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Cold cranking

S

Stevehaley

Member
Hi
Ive just bought a12yr old rv10 but the one thing that is irritating is the cold starting. It can take 4-6 tries to get the engine past the first compression but once it does it generally starts first time.
The previous owner/builder tells me this is ‘normal" however i can see reference in the logs to him trying a new solenoid but not sure if it was master or starter. The battery is only a year old and we left it on charge in case that was the issue but no change.
I have see references to changing the starter motor from lightweight to a 149ls but $1000 seems a bit extreme especially as others dont appear to have the same issue.
Ive yet to measure voltage drops at starter, starter solenoid, master solenoid and battery at start.

Regards
Stephen
 
Starting

Normally, after a flight, I move the prop past the compression stroke it stopped on. I have to move it anyway to allow the tug access. Hadn’t been a problem since. If I try and start it when it’s cold and up against the compression stroke, occasionally it takes a try or two to go through…
 
Richard Connell said:
Have you got some more details about the electrical system?
Battery(ies) type and size etc.
Click to expand...
All standard as far as i can see. Only one wire going forward uses aircraft frame as ground. Battery is a concorde rg25-xc supposedly 350cca.
Has a master solenoid by the battery.
What else do you need to know?

Stephen
 
Steve, have you checked the ground straps from the engine back to the airframe or battery? Check all the connections between the battery and the starter and then back to the battery.
 
Generally speaking, it sounds like the system is not getting enough current and/or voltage to the starter motor. Other than battery issues, most likely causes are excessive resistance in the power circuit. Issues to investigate, in order of probability

Battery weak - it needs a load test (100 A tester) to confirm it's health. Simply charging it is not a guarantee that it can deliver the current needed by the starter
connections of each wire between Batt + and starter
Connections of each wire between Batt - and starter (likely includes engine block & airframe)
solenoid on firewal has problems with internal contactor plates
solenoid on starter has problems with internal contactor plates
master contactor has problems with internal contactor plates
starter motor has worn brushes (not very likely)

Vans had an SB for the terminal crimps on the #2 wires being defective, if your plane used vans wiring kit. So will need a pull test on each of these as well.

You will need a bit of knowledge on how to use a VOM to test for all of these things. Search here for some good info.

Larry
 
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I suppose what i am really asking is can i expect it to turn over readily cold with the current configuration?
Ie concorde 25xc battery, lightweight starter and using the fuselage as the earth.
 
Stevehaley said:
I suppose what i am really asking is can i expect it to turn over readily cold with the current configuration?
Ie concorde 25xc battery, lightweight starter and using the fuselage as the earth.
Click to expand...

If all is installed and working right, the engine will crank easily and start up within a couple of blades. Anything less means something is wrong. I agree with Larry's troubleshooting suggestions - if you do this you will find the problem.
 
The lightweight PM starters have a poor performance history, your problem is a common complaint.
Switching to a wire wound starter like B&C or NL should definitely help.
 
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If I had these symptoms on an airplane, car, bike or lawnmower, assuming the battery checked good the very next thing I'd look at it the main power and ground wires for corrosion and loose attachments.

Since this is a home built, I'd also make sure they were the proper size for the application.
 
I'd go with WALT's analysis. Those lightweight Permanent Magnet starts are just not what you want. As he says get a regular wire world NL type starter and willing to bet that takes care of your problems. Look for a post under my username and you'll see the experience, including video that I experienced.
 
Aircraft Battery

OK, name me one standard category aircraft with a six cyl Lycoming
engine and a 25AH battery installed!

Hmmm, could get shot out of the saddle here.... but will risk it.
 
Don't know of any, but AH isn't terribly important for starting, CCA is. The 25XC has 350CCA, the 35a in my certified Piper 235 has 390CCA, so it has more, but not that much more. AH tells you how long after the alternator quits before all the lit up bits quit lighting up.

The Gill battery that was original for my plane is 23AH with 250CCA, so the 25XC should be more than adequate, and I guess that qualifies as a certified plane with 25AH or less :)
 
+1 Added to the list

Several years ago when I had my 10, I went through the same thing. Splurged and bought a NL version and was a happy camper. Several sessions of troubleshooting and wasted time but in the end the NL helped me out.
 
Flyingleap said:
OK, name me one standard category aircraft with a six cyl Lycoming
engine and a 25AH battery installed!

Hmmm, could get shot out of the saddle here.... but will risk it.
Click to expand...

I’m going to take a stab and say 50% of all RV10s have an odyssey 925 which is nominally 28AH.
The rest have 2xPC680s (32AH) or an earthx equivalent and maybe a scattering of Concordes.
I can start my 9:1 IO540 on a single PC680.

I’m inclined to agree it’s more likely to be the starter or compromised components along the way but it could be battery related.
The fact that the OP says the original builder said it was alway like that is an interesting clue though.
 
I had the same problem until replacing the starter. OK in the warm months, cross your fingers in the cold months, and keep trying until it makes it past the first compression stroke. Replaced with the larger starter and no issue in last 700 hours. First battery lasted 8 years and 5 on the second so far. When I called Skytek starters, they admitted the lightweight starter was undersized and not the right choice for the RV10 with battery in tail. At the time they had a swap program where you returned the lightweight and they provided the better one for maybe $100 dollars. That was 10 years ago, but you might call and ask them what they can do.
 
Not enough amps...

Mcmark said:
^^^^This!
How long is the positive cable run and what size is it?
Click to expand...

Continuing with what Mcmark said - Easiest and least $$ to check - no meter required. Jump/replace with temporary leads BOTH the + and - leads from battery to starter (I would run a ground wire vs using the fuselage ground). Do the whole overkill thing if you can - welding cable, someone's boat cables, HEAVY jumper cables, etc. You can "run the numbers" for the circuit ampacity requirements (assuming you know the starter draw), but if you simply go 2-4 sizes larger than whatever is already there, you'll know if it's the starter, solenoid(s), etc. If it spins over fine, then the original cable size is the likely culprit (bad connections, etc aside).
 
I wonder why some have this issue and others obviously dont.
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Because every RV is built just a little different. While the frame is all the same the systems installation can be vastly different from one to the other.

You know what they say about aviation, "the cheapest thing about flying is the pilot or the builder in many cases."
Shaving few dollars off by installing a smaller than required battery cable can easily cause the trouble you describe.

Mine has 2x18 amp Panasonic batteries and 2x #2 cables leading forward to the master and starter solenoid.
It starts instantly when cold and spins like the dickens for a couple of turns when hot.
 
I had a similar issue on a different aircraft. Switched to a larger diameter, coooer cable solved the problem.

Question I have is that you mention cold… how cold? We are already down below freezing in the morning in the northeast. I wouldn’t even think about starting my engine unless thoroughly preheated.
 
As previously suggested make sure it's not a weak battery or bad connections first. Leave the master on a few times and the battery won't get back up to normal charge.
It might not be spinning the crank fast enough.
 
What starter is installed on the aircraft? Simply saying it has a lightweight starter is not very specific. If it was a B&C starter I would not be looking at the starter first. If it’s a Plane Power starter I would be suspicious of it. How many hours are on the aircraft/starter? Checking all connections is always a good place to start. The grounds are as important as the power leads. There should be a #2 ground cable from the battery to the engine. Airframe ground for the starter is not a good idea. Copper is a better conductor than aluminum. Grounding the battery to airframe and engine to airframe will not likely carry the current well.
 
AaronG said:
I had the same problem until replacing the starter. OK in the warm months, cross your fingers in the cold months, and keep trying until it makes it past the first compression stroke. Replaced with the larger starter and no issue in last 700 hours. First battery lasted 8 years and 5 on the second so far. When I called Skytek starters, they admitted the lightweight starter was undersized and not the right choice for the RV10 with battery in tail. At the time they had a swap program where you returned the lightweight and they provided the better one for maybe $100 dollars. That was 10 years ago, but you might call and ask them what they can do.
Click to expand...

This whole saga is, unfortunately, not new. In 2009 I received a new IO540 from Lycoming (Vans special price) with the lightweight starter. I immediately emailed Lycoming, complained that that was not what I wanted. They agreed to send an NL if I returned the light weight starter, for zero net cost. I’ve never has an issue with starting.
 
Resolution

Just to update. Had a look at all of the wiring and it all looked in order. None of the solenoids had any significant voltage drop so replaced starter with nl variant.
What a difference turns over quickly and easily now for the sake of an extra 0.5kg.
What is interesting and tipped the balance fir me is that the Sky-tec fit guide lists the rv-10 as to use 149-nl NOT ls.
https://www.airpart.co.uk/assets/files/Uploads/2012/08/Application-Guide.pdf.
 
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