Thread: What Batteries - Dual Batteries

Originally Posted by Tombie2

You Dont run a winch from your Aux. battery....

Always wire winch to the Main battery.

Originally Posted by Urban Panzer

Why ?

The reason is due to current draw. For example, a Warn XD 9000 draws between 70A (no load) and 460A (full load). This current draw is way in excess of the alternator capacity and hence draws down on battery capacity. So, firstly, you have to have thick cables located as close to both the alternator and the winch source battery. The main battery is usually more closely wired to the alternator with big cables. To wire up to your auxilliary battery you have to have a starter battery, not a deep cycle battery, and the cables need to be big. Secondly, assuming you have a charging controller between the alternator and the second battery, it would have to have a capacity of over 500A (for the above winch) to enable the current from the alternator to reach the battery. As soon as the controller opened, you'd be drawing from the main battery, too, and the voltage drop would close the controller again, resulting in open and closing of controller. Don't think it would last long.

To do it, you'd have to have an extra wiring circuit and switch enabling you to connect the auxilliary battery to the alternator and isolating both from the main battery. Too complicated, too risky.

Originally Posted by Hamish71

DETAILED Pictures and measurements please! Particularly of the underside of the tray!

UMmmmm...PLEASE, May I have a picture of the underside of that battery tray? Thankyou.

Originally Posted by Hamish71

UMmmmm...PLEASE, May I have a picture of the underside of that battery tray? Thankyou.

Hamish,

I will get into the garage on the weekend and get some pictures for you.

Originally Posted by Mundy

The reason is due to current draw. For example, a Warn XD 9000 draws between 70A (no load) and 460A (full load). This current draw is way in excess of the alternator capacity and hence draws down on battery capacity. So, firstly, you have to have thick cables located as close to both the alternator and the winch source battery. The main battery is usually more closely wired to the alternator with big cables. To wire up to your auxilliary battery you have to have a starter battery, not a deep cycle battery, and the cables need to be big. Secondly, assuming you have a charging controller between the alternator and the second battery, it would have to have a capacity of over 500A (for the above winch) to enable the current from the alternator to reach the battery. As soon as the controller opened, you'd be drawing from the main battery, too, and the voltage drop would close the controller again, resulting in open and closing of controller. Don't think it would last long.

To do it, you'd have to have an extra wiring circuit and switch enabling you to connect the auxilliary battery to the alternator and isolating both from the main battery. Too complicated, too risky.

Mine is wired of the AUX batt (yellow top), had no issues to date.

I understand all your points, which is why my battery isolator is rated at 300AMP nominal and over 1200AMP cranking..........my original one would not have coped with the "possible" winch amperage draw which is why I changed it.

Once the engine is running, the winch will draw off both batteries anyway "through" your split charge unit. The one i fitted also has a "manual" switch (or remote) if you wish to connect the 2 batteries directly together....ie if the main starter battery goes down and you wish to jump start yourself...........and 2 batteries will help supply the winch far better than just one.
The TD5 has a 130AMP alternator, which should provide enough guts for winching.......well it has so far.

Would rather flatten the AUX batt using the winch than the main one.
Just my thoughts on it tho.......

Originally Posted by Urban Panzer

Mine is wired of the AUX batt (yellow top), had no issues to date.

I understand all your points, which is why my battery isolator is rated at 300AMP nominal and over 1200AMP cranking..........my original one would not have coped with the "possible" winch amperage draw which is why I changed it.

Once the engine is running, the winch will draw off both batteries anyway "through" your split charge unit. The one i fitted also has a "manual" switch (or remote) if you wish to connect the 2 batteries directly together....ie if the main starter battery goes down and you wish to jump start yourself...........and 2 batteries will help supply the winch far better than just one.
The TD5 has a 130AMP alternator, which should provide enough guts for winching.......well it has so far.

Would rather flatten the AUX batt using the winch than the main one.
Just my thoughts on it tho.......

If it works, then one can't argue with that. I'm not sure what 'yellow top' means but if it’s a starter battery then as a winch supply that’s fine. However, if someone connects the winch to a deep cycle auxiliary battery not designed for starting currents, then the life of the auxiliary battery will be seriously degraded if the sort of currents a winch demands are supplied from it

My apologies, I assumed the slang "yellow top" was well known.......

slang refers to an Optima Yellow top Deep cycle / Starter dual purpose battery.

YellowTop: OPTIMA Batteries

Originally Posted by CJT

Hamish,

I will get into the garage on the weekend and get some pictures for you.

Hamish,

Some dimensions,

Tray 260 x 355mm
Leg 1 83mm
Leg 2 120mm

Hope this helps

Originally Posted by CJT

Hamish,

Some dimensions,

Tray 260 x 355mm
Leg 1 83mm
Leg 2 120mm

Hope this helps

Thanks CHris.....confirms Im not as much of a hack when it comes to fabrication as I thought My mock up looks like this...I just assumed they may have done something "clever".

Many Thanks again.