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I just can?t do it captain, I need more power

N208ET

Well Known Member
Originally when I built my 0-360 up, she had dual Bendix Mags and a standard compression ratio. I used a Sky-Tec LS starter and a PC680 to supply the juice. This worked flawlessly for 500 hrs. She?d spin and start like clockwork.

Fast forward to a completely rebuilt engine, with 9.5 to 1 pistons and Dual PMags. If it was plugged in and warm, she?d barely swing enough to start. I upgraded the starter to a B&C, huge improvement. But she still won?t start. The voltage gets pulled down below 9V, which is what the PMags need to make a spark, I think.

Considering replacing the Battery with a EarthX, figuring that should solve all the problems. Opinions?

Randy
8A 0-360 Dual PMags 9.5 to 1?s Catto 3 Blade
 
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Considering replacing the Battery with a EarthX, figuring that should solve all the problems. Opinions?

Randy
8A 0-360 Dual PMags 9.5 to 1?s Catto 3 Blade

Randy:

It is possible that your current battery just needs to be replaced with a new one. Sounds like the capacity of your current battery is only a fraction of what it was when it was new.

IF you can do a LOAD test or CAPACITY test of your current battery, that would tell you the true story.

I have used a Concord AGM battery in my RV-6 since it was built. As my battery gets old, I notice a drop in voltage when the starter is engaged. When voltage gets below 9 V while cranking, my LASAR ignition may not produce a spark to start the airplane. Replacement battery brings the cranking voltage up to 11 or more volts with starter engaged.

I have replaced the battery when it was as little as 2-years old and had one last as long as 5-years.
 
You need both the capacity in the battery necessary to spin the engine well, as well as a clear path for the electrons to flow. First, your battery may be failing and unable to deliver the amps necessary to spin the starter with enough force. The fact that the resting voltage is in spec is not necessarily an indicator of it's ability to flow 100's of amps for 10 seconds. Load testing can be done at you auto parts store if you don't have a load tester. Second, there may be resistance in the electrical path (including the gound/return) between the battery and the starter that is limiting the flow of energy. The two most common issues are corrosion between the battery terminals and the cables (or ground strap) and excessive wear inside the starter solenoid. I just replaced my solenoid at 600 hours, as It wouldn't flow enough juice in the winter to reliably turn the engine. The starter solenoid is a wearable item and will not last forever in most situations. Some last longer than others due to manufacturing tolerances or installation issues.

It is a process when troubleshooting this issue. Research here on how to measure voltage drop at various points in the power path. However, if the battery is 500 hours old, I would start there. You shouldn't eally expect much more life out of it at that point. Small engine mounted batteries lead a tough life.

Larry
 
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It?s a new battery too

Should have mentioned that. I?ve checked all the connections and they are in great shape. I could do a load test on the battery but figured after 2 batteries doing the same thing, the new starter improving things drastically, and the wiring all good, what else could it be.
 
Should have mentioned that. I’ve checked all the connections and they are in great shape. I could do a load test on the battery but figured after 2 batteries doing the same thing, the new starter improving things drastically, and the wiring all good, what else could it be.

New battery is not likely the issue. WHile cranking, measure voltage drop across the starter solenoid. As I mentioned, that is a likely candidate and the first I would check. Mine was shot by 600 hours. THey are only $20.

Larry
 
I have seen this one time and it could be the battery.

I use a battery tender all the time (PC680) and for some reason left it off for a week or two.

I pulled the plane out and when I went to start it, the prop spun about normal, maybe a little slower, but I noticed the EICommander rebooted while starting. The EICommander doesn't take much of any power (think milliamps) so I was surprised to see it reboot.

I pulled out an extension cord, plugged in the battery tender, jumped in, pressed the starter button, and it fired right up. In other words, I didn't give it time to charge the battery.

That is first time I have ever had that happen but it is about time to replace the PC680, so I wasn't really surprised.

Another option is to add a 9 volt battery to one P-mag for such occasions. Here is a document describing how to install a 9 volt battery for emergencies like this.
 
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Considering replacing the Battery with a EarthX, figuring that should solve all the problems. Opinions?

Randy
8A 0-360 Dual PMags 9.5 to 1?s Catto 3 Blade

Rather than a lithium based battery, you need to go straight to the dilithium crystal.

Make it so...
 
Starting

This could be a poor ground path from batter to starter. On my 10-1 0 320 I had similar issues and cured the problem with a extra ground wire from battery ground to starter case. I know of one other case with similar results. Sky Tec starter and odessey battery
 
As mentioned, there are lots of places to see a voltage drop that can cause this problem (and cure it, without an EarthX battery). Ferret those out first, because if you spend the money for a new EarthX and still have the problem, you'll really be chapped then.

Having said that - I'm a very satisfied EarthX user, I love how it spins my prop on start and holds high voltage while doing it. You should consider the sealed, vented battery box if you have it in the cockpit or baggage area. I have the ETX900-VNT for my 9A with IO360 running SDS.
 
Measure voltage at P-mag lead and see how low.

Then as a test, wire up separate battery just for the P-mags and see what happens.

The voltage won't drop as much with just the P-mag load.
 
Measure voltage at P-mag lead and see how low.

Then as a test, wire up separate battery just for the P-mags and see what happens.

The voltage won't drop as much with just the P-mag load.

If you wire a separate battery to just the P-mag, be careful you aren't back feeding the rest of the electrical system. That's why, in the sample I linked to above, the switch isolates the P-mag from the electrical system.

However, you could run the test, knowing it won't start and/or put the test wires on the other P-mag to see what happens.
 
Ha

Rather than a lithium based battery, you need to go straight to the dilithium crystal.

Make it so...


Best idea I?ve heard yet!

The starter solenoid was the first thing I tried replacing, cause I figured it?s only $20. No effect. I had a bad ground experience on the Sky-Tec a long time ago, I doubt that?s the problem but it?s worth a try.

I thought about doing the 9 volt battery trick just to see if that could get me started in a pinch, which I?m sure it would. But that seems like a band-aid over a bigger problem that would still be unfixed.

If I leave the sump heater plugged in, she?ll spin much easier and as a result doesn?t pull the voltage down as much, she fires right up. My battery is on the firewall, so it isn?t far away from the starter to begin with.
 
slow starts, old solenoids

With regard to "barely swing enough to start": I was having groaningly slow starts that kept getting worse with time. New battery seemed to solve it but then it was back. Old alternator? Weak starter? At a remote airfield getting fuel an hour till dark - prop *barely* turned over to start. That did it -

Turned out I was getting 0.7volt drop across the master solenoid, and 0.3volt drop across the starter solenoid. 30 year old solenoids (yes I know, duh). A full volt loss! That's why a new battery seemed to solve it. I spent some cash to get the best solenoids around: Lamar P52-0034-1 master and X61-0030 starter.

Engine starts like a whirling dervish now. I'm looking fwd to opening up those old relays to see just how messed up they actually were

cheers,

- Steven
(1300 RV3 hours - another one yesterday!)
 
I am curious what type/size of wire used for you battery/solenoid/starter/ground. If it isn't mil-spec there could be some internal corrosion going on causing high resistance. Check all the terminals for signs of corrosion and loose terminals. I know some people use welding cable instead of the mil-spec tin plated copper. Is it a minimum AWG 2 gauge?
 
I am curious what type/size of wire used for you battery/solenoid/starter/ground. If it isn't mil-spec there could be some internal corrosion going on causing high resistance. Check all the terminals for signs of corrosion and loose terminals. I know some people use welding cable instead of the mil-spec tin plated copper. Is it a minimum AWG 2 gauge?

Are you sure about this? I far prefer welding cable offer mil-spec as it is much less susceptible to fatigue failure and doing my own ?torch test? find quality welding cable insulation to be more robust than mil-spec. I have never seen ?internal corrosion? - and considering welding cable spends decades in the sun and weather on the back of welder?s trucks I suspect internal corrosion is not an issue.

Carl
 
I got the wire from Vans

Wire looks to be in great shape. The plane sat for 3 years between engine overhauls, so the wiring and connections was the first thing I checked, next was replacing the starter and master solenoids, then replaced the battery with another PC 680 thinking the old battery sitting for 3 years was probably toast. No effect. Then I got the B&C starter. Now she?ll spin plenty fast but the voltage is dropping enough that the PMags don?t have enough umph to spark with the starter pulling that much current.

If a new battery doesn?t do it, I?m pulling everything out and installing a Coffman Starter!
 
I don't know that an EarthX battery will solve your problem but my -7A spins at least 3 times faster vs the PC680 it replaced. If you go this route, don't be surprised when your alternator maxes out (amps) for a little after enabling the alt field. Those batteries dump power like mad and take it back in as quickly as possible. Hot starts are also much improved.
 
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Are you sure about this? I far prefer welding cable offer mil-spec as it is much less susceptible to fatigue failure and doing my own ?torch test? find quality welding cable insulation to be more robust than mil-spec. I have never seen ?internal corrosion? - and considering welding cable spends decades in the sun and weather on the back of welder?s trucks I suspect internal corrosion is not an issue.

Carl

I have never done a torch test on the welding cable vs Mil-spec. I did use welding cable in the Cozy MKIV and it has so far held up very well going on 12 years now. No problems with corrosion on it and we did solder the ring terminals in solid. I bought a 500' roll of surplus mil-spec wire when I was building the RV-10. It was severally corroded from one end to the other. I kept cutting it at 10' intervals hoping to find the end of the corrosion but ended up tossing the whole roll. The corrosion was easily identifiable as a whiteish gray colored powder in the strands. Just making suggestions as there is obvious high resistance somewhere and the obvious seems to have been addressed.
 
Starting

Randy,

Have you checked out the Skytec high torque NL starter? If not I would bet that is the solution to your problem. I bought an RV-4 many years ago (now have an -8) and always had trouble starting just like you described. It had an Aerobatic AEIO-360 and a big fat aerobatic prop.

I tried all the electrical issues you talked about and had no luck until I put in a Skytec 149NL high torque starter. Problem solved for the most part. Sometimes on a hot start if I didn’t get it just right and had to make a couple tries then the battery would start struggling. Enter: the EarthX battery, engine never turned so fast and never, ever had a starting issue again.

Neither option is cheap but this ain’t a cheap hobby anyway. I would try the NL starter first if it fits in your cowl. If that solves your issue, good to go. If not then consider the EarthX battery- tiny package but those batteries are monster starters
 
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The 'NL' series and HT starters are from Skytec, the BC206 is from B&C.
I always prefer the B&C if it fits over Skytec.
 
I changed to a B&C

The B&C made a world of difference. So much so that after I put it on, it started it right up. But it was warm out, so I went out the next morning, didn?t have it plugged in, to try and turn it over just to see if it turned over faster. I didn?t have time to fly, so I pulled it out and left the mags and mixture off and hit the button. It turned over so much faster that I figured my problem had been solved. Wasn?t until the next day when I did have time to fly that I was once again wrong.

It?s not a cheap hobby, but I use my plane as a tool. When I fly it somewhere, I park and walk away not thinking about whether or not it will start the next morning cause it?s a little cold outside. So I?m going to be ordering a new EarthX.

Not one comment on the Coffman Starter, thought that would have got somebodies mind wandering.
 
Follow up

It took a few months, but I pulled the trigger on a EarthX 900 series battery. Problem is solved, big time! That thing spins the lyc over so dang fast it?s a little scary. With summer in full swing, the real test won?t be till this winter, but I have high expectations that it will do just fine!

Randy
8A
 
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