8 Amp

The BatteryMINDer is a 3-mode charger /maintainer /conditioner that extends performance and life of all types of 12 Volt or 24 Volt lead acid batteries. These include maintenance-free, marine, sealed gel, AGM, dry and valve-regulated batteries.


The voltage settings and charge rates (both user selectable) have been chosen, after conferring with leading aviation battery makers in the U.S. By providing each of these BatteryMINDer units with an “At-the-Battery” temperature compensating sensor, batteries can be safely charged and maintained for extended periods in temperature extremes from 32°F to 125°F. Without this type temperature sensing, batteries will be under-charged in colder temperatures (<70°F to 32°F) and over-charged in high temperatures (>80°F to 125°F).

Both models include full-time pulsed de-sulfation circuitry designed to safely dissolve sulfation build-up on the battery’s storage plates, restoring lost cranking power and extending life. Our de-sulfation method is fully automatic, does not use potentially damaging high voltage and is exclusively protected by two U.S. patents.

What is Sulfation (sul-fay-shun) and
How Does It Affect Batteries?

When batteries are improperly maintained (over-under charged or left uncharged for extended periods) small crystals of sulfuric acid from the battery’s electrolyte (liquid or paste) form on the battery’s charge plates. They act as a resistor (barrier) preventing the battery from ever again accepting a full charge, no matter how long a charging source may be connected. Once this occurs, the cranking power of the battery is severely reduced, as well as its life. Aviation batteries are affected the most because they have been designed for maximum performance in the smallest-lightest case possible.

VDC Electronics has developed simple, but highly effective circuitry, able to safely dissolve sulfation, restoring much, if not all, of the lost power, providing the battery’s cells are not shorted or structurally damaged. This U.S. Patented approach is believed to be the most effective method for eliminating even the oldest hardened sulfate. By generating safe, wide-band, random frequency electronic pulses, we are able to cover the full range of sulfate crystals sizes, in the shortest possible time. Depending on the amount of sulfate and its age, complete de-sulfation can occur within several days to several weeks. De-sulfation takes place automatically, while the battery is being bulk or maintenance level charged.
FEATURES

• For all size and type 12-Volt and 24-Volt aviation batteries (or two 12-V in series = 24-V) including sealed AGM-maintenance-free and filler cap maintenance type
• Guaranteed never to over-charge, regardless of time or temperature (32°F – 125°F) with correct battery type setting and ABS-248 or 124 temperature sensors correctly installed on either battery terminal connection
• Push-button selector for charge rate and battery types = ensures 100% compliance with major aviation battery makers’ specifications
• Auto-restart after power failure
• Safely charges up to 200% faster than conventional chargers
• Maintains from 1 - 6 batteries at a time (parallel connected)
• Automatically dissolves power-robbing sulfation using safe low voltage pulse technology (U.S. Patented)
• Microprocessor controlled pulsed output ensures 100% full charge
• Temperature compensation extends battery life by more than 200 Cycles (full charge-discharge cycles) with ABS temperature sensor1
• High efficiency design = low monthly operating cost of less than 50¢2
• Weather-proof enclosure
• Optional 12 or 24 Volt PowerPlug (fused) allows charger to be easily connected to battery via input 12 v or 24-v power receptacle
• 1 year 100% money-back guarantee + five (5) year “no hassle” warranty
Size/Weight: 5-1/2” L x 5-1/2” W x 2 1/4” H / 3.0 lbs.

by the way... mention that your a 337 Skymaster Club person and you can get a manufactures direct discount for one. A lot of our club owners now own them and have had great results while the bird sits throught he cold long winter.

Only warning we suggest is that you not turn on the ships radios or master switch when its in operation. The de-sulfication break down pulse spike can exceed 30 volt and could damage sensitive electronics if allowed to be placed across the terminals.

Hope this helps

Fly safe...GMAs

[Pete Somers]

OK Gmas
I see your point on these matters, however we all have different approaches to troubleshooting a system and Although you keep saying refer fo the Cessna Service Manual for write ups and defect rectification, but have you found, ahah that what the defect and how to rectify from a Service Manual, no. It comes from experiance an pure hard work.
That quiz question was not a trick, it is a factual question and the answer does not lie in the Service Manual! and it does not matter about the battery condition. It does not matter what type of a/c you work on experience is the only thing that is going to matter weather it is a Tiger Moth or a King Air.

I use an AVO MK8 for most of my measuring of resistance and voltage, it is an old unit but it does the job right, then use a 4 digit DVM for any setting up work like alternators, but each to there own as they say.
A member mentioned about checking bonding across control surfaces using a DVM, no way you need a bonding checker to do this as a DVM does not go low enough to check the bonding.

Is there an STC to replace the regulators on the '66 337 so that each alternator is fed from it's own regulator, sounds an expensive mod to me?

The Manufactures are more and more covering there own rear end by putting a life on items, these parts were always on condition but we have become the sue and sue more society that it has been blown out of proportion.
In the Cessna 337 Service Manual it also says the seat belts should be replaced at 5 years, anybody done this. If they did this sort of thing to your car you would have something to say.

Regarding the starter relays: The CAA over here insist on the fitting of a simple light to show the starter in engaged and the relay is energized, so a failure of the starter relay would be detected by the light being on. Simple but saves a burnt out starter?

Trick question, not my style. But would like an answer.

GMAs I have enjoyed this discussion and I hope that we can have more of these, as you have said for owners that read this I hope it has given you some insight of what is involved in maintaining your airplane and the older they get the more of a problem they are (just like us!).

Thanks GMAs
Pete

[GMAs]

Pete....
I too enjoy a good tech discussion. Yes indeed you all do it different over their. Putting a light on the dash showing the engagement of the starter would not be hard today using LED's... but then again the wire weight and is it necessary if the plane is maintained.

I used to know a guy who could use two fingers across the voltage source and tell you if it was 120,240 or 480... he wouldn't try 660 because he said his hand got cramps after for a few days... Yes technology has come a long ways from the old days of the edison jar measurements. We have several of the fluke inst that we use here and they seem to serve well... We also use a low freq generator to do surface contact checking... however most of the time a good cleaning, alodining and then mounting takes care of the problem of skin resistance on parts.

Well the service manual is the bible... but yes experance is the key to "gettin 'er done" right the fist time.

Yes I think they did away with the old single regulator... never worked right in the first place... and put in the same as the current dual regulators on the fire wall using the same parts.. shouldn't be that expensive.. but, here in the States we can use a form 337 and get field approval for these types of mods... I don't think a lot of the older ones here are running single vr's anymore... of course cessna quit making the plane that did...336 and early 337... and went on to a better system.

If it were me.. I would change... but if it were too difficult or expensive over their.. I would put a switch in so that only one alternator was working on line... of course your limited in current then if you go by the rules... Yes I would upgrade to the dual vr ... one each for the alternators. Today technology has the VR's built into the alternators on the belt driven ones.. I think some of the EAA guys have converted the Cont drive to use the newer alternators... thus you would have the VR's built into the alternator and wireing would be a breeze to convert the system over... then each VR is right inside the alternator... and of course they are electronic controlled so no adjustment necessary at the source... only IR drop from the rear to front would have to be delt with. A single sense wire could take care of that.

As to your question....
I disagree... with your response... the set voltage is in the Service manual.. and also the battery manufactures publications... they are the guide that you are to follow. Anything else and your not going to get opt life out of the battery. I am still scratching my head about the "...and it doesn't matter about the battey condition" I think most will disagree... that it does... i.e if the battery is low ... how do you set the vr's correctly... the manual clearly states that one should have the battery charged up and full before attempting to set he VR's ... while the plane is running... of course you could set them up using a test jig...on the bench... but then that doesn't take into consideration the IR drop of the connections and condtion of the wires.

Take care my friend

Fly Safe GMAs

[Pete Somers]

GMAs
Sorry i will put that question in a different way.
On the ground no engines running you check the field voltage at the alternator, what will the voltage be on a '66 337 and what will be the voltage on a '77 337, just for interest and i hope all you guys are taking note.

Thanks GMAs
Maybe meet up soon time

Pete