REFLECTOR: starter trouble

[Dave Philipsen]

Lou,

Instead of using your meter to read voltage as referenced to ground, 
start checking voltage drops on the various components.  From the 
numbers you quoted, there probably is not an appreciable drop across 
either of the solenoids.  But, you could check it by simply placing your 
meter across the solenoid while trying to start the engine.  If you 
fashion some sort of extension wire for your meter, you can read the 
voltage drop across any of the wires including the one that connects the 
output of your starter solenoid to the starter and the one that connects 
your battery ground to the engine. As was brought out before, there are 
very few cases where the voltage drop should exceed a volt.

You definitely have an excessive voltage drop on the order of 4 volts in 
there somewhere.  For starters (no pun intended), it sounds like you 
have about a 2 volt drop between the +batt and the input side of the 
master relay (assuming that your "voltage from power in of master" was 
referenced to battery ground). You should have very little there since, 
assuming your battery and master solenoid are in the nose like most 
everyone else's, the cable is very short...should be more on the order 
of less than .1 volts.



Lou Stedman wrote:
> I agree Brian but there is very little drop across the solenoids. I am 
> thinking wire connectors.
>
> Lou Stedman
> Velocity N7044Q
> Olean, NY
> ----- Original Message ----- 
> From: "Brian Michalk" <michalk at awpi.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Wednesday, October 08, 2008 3:41 PM
> Subject: Re: REFLECTOR: starter trouble
>
>
>   
>> Batt- to engine block: .6v
>> That's probably the best case scenario for voltage drop with the current
>> for that test.
>> Measure from Batt+ to starter+.  From your data, that number should be
>> close to 3.4v.
>> Try to get that 3.4v drop as close as possible to your ideal .6 volt drop.
>>
>> Your ground return probably has two connections, and one wire.   Battery
>> to wire connection, and wire to engine connection.  That's close to the
>> ideal.
>> Your positive side has more connections: batt-wire-solenoid,
>> solenoid-wire-starter.  Four connections, two wires, and the wire length
>> is probably longer.  From your data, it looks like you need to look at
>> the batt to solenoid section.
>>
>> Try minimizing your voltage drops.
>>
>> Lou Stedman wrote:
>>     
>>> Well I finally ran all of the tests on my starting system to find out
>>> why my started is having so much trouble turning over this engine. As
>>> I discussed before, I have a IO-360 on my VEL. My starter is a SkyTec
>>> LS. When I hold my key to start the starter will begin to turn , then
>>> hesitate and I let off on the key. Eventfully it will turn over. When
>>> it does it spins the prop fine and the engine starts at once. I
>>> downloaded the troubleshooting guide that SkyTec has and I wanted to
>>> share my findings. All of the voltage readings are taken when the
>>> started begins to loge down.
>>>
>>> 1.Voltage from plus and minus posts of battery while in failure
>>> mode           9.9 volts
>>> 2. voltage from ground on engine and + post of
>>> starter                                     5.9 volts
>>> 3. voltage from power in of master
>>> solenoid                                                      8.0 volts
>>> voltage from out side of master
>>> solenoid                                                       8.0 volts
>>> voltage from power in of starter
>>> solenoid                                                       8.0 volts
>>> Voltage from power out side of starter
>>> solenoid                                           8.0 volts
>>> 4. Voltage from minus side of battery to engine
>>> block                                  0.6 volts
>>> 5. Voltage at battery before starter
>>> engage                                                   13.2 volts
>>>
>>> Things I have tied:
>>>
>>> Removed and cleaned all connections.                           Results: 0
>>> Replaced my existing battery (Interstate 462 C.A.)
>>> Installed new Power Sonic Battery PS12400 (40AH, 435 C.A.) Results: 0
>>> Starter was returned to SkyTec for new housing and check.
>>> Results: OK
>>>
>>> My next step is to replace all of my connections with new copper
>>> connectors and solder them on.
>>>
>>> Your input is greatly appreciated.
>>>
>>>
>>> Lou Stedman
>>> Velocity N7044Q
>>> Olean, NY
>>> ------------------------------------------------------------------------
>>>
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-- 
Dave Philipsen
Velocity STD-FG
N83DP