Thread: CCA or Ah for batteries

CCA.
Amp hour for slow things like fridges.

Regards Philip A

CCA for high current.
Ah is for sustained draw over time as said above...

CCA for winch and starter
Ah for auxilary for fridges lights and the like.

I disagree with the posts so far. How many amps does your winch draw? If it is only say 100amps (likely) then either battery will do as their "Cold Cranking Amp" level is way above that, the battery with the higher Ah however will be able to run it longer.

If your winch is 1200W then it will draw:

Power = Volts x Amps

Therefore Watts = Volts x Amps

1200W = 12V x Amps

ie 1200 / 12 = Amps

Amps = 100

This means the first battery will theoretically be able to drive the winch for:

70 / 100 = 0.7hours or 42 minutes.

The second battery would be able to run it for a full hour or another 18 minutes.

CCA = Maximum Amps or power deliverable when the battery is at -18 degrees centigrade. It is more when it is warmer.
Ah = Electrical capacity of the battery (how long it will deliver that power)

If your winch drew more than 600 amps and was over 7200w then you would need the first 900CCA 70Ah battery. Otherwise the second 600CCA 100Ah battery will be able to do the job longer, is less likely to get too flat and bend plates.

Originally Posted by TJWA's Better Half

I disagree with the posts so far. How many amps does your winch draw? If it is only say 100amps (likely) then either battery will do as their "Cold Cranking Amp" level is way above that, the battery with the higher Ah however will be able to run it longer.

If your winch is 1200W then it will draw:

Power = Volts x Amps

Therefore Watts = Volts x Amps

1200W = 12V x Amps

ie 1200 / 12 = Amps

Amps = 100

This means the first battery will theoretically be able to drive the winch for:

70 / 100 = 0.7hours or 42 minutes.

The second battery would be able to run it for a full hour or another 18 minutes.

CCA = Maximum Amps or power deliverable when the battery is at -18 degrees centigrade. It is more when it is warmer.
Ah = Electrical capacity of the battery (how long it will deliver that power)

If your winch drew more than 600 amps and was over 7200w then you would need the first 900CCA 70Ah battery. Otherwise the second 600CCA 100Ah battery will be able to do the job longer, is less likely to get too flat and bend plates.

All this sounds good in theory but you are still going to start the vehicle and opperate a winch and deep cycle batteries are not made for hi current draw situations, that is why vehicles are fitted with a cca battery. When you are winching you will have the engine running.
The CCA "cold cranking amps" is the ability of the battery to supply its maximum current to the starter when the battery is cold.
The AH "ampere X hours" rating is the ability of the battery to supply current over a long period of time usually 20 hours. So a battery with a 60 AH rating can supply 3 amps for 20 hours before it's exhausted.

Hi TJWA, sorry mate, it just doesn’t work that way.

When discharging a battery, the higher the current draw the less capacity you have.

This is known as Peukerts Exponent and I have absolutely no intentions of trying to put it in plain english. If anyone is interested in learning about Peukerts Exponent, do a google.

Basically, if you try to pull the currents that a which will put, anything up to 400 amps, from a battery, the higher the CCA, the better the battery is suited to the task.

Even using your 70 Ah battery, your would be very lucky to get 10 minutes from the battery, but 5 minutes would be more like it.

This is why Best Practice winching is done by having the motor running and set to high idle. Winch for 60 seconds then, with the motor still at high idle, rest for 90 second, then repeat as many times as needed to carry out the recovery.

Originally Posted by drivesafe

This is why Best Practice winching is done by having the motor running and set to high idle. Winch for 60 seconds then, with the motor still at high idle, rest for 90 second, then repeat as many times as needed to carry out the recovery.

Tim, have you heard these words before

Originally Posted by drivesafe

sorry mate, it just doesn’t work that way.

Sorry Tim, couldn't help myself.

BTW what he said.

Yep what Tombie, hot rover and drivesafe say, in fact we had a winching session a couple of months ago where it took us 6hrs to get 4 cars 500mtrs not by choice by the way

One vehicle had his winch running off his auxiliary battery (only 2 winches between 4 cars) mine was off the main starter, his died mine didn't, he then had to change over to his main starter battery so we could get out of there

Baz.

Originally Posted by Redback

One vehicle had his winch running off his auxiliary battery (only 2 winches between 4 cars) mine was off the main starter, his died mine didn't, he then had to change over to his main starter battery so we could get out of there

Baz.

And they will never learn till its too late...

ALWAYS - ALWAYS wire the winch to the main battery OR a secondary battery array running a dedicated alternator (ala Challenge vehicles)