dual/multi battery system

Pretty well the solution is described in post #10 above by cairnspom and this link is useful also:

https://www.prospectingaustralia.com/forum/viewtopic.php?id=17531

The auxiliary and third battery is selected by a switch. I would use a relay selected by an illuminated switch because you need to go to a large rated switch and wiring in your cab otherwise.
Jon

blisters said:

Pretty well the solution is described in post #10 above by cairnspom and this link is useful also:

https://www.prospectingaustralia.com/forum/viewtopic.php?id=17531

The auxiliary and third battery is selected by a switch. I would use a relay selected by an illuminated switch because you need to go to a large rated switch and wiring in your cab otherwise.
Jon

Click to expand...

Thanks Blisters
More research and study to be done before I do anything and so I dont stuff it up ..
Cheers !!!

Ok so to set up what I wanted, I would need 2 of these isolator solenoids and 2 Redarc 1225 BCDC plus a 3 way switch (DPDT = Double Pole Double Throw or SPDT ) is that correct ?
Then Anderson plugs wiring and round connectors (lugs) brass battery terminals and two DC AGM batteries.
Oh and a wiring diagram to put the whole thing together...
http://www.ebay.com.au/itm/CONTINUO...247392?hash=item5b281150e0:g:3zsAAOSw9mFWGudW

or is this a better choice ?

http://www.ebay.com.au/itm/COLE-HER...251968?hash=item3604973380:g:J4gAAOSwukdXcLxL

By what you wrote about your setup requirements you would only require one redarc 1225. The setup described in these threads has been to use a switch to allow charging of two different auxiliary batteries by one redarc to avoid purchasing a second redarc as they are expensive. Purchasing two is the best option requiring no output switches and they can be installed close to the battery to allow for temperature compensation. As the temperature rises the charge voltage is compensated so if the single redarc is installed under the bonnet it might undercharge a second battery that is installed in a cooler place, or overcharge in the reverse scenario. But that is the compromise when buying one unit. Note redarc advises you may be able to switch the battery type to compensate depending on the install location and the particular battery chemistry.

For auto switching the input between the alternator and solar panels you require something like the redarc RK1260 kit but this looks like just a relay that switches to solar when the ignition is turned off.

If you went with one redarc to charge two batteries then you require a switch of some sort to switch the redarc output to either battery. Those solenoids most likely don't have the correct pole position, a switch/relay rated at continuous 30-40A will do the job. The reason why I would use a relay over a switch is twofold, one it reduces the heavy wiring requirement in your cab but secondly you can also automatically switch between battery types if you use different second and third battery chemistries. There is a wire from the redarc specifically to do this job and the relay can select whether to make the wire voltage float, go ground or high. The switch would activate both relays simultaneously selecting which battery to charge and its chemistry.

The type of relay depends on the purpose, availability and price. The SPDT will provide a normally closed and open output which is ideal for switching the positive wire and probably the cheapest option. You could use a second SPDT for auto switching the battery chemistry. Ideally you would use a DPDT for this purpose but I found it difficult to find these and they were expensive and not much difference in size to two SPDT.

I hope this helps mate.

Jon

EDIT: Removed fumble fingers

Thanks Blisters

Sometimes a wiring diagram is better. For the single dcdc charger switch setup it would look something like the following. Batt1 is normally charged and when the indicator light shows it as being charged flick the switch to activate the relays to charge the second battery as well as change the battery type.

If Batt1 and Batt2 are of the same type then the Type Select relay is not required, you'd just wire the redarc according to the doco. The multi source power wiring is well documented as is the variations in wiring it in using the ignition or not:

https://www.redarc.com.au/images/uploads/files/bcdc1225_instruction_manual.pdf

Note that it is assumed that the redarc is properly protected.

If you install a BCDC under the hood and switch it to charge a trailer AGM you will most likely suffer voltage drop.

Also you say in a previous post #20 that your start battery is a "Deep Cycle" at 55AH. I don't think so, deep cycle batteries are not built for the current load for starting a car (certainly not long term).

I've noted this before, a BCDC or any DC to DC charger, should be located as close to the battery as possible to avoid voltage drop. Also said before, I use one in the 4x4 and another in the caravan. The distance between the 2 batteries is too great unless you use bloody thick wire to avoid most of the drop.

Also if you can't find a heavy relay to switch, look for a heavy solenoid. I use a 70A continuous load which is IGN controlled to run both BCDCs and my Trailer hot wire Anderson. This also cuts out the start battery when engine off.

Yeah my mistake its a 55ah Calcium battery.
Im still baffled as to what to buy and how to set up a dual battery system in my land cruiser and what to buy and set up in the camper I bought.

Hi Nucopia,
PM sent.
Cheers SinHof.

nucopia said:

Yeah my mistake its a 55ah Calcium battery.
Im still baffled as to what to buy and how to set up a dual battery system in my land cruiser and what to buy and set up in the camper I bought.

Click to expand...

Having a standard battery isolator protects the starter from discharge but means the alternator charges all batteries if hooked together but the batteries will not be optimally charged. For the best battery life and depth of charge by the vehicle you move to a dcdc charger which are pricey. The advantage also is you can hook up you solar panels when the alternator is not charging.

The correct solution if using dcdc charging is to have a dcdc charger located next to each battery, think of the charger and battery as a single unit. The location of the charger is important as they compensate charging voltage with temperature variation. You then just have to size the dcdc charger, wiring and solar panels to suit your battery capacity. condor has a very good writeup about his system that is correctly sized and proven so you could copy this or use the info to suit your application. I noticed in your earlier post that the vehicle and trailer battery should be able to be charged separately and by solar, so you'll need a dcdc converter located at each battery i.e. one in your vehicle and the other in the trailer.

Jon

Thanks Jon
Much appreciate you help mate.
It might be expensive to do at the start (2 x dcdc) but in the long run it will be a better option all around with battery life I gather.

That's right your batteries will last longer and also perform better as they will operate from a higher level of charge which is obtained faster.

Two dcdc are a much better solution than one as they are being used as designed. Price is a factor which is why the switch solution is around but that is a compromise solution that will work well in limited situations.

Jon