Hello all -
I have an OS .46 LA and the instructions say you need 1.5V to the glow plug to start it.
I have a massive glow starter that contains a "D" size NiCd battery. When I charge it overnight it measures 1.41 volts right off the charger.
24 hours later it measures 1.31 volts.Is this enough voltage to start the engine reliably? What do you guys use?
Cheers - LeeH
No problem, discharge current available from a sub C or larger NiCad, (especially in direct contact glow drivers without leads) make it more than adequate to heat glow plugs. The "instructions say you need 1.5V to the glow plug to start it" simply refer to the rating of the old telephone batteries which used to be used and from which the voltage dropped quickly when the heavy 1 - 1.5A load when the glow plug was connected. Treat 1.5V as a maximum, any more will either burn out 1.5V rated plug or cause premature failure. When using a 2V accumulator or GellCell [aka SLA cell] then use at least 30" of heavy cable to reduce voltage arriving at plug. Many good articles under Electronics or " Engines,Plugs,Tuning, Petrol, Turbines, Mufflers, Cleaning, etc" sub section "Carburettors, Tuning & Performance Testing, Glow Plugs." at
HI There AT
30" of heavy cable as you suggest will do very little to reduce the voltage at the glow plug. While I am not sure about the currect draw of the glow plug, unless it is VERY high (say 100amps or so) the small amount of resistance in 30" of heavy cable will be insignificent. Your suggestion would have been closer, but not close enough, had you recommended very light cable, which because of the smaller cross section of the conductor would have a higher resistance and thus a greater voltage drop.The easiest way to drop the voltage down a bit (.6v) would be to simply include a diode rated at the appropriate amps in series with the 2v cell.
David
"A.T." wrote:
When using a 2V accumulator
Yes it is! A NiCd is 1.2 volts. That should be fine. I use two D size Duracells and they last all summer!
Mike
An alkaline cell will not provide 1.5 volts when connected to a glow plug (drain in the 4 amp range). That much current will suck a primary cell down to about the same as a Ni-Cd, 1.2 volts.
I ran some tests on glow plugs vs Voltage once. Most plug I tested would start an engine ok with the (plug) Voltage down to about .9 Volts. Regards Gene
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