Battery Load test

[Warren Milberg]

Since the number of volts one's battery produces doesn't start the engine, but rather the number of cranking amps does, how do you test a battery that shows "fully charged" when using a VOM (i.e., 12.6 - 12.8 vdc) that you suspect may not be producing adequate amps? I'd rather not buy an amp meter if possible....

 

[Ross]

Measure the battery voltage

with no load and then with the cranking load. If the battery is "good" the voltage won't drop very much. In your car if you turn on the headlights and then crank the engine, with a good battery the lights dim a little but with a bad battery the lights go out.

 

[ruedi ross]

load test

using the starter for your load is ok IF you know your starter is not the problem. A dragging starter will draw excessive current and drop the battery voltage lower than it should be. Why not pull the battery out and have it tested at a repair shop? If you are friendly with the shop they may let you take their tester to the boat. If you do use the starter as a load check your voltage at the battery and the starter, this will tell you the condition of the cables and connections as well.

 

[sailaway78]

Battery Test

You can take it to almost any place that sells batteries, and they can test if for you. Most do not charge for doing this. They have a maching designed for this, and it leaves no question about the battery condition.

 

[Dave]

Battery Load tester

A few years ago, I broke down and bought a battery load tester. I think it was around $50 at an auto parts store. I can test the load capacity of my batteries in place and not have to wonder about condition or haul them out semi-annually to have them checked. Since I have 2 group 27's on the starting bank and 4 group 27's on the house bank with a combiner between the banks it would be a monumental task to haul them ashore.