Dual battery controller which one to use

[It'sNotWorthComplaining!]

I'm wanting to fit a dual battery controller, so what to buy, Drivesafe used to have the traxide, but it doesn't appear to be priced in the shop any more.
What is the best bang for Buck?

[Chenz]

I had my auto electrician fit the Pirahna dual battery system and have been happy with it doing both the Hay River and Madigan Line trecks with no battery problems running a fridge and invertor as well as a host of other accessories like laptop and GPS. The link below will tell you more.

DBE150S-Micro - Default Store View (http://piranhaoffroad.com.au/index.php/default/dbe150s-m.html)

[dmdigital]

Traxide - DBC's (http://www.traxide.com.au/DBS.html) - Just give Tim a call and talk to him, very helpful, good bit of kit and easy to install. I have the SC80 in my Puma.

[Drover]

I have used a RedArc "Smart Start" solenoid (SB112) for the past 4 years, first in my old Disco 3 and now in the Fender.

It works a treat and never had an issue with it.

Value for money at about $100 bucks on ebay from various suppliers. Australian made, no compromise on quality. Easy to install.

Cheers

[d2dave]

I have been using the simple and cheapest and that being the solenoid which joins the two batteries when the engine is running.

A lot of people will bag this and I am at a loss to work out why.

I have been running this since about 1994 without a problem. I even switched it from my last vehicle to current one.

It is now 15 years old and still works great but because of its age I have purchased a spare which I carry with me when in the bush.

The photo was taken for other reasons but you can see the solenoid top right hand of picture.

Dave.


http://img696.imageshack.us/img696/9011/powersteering.jpg (http://img696.imageshack.us/i/powersteering.jpg/)

[Utemad]

I've got Drivesafe's SC80. Great unit.

It's still on his site.
relays (http://www.traxide.com.au/DBS.html)

[omvanders]

I have been using the simple and cheapest and that being the solenoid which joins the two batteries when the engine is running.

A lot of people will bag this and I am at a loss to work out why.

I have been running this since about 1994 without a problem. I even switched it from my last vehicle to current one.

It is now 15 years old and still works great but because of its age I have purchased a spare which I carry with me when in the bush.

The photo was taken for other reasons but you can see the solenoid top right hand of picture.

Dave.

I'm curious. Apart from cost and simplicity, are there any other benefits to this setup? Please do tell.

[Utemad]

If you want to go the way of Mr Whippy, Drivesafe has a 100 amp continuous duty solenoid for $36. I just put one in a mates car to isolate his Andersen connectors from his start battery when the ignition is switched off.

It's on this page.
http://www.traxide.com.au/relays_7.html

[d2dave]

I'm curious. Apart from cost and simplicity, are there any other benefits to this setup? Please do tell.

What other benefits are needed? It does what is needed, isolates the aux battery when engine is off and keeps both batteries charging when engine is running.

If you wanted to use heavier cables you could wire up a switch to use if you flattened your starting battery, you could engage the solenoid and start off the aux.

As the way I have it, I have to use one jumper lead (positive to positive) when I have a flat starting battery.

Dave.

[d2dave]

If you want to go the way of Mr Whippy, Drivesafe has a 100 amp continuous duty solenoid for $36. I just put one in a mates car to isolate his Andersen connectors from his start battery when the ignition is switched off.

It's on this page.
relays (http://www.traxide.com.au/relays_7.html)

I have mine wired to the alternator, so with out the engine running my starting battery is completely isolated. Makes it idiot proof.

When I first installed this I ran it off the ignition switch and one day I left the ignition on with the engle running. Guess what, both batteries flat so that is when I rewired it to the alternator.

Dave

[PAT303]

I have used a RedArc "Smart Start" solenoid (SB112) for the past 4 years, first in my old Disco 3 and now in the Fender.

It works a treat and never had an issue with it.

Value for money at about $100 bucks on ebay from various suppliers. Australian made, no compromise on quality. Easy to install.

Cheers

We only use them on all mine site vehicles,they are the best. Pat

[omvanders]

What other benefits are needed? It does what is needed, isolates the aux battery when engine is off and keeps both batteries charging when engine is running.

If you wanted to use heavier cables you could wire up a switch to use if you flattened your starting battery, you could engage the solenoid and start off the aux.

As the way I have it, I have to use one jumper lead (positive to positive) when I have a flat starting battery.

Dave.

What about if you have a stuffed alternator... don't both batteries suffer, leading to possible stranding without a starter charge?

[Utemad]

I have mine wired to the alternator, so with out the engine running my starting battery is completely isolated. Makes it idiot proof.

When I first installed this I ran it off the ignition switch and one day I left the ignition on with the engle running. Guess what, both batteries flat so that is when I rewired it to the alternator.

Dave

I used to have this sort of setup in my Rodeo (although I used two 30 amp relays wired in parallel :) ).

I always wanted to try the alternator switching idea but never did. Just used the 'start' circuit.

Another problem wiring the switching wire to the 'start' circuit is that my cranking battery had died but I didn't know until my second battery also died. Of course you find that sort of thing out when you're on a trip away.

[d2dave]

What about if you have a stuffed alternator... don't both batteries suffer, leading to possible stranding without a starter charge?

If your alternator is stuffed it doesn't matter what system you use.

You will end up with flat batteries.

With my system I have a volt meter wired to the aux battery so that I know that the solenoid has engaged.

Dave.

[d2dave]

I used to have this sort of setup in my Rodeo (although I used two 30 amp relays wired in parallel :) ).

I always wanted to try the alternator switching idea but never did. Just used the 'start' circuit.

Another problem wiring the switching wire to the 'start' circuit is that my cranking battery had died but I didn't know until my second battery also died. Of course you find that sort of thing out when you're on a trip away.

This is another reason why I wired it to the alternator. As I said earlier it makes it idiot proof.

Dave.

[alien]

My hands up for the Redarc SB112 also.
Fitted it after my Pirahna died(Intermitant on a trip and nothing by home leg).
Hooked up the tell-tale also as it flashes for over or under charging(and the wire was there from the other unit(pics in link below).

[dobbo]

Redarc SB112

[drivesafe]

Hi It’sNotWorthComplaining, before you do anything, what are you planning to use your set up for.

Think about the type of uses and the amount of time you want to have accessories powered for between charging battery(s).

[crump]

Talk to Traxide (Drivesafe), plenty of happy customers on the site.

[It'sNotWorthComplaining!]

Hi It’sNotWorthComplaining, before you do anything, what are you planning to use your set up for.

Think about the type of uses and the amount of time you want to have accessories powered for between charging battery(s).
Ist I have a Fridge, to be used only when touring
I also wish to supply lighting to the Camper trailer.
I later fit a winch

[dmdigital]

Ist I have a Fridge, to be used only when touring - Yes need a DBC
I also wish to supply lighting to the Camper trailer. - Assume via anderson plug so need one that can do this as well (SC80)
I later fit a winch - don't need the DBC for this, run the winch from the main battery.

[350RRC]

IMO it depends what you want to do with the second battery, mine is just there for 'security' sitting in its stock second tray.

I have nothing connected to it so I don't need the added intelligence of Drivesafe's unit that lets you use the capacity of both batts to run a fridge and still be able to start your car.

I bought a Redarc unit just on impulse to replace a Jaycar thing that worked fine, but doesn't fully charge the batteries because it uses diodes.

Either one of Drivesafe's units or Redarc would be what I'd use depending on intended use of your spare battery.

cheers, DL

[drivesafe]

Hi again It’sNotWorthComplaining and sorry this is a bit long winded.

If you have not done anything yet, the best for you, going on what you plan to use your dual battery set-up for, would be to fit my SC40 with some heavy cable and a marine battery switch ( see the diagram below ) and my TPSE kit.

This is not just a case of buy my controller instead of some other brand, these are some big advantages when using my controllers that no other brand can offer.

The biggest single advantage is the fact that my controllers do not isolate the cranking battery as soon as the ignition is turned off ( or soon there after ) as every other isolator does.

Instead, my controllers keep all the batteries connected until the common voltage is at about 12v. At this point the cranking battery is then isolated.

What this does is allow your accessories, like your fridge and camper lights to be powered from both batteries and while the obvious benefit is that the accessories will operate far longer before you need to recharge your batteries, it also gives you a few additional and not so obvious advantages.

Because you are spreading the load over two batteries instead of one single battery, you actually get more capacity available and this not just the added capacity of you cranking battery, you will actually get more usable capacity out of your auxiliary battery and I’ll explain why.

The high the current load on a battery, the less capacity it has and theoretically speaking, a standard flooded wet cell battery will give you 20 hours of use with a 5 amp load applied.

If you apply a 10 amp load you WILL NOT get 10 hour, you will actually get just under 9 hours of use and applying a 20 amp load will only give you less than 4 hours use instead of the 5 hours you would expect.

Putting this in terms that relate to actual use, if you had a 100 Ah ( Ah = Ampere Hours ) auxiliary battery and a 100 Ah cranking battery and if you were drawing an average of 10 amps from a single battery, you could do this for 9 hours before you had to recharge your battery.

If you use one of my controllers and had the load spread over two batteries, you would get 10 hours use before my controller isolated the cranking battery and you would still get another 4.5 from the remaining capacity in the auxiliary battery.

So spreading the load over two batteries will give you a longer operating time between charges and this applies to smaller loads as much as it applies to much larger loads.

In reality, you would not discharge your auxiliary battery below 30% and this would mean, if using some other brand of controller and drawing 10 amps, you would get a little over 6 hours use before you needed to recharge your battery.

Using my controllers, you would get nearly 11 hours use before you needed to recharge the batteries.

Now, with the set-up you have posted, it’s unlikely that you will be drawing anywhere near that high a current ( averaged out over 24 hours ) but the principal is the same. Even if your cranking battery is only a 70 Ah battery, you will still get AT LEAST a 50% increase in available stored capacity.

Another advantage to using my controllers is that if you free camp at some time and while stopped, you use say 60 Ah of battery capacity. With any other controller, you will not only have taken your auxiliary battery down to 40% SoC, if you have one of the new alternators that have low operating voltages, you will need to drive for at least 6 hours to fully recharge the battery.

With my controller, neither battery will be below 70% SoC and will need less than 4 hours driving to fully recharge both batteries.

Another major cost saving advantage when using one of controllers is that because you don’t have to take the auxiliary battery anywhere near as low as you do with other brands of controllers, you auxiliary battery should have a much long life span.

It’sNotWorthComplaining, the advantages for using my controllers goes on and on but you should get a basic idea of the main advantages from the info above but if you need to know more just ask.

One more point, if you are considering fitting house batteries in your camper trailer in the future, then I would recommend you get my SC80 instead of the smaller SC40.

BTW,the winch set-up also gives you a jump start facility if you cranking battery ever fails.

http://www.traxide.com.au/sc4_page_images/SC40-winch.jpg

https://www.aulro.com/afvb/images/imported/2010/01/1513.jpg

[Drover]

The RedArc SB112 keeps both batteries linked together until the cranking battery drops below12.5v, allowing you to draw from both batteries. It will not isolate just because the engine has been turned off.

When the engine is started, the RedArc will monitor the starting battery and when it reaches 13.2v it will link the batteries together and provide charge to the auxiliary battery.

Also, have a look at the current “Extended camping – fridge options?” Thread in the “Camping, Tucker and bush basics” forum. Lots of good chatter on auxiliary battery selection.

[drivesafe]

Hi Drove, at 12.5v, the battery is still at 90% SoC so the redarc is not using much of the cranking batteries capacity.

Next, it does not monitor the cranking battery in any way or form, it just monitors the vehicle’s voltage and once the motor is running, the ALTERNATOR’S VOLTAGE will rise and the controller will cut-in as soon as the ALTERNATOR’S VOLTAGE is at 13.2 or higher.

Most DB controllers work the same way ( including mine ), they DO NOT monitor the cranking battery and actually have no idea of what the SoC of the cranking battery is at when they cut in.

For all they know, the cranking battery may have been near flat and only just got the motor started but as soon as the ALTERNATOR’S VOLTAGE rises above 13.2, the isolator cuts in and this is usually no more than about a minute at most after the motor is started, while it would actually take a few hours to charge the cranking battery.

So waiting for the cranking battery to charge before the isolator cuts in is not a realistic operation and when you consider that the standard alternator can easily charge two or three batteries at the same time, why wait, when you can be charging all the batteries at the same time.

[drivesafe]

One more point Drover, my SC40 has been specifically designed to keep the batteries connected for long periods of time after the motor is switched off and to this end, the SC40 only draws about 130 ma while a solenoid type isolator’s coil draws between 700 and 900 ma.

So a solenoid type isolator will be drawing heaps of the battery’s capacity just to keep itself energised.

BTW, the better the quality the solenoid is, the HIGH the coil current is.

[d2dave]

Hi again It’sNotWorthComplaining and sorry this is a bit long winded.

Instead, my controllers keep all the batteries connected until the common voltage is at about 12v. At this point the cranking battery is then isolated.




At 12v a battery is flat and probably won't start the car.

This might be a good system, but for me I feel much better when I'm in the bush, that when I turn my engine off my starting battery is completely isolated. If stopping for extended periods I then use a solar panel.

Dave.

[Utemad]

At 12v a battery is flat and probably won't start the car.

Starts my car fine every time.

I'd also think that the 12.0v measured that the unit cuts out at is most likely going to be when the system is under load such as when the fridge kicks in to cycle. So the load kicks in and the volts drop and the isolator does its thing. Then the start battery's voltage raises a little bit as it is no longer under load.

That's my understanding anyway.

[numpty]

I use a large marine switch with 2 starting batteries and have done for over 20 years. I have never had a problem with this setup either (and it's cheap). Only drawback is remembering to switch batteries occasionally, but once you get used to the system, that becomes less of a problem as well.

[drivesafe]

At 12v a battery is flat and probably won't start the car.

Hi Dave, as Utemad pointed out, the voltage reading is based on the battery being under load and while a battery is in a vehicle, the load can be as small as the amount of power needed to keep the memory in your sound system, so a loaded battery voltage reading of 12v means the battery’s SoC is about 50% and at 50%, you will have no trouble starting to most difficult to start vehicle, on the coldest morning.

Also,as we have been make these units for over 20 years now. They are well and truly tested and proven to be ultra reliable and don’t cause any problems with starting.

Add to this the fact that most of our gear actually goes into new equipment made by the RV industry, including just about every Winnebago motor home made in the last 15 years, so my gear is well and truly tested and proven.

[Lionel]

At 12v a battery is flat and probably won't start the car.
Dave.

Not true! If a healthy battery is discharged to 12V it will still easily start the engine.

I have proved this many times with my vehicles.

Cheers,

Lionel

[Disco44]

I use the same set up as " Mr Whippy" and have done for years with no problems.With it I run the starting battery and 2 deep cycles one of the deep cycles is 105 amp hour. I will take his advice but and get another as a spare as mine has been going for years too.
John ( disco 44 )

[d2dave]

Not true! If a healthy battery is discharged to 12V it will still easily start the engine.

I have proved this many times with my vehicles.

Cheers,

Lionel

A battery at 12v has less than 25% charge. Do this often and your battery wont last long. Even deep cycle batteries will have a short life if you did this often.

Dave.


http://img29.imageshack.us/img29/7479/img3935m.jpg (http://img29.imageshack.us/i/img3935m.jpg/)

[Lionel]

A battery at 12v has less than 25% charge. Do this often and your battery wont last long. Even deep cycle batteries will have a short life if you did this often.
Dave.

This is a different issue. I was responding to your statement that "At 12v a battery is flat and probably won't start the car"

It IS true that one shouldn't routinely run the battery too far down, but in practice it doesn't happen that often if you are careful. Certainly a solar panel is a good thing to use.

Cheers,

Lionel

[drivesafe]

Hi Dave, mate have a look at the picture you posted, it states at the top of the graph that this info is for OPEN CIRCUIT VOLTAGE and I didn’t explain this properly earlier in this thread but that graph does not apply to any battery in a motor vehicle, unless all cable connections to the battery have been removed and the battery is allowed to stand for at least 24 hours.

This is not what happens with motor vehicle batteries.

The chart below is a far more accurate indication of the SoC battery voltage when the battery is in a vehicle.

https://www.aulro.com/afvb/images/imported/2016/06/640.jpg

[B92 8NW]

Hi Tim, do you have a standard underbonnet SC80 kit? I can only see the SC40 underbonnet kit on your website.

[drivesafe]

Hi B92 8NW, here’s a link to the SC80 web page on my site.

trax1sc80.html (http://www.traxide.com.au/trax1sc80_2.html)

[justinc]

Just a point here about the comment made about isolating the main battery when the system reaches 12V. If you sit there with a multi meter attached to the main crank battery and watch the voltage AS the isolator isolates, you will see the main battery voltage rise by as much as .35V when the other battery/ies are isolated from the main. I recently had a few isolating issues with my SC80, but after another chat to the long suffering Tim (:D), I decided to persist and discovered that after remounting the unit and more importantly EARTHING the green wire properly (!!!) it now works as it did when I first fitted it.

Just did a trip with CT and fridge etc etc and all 3 batteries are managed as they should be!

The SC 40/ 80 is a very clever bit of kit.


JC

[drivesafe]

A point I forgot to mention is my warranty, which is of particular advantage to DIYers.

ALL the gear I manufacture comes with a 2 year unconditional warranty, OTHER THAN BEING TAMPERED WITH, plus a 30 day installers warranty.

The 30 day installers warranty works in that should the installer do something wrong while installing the gear, like slip with a screwdriver and jam it through the controller module, it will be repaired under warranty.

Outside the warranty period, if the gear fails for any reason OTHER THAN BEING TAMPERED WITH, it will be repaired at the cost of the return mail.

A note on the 30 day installer warranty, this was not included for the benefit of DIYers but was actually included in our warranty some 30+ years ago, when most of our sales were to car alarm installers and auto electricians.

I had so many returns from auto electricians and they always made out that it was a mystery problem and I would some times spend hour trying to find what had caused the problem, only to realise that the auto electrician had not wired up the alarm properly in the first place.

I was discussing the problem with my biggest customer, who had virtually no returns and he suggested the 30 day installer warranty as a means of saving me hours of unnecessary fault finding.

It work a treat and from that point on, the auto electricians simply told me what they had done something wrong and not tried to make out there was a mystery problem as a means to get the controller replaced under warranty after they had stuffed up.

This also allowed me to make changes to the design to improve the installation reliability, to make my gear idiot proof.

This warranty is now applied to all our customer, trade or otherwise.

[It'sNotWorthComplaining!]

A point I forgot to mention is my warranty, which is of particular advantage to DIYers.

ALL the gear I manufacture comes with a 2 year unconditional warranty, OTHER THAN BEING TAMPERED WITH, plus a 30 day installers warranty.

The 30 day installers warranty works in that should the installer do something wrong while installing the gear, like slip with a screwdriver and jam it through the controller module, it will be repaired under warranty.

Outside the warranty period, if the gear fails for any reason OTHER THAN BEING TAMPERED WITH, it will be repaired at the cost of the return mail.

A note on the 30 day installer warranty, this was not included for the benefit of DIYers but was actually included in our warranty some 30+ years ago, when most of our sales were to car alarm installers and auto electricians.

I had so many returns from auto electricians and they always made out that it was a mystery problem and I would some times spend hour trying to find what had caused the problem, only to realise that the auto electrician had not wired up the alarm properly in the first place.

I was discussing the problem with my biggest customer, who had virtually no returns and he suggested the 30 day installer warranty as a means of saving me hours of unnecessary fault finding.

It work a treat and from that point on, the auto electricians simply told me what they had done something wrong and not tried to make out there was a mystery problem as a means to get the controller replaced under warranty after they had stuffed up.

This also allowed me to make changes to the design to improve the installation reliability, to make my gear idiot proof.

This warranty is now applied to all our customer, trade or otherwise.
AND your supporting a forum member that drives a Landy.
I bet Redarc execs drive Toyotas :mad::mad::mad::mad::mad:, that's enough reason on it's own.:D

[Redback]

Only way to go is Traxide IMO, never had a problem in 4yrs and it's a plug and play type unit, install it and forget it:BigThumb::BigThumb:

[It'sNotWorthComplaining!]

Only way to go is Traxide IMO, never had a problem in 4yrs and it's a plug and play type unit, install it and forget it:BigThumb::BigThumb:
Thanks every one. I've order the Traxide. :cool:

[dmdigital]

I'll just add that you can't fault Tim's after sales service!:):):):):):):)

When traveling and everything seems to have gone wrong it's very comforting to know there's someone knowledgeable that you can contact and who understands the logistics of getting a new unit to you.

Thanks again Tim for your help in July 2009!!!!!!!!!!!!!!!!:BigThumb::BigThumb:

[It'sNotWorthComplaining!]

I'll just add that you can't fault Tim's after sales service!:):):):):):):)

When traveling and everything seems to have gone wrong it's very comforting to know there's someone knowledgeable that you can contact and who understands the logistics of getting a new unit to you.

Thanks again Tim for your help in July 2009!!!!!!!!!!!!!!!!:BigThumb::BigThumb:
That's very comforting to know.
Too bad Tim didn't have a Land rover frachise.... when something goes wrong they skip town!:mad:

[maggsie]

I have just fitted the SC80 to my 04 Disco and can add that Tim's after sales service is first class.

Maggsie
04 V8 Disco

[Slunnie]

I'll just add that you can't fault Tim's after sales service!:):):):):):):)


I have just fitted the SC80 to my 04 Disco and can add that Tim's after sales service is first class.

I can vouch for this also. Absolutely 2nd to none and very very quick!

[It'sNotWorthComplaining!]

The Traxide SC80 arrived today. I was impressed that Tim went to the trouble of including and installation CD that showed variuos options of install.
Thanks Tim.
Finding a warm dry place in the engine bay was a problem on my Disco, no spare body panels. I thought of mounting it under the main fuse box near the battery but no room, and it would have to be mounted on it's back.
So I pulled the right hand side headlight out and mounted it to the right side of the headlight on the panel in front of the battery.
I'm sure it would be dry enough in that spot and it's out of the way.
Will post some pics after I have finished:)

[drivesafe]

Finding a warm dry place in the engine bay was a problem on my Disco, no spare body panels.

Hi mate, a little trick when needing somewhere to mount my controllers.

Because they have such a low profile, if you have enough space on top of the battery when the bonnet is closed, you can make up a mounting plate out of a sheet of aluminium, fix the SC40 or SC80 to the plate, along with any circuit breakers and then use the battery’s hold down clamps to secure the plate in place over the battery.

[VladTepes]

Tim that's the sort of useful technical advice that gets in the way of all the rubbish on this forum.....

Cheers

[hoadie72]

Hi Tim,

With the SC40, where would you wire in a solar panel, which has a controller.

Based on what I've read in your previous posts, it seems to me there would be benefit in connecting it to the main battery, as both the main & axillary batteries will be charged (once the main battery is over 12v).

Or have I read this wrong?

[extreme6.5]

I run a rotronics MH10 in my 110.
Been in for 7 years and has never missed a beat.I just run a 29L Engel(30 yrs old!!) and lights, plus an inverter to charge phones/laptop/ipods etc. I couldn't quite bring myself to spend the $ when it came to a deep cycle battery so my auxilliary is just a standard heavy duty battery, cost about $140- I think.
We camp about 4/5 times a year, 2/3 nights out, plus some longer trips of 2/3weeks and this setup works fine for me.

The aux battery runs the engel and lights for 3 days and 2 nights when camped no problem, is shut down by the rotronics on the third night to protect it.
Engel is still cold enough on the last morning to get the tucker home ok.(All the beer is gone by then...)
So for anyone looking at setting up a system, I'm just making the point that all those $ on a deep cycle may not always be necessary....
My aux battery has been in use on above basis for 4 years and still goes well.
The cranking battery I havn't had to change in the 7 years I've had my 110.It could well be the original, (I bought the 110 as a 2yo vehicle)which would make it 9 years old, gotta be happy with that:D:D:D.....

[drivesafe]

With the SC40, where would you wire in a solar panel, which has a controller.


Hi hoadie, you can connect to either battery and have different out comes.

If you connect to either battery and the SC40 still has the batteries connected together, both batteries will be charged by the solar panel.

If you have the solar panel connected to the cranking battery, and if the SC40 is in the isolate mode, once the cranking battery voltage rises above 13.2v, the SC40 will cut in and both batteries will then be charged.

If you have the solar panel connected to the Auxiliary battery, and if the SC40 is in the isolate mode, no matter how high the auxiliary battery voltage gets, the SC40 WILL NOT connect the batteries until the motor is started.

Cheers.

[It'sNotWorthComplaining!]

Hi mate, a little trick when needing somewhere to mount my controllers.

Because they have such a low profile, if you have enough space on top of the battery when the bonnet is closed, you can make up a mounting plate out of a sheet of aluminium, fix the SC40 or SC80 to the plate, along with any circuit breakers and then use the battery’s hold down clamps to secure the plate in place over the battery.
I thought of that, but reading the install instructions it advised to heve it with the leads facing down, (* probably to act as a drain if water got in)
I just finished installing it so I am going to post some pics.
The instructions suggest installing a circuit breaker near between the outlet lead of the SC80 to have a circuit breaker between it and the aux battery.
I installed a 50 amp one after the SC80. But would it be advisable to also fit one to the input lead to the aux battery pos+, it there was a short from the SC80 end it would break the circuit, but if there was a short from the AUX battery Pos+, it would not trip? ..

[cookiesa]

The only issue for me is the fact that it will shorten the life of your primary battery. First of all the battery is being "cycled" more often (assuming you use your fridge or accessories reasonable often), and that it is being discharged and left discharged for periods of time, (again dependenat on your exact useage), both of these are dtrimental to the life of a standard cranking battery. One of the key features of a dual battery system for me is that the main is left in as good a condition (eg charged as much as possible) as it can be when you are stopped. This of course means you are more likely to have a good battery for starting.

Of course everyone has different needs so it is a case of matching the system to your needs.

[It'sNotWorthComplaining!]

The only issue for me is the fact that it will shorten the life of your primary battery. First of all the battery is being "cycled" more often (assuming you use your fridge or accessories reasonable often), and that it is being discharged and left discharged for periods of time, (again dependenat on your exact useage), both of these are dtrimental to the life of a standard cranking battery. One of the key features of a dual battery system for me is that the main is left in as good a condition (eg charged as much as possible) as it can be when you are stopped. This of course means you are more likely to have a good battery for starting.

Of course everyone has different needs so it is a case of matching the system to your needs.

Your right about exact usage.
I for one don't camp in a spot for weeks on end and not move. When I set up camp be it for a few days, I will always setup a base camp and use the vehicle to explore, so it will never just sit there not charging the battery allowing it drain.
On the other hand, some of the Christmas campers like those that squat along the foreshore every year in places like Rye -Portsea for 4 weeks at a time, then they may have problems.;)

[drivesafe]

The only issue for me is the fact that it will shorten the life of your primary battery.

Hi cookiesa, and this is not what happens.

I can only theorise why the cranking battery last longer, but the reason the auxiliary batteries last longer is because unlike other systems where the auxiliary battery is taken much low to do the same chores, because the SC40 and SC80 share the load over two or more batteries, none of the batteries are worked anywhere near as hard, both during the discharge cycle and the charge cycle, the auxiliary batteries definitely last longer.

One of the theories for why the cranking batteries seem to last longer is because they are always in use, even though it's with very low current draws, but this keeps the batteries active and seem to keep the batteries healthier, and this was put to me by one of the battery suppliers.

The point is though, after 20 years, if there was a problem, it would have well and truly shown up by now, and to date, no problems have shown up and many of my customers have reported average to better than average life spans from both batteries.

[cookiesa]

It is quite simple, batteries have a life span, this is affected by charge, storage and cycling.

The amount will vary greatly based on how the vehicle is used, but if your honestly saying that constantly drawing charge from a standard cranking battery, and with the possibility of it sitting in a semi discharged state for possibly a few days, (depending on how the vehicle is used) is extending the battery life of the main battery then you contradict EVERY battery manufacturers own scientific research.

As I said there are many different systems, and many different ways our vehicles get used, the most important thing is to match the system to your load and useage. I was not having a go at you or your product, there are plenty of satisfied owners on here and elsewhere, just like there are for many, (not all) of the other systems. Like all systems your system has advantages and disadvantages, comes back to matching the system to your needs.

[drivesafe]

Hi cookiesa, you missed the point. It’s not that the cranking battery sits there for possibly a few days in a semi discharged state. This I agree, as many battery manufacturers state, is not good for any battery.

With my controllers, all the batteries are being used continually so the chemical reaction is kept active and if you check with the same battery manufacturers, keeping batteries active, no matter how small the load and/or the charge is, will stop sulfation for occurring. This is the theory why the cranking batteries used with my controllers seem to give good service.

[cookiesa]

The only way it can not sit there in a semi discharged state while your camping and using your fridge etc is if there is additional charging, eg solar. You have already stated the system allows the main battery to be pulled down to 12 volts before disconnecting it. Therefore unless there is no draw from the batteries or some way of charging them the primary battery will not be fully charged.

Anyway more important things in life to worry about. As I said your system has benefits, it also has, like all systems it's drawbacks and people need to look at how they will be using the system and what they want/expect from it then decide on the best system for them.

[drivesafe]

Hi again cookiesa and while your THEORY sounds nice, as there have been tens of thousands of my controllers supplied over the last 20+ years and your THEORY has yet to happen, I think it’s pretty safe to say it’s just that, an unsubstantiated THEORY.