Thread: Best dual battery setup for winching...

Originally Posted by drivesafe

Winching off the starting battery, with the motor running is by far the best set up because the cable distance from the alternator to the winch is at it’s shortest so the voltage drop is less and the winch will run better.

Best practice for winching is motor kept on high idle at all times.

Operate winch for 60 seconds then rest for 90 seconds.

This allows to winch to cool a bit and allows the battery to replace some of the bulk charged used while winching and will then be in a better state of charge for the next 60 seconds of winching.

There is a number of advantages when using the auxiliary battery at the same time while winching.

You have more power available while winching.

Because you are spreading the load over two batteries, you won’t be discharging two batteries as low as you have too when only using one battery.

You can charge two batteries at the same time so you are replacing twice as much used power during the 90 seconds of rest time.

Because you spread the load over two batteries, this means you don’t take two batteries as low as one battery needs to be taken, therefore you will bring the two batteries to a much higher state of charge during the 90 second rest time, which means you have far more power available during each 60 second winch cycle.

If you intend to use your auxiliary battery during winching, you need to fit a cranking type battery as your auxiliary battery.

I personally would not both trying to use house batteries ( in a caravan or camper trailer ) to assist while winching because you need to run huge cables back to the house batteries or you will only get a few amps of assistance while winching and again, you would also need to fit cranking type batteries as house batteries.

One last point, by spreading the load over two batteries, it will help extend the operating life of the cranking battery.

Don't agree with some points here.

On a D1 the alternater is mounted on the passenger side, very close to the aux battery.

Lets say your alternator is 100 amp. Your winch at load is pulling 300 amp. So if you winched for one hour you will have drained 200 amps from batteries.
200 divided by 60 = 3.3 So you are draining you battery at 3.3amps per minute of winching.

If you are winching off one battery or two the alternator will recharge in the same time

Originally Posted by Mr Whippy

Lets say your alternator is 100 amp. Your winch at load is pulling 300 amp. So if you winched for one hour you will have drained 200 amps from batteries.
200 divided by 60 = 3.3 So you are draining you battery at 3.3amps per minute of winching.

Hi Mr Whippy, it’s not quite that straightforward, the higher the current drawn from a battery, the less current you actually have available.

You try to pull 100 amp loads from a 100 A/H battery, you will be very VERY lucky if the battery lasts 15 minutes before it’s flat.

Furthermore, you can pull much higher currents from a fully charged battery than you will from a battery that is nearly flat, so the higher you keep the battery(s) the more current you have when you need it.

Originally Posted by Mr Whippy

On a D1 the alternater is mounted on the passenger side, very close to the aux battery.

Next, if the alternator is near the auxiliary battery and you run a cable from the alternator to the auxiliary battery, it’s no longer an auxiliary battery, it’s now a second cranking battery and yes, then you will have an advantage, but with most vehicles, this is not the norm.

Originally Posted by Mr Whippy

If you are winching off one battery or two the alternator will recharge in the same time

Your point is?

I understand that it is not that straight forward I just threw in those figures to simplify things.

In your original post you said,
Winching off the starting battery, with the motor running is by far the best set up because the cable distance from the alternator to the winch is at it’s shortest so the voltage drop is less and the winch will run better.

In my reply I stated that my alternator was much closer to the aux battery than the starting one. I have a cable running directly off the alternator running through an isolation solenoid therefore making it an aux battery.

Dave.