Main battery flat with red arc isolater

Evening guys I have recently had a dual battery system installed with a red arc isolater (arb artarmon) to run my fridge and my main battery has gone flat and I couldnt start my mighty patrol, I think it is from blaring the radio while I was installing my roof top tent, I may sound like a retard but I thought that the point of the isolater was to drain the secondary battery straight away and leave the starter battery alone?? I have a volt meter in the back of the car and it was reading 12.6V at the time (which I found strange) do the accessories run straight off starter battery and that is why it is flat? Thanks guys I am a bit worried as my partner and I leave on Saturday for a round oz trip and I do not want to be out woop woop with a flat battery!!

It does sound like your radio runs off your starter battery and any other accessory which you had prior to fitting the second battery.
Did you have a radio before installing the second battery?

If you are heading off to remote parts it would pay you to get someone to show you around your vehicle. Either that or add a bigger amount to your travel budget. ‘Out there’ labour costs can be more than double what you’re used to.

All the standard equipment in your car from New runs off the starting battery. Any accessories you add like your fridge should run off the auxiliary battery. That's why your radio discharged the starter and the auxiliary was still charged.

I have also had a redarc isolator fail, so check it is switching in and out of circuit.

As said factory items, such as your radio/headlights/interior lights, run off the starter battery just like every other car out there. The auxiliary battery only generally runs aftermarket accessories which have been specifically wired up to it. Often fridges/compressors/camp lights and other accessories. Unless you have had your radio re-wired to only supply from the auxiliary battery you will simply continue to run your start battery flat. A redarc does not do any magic and make everything run from the auxiliary battery, you need to physically wire it that way, all the redarc does is allow the auxiliary battery to charge (without a permanent connection).

As Cuppa said if you don't understand your vehicle and what is connected where it could become an expensive exercise out and about so get someone local to explain and show you how best to utilise your auxiliary battery.

You will want to get the condition of your starter battery checked now as well IMO, personally if it was me going around OZ, id want a new starter battery before the trip, last thing you need is for it to die out in the bush, plus as cuppa mentioned upon, out bush you may have to pay through the nose for a new battery when you are stuck.

Yeah I did a bit of research last night in to the battery setup all good, the rear light was. Left on for about a week as well, brand new car (4 weeks) so the battery is fine just me being a retard I jumped it off the second battery

Good to hear, I was having a bit of trouble thinking that the radio alone would have flattened your battery overnight. Don’t just leave charging the starter battery to the alternator whilst driving. Wack it onto a mains charger straight away & charge it fully ........ if you want it to have a long & healthy life that is. ;)

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Originally Posted by Cuppa

Good to hear, I was having a bit of trouble thinking that the radio alone would have flattened your battery overnight. Don’t just leave charging the starter battery to the alternator whilst driving. Wack it onto a mains charger straight away & charge it fully ........ if you want it to have a long & healthy life that is. ;)

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are all tackle chargers much the same or is there a better one to buy?

Trickle chargers. Tbh I’m really not sure what a trickle charger is these days ......... I recall buying what was referred to as a trickle charger once, specifically for a motorcycle. It’s output was rated in milliamps & it’s advertising said it was ok to leave it connected all the time. I left it for a month or three after which I found a dead battery with no fluid left in it.

I suspect what you mean is a ‘Smart Charger’, one which is a multi stage charger which determines when the battery is full & reduces it’s charge rate but then holds the battery in ‘float’ mode at a constant voltage once fully charged.

There are differences in how different chargers determine when a battery is full, but basically any well known brand of smart charger is a useful asset to own. Buy known quality & it should last you a lifetime. Buy an unknown cheapie & it may last you, or may kark it after a short time. I had one , an ebay special, which died after less than 6 months.

Some brands like Ctek have recommended chargers based upon battery capacity. Any charger will charge any battery of any capacity, BUT, if you want to be able to go away & trust that it will do the right thing, follow the recommendations. I had two Ctek’s in my bus, a 24v & a 12v. Both were very reliable, but one was undersized for the battery bank it was charging. Problem was that the ‘smarts’ in Cteks sees them ‘check’ on the battery every 10 days whilst in float mode. If sized too small this can result in them going into bulk charging mode when it is not required resulting in overcharging (something which will kill batteries just as effectively as undercharging). I highly recommend Ctek chargers when matched to battery size (& they do have a reasonably wide range - I was just a cheapskate when I bought one too small). They are not cheap though.

Projecta Chargers, particularly their ‘Intellichargers’ seem to offer a lot for less money but I don’t like them, I’ve heard too many stories of them failing. I have one in the Tvan, but I wouldn’t trust it enough to leave it connected without frequent monitoring.

I also have a 12v/24v Matson smart charger which does a good job. It doesn’t actually tell you when it goes into float mode, it just says ‘Full’. However I have tested it over time & know that ‘Full” means it has switched to ‘Float’. It holds the battery in float indefinitely very nicely.

I expect there are many other smart/multi stage chargers which do a good job too, but I have no direct experience of them. Others may add their favourites.

Advertising spin is rife. A zillion different charging stages is really no better than a few. The essentials that are needed are ‘Bulk’ (aka ‘Boost’) ‘Absorbtion’ & Float. Nice things to have are ’Soft start’, & a ‘recovery’ setting (usually a higher voltage to try as a last ditch effort to revive a dying battery) & a ’Supply’ mode. I would like to see smart chargers sold with adjustable charging settings so that the owner can match precisely to the battery manufacturers charging recommendations. Mostly it is a matter of getting as close a match as you can.

Worth paying extra for is a charger with settings for a variety of different battery chemistries. Most will have settings for ‘Wet’ (or flooded), AGM, GEL, & Calcium. Having these will mean you don’t need to get a new charger when you change battery type in a year or two’s time.

A good smart charger will ‘read’ the battery to determine the best charge to give it. This can however result in some charger’s failing to charge. I have had occasion when my Matson told me that a battery was stuffed & wouldn’t deign to charge it. However a couple of hours on a small ‘dumb’ (linear) charger & then back onto the Matson saw the Matson accept it & then go on to fully charge it. So don’t throw out your old cheapie if you buy a smart multi stage charger!

Charger capacity. My Matson is nominally a 20 amp charger,(@12v) but has settings also for 10 amp & 2 amp. It recognises when a lower amperage is required to ’squeeze’ that last bit into the battery (normal smart charger behaviour), so on a larger battery I might start it off at 20 amps but it will knock itself back to 10 & 2 as required. If I were charging a small battery (e.g.a motorcycle battery) I would most likely just put it onto the 2 amp setting to start with. Even with those settings the actual charge amps will vary - the setting being the max, but the actual charging amps being determined by what the battery will accept.

Here’s a link to a bit more of an explanation from my good mate Val. http://www.fridge-and-solar.net/smart.htm

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Originally Posted by Cuppa

I was having a bit of trouble thinking that the radio alone would have flattened your battery overnight.

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Cuppa some of these "radios" need bigger cables that your starter motor Bang Head

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Originally Posted by macca

Cuppa some of these "radios" need bigger cables that your starter motor Bang Head

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Yeah, but I’d reckon that most folk with one of those big powerful doof doof units would already know how the thing was wired up ...... hmmm but then again maybe not. What? Pardon? Couldn’t hear you properly, I have this strange buzzing in my ears. :)

I you intend to run your radio say at camp or watching some sport , wire it hot to your Aux battery and this problem will be avoided,
Same goes for you UHF wire it off the AUX battery as well. if your waiting for some to arrive you'll be safe knowing youre not flattening the Main.
Leave the start battery for that starting

Good advice from TD.

It doesn't take that long when the drinks are flowing around a camp fire for the stereo to flatten your battery. Not really worth risking your starter if you are in the middle of no where.

I've also gone the path of re-wiring my UHF to the Aux battery, just in case you want to monitor while in the camp or are expecting a call from someone not yet returned from a bush walk or fishing the banks of the river or whatever.

It is also a good idea to have a jump starting switch that parallel's your batteries for remote trips.