Re: 1992 Evinrude V4 90 HP correct sized CCA battery?
There are a few areas that you will need to investigate, that battery should crank her fine, but as Tash stated, the bigger the better in most cases. You may want to get the battery load tested, most places will do this for free.
I would definately start by removing all connections at the battery, starter, solenoid, and most importantly, the engine ground. Polish them to a shine, then retighten. Inspect the wiring for nicks, cuts, abrasions, and replace as needed. If the wiring "crunches" when you flex it, that is another sure sign of corrosion.BTW, get rid of those wing nuts on the batteries, ther are a no no.
If you have access to a DVM, voltage drop testing will isolate a faulty section of wiring, or a poor connection.
First set your DVM to the 20 Volt scale
Put your POS voltmeter lead on the battery POS terminal and the voltmeter NEG lead on the large incoming solenoid/battery terminal post and give her juice. If the meter reads more than .3 volts, the battery cable is bad, corroded or you have a faulty connection (loose).
Next, connect the POS lead to the incoming large solenoid post and the NEG lead to the outgoing large solenoid post while giving her juice. If the voltmeter reads greater than .2 volts, the solenoid is bad, corroded or has a faulty connection.
Next, connect the POS lead to the outgoing large solenoid post and the negative voltmeter lead to the starter positive post and give her juice. A reading of over .2 volts indicates faulty wiring between the solenoid and the starter.
Finally, connect the NEG lead to the NEG battery post and the POS lead to the engine block and crank the engine. A reading greater than .3 volts indicates a faulty negative cable, corrosion or a faulty connection.