[shep]

Whats the best way to wire up a system with cranking and deep cycle battery's under the bonnet an a third battery in a trailer?

[Scrawny]

What going to run off the trailer battery? I haven't read your camper thread, maybe I should wander over for a look

[shep]

Trailer will have a few lights, water pump and a fridge. Will stick a 100amp battery in the trailer

[canberramav]

I have my cranking battery then the isolator ( I use traxide and highly recommend ) then I have 2 x 55amp batteries behind the seat and then a 110amp on the trailer. The trailer battery is hooked up to the 55amp batteries with a Anderson plug setup.
Basically all 3 of the deep cycle batteries are linked together as one.

Don't know if this is the best way but works for me

[canberramav]

So in the setup you described just use 6mm cable and run it from your second battery under the bonnet to the back of the car and plug in from there.
Use a circuit breaker right near the battery just in case.

Also look on eBay as you can get all this in a kit cheaper than anywhere else.

Use 6 b&s not regular 6mm cable as its not big enough.

Type in 6b&s into eBay and you will find what you need

[rick1970]

My Rangie has the main and aux battery in the car joined with a cheap continious duty solenoid setup. Manual reset curcuit breaker off the aux battery, 2 x 6mm wires to the rear, 50amp Anderson plugs, second curcuit breaker at battery in the camper. All electrics in trailer earthed direct to battery, not chassis.

Works ok for a simple setup. Minimal voltage drop to trailer battery, 14.1v at either battery in car and 13.9v at trailer battery.

[royce]

do you want the trailer to be able to draw from the vehicle Aux battery as well as its own?

if so just wire positive to positive on all Auxillarys, its far from excellent but it will work.

otherwise, bang some big solar on the trailer, keep a totally independent system so it will stay charged with your fridge in there and not hooked up to the car

[mnemonix]

Another +1 for a traxide controller.
I have 1 under the bonnet +2 under the tray. Traxide website has multiple wiring options for you.

[303zuke]

royce wrote:

do you want the trailer to be able to draw from the vehicle Aux battery as well as its own?

if so just wire positive to positive on all Auxillarys, its far from excellent but it will work.

And also provide a heavy earth cable between the trailer battery and the Aux. Don't rely on the towball or the Earth circuit in the trailer plug. As CanberraMav suggested, a two pin Anderson plug will do the trick.

[11_evl]

I use one of these for after the start battery. Works well.
http://www.redarc.com.au/products/produ ... arger-40a/

[Built4thrashing]

I run the standard dual battery system in the GV with an auto isolator. The caravan is then connected to the Aux battery by a cheap auto isolator. Caravan will only charge when the GVs aux battery is completely charged. I did it this was as the GV has the fridge in it and is more important to keep charged. When camping we run the fridge on LPG and the pump is hardly used.

Plus if we camp for any extended time ill pull out the solar panels.

[shep]

I can get these for $60
http://www.elecspess.com.au/products/product/VSR100K?
so was thinking off putting one between the 2 battery's under the bonnet and then one between the cars deep cycle and a Anderson plug at the back of the car.

Would that mean that first the cranking battery gets charged followed by the cars deep cycle and then the trailers battery?
Would there be much voltage drop with 7 or so meters of 14mm2 cable?

[Rusho]

Was the 14mm cheap Shep(free???) It 'should be ok...Hope this helps

http://www.rpc.com.au/pdf/efn133.pdf

[pezz]

Alot of caravans run a dc to dc charger to avoid the problem of voltage drop.. they are normally around 20amp

[royce]

shep wrote:

I can get these for $60
http://www.elecspess.com.au/products/product/VSR100K?
so was thinking off putting one between the 2 battery's under the bonnet and then one between the cars deep cycle and a Anderson plug at the back of the car.

Would that mean that first the cranking battery gets charged followed by the cars deep cycle and then the trailers battery?
Would there be much voltage drop with 7 or so meters of 14mm2 cable?

Run em both off the crank battery, the whole idea they charge one battery then the other is a wank, I've had to JumpStart mine before and the isolator still clicked straight in, it only looks at voltage not state of charge, alternators all put out more current than a normal battery will charge at.

Then you have less connections to the rear and less failure points in keeping the trailer charged

[ianw53]

I run a standard dual battery system in my Pajero, and then use a Redarc DC-DC charger to charge the AGM battery in the back - works very well.

[got_bar_work]

I have a ctek dc.to.dc.charger with solar.mppt solar reg in my camper works great

[Davros-1]

First, understand how your batteries are charged :-

http://www.caravanandmotorhomebooks.com ... rgers.html


And how your battery reacts to charging and connections :-

http://www.caravanandmotorhomebooks.com ... eries.html

http://www.caravanandmotorhomebooks.com ... eries.html


Above all you never fit batteries inside a vehicle or a camper trailer. Never, ever. There is no manufacturer I am aware of that does not state that all conventional battery types have the potential to gass off if overcharged - hydrogen gas in concentrations above 4% in the air can burn about the same as a gas lighter, get to 10% and it is extremely explosive. The advice to fit AGM batteries without external ventilation was universally withdrawn in 2000 by all Australian brands, there is no way you should ever fit any battery type inside a sleeping area or a passenger space. From a road crash rescue point of view I do not like dealing with acid burns, on me or anyone else.

Your alternator cannot see other batteries, only the total circuit, and so it cannot manage the requirements of differing types in the same charge circuit. For around $400 or so multistage regulators are a common fitment in the marine sector, but if you are going to run different types of batteries you will need one for each type as again the charging system cannot see differing types, only the total system voltage. Your batteries only charge when a voltage higher than the existing one internally is applied to it, and as the battery gets more charged the current needs to be limited at the same time the voltage is raised - within certain safe limits depending on the battery type, this is way better explained by Collyn in the links above.

I have fitted and maintained many multiple battery systems in marine, vehicle and remote power scenarios, two things I have learnt over the last couple of decades, 1st is that the cheapest stuff you can buy (batteries, chargers, switches etc.) will ALWAYS be the most expensive in the long run. And 2nd that there is no magic or voodoo involved, it's just physics and facts.

[shep]

There are many manufacturers that fit battery's inside cars

I havent come across dc dc chargers before so thanks for the tip, have a 40 amp jobbie on the way.

Will have the cranking and deep cycle battery's under he bonnet joined with the VSR kit and and then have 100amp
cable from the deepcycle to a Anderson plug on the trailer and a dc dc charger to the trailer battery.

[Ace]

Fully sealed batteries should be fine (not legally binding) but I have seen a guy at wk weld up big stuff lifted up on our old forklift and it turns out Hydrogen? is explosive... a small amount goes off real well with some mig splatter haha. Possibly charge em all and some switch manual or costly so as to not drain the starting 1?

[shep]

no such thing as fully sealed battery. even aa batteries have a vent. it is were it vents that is important

[Davros-1]

There are many manufacturers that fit battery's inside cars

I know of Jaguar fitting the battery in the boot - total PITA if it goes flat and you need the power to unlock the boot, which is keyless entry....

I'd like to know which modern vehicle fits starting batteries inside the passenger area, to fit batteries in campers, boats etc. they have to be in a fully sealed container vented to the outside of the vessel/living space. There are standards also as to where this venting has to be in relation to ventilation and other air intakes, doorways, windows etc. too.

I remember when the AGM batteries first went big, the claims made included that they could be mounted at any attitude, including upside down. Didn't take long for that to be proven a bad idea, as already said, all batteries that can be re-charged can also vent. The sealing system is as simple as a seal held over a hole with a spring - like a blowoff valve on an aircompressor but a lot less pressure needed to activate it. It's only some pretty cool design features that allows the full re-combination of active materials during the charge cycle without venting, but if pushed too hard internal balance will be lost and the battery will vent rather than physically blow up due to internal pressure build up. Once a sealed type battery vents it will mostly have lost enough electrolyte and liquid to quickly fail - you just might be able to replace it in theory and have the battery keep working - but this is very rarely possible even if you had all the stuff right there and knew exactly what to do with it.

[Gwagensteve]

BMW's have had the battery under the rear seat of eleventy gazillion years. Volkswagen Touraeg - under the driver's seat (maybe passenger - it's one of them) They are in the cabin.

Steve.

[Davros-1]

Just looked up the RCR manual - both those Manufacturers brands are red flagged (not just for that), along with all hybrids, full electric and several asian import mini cars.

Shows I've never owned one I guess.... The battery compartment must be fairly substantial I expect.

Trying to keep a bit to the thread, it's one thing to modify our vehicles, another thing entirely to build in a hazard when the risk can be easily avoided by sticking to proven (and as already stated - often mandated) battery locations. If a vehicle is accepted by the authority under ADR testing and for whatever reason that includes batteries in the passenger cell well I guess that shows I don't have anything to do with that part of it. Frankly I don't know why one sector of government vigorously maintains a particular standard while another cheerfully ignores it, but then again I don't know about a lot of things. It doesn't make the reality any less profound if things go wrong, and THAT from time to time I have had to deal with - and it does tend to get your full and undivided attention.

There are many more chances for things to go wrong when you start running multi battery systems, once you are running separate start and house battery systems you are way beyond the supercheap/kmart type fittings and chargers. If you do cook a house battery in an enclosed space it just might go bang if some form of ignition is present - if it does it absolutely looks like a bomb went off, and good luck to anyone in there at the time.

[henno]

Bumping an old thread.

My new land barge has a dual battery setup already (100 series landcruiser with a simple ignition switched solenoid type controlling the two batteries in the stock locations) and there is also a winch wired into the mix. I want to add a fridge to the rear. I assume that the best way to do this would be to get a DC-DC charger and run power to the rear with an AGM battery of sorts. There's already wiring there for a fridge from the previous owner but it is just going to the current 'AUX' battery.

The cheaper the setup the better, but I am also from the school of "Do it right and do it once". I'm thinking about replacing that solenoid with a proper VSR anyway, but I need to check how the winch is wired to make sure that a bazillion amps aren't shooting across the solenoid under winch load.

The simplest setup might just be to wire in a DC-DC charger off the main and leave the existing AUX setup as it is? Not the cheapest way to go though.

Ideas?

[fordem]

Simple solenoid or VSRs should really only be used when the batteries are the same type (chemistry), capacity & age, because all they do is control the conditions under which the two batteries are paralleled for charging - if the batteries are different in any way, they will not charge properly when paralleled.

The real question is how will the batteries be used - the previous owner may have had a different plan in mind - if the intent is to have two batteries to boost capacity when winching, then a simple solenoid (with enough capacity to support the winch) linking identical batteries is all you need, if it's to power a fridge, a DC~DC charger feeding a deep cycle battery would be the way to go, and if you're going to add a third battery for the fridge, then a DC~DC charger would be the best bet there also.

[henno]

fordem wrote:

if the intent is to have two batteries to boost capacity when winching, then a simple solenoid (with enough capacity to support the winch) linking identical batteries is all you need

That is the current system, as it stands.

fordem wrote:

if it's to power a fridge, a DC~DC charger feeding a deep cycle battery would be the way to go, and if you're going to add a third battery for the fridge, then a DC~DC charger would be the best bet there also.

As I expected. I was just thinking/hoping I could save a few hundred clams and perhaps substitute the second under-bonnet battery for something that can handle deeper cycling as well as very (very) limited winch use if ever required.

[fordem]

This is when we start looking at compromise - true deep cycle batteries should never, ever, be subjected to the high amperage demand of a winch, and starting batteries, which are designed to deliver the high amp discharges of a starter or a winch will not withstand the repeated deep discharges of "cycling service" (see note below).

Several battery manufacturers have created batteries that can be considered dual purpose, they work reasonably well in both situations, if you were to use one of these as the second battery, you could get away with it - charging and paralleling the batteries when needed for winching becomes the challenge - vehicle charging systems are designed to recharge the starting batteries, and when batteries (even identical batteries) are paralleled, either through a simple solenoid or through a VSR, the recharge rate is going to be dictated by the system voltage, if one battery is more discharged than the other (this is the reason the isolator is fitted - to prevent both from being discharged), then one battery ends up overcharged and the other undercharged - I would be looking at a DC~DC charger, and some form of manual disconnect/reconnect switch to handle the occasions on which I needed to use it with the winch. The DC~DC charger prevents the second battery from impacting the system voltage, and thus the charging of the primary battery, whilst allowing the secondary battery to charge at it's own rate, so that, whether or not it charges fully is now a matter of the time it takes to recharge.

Please be aware that it may be necessary to disconnect the charger before paralleling the batteries, as what you're essentially doing is shorting the charger output to it's input.

Note.

The design & physical construction of starting & deep cycle batteries is different - the life of a starting battery is essentially a brief high current discharge (whilst cranking) followed by an immediate recharge, and whilst they are subjected to a small continuous discharge when the vehicle is switched off (clocks, ECU, etc.), the depth of discharge is minimal, they are recharged frequently and for the most part maintained at or near full charge. Deep cycle batteries see smaller currents over longer periods, and are discharged to a greater extent (a deeper discharge) between recharges, and for reasons mentioned above, they may not be recharged fully, if ever.

In case of emergency, either type of battery, can be used in either situation, but, continued use of the battery in the wrong manner will shorten it's life, sometimes dramatically.

[shep]

I use cheap long warrenty battery's like the red top exide jobbies and isolate with a simple solonoid.
2015 79 landcruiser has 2 N70 red tops and runs a heap of radios (4x25watt) and a fridge that is never turned off. Only need to plug the car in if it isn't driven for 4 days.

2014 challenger that when my camper is attached has 2x N70 and 2 X N50 battery's all sorted with solonoid isolators, works perfectly.

2013 jimny has two 600cca 60amp battery with solenoid, because it can go for long periods between use I leave the car plugged into mains power.

The only battery out of all of those that has given an issue is the deep cycle in the Toyota and that was a melted case when I got the car a bit hot at a fire, all the plastics melted of the side of the car as well so not the battery's fault.

you can have a great battery system without spending $1000 and so what if the deep cycle only goes to 95% capacity, $800 for a extra 5amp hour is pretty silly imho.
The red top battery's I use cost $140 and have a 42 month warrenty.

[henno]

Well, this was an epic fail. I have spent so much time on trying to calculate a way to keep it as a two battery system, as well as rewiring the rear anderson plug with thicker gauge to minimise voltage drop the best I can (measured at 0.08v under full load of the fridge) but so far this week after a few gremlins, I have replaced the existing battery of unknown age with a brand new N70 and it is DOA after only a few days' work.

I put the new battery in Friday. Drove for three hours on Saturday, arrive home about 2pm. Went for another drive Sunday for about half an hour and this morning (Monday) everything was dead.

I could just pony up for an AGM but my real concern is that they can only really take a charge of 25-ish amps (and most DC-DC chargers seem to put out that much) so cycling the battery takes a lot of driving time in order to fully and properly recharge the AGM.

I was really hoping to find a 'half way' solution between deep cycling and CCA (as it will get used with a winch, albeit very rarely) as I only really need to get one, maybe two days out of the fridge, not 4-5 days like I see from some setups. But it seems I am going to have to go with a three battery system. Which sucks, because that is more weight and more money, both of which I was hoping to keep at a minimum.