Hey guys,
Ok I am kinda not the "knowledge master" of mechanics , but am kinda wondering, what size battery would be the most proper for my 81 F100?? 6 cyclinder manual tranny. What are the minimal cranking amps needed for this truck?? Just recently bought this truck and Geesh that battery looks awfully small for the truck,plus it loses ampage quickly but only does it randomly though. Just replaced the ignition module in it thinking that might be the issue...
Any help would be greatly appreciated

 

My Ford Spec manual says your starter draws between 100-180 amps and your battery should have a minimum capacity of 380 cold cranking amps.

 

Keep this in mind:
Your starter will only draw the amperage that it needs to turn the engine over:
So, if the replacement battery is rated at 500 CCA (cold cranking amps) or at 650 CCA, the amperage draw to the starter will be the same, the difference being that the battery that is rated for 650 CCA can suppy that much more amperage if needed, (the Internals of the battery are constructed to allow this higher amperage).
The battery needs to be able to fit. The larger batteries will usually allow longer amperage drain intervals without recharge, but if the alternator & voltage regulator are working properly, bigger may not always better...since the cost will go up. Sears Diehard is a good line & they can reccomend a good battery for you...keep the cost in mind.

The amperage drain problem may be one of a couple of things.
First... make sure the battery is getting a charge while the engine is running, (use a volt meter, on the pos & neg terminals of the battery...should read around 14v), if not this could be an alternator, voltage regulator, bad connections. (the voltage should be around 12.5volts with the engine off)

Second...(this happened to me personally) using an ammeter, check the amperage draw with every thing OFF. You do this by lifting a battery cable & placing the ammeter in SERIES with the removed cable end & the associated battery post. NOTE: Make sure you dont short any thing out! (my dash clock was bad & it was drawing 35 milliamps which drained my battery every 3 days if I didnt run the engine).

Good Luck,
Deano

 

It's the CCA = Cold Cranking Amp that it most important in a place where the weather changes and can get cold.

The size of the case is not important> The plates inside is what makes it all happen.

I have the largest battery I can get 1000 CCR in my truck.

Most average between 650-850 CCR

To Me : The More the better.

 

I have to second that.
All the vehicles in my household have 1000 amp batteries. It does get pretty cold in Ne. sometimes and the extra sure comes in handy those days.
I used to have a 650 in the pickup, and it would struggle on cold mornings. Put in the 1000 and it always pops right off.

 

I agree with both of you guys..I have twin 750's in my 7.3L Powerstroke.
The only disadvange that I was trying to point out is the cost. The straight 6 that Bossman32 has would do very well with a 1000CCA battery, It'll just cost more to purchase. If the money isn't an issue, get one with the higher CCA, especially if Bossman32 is in a colder climate state.

goodluck.

 

I highly recommend the MotorCraft Silver Series - $80 at most dealerships; 3 years free replacement; 5 more years prorated; warranty service in any city and most towns.