[VitNick]

Have been looking at installing dual batteries, primarily as I now have a winch and don't want to get stuck with a dead battery. So after looking around I've found two solutions

Redarc SBI12 http://www.redarc.com.au/products/produ ... _12v_100a/ which is a 'plain' isolator
where as the BCDC1220 http://www.redarc.com.au/products/produ ... tart-bcdc/ will charge two dissimilar batteries, an up/ lower the voltage to account for voltage drop (in a nutshell)

Problem is the fancier one you can't jump start or join the batteries in parallel, without another solenoid and some extra wiring, as per diagram below


The reason I'd be more inclined to go with the fancier/ more expensive option is so the battery can be charged properly and doesn't need to be near the engine bay i.e under seat or somewhere

Who has either? or the set up in the pic? I'm keen to hear some feedback / reviews

[Ausuki]

is 20 amps enough to keep up with your winching?

[VitNick]

Thats the problem with the second setup, you can't recharge the battery nearly as quickly as you can drain it, so no real gain draining it. But you can flatten the main one and still have the second one to start the car up. May have a look into a single truck battery depending on how well it will fit in the limited space.

[fordem]

I see very little reason to use an isolator with a dual battery winch setup - the main reason to use dual batteries when winching is for increased capacity, adding an isolator and then paralleling the batteries whilst winching defeats the purpose of the isolator. The real reason to have an isolator is when the second battery is a camp site power source, low amperage loads run off the second battery, leaving the primary available for starting.

Whilst winching, you're going to have the engine running so that should remove the "dead battery" issue, however, for the sake of discussion let's proceed ...

To avoid draining both batteries you'll need to have one isolated whilst winching, at the same time you will need to have alternator charging the winch battery at max rate, so that means you're connecting the winch to the primary battery, and you're going to keep the secondary battery isolated - any isolator with a "parallel/jump start function will do what you need. After you're finished winching - if necessary - push the button, start the engine, release the button - BUT - as I mentioned before, the second battery is going to be completely idle during the winching.

[Scales]

I got an sbi12 (and a winch)
LOVE IT

But if I were to do it again, I'd get a 200amp version WITH 2-way sense terminals.

I havent had a problem with overloading the solenoid with the winch yet or anything. But 200amp would give piece of mind in that regard.

Id go dual sense because I use a solar panel hooked up to my aux battery when Im camping, and it would be good for it to automatically close the 'noid when I have it hooked up so it can charge the main battery too. At the moment I just flick the override/jumpstart switch for a few minutes and turn it off again and it acts as a "hold in" circuit to charge the main batt. Then it just drops out overnight when the solar panel volts drop (as its supposed to) I know I could just connect panel to the main batt, but I have my reasons for doing it this way so just go with it And it wont hurt having dual even if you dont utilise it.

PS my jumpstart overide switch is an ON/OFF switch, not momentary, so i can hold the solenoid down when winching. works a treat.

Look at the c-tek dc/dc chargers if you want to charge a battery in the boot. lower rate of amps so can run smaller gauge cable but you wont be able to winch off it obviously with pissy cable back there.

Hopefully that makes sense, pm me if I need to explain a bit better.

[droverdave]

Remember that winching is high amps but low amphours...

Check your batteries amphour rating, and workbackwards to see how much capacity you actually have.

[VitNick]

Thanks Fordem, made it alot more clear for me. I think I'll either go with a set up like Scales with a larger version of the sbi12, but fitting the battery in may be a bit interesting in the engine bay, not too keen on such high power cables all the way to the boot/ under seat. I also had a look at 'truck' batteries with cca ratings over 1000, one of them could fit where the old battery is, with some extra fab work, which wouldn't be too hard. Could possibly negate the need for a second battery as it would be pretty unlikely that you would drain such a large battery in a 'normal' amount of time. Will put some pics up of available space later on, at work atm.

[VitNick]

Was thinking either one large battery where the old one sits now, or a second one possibly where the windscreen washer bottle is like I have seen a few people do

[Scales]

2nd battery > bigger batt. IMO.

Has a wider range of applications than just winching, fridges, inverters etc. Depends how hard it is to move the washers etc.


I disagree somewhat with fordem, isolators and winching IS useful. I ONLY winch when both batterys are linked. less strain on the electrics (batt and alt) that way, and prevents damage to the main battery from the high load from the winch (which has already happened to me before this setup). As long as the engine is running and you disengage the manual override after winching you'll be sweet.

and also important not to just winch constantly. have to utilise a proper duty cycle. something like 1:3 ratio, ie. 5 seconds on, 15 off. Thats a judgement call on the situation obviously.

[fordem]

Scales wrote:

I disagree somewhat with fordem, isolators and winching IS useful. I ONLY winch when both batterys are linked. less strain on the electrics (batt and alt) that way, and prevents damage to the main battery from the high load from the winch (which has already happened to me before this setup). As long as the engine is running and you disengage the manual override after winching you'll be sweet.

You are not in a PURE winching environment, your secondary battery is intended for campsite power and you have an isolator to prevent the starting battery from being drained whilst the engine is off. Because you have two batteries you parallel them whilst winching to reduce the load on one battery, but once those batteries have been paralleled, the isolator will not prevent them from both being drained - you have to do that by releasing the button.

What purpose is the isolator serving in your winching operation that could not be done with a piece of cable ? And if you tell me disconnecting the battery when you release the button, my response is going to be release the button on the winch controller.

Now go back and read the first paragraph in my earlier post - did I leave something out?

[Scales]

maybe i just mis-interpreted your post, take a chill pill bud. After another re-read i think we're probably saying the same thing but in a different manner.



no need to get your defences up, was disagreeing with respect.

[Chop]

The Redarc Isolators a great bit of kit, I think they're worth every penny.
My recent 4 week trip had my Engel running as a freezer the whole time, from the 13th june-12th july. 29 days on and anyone that's run their fridge as a freezer knows it runs all the time especially once the ambient temp gets up.
Didn't have any trouble with it even when we had a few quiet days without much travelling.

I have my winch hooked up to the main, I don't have the link set up. I'll winch with the car running and not give it a rest. I want my aux battery as back up if for some reason the main drains.

[VitNick]

so decided on getting the red arc SBI12, as I am running a 6000lb winch so hopefully the current draw won't be excessive (can't find the data sheet for it). the dual sense would be nice but I don't think i would use it. Not the tricky part batteries, I can fit a second batttery where the washer bottle and overflow is, with a new braket to hold them. But I am limited with height at that point to 130mm (will make up a cardboard battery to check). But I can't find a battery that would fit in there, except maybe a optima on its side? Anyone have any ideas? I want to try and keep the batteries the same, so most likely whatever goes in the front will go in the stock place as well. Without spending heaps, as I am your typical tight ass uni student altho I think I may have to spend up

[Jezza86]

i have a optama spiral cell blue top 900AH in my boat, while i was reading up on them i noticed that they could be installed upside down if you wanted, but there seamed to be a pretty specific maximum temperature also.
i remember thinking perhaps this battery should never go under the bonnet of my car, as the temperature there gets so hot i cant touch the bonnet stay.
i cant say i have read many batteries, so i dont know if they all state a maximum temperature, but the optima just struck me as low

[Jezza86]

reading it again i don't think the suzi current limit is going to do damage if it gets too hot... most wouldnt be able to deliver 100A to a battery

[Scales]

you should be right with the 6000lb winch, mines a 9000lb and i got no drama.
just be sensible with the loading and itll be fine.

How about putting the battery behind the airbox? its a bit dark in the pic but that looks like an okay spot.

some of those european car batterys are fairly low profile. I just went into the local 12v shop with a tape measure and found what i needed (then went to supercheap and got it lol)

[VitNick]

Jezza86 I don't think I'll have a problem with heat, the under bonnet temperature is pretty low, I guess the body lift has increased the volume of air around the engine and body. The current shouldn't be a problem as long as I choose the cca ratings and make sure I load them evenly.
Did think about that Scales, I will see what sort of space I have there but It may be close with the brake master. Will get the tape out tomorrow and have a play around, I guess its also less work then remounting the washer/ radiator overflow. Will have a closer look at the low profile batteries.