dual battery set-up

I'm confused. There seems different types of dual battery isolators available. Electronic, diode etc. Some only work with external sensed alternators. What does all this mean? I have a TD5 Discovery 2 and a second

100ah deep cycle battery. I would like to hook this second battery up to the alternator for charging when the vehicle is running and automatically switch to the 20 watt solar panel when stationery. I have a solar panel controller. Ideally, I would want the isolator to charge the main battery as a priority before charging the auxillery and prevent drain between the two batteries and then the solar charger to take over but only charge the auxillery when the motor is not running. If this all makes sense, anybody know a good place to start. Steve W (in Aus)
Reply to
Steve/Aus
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Best Option: Fit a 2nd alternator

Next best: Diode type charge splitter with externally sensed alternator picking up charge voltage from battery +ve terminal.

Less good: Automatic changeover relay.

Reply to
EMB

Well, I wouldn't start in Australia!

Reply to
GbH

Seems NZ is as good as any if not better than most!

Reply to
GbH

YGM just a starting point Derek

Reply to
Derek

In message , Steve/Aus writes

Charging wise what you want is pretty standard arrangement from a motorcaravan.

Alternator will quite happily charge both batteries simultaneously

A couple of voltage sensitive relays will do it, fed from output of alternator

1st one to connect/disconnect aux battery to alternator for charging. and one to switch aux battery to solar panel.

What do you use the aux battery for and when?

Reply to
hugh

NZ hmm then why is there such an influx to Oz..coz it is too bloody cold.

Onto the matter at hand a constant duty rated solenoid is pretty easy (what I use..I have a jumper cable as a spare just in case ;-) )

Cheers, Greg

Reply to
touchtone

Visit a campervan store and see if they can supply a Zig Controller or the like, they automatically control the charging of the vehicle battery and the leisure battery - vehicle battery has to reach a high % charged status, then will charge the leisure battery from the alternator.

Most can sense when 240V has been connected and will recharge the leisure battery, usually they wont recharge the vehicle battery unless there is an isolator relay for the alternator.

The newer models also have the solar input and will top up the batteries.

Its not new technology, I have a Zig unit on a Merc Campervan from the mid

1980s.
Reply to
Roger

I'll second the voltage sensitive relay method. Dead easy to fit! Basically a small electronic unit connected to measure the voltage across the primary battery. When that voltage reaches about 13.8v, the unit switches a relay to connected so as to parallel the second battery across the first by switching a +ve feed. The unit disconnects the secondary battery when the primary battery voltage falls below about 12.8v.

You don't really need a second one, if the solar panel already has a controller, as secondary battery voltage is prevented from feeding back into the solar already!

Neil

(Reply via NG please)

Reply to
Neil

Thanks all for the replies. I ended with a Northstar (usa) 100ah AGM battery that fits neatly in the side bin in the back of the disco along with a 2000w inverter. That runs to

100ah circuit breaker and then a voltage sensing solenoid isolator mounted under the bonnet (mounted along side the brake booster). Looking in the back of the car, you would not know the system is installed as it's all hidden in the side bin. Runs fridges etc. and, although not in Adelaide YET - angle grinders for wheel clamps!

The battery is similar to this only it's 100ah

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isolator is locally made in my city
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W (in Aus)

Reply to
Steve/Aus

People Hi,

a good friend who owns a Discovery 3 TDV6 and has recently fitted a dual battery and the respective charging system.

The dual battery charging system he fitted came from this source

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Up to now he is extremely satisfied both with the performance of the kit (batteries are charged as promised) and mainly by the quality of the kit and the fact that EVERYTHING was included for its proper installation on his LR3.

They also sell Anderson plugs at a very good price for batches of ten units so this may be a good idea for a group purchase (hint.....)

Take care Pantelis

Reply to
Pantelis Giamarellos

Very interesting site, but t works better as

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Now what I need is a way of charging my batteries when they are set up as a 12v AND a 24v supply!

Cheers

Peter

Reply to
puffernutter

Peter and all please excuse me for the typing mistake. Mea culpa !!!!

I think they also offer a 12 AND 24 v supply arrangement.

Take care Pantelis

Very interesting site, but t works better as

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Now what I need is a way of charging my batteries when they are set up as a 12v AND a 24v supply!

Cheers

Peter

Reply to
Pantelis Giamarellos

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