L405 Dual Battery System

[DuncanH]

Hi All,

I am planning to buy a second-hand L405 (Probably MY20/21) in the next month or so. Wanted to ask what people are using for dual-battery set-ups (actually triple-battery as I also want to charge the batteries in a trailer).

I currently have a L322 with a dual-battery isloator from Traxide (DT90 unit) and a cable running out to the rear-bumper with an anderson plug for the trailer.

I am hoping to have a similar setup in the L405. I have seen a few mentions of Autospark in Perth doing installs. Sadly I am in Sydney and when I called Autospark they did not have a kit they could supply to me.

Any guidance from those of you who have done this already would be much appreciated!

Thanks,
Dunc

[CSBrisie]

Hi Duncan
sorry in advance I cant help with Instal, whilst I live in Brissie, I bought my demo MY17 from LR in Perth, so I had Autospark fit the dual battery system (search in this forum and you should find photos of it).
They had to custom make the battery cradle as I have rear aircond; added some additionl Hella plus, deep cycle battery in right rear compartment; Redarc DCDC charger etc etc. I have had the car for 5 years and its been a faultless system so they certainly know what they are doing (fitted rear Anderson plugs x 2 (in and out). So, in summary, as a minimum they are the guys to "pick their brain" if any issues when you find someone in SYD. That said, BatteryWorld have a good reputation too for these systems - I fitted a DBS in my wifes C250 estate a few years back - BW did a brilliant job.
cheers

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[DuncanH]

Thank you CSBrisie,

That looks like a neat job by Autospark. I will probably do a temporary setup for now with a battery box and the traxide isolator. Then I can take my time to find a more permanent spot to hide the battery behind trim like you have (and maybe switch to lithium with a DCDC charger).

Does anyone have any tips for removig the side trim panels in the boot to get to a high-current 12v power supply (from Autospark's photos in an older post on here it looks like the best spot is on the passenger side)?

Thanks,
Dunc

[Graeme]

I've ventured into lithium to run a fridge and amateur radios in my recently acquired D350 for the reduced weight and the promise of it lasting more cycles than AGM. I have a Kings 60Ah battery and 25A DCDC charger in the RH recess, strapped to the nearby tie-down. It gets power via a dual-sensing VSR and 50A CB located on top of the main battery, with the rear Anderson also from the VSR and 50A CB. A remote switch can switch on the VSR if the rear outlet is required without the engine running or if the DCDC charger is bypassed so that the Lithium can feed back to the main battery if required. The van is still AGM.

[drivesafe]

Thank you CSBrisie,

That looks like a neat job by Autospark. I will probably do a temporary setup for now with a battery box and the traxide isolator. Then I can take my time to find a more permanent spot to hide the battery behind trim like you have (and maybe switch to lithium with a DCDC charger).

Does anyone have any tips for removig the side trim panels in the boot to get to a high-current 12v power supply (from Autospark's photos in an older post on here it looks like the best spot is on the passenger side)?

Thanks,
Dunc
Hi Dunc and your Traxide isolator will work better than any DC/DC setup for lead acid batteries ( AGM or Wet Cell ) you only need DC/DC if you use Lithium batteries, but you need to look carefully when going to a lithium battery setup.

[Graeme]

I'm not amused that with a 20A mains charger charging the starting battery that as soon as the VSR switches on, the DCDC charger charges at full current which is more than the mains charger is supplying so drags down the starting battery. A relay that uses an engine-running signal to switch on and a Lithium BMS that handles alternator voltage would be a better system.

[drivesafe]

I'm not amused that with a 20A mains charger charging the starting battery that as soon as the VSR switches on, the DCDC charger charges at full current which is more than the mains charger is supplying so drags down the starting battery. A relay that uses an engine-running signal to switch on and a Lithium BMS that handles alternator voltage would be a better system.
Hi Graeme, with any vehicle with a SMART alternator, a DC/DC device should have its IGNITION sense connected.

When wired up correctly, the DC/DC device will turn off in STOP/START vehicles when ever the motor stops, and in situations like above, the DC/DC device will not turn on when the cranking battery is being charged with a 240vac battery charger, regardless of whether an isolator turns on or not.

[Graeme]

This DCDC charger has an ignition sense, currently unconnected. I wondered if the ignition sense would prevent the charger from starting if the input was permanently connected to 12V rather than through the VSR, but how would the charger know the difference between the sense wire being unconnected and the ignition is off? Perhaps because the starting battery voltage initially would be below the cut-in voltage then it sensed ignition voltage that it would then change to ignition sense mode. There isn't documentation that describes how it uses the ignition sense other than a comment that using ignition sense changes the cut-in voltage. Perhaps I should try with the DCDC charger permanently powered with the ignition sense connected then check how this charger behaves. The LR trailer socket aux supply uses an engine-running relay so it's easy to tap into the fuse for an ignition sense.

Unplugging the charger's input connector is easy as it's just inside the boot, so not a big issue. The van is currently attached preparing for a short trip starting Tuesday. The van's 240V charger is now also charging the starting battery, but I still don't want the Lithium to charge as the starting battery needs lots of charge, possibly due to being 4 years old and only getting short trips and lots of door openings at home.

[drivesafe]

Hi again Graeme and the ignition sense wire has a number of purposes.

The first is to allow the DC/DC device to turn off when the motor is not running.

NOTE, in your vehicle, you can connect the DC/DC devices IGNITION sense wire to the vehicles FRIDGE Circuit at the tow hitch.

This will then switch the DC/DC device off when the motor is not running and will not switch on with the vehicles Ignition switched on but the motor is NOT running. Specifically with STOP/START operations.

Next, when the DC/DC devices IGNITION sense wire is connected correctly and the vehicle has a SMART alternator, even when the alternator voltage drops below the DC/DC devices LOW VOLTAGE level, the DC/DC device will keep charging the battery.

NOTE, most new DC/DC device will reduce the output CURRENT ( the charge current ) if the alternator voltage goes below a set level.

This is a safety function to stop the DC/DC device from drawing a high level of current in a low alternator voltage situation. ( the lower the INPUT VOLTAGE from the alternator, the higher the INPUT CRRENT has to go, to compensate for the low voltage ).

It was not uncommon for older type 40 amp DC/DC device to draw as much as 90 amps in low input voltage situations. This why new DC/DC devices reduce the charge current rather than draw unsafe input currents in low input voltage situations.

[Graeme]

I'll give it a try. This charger is an updated version of an earlier one so perhaps smarter too, not that I have any information on either versions.