Voltage at engine while cranking F225TXRD

[fairdeal]

So, I suppose that I need to measure the V drop between the Batts and the connection block. And again between the Batts and the connections on the engines themselves. And / Or, measure the resistance of the Batt cables and see if internal corrosion is stealing my amps.

Plz learn me how to do that on my DVM, as its got about a million settings a
I assume that I'l have to add a long piece of wire to the battery lug to do this. Will that cause inaccurate readings due to voltage drop?

Measuring the voltage is more direct and informative than trying to measure resistance.
But you need to be measuring while the engine is cranking - so that may require a helper (I set my phone up to video the meter)

You just need to set your meter to DC volts -
if its not autoranging,
start by selecting the lowest scale that is higher than 13 volts
then, as I did in this thread,
- measure between the battery terminals while cranking
- measure between the + engine lug and engine ground while cranking

the difference in volts is the total of all the voltage drop points you have

next you want to find the individual drops of that total, to see where it may be correctable.

so- again, measuring while cranking - measure across each connection -
i.e. from the terminal itself, to the cable lug that is attached to it

then - yes, if necessary by using an extension wire for your meter -
measure at the two ends of cables.

The wire extension on the meter leads will not significantly affect the reading -
because unlike the wires to the starter motor,
there is almost no current going through the meter.

[pstephens46]

Thanks for info on the clips. I would like to build an extra long set of leads for this type of thing.

This is a good reference thread as voltage drop is a common issue.

An issue that often drives people nuts and ends up with money being spent on unneeded parts.

I have lived it....

[pstephens46]

Oh.....did you happen to check the ground lead in a similar fashion?

[99yam40]

OK, with the voltmeter leads
- on the battery positive terminal
- on the engine positive cable lug
while cranking:



so as already indirectly derived, a loss of ~1.15 volts due to the cable
(and another 1.15 lost on the return to ground)

Its the original 2005 Yamaha cable - soldered lugs.
About 3-4 feet longer than it needs to be - excess folded and ziptied above the bilge.

Given that the engine always starts immediately - I'm not motivated to mess with it.
Certainly not to pull it out of the rigging tube to replace or modify it.
And without the proper hydraulic crimper,
I'm not going to attempt to shorten it in situ.

But interesting to know the numbers: that the engine cranks - and starts fine - with 8-8.5 volts at the starter lug.

before saying that, I would hook up to the red starter lug and to the case of the starter for the ground to see exactly what the starter is seeing/running on

[panasonic]

Those Yam cables are pretty nice. Compared to some of the junk found at big box stores. I would be careful with the quality.

Always got a laugh when Solo would write about his battery cables that crumbled in his hands....Kmart for sure!

Yamaha cables I took off my brother's 6 year old F60....no start...I wonder why?

[pstephens46]

Yamaha cables I took off my brother's 6 year old F60....no start...I wonder why?

You shouldn't let them go swimming.

[panasonic]

You shouldn't let them go swimming.

The only thing I found on the engine that was bad....battery cables. Rest of the engine was in excellent condition. Battery cables...about 4 feet long were a mess...corroded through the whole length ..don't know how they got in such a mess in a short time.

[throrope]

Sounds to me you're struggling with a prior owner's fix. If I read you right, the starting lines were too short to extend to the battery and extension cables were installed. You may be left with auto instead of marine cables.

Marine wiring is specifically different than normal or auto wiring. Strands are often individually tinned before combined into a cable for corrosion resistance. Insulation and jacketing is also different. They are applied to prevent water intrusion along the length of the cable. So, if you have auto cables instead of marine, you may find corrosion progressing along the wire under the insulation from the connectors.

IMHO, I'd forgo diagnosis and suggest replacement of cables, especially if you don't know how old they are. I'd also replace with one wire size bigger than required for that total length. Also, clean all connectors and cover with dielectric grease such as CRC Marine Battery Terminal Protector