starter amp ???

[Bill Harris]

Those starter are usually 1.4KW (around 1.9HP). At 746 Watt/HP, Mr Ohm sez that with a 12V battery it takes 116.67 Amps to dissipate 1400 Watts. That, of course is at 100% efficiency. If you assume a 70% efficiency the starter will draw about 152 Amps at rated output. The mini-starters use permanent magnets for the field so they draw a lot less current than the old style wound field (electromagnetic) starters which draw a lot of current just to create the static field.

Note the importance of having really good cabling and connections between the battery and the starter. If you drop voltage across the cabling, the amperage will go up quickly. If you only supply 10V to the starter due to drops or insufficient battery capacity, the amperage will go up to 182 Amps to get rated output from the starter. This is a vicious circle since as more current is drawn, more voltage is dropped across the resistive cables/connections so the voltage at the starter goes down, the current tries to go up.... and so on.... leading to the dreaded "click-----nothing".

Sorry for the lecture.. I'm bored....