Duel Battery Solenoid

[d2dave]

I have to wire up a duel battery on my sons D2 Td5. The 2nd battery will in the rear RH bin.

ATM he is on a tight budget so I was going to go the cheap option with a starter solenoid.

CONTINUOUS SOLENOID DUAL BATTERY BATTERIES 12V VOLT SOLENOID ISOLATOR 200A AU | eBay (https://www.ebay.com.au/itm/284524778271?hash=item423eff931f:g:OWsAAOSw7wphjN2 q)

I have been using one of these on my D1 hassle free for about 16 years.

I have it wired to the alternator so it only connects when engine is running and I do have the diode to stop back currant

My question is this. Are there any issues using one of these on a D2 with all the electrical stuff that a D2 has over a D1?

I have a Drivesafe one in my own D2.

[Tombie]

I hate it when batteries fight [emoji56]

The set up will work, and the capacitor will prevent the surge so that’s fine.

A simple VSR would be easier if he can stretch to it.

[d2dave]

I hate it when batteries fight [emoji56]

The set up will work, and the capacitor will prevent the surge so that’s fine.

A simple VSR would be easier if he can stretch to it.

Thanks Tombie. I was also looking at one of these but the cheap price concerned me a bit. However, it it doesn't last not a lot is lost.

Whats your thoughts on this?

M6 1/4" Dual Battery System Smart Isolator Voltage Sensitive Relay VSR 140A 12V | eBay (https://www.ebay.com.au/itm/144216261198)

[Red90]

Use the VSR to switch the solenoid.

[d2dave]

Use the VSR to switch the solenoid.

If the VSR works to switch the solenoid it will work to connect the batteries, so using it to switch the solenoid would be pointless.

[Red90]

The problem is with a small VSR like that you would then need to protect it from over current with a breaker or fuse. The solenoid won’t need that. When the circuits trips, you probably won’t know and you have a less reliable system.

[drivesafe]

Regardless of what type of isolator is used, you will need a fuse on the positive ( + ) cable, at both batteries, to remove the chance of a short causing a fire.

[PhilipA]

I have had a solenoid controlling my second battery for about 6 years and no problems on my D2. It is just wired off the ignition on positive .
Regards PhilipA

[d2dave]

Regardless of what type of isolator is used, you will need a fuse on the positive ( + ) cable, at both batteries, to remove the chance of a short causing a fire.

Thanks Tim.

I was aware of this as I have the same set up in my D2 with one of your kits and you supplied me with 2x 50 amp circuit breakers, one for each end.

[d2dave]

I have had a solenoid controlling my second battery for about 6 years and no problems on my D2. It is just wired off the ignition on positive .
Regards PhilipA

I had my old Rangie wired this way. It worked well until the day I accidentally left my ignition on and had two flat batteries.

This was when I hooked it to the alternator.

[d2dave]

The problem is with a small VSR like that you would then need to protect it from over current with a breaker or fuse. The solenoid won’t need that. When the circuits trips, you probably won’t know and you have a less reliable system.

Why would I need this. The VSR can handle 140 amps and the alternator is 120 amps.

And having said that, I have an amp meter in my D1 connected only to the aux battery and even when flat I don't think I have seen more than about 50 amps going to it.

[Red90]

When you house battery is drained and you start the engine, the batteries will connect and drop a lot more than 140 Amps across.

[PhilipA]

When you house battery is drained and you start the engine, the batteries will connect and drop a lot more than 140 Amps across.

But that is only between batteries and they are giant capacitors which will smooth any fluctuations.

In practice I find that any transfer is not instantaneous but takes a while to happen and by that time you have started the car.

In fact when I look at my 2 volt meters it takes minutes for the batteries to equalize. BTW, I never let my 120AH AGM get below 11.5 and the only load is the Engel which has a cutout at 11.5.

The bigger surge on a D2 is when the fuel pump activates and the capacitors in the ECU spool up. Maybe glow plugs but no light. This is worth about one volt from the starting battery and I only usually start after the voltage has recovered from say 11.6 to 12.4 or so.

I still haven't figured what the similar surge is on shutdown but the starting battery drops a volt then also for a few seconds. Again maybe glow plugs cleaning or something.

Memo to self .Don't forget to turn off the ignition. Never have done that.

In fact I have another don't forget as I have my 20/20amp DC charger and 12v element fridge in the van wired with the accessory position through a switch and 200amp relay. However I would have to consciously decide to leave acc on to maybe charge my van lithium from a solar panel via the second battery as well as leave the car connected to the van.

Regards PhilipA

[drivesafe]

When you house battery is drained and you start the engine, the batteries will connect and drop a lot more than 140 Amps across.
The 50 amp circuit breakers supplied with my isolators, easily hand the start up currents required to start any motor.

I have many customers who have jump started through 50 amp auto resetting circuit breaker and the circuit breakers do not trip while starting.

It is not just the amount of current that is required to trip a circuit breaker or fuse, but the time that current is applied to a circuit.

As this high current is only applied for a few seconds at most, 50 amp fuses or circuit breakers are fine.

[Red90]

I give up. You are not understanding. I’m out.

[drivesafe]

I give up. You are not understanding. I’m out.
I understand what you are talking about, and I should have posted up more info.

But as the second battery is going to be in the rear of the vehicle, even if it had dropped a cell, the maximum current draw would be around 70 amps for a very large faulty auxiliary battery.

And this is why a I used jump starting as an example, because it does draw more than a flat auxiliary battery.

The maximum current draw, for a very low 100Ah AGM would be 60 amps for a short time, tapering off from there.

[Tombie]

When you house battery is drained and you start the engine, the batteries will connect and drop a lot more than 140 Amps across.

For decades the biggest “market supplied” DBS were rated at a max of 100a.

Example of Traxides 90 unit - rated 90a

It’s not a problem.

[Tombie]

I give up. You are not understanding. I’m out.

Unfortunately I’d say it’s you who isn’t quite understanding.

[drivesafe]

For decades the biggest “market supplied” DBS were rated at a max of 100a.

Example of Traxides 90 unit - rated 90a

It’s not a problem.
Yep, I use to have a 45 amp isolator, the SC40, and as alternators got bigger and bigger, the SC40 did prove to be too small and production of the SC40 ceased about ten years ago.

My SC80 ( a 90 amp isolator ) and the DT90 also a 90 amp isolator work fine in all situations but one.

These two isolators are not designed and are not suitable for winch applications and this is why I introduced my USI-160 isolator a little over a decade ago.

While both the SC80 and DT90 have a CONSTANT current load capability of 90 amps they regularly handle much higher currents for short periods of time without any problems.

I have been experimenting with lithium auxiliary batteries for some time now and they will provide upwards of 150 amps while starting a motor, and the DT90 not only handles this without issue, I have also been experimenting with different size fuses.

I began with 80 amp fuses and every so often I would reduce the fuse size.

At present, I am running my 100Ah lithium through a 50 amp fuse and even with the high starting currents, the 50 amp fuse has not blown once.

NOTE, the cranking battery is under the bonnet and the Lithium is in the boot, connected via 6B&S ( 13.5mm2 ) twin cable and the vehicle has a 140 alternator.

Alls well so far!

[Grahame Roberts]

I have to wire up a duel battery on my sons D2 Td5. The 2nd battery will in the rear RH bin.

ATM he is on a tight budget so I was going to go the cheap option with a starter solenoid.

CONTINUOUS SOLENOID DUAL BATTERY BATTERIES 12V VOLT SOLENOID ISOLATOR 200A AU | eBay (https://www.ebay.com.au/itm/284524778271?hash=item423eff931f:g:OWsAAOSw7wphjN2 q)

I have been using one of these on my D1 hassle free for about 16 years.

I have it wired to the alternator so it only connects when engine is running and I do have the diode to stop back currant

My question is this. Are there any issues using one of these on a D2 with all the electrical stuff that a D2 has over a D1?

I have a Drivesafe one in my own D2.

Have a look at Sidewinder products. Aussie made for just under $70. Monitors available also.
I’ve had one on a D1 for years and now on my D2 with no issues. Simple and effective. My battery is in the rear the same as yours. Get a thick cable and run it through the chassis and up inside where the rear tail light cavity is located.

[Tins]

I hate it when batteries fight [emoji56]



I see what you did there. I remember when fuel systems were at each other's throats.

[drivesafe]

Have a look at Sidewinder products. Aussie made for just under $70.
They are not Australian made, they are Chinese!

[d2dave]

Ok. we have decided to go with the basic solenoid connected to an ignition switch feed.

Phillip. Where have you sourced your 12 v feed.

I have had a thought. Could it be powered off the fuel pump relay, as it only runs with engine running.

To keep the currant draw small, I could use the fuel pump relay to power another relay which would power the solenoid.

Thoughts on this idea anyone?

[PhilipA]

Phillip. Where have you sourced your 12 v feed.

From a piggyback fuse from the interior fuse box which is ign on triggered . I love those piggyback fuses.

I cannot remember which one but there are several that are only on with the ignition.
Just look at a wiring diagram. Maybe electric mirrors or sunroof or something like that.
Regards PhilipA

[onebob]

Ok. we have decided to go with the basic solenoid connected to an ignition switch feed.

Phillip. Where have you sourced your 12 v feed.

I have had a thought. Could it be powered off the fuel pump relay, as it only runs with engine running.

To keep the currant draw small, I could use the fuel pump relay to power another relay which would power the solenoid.

Thoughts on this idea anyone?

If using "piggyback" type fuse holder to tap 12V the info below is from a post of mine way back in 2012

Fuses 24,25,27,28,30,31 are 'ignition on' power sources...

Fuses 15,16,18,19,26,32, are 'accessory on' power sources

Fuses 1,2,4,5,6,7,8,12,13,20 are 'ALWAYS powered on"

I run my UHFCB off fuse 5 (unused on mine but reserved for Daylight Running Lights on the posh models)

Refer to the attached fuse box diagram for fuse positions and also for an easier to access 12V source that may be unused and available on your vehicle.

Disclaimer: This info is from my own scribbled notes, they're accurate for my D2 though can't vouch for other D2s so check before using - and as always all care was taken but no responsibility accepted.
175728

[d2dave]

Thanks Phillip.
I will easily find one from the fuse box.

I was asking the question in the hope that there was one some where in the engine bay, to save the hassle of having to feed a wire through the firewall.

[PhilipA]

I was asking the question in the hope that there was one some where in the engine bay, to save the hassle of having to feed a wire through the firewall.
There is a big grommet under the steering column, which exits underneath the booster. You cannot see it from the engine bay.
You have to peel back the insulation to see it from the cabin..
To feed the wires I use an ALDI drain cleaner to push through from the cabin with the wire attached. I have several wires going through there Including boost gauge , EGT, temp gauge and more.
Easy Peasy once you know it is there.
Regards PhilipA