Thread: Dual battery systems

There's plenty been written on this but for me, I can't see the point of them. They just limit the charge your batteries can get. The cars alternator does a far better job IMO. I don't get why people make things so complicated to be honest. I only see them as a marketing ploy as all the blurb I've read on them and every 'expert' I've spoken to all drag out the same drivel which doesn't hold up to close scrutiny. I'm an Electrician by trade and work on generators and engine control so I'm just putting that in so others don't think I'm coming from a background that may not understand them - I do, better than most.

I've got 3 vehicles set up with at least 2 batteries, one with 3. Add to that all of those vehicles tow my caravan that has 2 more in it and everything works great. One vehicle is old school 1970's the next is old school 1980's and the last although over a decade old now, would fall into the more modern category - an L322 so certainly packed with electronics, but nothing as fancy as a D4.

All batteries are different brands and types, no issues with any of them and the setups range from the most simple - all batteries connected together all the time (I've actually found this works best for me), one with a cheap automatic battery isolator, and one with a Traxide unit - this was in the L322 and worked very well at keeping the vehicles main battery at a higher level of charge. It has much better smarts than any other controller on the market.

This is the system I would go for in a modern vehicle IMO.

Hi Mike, and your situation is quite common.

Anyway, I posted this up some time ago but it may be of some help to you.

This is an E-mail I received late 2014 and demonstrates the need to get RELIABLE info for equipping a vehicle with a DBS that actually works and not rely on what so called experts in this field tell you.

These guys fitted their own DBS and had no problems, yet the fifth guy got his DBS ?professionally? installed, and look at the results.

Note, the D2 has a constant voltage alternator, the D3 has a variable operating voltages, and the D4s have Regenerative Braking Voltage operation.

This covers just about every type of alternator operation.

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Hi Tim

Sorry for the long email ? in the second half of the email my mate with a 200 series wants to know if you can help him

It seems like only yesterday that we installed your dual battery kits in 4 vehicles (D3, 2 x D4, D2) ready for a big trip. We've been back a while so I just wanted to give you an update on how the battery kits went.

In short, they were brilliant. We installed all 4 kits you sent us in one day. Aside from the fiddly process of removing trim pieces and working in the tight confines of a Land Rover engine bay the installation was straightforward with your instructions.#

Throughout the trip the kits never missed a beat ? and others on the trip had lots of electrical issues.

On a few occasions the battery guard did it's job cutting out the fridges, but this was usually when we were camped in one spot for a few day (very little or no driving) in very hot weather (making the fridges run almost non-stop). It took surprisingly little driving to provide a good bulk charge back into the batteries.

We travelled the Tanami Track, Gibb River Rd, Kalumburu Rd, Mitchell Falls NP Road and the Great Central Road and nothing rattled loose or played up in any way.

Our friends in a 200 series Land Cruiser, on the other hand, did not fare so well when it came to electrics. Following local advice he had a Ctek DC-DC charger installed professionally by a very large and well known auto electrician here in Newcastle. They also installed an auxiliary circuit for his fridges and accessories etc connected to the aux battery.

In short the system never worked properly. Initially the DC-DC was installed in a very hot part of the engine bay making it cut out once the engine warmed up. We repositioned it behind his grill but even then he only got a useful charge on big driving days.

On days were we did short trips around camp he was always having problems with a flat aux battery (including the extra aux battery on the trailer). To further add to his woes the auto elec did NOT install any form of low voltage protection on the circuit for his fridges and accessories.

He ran his batteries far too low a few times and it didn't take long for the aux in the engine bay and the aux on the trailer to both die completely.

He couldn't believe how well our systems worked. So he was wanting to find out a little more:

Feel free to use my feedback as a testimonial if you wish.

Thanks

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Not long after receiving this e-mail, the poor guy in the Toyota purchased one of my isolators and to date, has not had any problems, unlike when he had with the DC/DC device.

Thanks Gav,
I haven doing some reading here and elsewhere. There seems to be an opinion that isolator so take longer to charge and don't charge the second battery fully.
But I don't really understand the reasoning.
Unfortunately I didn't have the Traxide system long enough to form an opinion.
Cheers
Mike

The alternator is more than capable of fulling charging the second battery, it's one of the DCDC myths that gets pedalled. Alternator will also charge much faster as the battery can draw what it needs rather than the DCDC device limiting the current (which it does).

Thanks Gav and Tim,
It seems to me that there is an imperative to sell the higher price DC DC systems, and also the same imperative for people who have bought them to justify the expense. I have noticed this in other posts on this forum.
For the driving I do which is mostly low speed on the horrible freeway system, here in Sydney, with the, far too occasional, trip away; the isolator should work fine? Given that there is no load on it most of the time.
I did notice that the fridge cut out overnight while I was on my last trip ( unfortunately also my first trip with the Traxide system installed).
I assumed then that the second battery, although new, had not been properly Charged in the first place. It certainly provided power for a good time once the engine had been started or maybe I had the Waeco set on the wrong cut out value.
Cheers
Mike

Mike.
Go with the Traxide.
Tim looks after AULRO folk and repeat offenders.
ITS GOOD GEAR
Andrew