Join Date: Aug 2013
Thanked 19 Times in 19 Posts
Rep Power: 7
Re: House batteries won't start engine - ideas?
Firstly, Mainsail is pointing in the right direction. It is most likely not the batteries, but somewhere along the line the resistance is to high. Note that the Voltage drop over the resistance is R*I, and I being in the 200-300 Amps, then even a small resistance will result in rather considerable voltage drop which in its turn will show up as as a buzz in the solenoid, but no more.
My guess, there is not much info to go on so it has to be guesses, is that your cable is too thin. Maybe just intended to take some charging (which usually is in the range of 5-20 Amps, most often i the lower range), then small cross area is not a problem. There are other things to say about this, depending on how your charging relays are working etc.
Also the switch is probably not built for these currents of 200-300 A. Simply, you are not intended to start your engine in this way. For the occasional start using the support batteries use jumper cables. Some few $, a good investment.
Secondly, yes Yanmars may be difficult to start. Symptom: engine doesn't start when strating bottom is pressed, one has to do this 3-4-xx times and the it starts. That is usually another story:
For some reason Yanmar is taking the complete solenoid current through the starter key, ie from starting battery up to the key (often in the ****-pit) and then back again to the solenoid. Typical current is some few amps, but the wires are rather thin. There are also usually one or two connectors on the way, and then the key in itself.
If this happens then:
a) open key lock and clean. Easy to do. Bottom is a solid plate of cupper, clean, even sand it. (It is obvious that this becomes corruded after some years in a salty environment, so why Yanmar has this solution is unclear).
b) open up the connector(s) and clean.
If this doesn't helt then you have to invest some $5 in a rely that you place on the soleniod, and control by the the key switch and wire (some easy chaning the wiring). This will usually fix all these cases.