Dual Battery Options and Fitting

[drivesafe]

So with these bogus claims you talk about, one would assume you are a qualified auto electrician or electrical engineer?

Or are you just a salesman being bias towards other charging technology that competes against your product...

I've worked in this industry for just over 40 years, designing and manufacturing auto electrical and electronics equipment.

I would not expect anyone to take me at my word just because I posted it up here, so here are some easily verified facts to back my statements.

Solenoide type dual battery setups have been in regular use for 50 odd years now, and I started producing VSRs near 30 years ago.

Just 25 years ago, most vehicles had nothing bigger than a 55 amp alternator, yet adding a second battery or two did not "burn out" these small alternators.

Even today, the vast majority of dual battery system are based on solenoid/relay type systems.

In all this time, if you could mythically overload an alternator, why is there not lines of vehicles waiting at auto electricians and service centres, getting their alternators repaired or replaced.

Also, if it is so dangerous for your alternator, if you use a VSR type isolator, why is it that companies, like Redarc, still sell them, and heaps of them.

I have been supplying a kit for air cooled Kombis for around 10 years now, and being as most still have the standard 55 amp alternator, if the myth had any legitimacy, with all these kombis alternators charging two batteries, powering a fridge and any other accessories, plus providing the vehicle's electrical needs, and if they are being driven at night, powering all their lights, again, why is there no queues of kombi owners buying new alternators.

Furthermore, I deal in both VSR type dual battery system, and when I have a customer who will genuinely benefit from using a DC/DC device in their system, I refer them to the best type of DC/DC device for their specific needs. So I not only have an understanding of both types of DBS work, I also do not have a bias against charging technologies, I just prefer to use the technology that offers the best results in each specific setup.

The reality is that you can't overload an alternator, and there are very few vehicles, where the second ( auxiliary ) battery is fitted in the vehicle, that need any form of DC/DC device to be able to charge auxiliary batteries properly.

[tennysonian]

I have a 2011 T5 Multivan and looking for a second battery solution for camping (ideally under passenger seat as highlighted) but not feeling up to DIY solution.

Can anyone recommend auto electrician or outfit in Sydney (ideally near Ryde area) with experience in Multivan second battery installations?

[Bryn23]

Thanks for your input Drivesafe,

It good to know, that you do know what you are talking about.

My experience of having to replace two alternators and having them rebuilt/rewound by auto electrician differers from your experience.

I can only go of what i learnt from my sparky at the time. but i personally think that there must be a reason why they offer bigger alternators as an option.

but like i have said i'm not a electrical engineer and as you have stated that you design and manufacturing auto electrical, so that must mean that you have a qualification in this field.

[drivesafe]

My experience of having to replace two alternators and having them rebuilt/rewound by auto electrician differers from your experience.

Hi Bryn, I occasionally come across someone who has had an alternator “burnt out”, but in almost every single case there has been a contributing factor.


The most common cause that I have come across is not cleaning the motor ( including the alternator ) after doing some serious off-roading.


But these are “one-up” situations and have nothing to do with this mythical “overloading” or “stressing” of an alternator.

I can only go of what i learnt from my sparky at the time. but i personally think that there must be a reason why they offer bigger alternators as an option.

The common reason for fitting a larger alternator, is to cater for loads greater than the existing alternator is designed to meet.


For instance, quite a few companies I deal with have service vehicles, equipped with large 12v to 240vac inverters, up to 2,700w, to run power tools, like large grinders and the likes.


These vehicles have the alternators upgraded because the standard alternator just does not have the output capacity to power such large inverters, let alone provide power for the vehicle’s own needs. A 12v to 240vac 2,700w inverter can draw over 200 amps.


This again has nothing to do with preventing “mythical overloads”. The standard alternator just does not have the capability to provide enough power to run such a large inverter.

[Multivan1]

HI Guys.

I have a 2017 T6 Multivan and want to install a Dual Battery.

I am trying to limit dis-assembly and have noticed a 6mm (approx) power wire under the passenger seat. Whilst this appears to be a junction for smaller power leads I was wondering if I could use this power wire to my dc-dc charger then ultimately to the 2nd Battery.

Firstly do most people run the power wire from the main battery through grommets/wheel wells etc?

Two- Does anybody have a wiring diagram so I can see if it is viable to run off of existing power under seat?

Surely with the factory dual battery option I have a feeling they may use this existing power wire.

Thoughts please.

( I am using a Project IDC25 and a 100AH AGM battery mounted in a box in the rear of the van. It is only to be used for powering a 40lt fridge and LED lights for a Max 2-3 days possibly with a solar top up)

Thanks in Advance

Mark

[Transporter]

Hi Mark, you only need to run positive wire from the main battery to power up the DC charger, then the ignition +12V sourced from the connector under the seat. Remove the plate behind the battery you will see the grommet there, through which you can run the wire into the cabin and under the carpet, under the seat. For battery up to 110CCA use up to 25A DCDC charger, otherwise you will cook your battery. Install the charger as close to second battery as possible.

[drivesafe]

Hi again folks and I am now a sponsor.

I have posted up some basic details of my business here

http://www.vwwatercooled.com.au/foru...ml#post1257627

I will be posting up more detailed info about my isolators in the near future, but if you have any questions, please ask away.

[heyasam]

First wanted to say I'm a long way off setting up dual batteries on my multivan. That aside the idea of using an isolator that adds some of the starter battery capacity to the house battery uses I think is interesting. Does that beg the question though what would be a good dual purpose battery for starting, and what battery could fit under a multivan seat that had an aftermarket swivel installed? Could a matching dual purpose battery fit under multivan seat? I would probably like to stay away from agm if feasible. I'll also at some point have to look into under seat mounting options, i read somewhere the standard tray can be modified to fit? Have a spare one of those now! Also saw the little kit that travel volts uk sells. Though like an earlier post suggested be good to have space to run wires through the floor, not sure if some mounting options prevent that?

[drivesafe]

Hi Heyasam, I am flat out at the moment but will go into more details shortly.


First off though, you do not need to replace your existing cranking battery with a multi purpose type battery. All cranking batteries can be safely and continuously cycled down to 40% without having any long term effects on the battery’s longevity.


Up until 15 or so years ago, when deep cycle batteries became more available and cost effective for RV use, cranking batteries were used as both auxiliary and house batteries and and worked quite well.


The only requirement when using a cranking battery as an auxiliary or house battery, is that you avoid cycling them below 40% SoC or 11.9v. Any lower and you may reduce the life span of a cranking battery.


BTW, CCA requirements are based on a cranking battery being able to supply the marked current rate with the battery discharged down to 40% SoC, at 0 degrees.


So your existing cranking battery is fine.


Not sure why you prefer not to use an AGM as your auxiliary battery?


Both AGMs and Lead Crystal batteries are idea for this type of setup.


Again, I will post up more info shortly, particularly about the VW “smart” alternator operation and how my isolators improve this system.

[heyasam]

Thanks look forward to more info. Just been unlucky with agm in the past, was able to return the battery in question fortunately. Seems that wet cell or others maybe more tolerant of different charging parameters, cheaper, can be topped up etc, though yes don't want to vent inside the van, ideally something with vent line you can run outside.