DBS questions

[SimmAus]

Hi All

Busy looking around my “new” D4 and I’ve noted it had a DBS fitted by an auto sparky.
I’m a great fan of the Traxide system, and have been in touch with Tim already.

The pics below are of the cranking battery connections (don’t like the the negative terminal connection to the AGM):

https://www.aulro.com/mobile-gallery/f7d5268540b6a3c0decc1f0c82fdb3a9.jpg

The isolator:

https://www.aulro.com/mobile-gallery/0da4c6ef89b12e2706df3274732d351b.jpg

And this thing, which is joined up to the isolator and back to the cranking battery:

https://www.aulro.com/mobile-gallery/c66df6302332cb2cbde9796ae4d607c8.jpg

The wiring is 7mm external diameter (measured with calipers) on the batteries, and a 5mm diameter cable runs to the rear (attached to chassis under car - ouch!!!)

Because I’m unsure of this setup (and unhappy with some of the connections to battery and under car cabling); I’m almost 90% sure I’m going to rip it out and put in the Traxide unit....

Any ideas / identification on these things above?

Cheers
Mark

[drivesafe]

Hi Mark, and as you have posted, you need to get those cables/wires off the cranking battery's neg ( - ) terminal.

The blue box marked "THUNDER" is most likely a DC/DC unit, but where is the second battery?

[SimmAus]

Hi Mark, and as you have posted, you need to get those cables/wires off the cranking battery's neg ( - ) terminal.

The blue box marked "THUNDER" is most likely a DC/DC unit, but where is the second battery?

Thanks Tim

Second battery is in usual spot...in front of cranking battery.

[drivesafe]

Second battery is in usual spot...in front of cranking battery.
OK, then see if there is cabling running from your cranking battery to the THUNDER unit, and then cabling running back to your auxiliary battery?

It just seems a strange place to put a DC/DC device, so it may not be one!

[DiscoJeffster]

Look like it’s a DCDC to me.

DC to DC Charger for Dual Battery Setups | 40amp | Thunder Auto (https://thunderauto.com.au/product/dc-to-dc-charger-40a/)

[drivesafe]

Look like it’s a DCDC to me.

DC to DC Charger for Dual Battery Setups | 40amp | Thunder Auto (https://thunderauto.com.au/product/dc-to-dc-charger-40a/)
More likely a 20 amp DC/DC unit, based on the size of the circuit breaker ( 30 amps ) that appeares to be connected to the unit.

[drivesafe]

Mark, and this is just a guess, It looks like the isolator controls the power to the Anderson plug at the rear and all the cabling is 8B&S ( 7.9mm2 ) which is way to thin. The cabling may even be as small as 6mm AUTO ( 4.5mm2 ) it’s a bit hard to tell from the photos.

Also, it looks like the they may have run the cabling to the rear via the chassis, and this will pose a problem if you need to have the motor serviced. A body-off requirement.

[SimmAus]

Thanks
I’ve just ripped the whole lot out...well, most of it.
Very “strangely” wired up for my non electrical brain (if that makes sense). Tim, I think you were right...the isolator 12v positive went to the rear of the car to the Anderson.
The thunder box was as posted above...and now is now almost in the thunder box..
There was some power to a tow pro unit and another dual cable running along passenger side to the rear for something I haven’t found yet.
Yellow top is at 11.30v (is that dead now?)
Cranking battery was at 12.4 and car said battery was low.
Now on the CTek.
Fun Sunday arvo!!

[drivesafe]

Hi again Mark, just charge your Optima, at 11.30v while low, it can be safely discharged down to 10.5v.

So as long as it has not been that low for too long, a good charge should be all it needs.

[kelvo]

Hi Mark, and as you have posted, you need to get those cables/wires off the cranking battery's neg ( - ) terminal.
Can you explain why Tim?

The way the extra negatives are connected in the photo shows they are before the current transformer/shunt and the cranking battery. Using the same terminal as the main vehicle negative lead from the body.

If they had been connected directly to the battery negative terminal then that would have been incorrect.

[DiscoJeffster]

Can you explain why Tim?

The way the extra negatives are connected in the photo shows they are before the current transformer/shunt and the cranking battery. Using the same terminal as the main vehicle negative lead from the body.

If they had been connected directly to the battery negative terminal then that would have been incorrect.

Kelvo, I agree. The picture definitely shows it connected post shunt so should be the equivalent of being connected to the body for all intents and purposes.

[drivesafe]

Hi Kelvo, and while the connections are made after the sensor, any additional current coming from those cables will still have to use the battery’s earth strap ( cable ) as there negative return to the alternator. This will result in a voltage drop ( small or large ) in the earth strap and will effect the accuracy of the sensors reading.


The closest you can safely connect to the cranking battery’s negative ( - ) terminal, is where the earth strap bolts to the inner guard.