voltage drop in ignition common?

[rsfeller]

i just bought a 1984 Cruisers Inc Avanti Vee and have been giving it a hard upgrade on land for the last month. Previous owner mentioned voltage drop concern. Got rid of the battery isolator for newer combiners, anyways...<br /><br />no noticable voltage drop anywhere on the boat DC system accept at the ignition switches and everything after that (gauges) with an 1.4 to 1.6 drop. This is with no engine running just battery info. The reason i am curious if this could be normal is i've have longer runs in the DC system with no concerning voltage drop...just at the ignition. is components in the engine (between battery and ignition obviously) sucking of voltage to give this drop?<br /><br />any comments would be appricated w/o a lecture on 3% and 10% voltage drop!<br /><br />thanks all.

 

[Moody Blue]

Re: voltage drop in ignition common?

Doesn't sound right to me. Thats a substantial drop given that nothing is running. Sounds like you have a bad connection somewhere in the circuit. With no load, you should measure 12V everywhere.<br />Spent and hour yesterday trouble shooting a bilge pump that wouldn't work. Turned out to be a bad contact in the fuse holder under the dash. Measured 12.6V both side of fuse at no-load. Everything looked fine until I turned on the pump. Voltage at load side of fuse dropped to 0V while battery side of fuse was still 12V. Cleaned terminals and everything is fine now.

 

[demsvmejm]

Re: voltage drop in ignition common?

As RodC is pointing out, you need to test voltage at all points of concern with the load on. If your battery voltage at the battery drops with the Key On Engine Off, then your voltage drop at the key is ok, but the system voltage drop may not be. If your KOEO battery voltage stays at 12V and you still have excessive volt drop, you will need to trace from your ignition switch back to the battery until you find your culprit. By the way, is this voltage drop measured across the contacts of the switch? If so you need a new switch.

 

[rsfeller]

Re: voltage drop in ignition common?

it appears to be at the contact of the switches and downstream from there as well as the entrance to the switch. battery voltage at the battery stays the same when KOEO is engaged.<br /><br />so i figured it something in the wiring loom of the engine which is far more complicated than i can get into at this time, hoping something obvious to 20 year old wiring of 351 pleasurecrafts...