AIR COMPRESSOR GP 7N3902 - Caterpillar

Never disconnect any charging unit circuit or battery circuit cable from the battery when the charging unit is operating. A spark can cause the combustible gases that are produced by some batteries to ignite.If the engine must be started by an external electrical source, then always connect the positive jump start cable "+" to the positive terminal "+" of the battery.To help prevent sparks from igniting combustible gases that are produced by some batteries, the negative "−" jump start cable should be connected last from the external power source to the negative "−" terminal of the starting motor. If the starting motor is not equipped with a negative "−" terminal, connect the jump start cable to the engine block. Grounding Practices
Proper grounding for the engine electrical system is necessary for proper engine performance and reliability. Improper grounding will result in uncontrolled electrical circuit paths and unreliable electrical circuit paths.Uncontrolled engine electrical circuit paths can result in damage to the following components: main bearings, crankshaft bearing journal surfaces and aluminum components. All grounds should be tight and free of corrosion. The alternator and the starting motor must be grounded to the negative "-" battery terminal.For engines that have an alternator that is grounded to an engine component, a ground strap must be used. The ground strap must be connected to the component and to the negative "-" battery terminal. The component must be electrically isolated from the engine.A ground plate with a direct path to the negative battery terminal "-" can be used as a common ground point for the components of one engine system.The wire size that is used for the ground plate must be large enough to handle the full charging current of the alternator.