29 volts at choke?

[nigels]

1999 4.3 with Thunderbolt V 2bl carb

I measured 29.3 volts (engine running) at the choke is this correct?

 

[Don S]

Re: 29 volts at choke?

No it's not correct, unless you are also showing 29.3 volts on your battery.
How exactly are you checking it?

 

[nigels]

Re: 29 volts at choke?

Using voltmeter directly onto positive at choke and ground, engine running. I thought it weird I expected 13+- volts, voltmeter on panel says 14. something

 

[Don S]

Re: 29 volts at choke?

Check the purple wire on the alternator and the coil + terminal with the engine running. They should be seeing the same thing.

 

[Lyle29464]

Re: 29 volts at choke?

A cheap meter set on A/c will give some strange readings. 29 39 etc is not unusual

 

[nigels]

Re: 29 volts at choke?

Stupid me, just had the muffs on, and measured 13Volts but 29 volts AC, must have had the Multimeter on AC instead of DC.........which solves one mystery but creates another, I see the manual states: (When checking battery terminals to see if you are getting charge from the alternator)

NOTE: If the voltage reading is within specifications, switch voltmeter to AC volt position.
There should not be more than a 0.250 AC voltage reading with the engine running. A reading
more than 0.250 AC volts indicate defective diodes in the alternator.

So I obviously have defective diodes....whats the implications of this, can I live with it? Can I fit external diodes or do i need a new alternator?

 

[nigels]

Re: 29 volts at choke?

A cheap meter set on A/c will give some strange readings. 29 39 etc is not unusual

You must be a mind reader, how did you know i did that, lol, can you diagnose my diodes from so far away lol?

 

[Bt Doctur]

Re: 29 volts at choke?

i think you need to re-check your measurements . a quick test is to put the meter on the battery and record voltage, start engine ,rpm to 1500 ,record voltage, should be higher.Using a meter on AC your checking for AC ripple aka :bad diodes.
bad diodes will also cause a drain condition .with everything turned off in the boat(stereo, amps, etc) remove the positive battery cable and
using the DC current scale ,see if there is a discharge with the neg lead to the battery pos. and the pos meter lead to the battery cable.

 

[nigels]

Re: 29 volts at choke?

i think you need to re-check your measurements . a quick test is to put the meter on the battery and record voltage, start engine ,rpm to 1500 ,record voltage, should be higher.Using a meter on AC your checking for AC ripple aka :bad diodes.
bad diodes will also cause a drain condition .with everything turned off in the boat(stereo, amps, etc) remove the positive battery cable and
using the DC current scale ,see if there is a discharge with the neg lead to the battery pos. and the pos meter lead to the battery cable.

Battery at 12.7 start engine and it reads 14.7. Engine off, disconnect positive cable (battery now at 13.05V) and measure between terminal and cable, zero with battery isolator switch off, put isolator switch on, then i get -12.90v

 

[Bt Doctur]

Re: 29 volts at choke?

not volts, current .0-10 A scale , black meter lead to pos battery, pos meter lead to battery cable.

 

[nigels]

Re: 29 volts at choke?

not volts, current .0-10 A scale , black meter lead to pos battery, pos meter lead to battery cable.

On 10amp scale reads zero with battery switch on.

So no drain, but what about those diodes?

 

[Bt Doctur]

Re: 29 volts at choke?

no backdrain in most cases mean no leakage thru the diodes, alt is showing good voltage , no backfeed, so I would pronounce it fit for duty.

 

[nigels]

Re: 29 volts at choke?

no backdrain in most cases mean no leakage thru the diodes, alt is showing good voltage , no backfeed, so I would pronounce it fit for duty.

So even though I am registering 30 volts ac from the alternator I am good to go? Not going to damage anything?

 

[nigels]

Re: 29 volts at choke?

And thanks to yall for the help!