A quick check to see how many amps your starter is actually drawing would be in order as well.
--- In [email protected], William R. Bayne <ercog...@...> wrote: > > > Linda, > > Once again, I agree with Hartmut. A healthy 25amp battery will serve > your needs just fine. > > WRB > > -- > > On Jun 18, 2010, at 02:23, Hartmut Beil wrote: > > > > > > > Linda. > > > > My experience with batteries is that a battery that is dying can > > crank the starter fine for a few rotations, but is still source of > > trouble. > > > > A Generator/regulator that is loading the battery properly can create > > the same effect. > > When all 3 parts of the system are in good working order, you won't > > experience the problems you are describing. > > > > As a matter of fact, I was jump starting cars with my 12 Amp/h > > Motorcycle Battery with no problems. > > It is not the size of the battery that matters, it is the cranking > > power that it can develop. > > > > Understandable a battery with a dying cell will develop little > > cranking power, as are some batteries that are not designed for that > > purpose. > > A good 12 amp battery should be able to start your engine as well as > > the 24 amp one or the 35 amp one. > > > > If you have these intermittent problems , I am hesitating to come to > > fast conclusions that the battery is not big enough. > > This is the logic of the inexperienced. > > > > It is usually either the starter itself or the charging system. Of > > course one has to verify first that the battery itself is good. > > I am afraid you mechanic wants to fix a problem from the wrong side > > at your costs. > > > > Hartmut > > > > > > To: [email protected] > > From: laspr...@... > > Date: Thu, 17 Jun 2010 16:09:08 -0700 > > Subject: [ercoupe-tech] batteries > > > > What John wrote below helps a lot to understand the relationship of > > battery & generator. The problem I've had recently has not related > > to running enough electrical items in flight, rather, it has been > > battery capacity for cold starts: e.g. when my local A&P ran a bunch > > of "test starts," such as when he was adjusting the pull-starter he > > tried it out a bunch of times, or when he cleaned the spark plugs and > > was testing whether that smoothed-out how the engine was running. > > Then when I went to fly next, there was not enough power to start > > up. Yesterday, he had to give it a "jump start," but after I flew > > 45 min. to my destination, did 3-4 starts & run-ups there for the > > prop-balancing guy, and then it sat for 2-3 hrs. but still started > > fine for me to fly home. > > > > John (et al.), can you please address battery capacity for cold > > starts? Is it correct that a Concorde 35 will be better for this > > purpose than a 25? The A&P wants me to get a 35 (and, Hartmut: he > > says a field approval is no problem, and he'll measure the box for > > fit, before buying it.) Is a 35 better for my purposes than a 25? > > Other than the few lbs. extra weight, am I asking for any kind of > > additional problems if I get the 35? My 414-C has a C-85 and a > > generator, not an alternator. > > > > Linda > > N3437H (Sky Sprite) > > L.A. > > > > 1a. Re: batteries > > Posted by: "John Cooper" j...@... > > Date: Wed Jun 16, 2010 6:16 am ((PDT)) > > > > On 6/14/2010 7:31 PM, Todd Fischer wrote: > > > > > Reading the Univair memo it sounded like the older generators just > > > couldn't handle charging the larger batteries and only approved the > > > RG25 batteries. > > > > > > > > This is a misconception. The larger battery has more capacity, so it > > will take longer to discharge, as well as longer to recharge, but, > > unless you continually discharge it, which means your constant > > electrical load exceeds the generator capacity, it will remain charged > > the same as a smaller battery. OTOH, if you are exceeding the capacity > > of the generator on a regular basis, the smaller battery will go flat > > faster. > > > > If the RG-35 battery is in good shape, and you charge it up (once), and > > you do not exceed the capacity of the generator with your electrical > > load, then the battery will work fine. > > > > As an aside, the constant load on the electrical system should not > > exceed 80% of the generator capacity. Constant load includes comm > > recievers, nav radios, transponders, nav lights, etc.; everything that > > is not intermittent, e.g. landing lights, flap motors, gear motors, > > comm > > transmitters, etc. > > > > -- John Cooper > > Skyport East > > www.skyportservices.net > > > > > > > > Your E-mail and More On-the-Go. Get Windows Live Hotmail Free. Sign up > > now. > > > > >
