The International Cessna^® 170 Association

Well, I busted my hump this morning to get the "chores" done, drove down the hill to the airport, loaded up the airplane with the dog and my pack...all excited to get out to the annual summer solstice fly-in at the 8 Mile strip. And then ol' Murphy showed up...battery was completely dead. Not exactly sure why, but I suspect that the "Master Switch - On" position may have had something to do with it. Damn airport gnomes.

So, I hand propped the motor, started right up, but didn't show any movement on the Alternator gauge. Figured I'd break the error chain there, so I opted not to head out the 55 or so miles to the strip. I knew that I'd be able to hand prop it the rest of the day, but once Mr. Murphy is around, he doesn't just leave without a couple more hijinks.

I'll pull it and put it on the charger later, to see if I wasted it, or if it will take a charge and keep on ticking.

Bummed out that I missed the event, was gonna be my first. Hope it was a blast; looks like the WX cleared enough to be a nice day out there.

Karl
N43F
1954 170B (B is for battlewagon)

Karl,
Good call, I have a problem with taking off with a completely discharged battery......Yea you can start and charge the battery with an arm-strong starter.....But you never know what is happening in the battery box.....Obviously a lot of acid gas, and that is just going to create problems in your battery case.....The best way to fix a battery problem is start with a fully charged battery and go from there.....Brad

Yep, good decision-making skills.

An alternator cannot begin to re-charge a battery because it's "field" is not activated except by existing aircraft current (normally supplied by the battery...but yours was dead.) The only way to get things going again is to "jump-start" the battery with jumper-cables.... an excellent reason to install a ground-service plug so you don't have to open the cowl and/or the battery box to jump-start.

A generator-equipped airplane has an advantage in this situtation because a generator's "field" is already magnetized (polarized) and will activate the generator and re-charge the battery after hand-propping.

See the discussion on Battery Power Receptacle (in the Hangar forum) if you have further curiosity on the matter. http://www.cessna170.org/forums/viewtop ... f=2&t=6287

Somebody remind me,why did we rush to alternating current generators in the first place? I don't remember having any big problems with the old DC generators & as Gahorn mentioned the DC generator has certain advantages.

Zreyn wrote:Somebody remind me,why did we rush to alternating current generators in the first place? I don't remember having any big problems with the old DC generators & as Gahorn mentioned the DC generator has certain advantages.

They appear to have greater capacity (amps), and they produce more current while you're idling, waiting for your clearance and turn on the runway. Anything else? That's all I can think of. Maybe someone else can explain the capacity thing.

Zreyn wrote:Somebody remind me,why did we rush to alternating current generators in the first place? I don't remember having any big problems with the old DC generators & as Gahorn mentioned the DC generator has certain advantages.

Alternators have the great advantage over direct-current generators of not using a commutator, which makes them simpler, lighter, less costly, and more rugged than a DC generator. The stronger construction of alternators allows them to use a smaller pulley so as to turn faster than a DC generator, improving output when the engine is idling. Alternators use a set of rectifiers (diode bridge) to convert AC to DC. To provide direct current with low ripple, alternators have a three-phase winding. Alternators are also lighter and easier to package on the engine.

I sure wish someone would post a comment in the forum next year about the fly-in before it happens. This is the second year in a row I missed it. I read the Flypaper when it comes out and by the time of the fly-in, I forget about it. And there I was at home all day working in the yard when I could have been flying and eating hot dogs.

Hey, Richard!

Don't forget about NEXT YEAR! (Hope that helps.)

Thanks George, you reminded me just in time so I'll forget it.

I take it that you're in AK and not TX these days? I'm in Grapevine going thru Initail KingAir350 type. Wondered if you're in town for a beer.

I had always thought that a dead battery would charge off of a generator after armstrong starting, but I now believe that a battery can be too dead to take a charge. I had left my master switch on far to long. I hand propped, and was off for a three hour flight. Everything went well until I pulled the throttle on downwind. Lights and radio went dark and silent. I put it on a charger overnight and everything came back to normal. I now leave my rotating beacon switch in the "on" position so I can hear and see the switch is on.

Larry

gahorn wrote:I take it that you're in AK and not TX these days? I'm in Grapevine going thru Initail KingAir350 type. Wondered if you're in town for a beer.

I'll take a rain check on that beer in October.

Larry Holtz wrote:I had always thought that a dead battery would charge off of a generator after armstrong starting, but I now believe that a battery can be too dead to take a charge. I had left my master switch on far to long. I hand propped, and was off for a three hour flight. Everything went well until I pulled the throttle on downwind. Lights and radio went dark and silent. I put it on a charger overnight and everything came back to normal. I now leave my rotating beacon switch in the "on" position so I can hear and see the switch is on.

Larry

Larry, I miss spoke as George pointed out earlier. The field needs excited, if the battery is completely dead....nothing will happen on the charge side. You can start the engine and excite the field with a 9 volt transistor type of battery...But the best way to fix a dead battery is pull it.....(I don't like to leave a battery in the box because you can get acid run off and have corrosion issues in your box). charge it and check it for load....If every thing is OK then you are good to go....Brad

In order to get the battery on-line for charging you have to find a way to get the battery relay (on the front of the battery-box) to close. In order to do that you either must have at least a token amount of charge in the battery (sufficient to operate the relay), or you must jump across the two large terminals of the relay while the cockpit master is activated. That is done automatically if you have the diode I described in the other message thread regarding voltage "spikes" installed on the relay per the Service Bulletin.

I now leave my rotating beacon switch in the "on" position so I can hear and see the switch is on.

Hey that's a good ideal Larry!