What is the Bare minimum CCA rating for these cars?

I think I may have found a lightweight alternative battery for my car as the stock motorcraft battery is going to die soon. However, I'm pretty sure that my stock motorcraft battery is rated at 525 or 550 CCA where as the lightweight battery that I am looking at is about 1/2 of that.

Before folks start spouting off saying that it won't work, I do know that the battery has been tested in a Honda CRX 1500 and Also provides satisfactory performance in Mazda RX-7 3rd Generation cars. Mazda's stock battery in those cars is rated at 470CCA.

SO I want to know, what is the bare minimun CCA rating needed to start the car. My engine is in a good state of tune and is stock.

Well, this may help some.

According to Helms:

Normal current draw 150-250 amps at cranking speed (180-250 rpm)

Free spinning current draw: 80 amps

Maximum load: 800

So I would venture a guess that 250 would be sufficient under most circumstances. 250 may not perform well in cold weather though.

Thanks dave....

Actually this information is great! The particular battery that I'm looking at generates 680 cranking amps above freezing. But it's CCA rating is 280.

Based upon what the helm's manual is telling you, a current draw of 150-250amps, that means a battery with a CCA rating of 280 will provide sufficient current at below freezing temps.

The only hard evidence that I have read so far is the test in a Honda CRX 1500 where it was started, stopped, started with the alternator disconnected, stopped. Started again and tested it's current draw, it recovered very quickly. Then they took it out and started a VW diesel twice (a typically harder engine to start).

I know some guys are using them in their RX-7's so I figure it should have the juice to start our cars.

Now, unless your going to tell me that current draw increases in the colder it gets, I think I'll be writing a little article.

I don't know if it matters, but all the fluids, (engine, tranny) are a lot stiffer in the cold. When its really cold my old truck will roll forward like its in gear when its in neutral before it warms up.

There is a problem with your truck.

If your truck was in Neutral but would roll foward, there is a problem with your shifter linkage (automatic) or clutch cable (manual). But only if you have selected 1st gear and are holding the clutch to the floor. As the truck warmed the clutch would release..... that is about the best theory I have.

yes, I understand that Fluids (such as engine oil) becomes more viscous at lower temps. Hence the higher current draws from the starter. But the range that dave gave is probably that range. 150 on a hot day and 250 on a bone chilling one. I think I'm going to go ahead and order the battery, if I've got problems I'll send it back.