BUGA Community
Technical => Electrics, Audio and Security => Topic started by: delrazor on May 21, 2010, 08:34:13 PM
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Hi, is anyone familiar with the dual battery switch that I have discovered in my van?
If you look carefully at the pic, you'll see a big black knob that looks like a big kitchen tap.
(http://blogpress.w18.net/photos/10/05/21/194.jpg)
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I see your knob...i see your knob...ohhhh hangon this wasnt a "Spot the.." game was it?? ahaha Nope i dont have one, i doubt my battery area would fit 2 full size batteries....is yours swb or lwb?
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Looks like a manually operated dual battery switch. Not a very good spot to mount it if you want to switch batteries often.
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yep looks like a dual battery switch2 me.
it will have 4 positions like a clock face 12 3, 6 and 9oclock
batt /1
both batteries
battery 2
and no power at all
its not advisable to switch between settings while motor is running.
and alternate between the 2 single battery settings when charging .
starts a motor unreal on both.
but still gives just 12volts on 1, 2 or both.
i put 1 in my van and in my boat.
passanger side of my van =
(http://i290.photobucket.com/albums/ll265/marty23121961/P1015262.jpg)
(http://i290.photobucket.com/albums/ll265/marty23121961/P1015263.jpg)
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Now thats a better position for it.
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excellent news. At least we can camp without the worry of getting stuck.
What happens when one battery shits itself?
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if 1 goes dead, switch to both, start and switch back to the flat 1 and drive a good distance,
u can swap from 1 battery to both and to second battery while its running but i was told it damages the inside terminals, if done too much.
also read the writeing on the dial=
says not to turn to off position while motor is running.
if camping try use 1 battery , always keep 1 full.
but ive had 2 flat batteries out in my boat (before i fitted the twin battery switch)on a weekday in a secluded spot with no chance of a jump off a passing boat and just wired the 2 batteries in a series like 2x 6 volt batteries=12volts and got the motor going and back 2 civilisation.
but dont do that with 2 x fully charged batteries as it will produce 24volts and fry 12volt electrical things.
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Delrazor
Check out what type of batteries they are, one should be a cranking (normal) battery and the other a deep cycle battery.
The cranking battery is designed to give large current draw for a short period of time and stay at 12 volts, then be recharged back to full quickly - usd for normal car stuff - mainly starting the engine.
The deep cycle battery or house battery is designed to give a smaller current draw over a longer period, and can drop its voltage below 12 volts and recover after charging, and can do this regularly.
The deep cycle battery is for the vans lights fidge etc when camped up.
When driving the switch should be to both batteries, when you camp for the night you switch over to just the deep cycle battery, keeping the craking battery "full" for the next start up, usually the next morning.
When you go to start the van the next morning you switch to the cranking battery only, start the engine and let it idle/warm up and top up the cranking battery again.
Then you switch to the two batteries again so that both will be charged up while you drive.
Someone on here showed how to automate this proccess with two relays, better tnan having to remeber switch it over all the time
Warren
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I can show how to simplify the process with just one relay. I'll do a diagram when I get a spare 5 minutes.
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Yes please Shane :D
Warren
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Hi guys,
I just did this quick drawing. I hope it makes sense to you.
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interesting shane, thanks mate
Warren
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With that arrangement theres no chance of your crank battery being discharged.
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I'm guessing that the relay in this set up would have to be a high amp relay for the starter motor to operate.
if so what size relay should someone be looking for?
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In any setup you should use the highest rated relay you can find. Just pop into your local auto electrician. They should have them in stock.
Stay away from these, they are rubbish:
(http://www.fridge-and-solar.net/other/redarc-10-sbI12.jpg)
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I just did this quick drawing. I hope it makes sense to you.
I'm a bit fuzzy on the lekky side of things,( as opposed to really fuzzy with the mechanicals :D),
I have a solinoid between the two batteries, so i have two batteries to crank,and they both charge when the motor is running but two independant systems when the key is off, but it looks like they both achieve the same thing
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Worzel
Shanes system will not allow any current to be drawn from the crank battery once the ignition is off.
your set up will stop either battery trying to "top up" the other but still allow both to have curent drawn from them, depending on what circuits are connected to each battery.
Both systems will have both batteries available for cranking and charging once the ignition is switched on.
Warren
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Warren is correct. My setup completely disconnects the main battery when the ignition is off allowing you to run your stereo, head lights etc without the worry of not being able to crank her over.
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what about mixing good batteries with not so good batteries thats a no no yeh?
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Benny, if you just have two dissimilar batteries running in parrallel they will try to find a common level, so the lower charged battery will draw power from the other battery.
Dual battery systems have an isolater that prevents this. They use diodes to isolate the two batteries (diodes are like a one way valve for lectrickery).
The main problem I see with Shanes system is that, if the house battery has dropped considerable voltage over night, when the engine starts and the altenator start recharging both the crancking and house battery a large amperage could be drawn, possible overloading the standard altenator.
In the older manual type systems the house battery would be switched off for the first 10 minutes or so to allow the cranking battery to be fully charged before trying to charge the house battery.
Note - as a battery gets closer to its fully charged state, the amount of current that it can take reduces exponentially.
Deep cycle batteries can take 8 to 10 hours to get back up to full charge, possibly longer.
I have heard that "Marine" batteries are a good (and cheaper) alternative to deep cycle batteries as they are a blend of cranking and deep cycle - I have not tested this though.
Warren
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Benny, if you just have two dissimilar batteries running in parrallel they will try to find a common level, so the lower charged battery will draw power from the other battery
thanks warren ;) within that beutifully worded statement u have dropped th penny rite on the question mark wot has hung over my pondering of me mitsi 4x4 which had a 2 batt setup which woz in short shytefull always drainin not behavin itself ,took second one off an ran fine,but always wondered why when second batt was workin ok on own too.. 1 was from hz v8 wagon the other woz off a vile little barina thingey.. enlightenment is such a fortifying emotion ;D thanks again bloke for answering a mystery WTF? which has mellowly haunted me ,when the missin green van hasnt been ;)
e
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You don't have to worry about overloading an alternator. Its not possible. Unless of coarse the battery is a dead short and in which case your fusble link will blow.
With my setup you also don't have to worry about a sad deep cycle battery draining the crank battery. Your alternator regulator is going to force out charge voltage when the engine is running so the crank battery will always charge. When you turn the engine off the crank battery becomes isolated.
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Shane, thanks for the insight.
I had been thinking about getting a dual battery setup along the lines of the 4wd type setups, they are generally costly and in some ways sophisticated - however some reviews make this sophistication out to be a draw back rather than an advantage.
You say not to run a Redarc, which seems to be a fairly common brand. Are you able to recommend any other brands that you think/know are worth the time effort and money? If you have tried any and have part numbers that'd be even better ;)
Cheers
Matte
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So just to complicate matters, is it possible to incorpotate this relay system into the manual switch setup?
ie. use the relay setup, but be able to isolate the batteries if one goes funny.
I just woke up so ignore if this doesn't make sense. derek
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Um depends on how you wire it wired
If you had another relay from the house battery to ground (like shane has on the cranking battery) you could add a manual switch in the control wire that comes from the ignition to the relay, giving you a manual over ride.
The simplicity of Shanes layout is that its all automajick :D
Warren
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Shane, thanks for the insight.
I had been thinking about getting a dual battery setup along the lines of the 4wd type setups, they are generally costly and in some ways sophisticated - however some reviews make this sophistication out to be a draw back rather than an advantage.
You say not to run a Redarc, which seems to be a fairly common brand. Are you able to recommend any other brands that you think/know are worth the time effort and money? If you have tried any and have part numbers that'd be even better ;)
Cheers
Matte
Mate don't worry about those complicated systems the 4WD joints try and sell you. They provide no extra benefits over my set up apart from some of them having a voltage meter on them.
The redarc relays just disconnect the deep-cycle battery from the main battery when the voltage drops to a certain point. So you are still able to flatten your main battery by leaving your lights or stereo on. People rave about them because they are a neat little automated package that is easy to install. Problem is they are more expensive than a standard higher amp rated solenoid relay and they just don't last that long. I have one here which I trialled in my 4x4 for a while.
I recommend you get your hands on just a standard high amp solenoid relay. One that looks just like this:
(http://www.hhokitsdirect.com/images/relay.jpg)
I use a 400amp one in my 4.2D 4x4 and I think it cost me between $70-80.
If you guys are interested I'll try to find and buy some at trade price? I would need to order a few though.
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Hey Shane, yeah i had thought the same about the 4wd setups, and then i saw the simplicity of your design..
Looking at that photo i have seen something similar kicking around my grandads shed somewhere, but i'm not sure of the amperage.
Would you get a 400amp relay for a 400cca battery, therefor a 600amp relay for a 600cca battery? or a 400amp relay is fine for a 600cca battery?
I'm pretty keen on the idea as i'd like to be able to run a few different things while parked without risking being stranded.
If you can get some high rated ones at a good price i'd be keen, if we can't get enough together for it tho, i can probably get trade for myself.
Cheers
Matte
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A 400amp relay is pretty large and would only be required for high compression diesels or V8's. A 200-300amp will be fine for your average little holden 6.
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Shane, i've got a 350, and the 540cca battery has trouble starting when the motor is hot, so i'll look at going back to a 620+cca battery. will i need the relay to match the cca rating of the battery? is what i was asking in a round-about way :)
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No. Infact I don't think you would even find a 600amp relay. I guess you could run two in parallel.
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Cheers Shane, i'll look into things further
much appreciated for your continued efforts
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That solanoid looks like the one used on ford v8's starters with the external solanoid (clacker)
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Howdy ;D
When I put my new Bosch starter in, it wouldn't crank when it got too hot (it's right next to the extractors, so get's hot often). The answer here (MaTTe) is a starter relay - it never fails and is a very strong crank ;D
Thought I would chuck up a quick diagram of how my dual battery/starter system is wired, including the starter relay, incase anyone needs to incorporate a starter relay into their setup or can benifit from another way to use the solenoid.
Hope it helps someone.
Cheers!
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Hey Mark, i used to have a 620cca battery in the van, but when the immobiliser ran the battery down as it sat for so long, the battery dropped a cell. That battery never had any troubles starting the van on a 40degree day when hot. But that being said, a relay is actually a great idea.
I might look into incorperating a relay in there as well.
What sort of circuit breaker are you using?
cheers,
Matte
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Howdy MaTTe man =)
Yes the relay works great - I am really happy with it. It took ages for me to figure out why it randomly wasn't cranking over. Then i figured out it only happened when i had been driving for a while and went to start it while it was warm. Then it clicked. I just grabbed the highest rated circuit breaker from Autobarn that I could get my hands on. You could also use a fuse if you wanted to, but the CB just short circuts instead of blowing ..handy
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cheers Mark, thats great to hear.
Are you using a relay similar to the type Shane posted for both the starter and the battery isolation? Or are you using some kind of high rated little black bosch or similar?
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Hey mate,
I am using a similar solenoid (that Shane posted) for the battery isolation only. And am using a standard 12v relay (30A - i think) for the starter relay. It's like this one:
(http://www.rawcomponents.co.uk/media/catalog/product/cache/1/image/5e06319eda06f020e43594a9c230972d/n/a/nagares.jpg)
I just split the wire (with terminals into Y shape) coming from ignition , one end goes to the soleniod and one to the starter relay.
Hopefully that makes sense. Have another look at my diagram if it doesn't. Let me know how you go =)
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Hey Mark, thats great, cheers.
I had thought by your diagram that it was a relay similar to that, however i wouldn't have thought a 30A relay was upto the task, but there you go.
I'll save all of this info, and have a go at fitting this all up over the next couple of weeks
Cheers for all of your help fellas!
Regards,
Matte
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sorry boys but if you look in the photo it says 100A?
how much that one set you back mark b?
ben
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Howdy lads, that picture is one that I chucked up as an example of the type of relay I used.
My one is actually a 35A one - a standard on that u use on either an air horn or driving lights etc.
I had it lying round, so not sure how much..they're not expensive tho ;D
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oh lol...
dont think this will handle the current of a battery thou mark b.. you need something much bigger..
ben
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Nah man,
you can even go down to 30A relay if you want to..
have a read:
http://www.biopatent.com/solenoid.html (http://www.biopatent.com/solenoid.html)
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It will be fine for a starter relay but not a dual battery setup.
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Mark, a bit of an update - delayed - but update none the less
I went to fit the started relay about a week and a half ago, only to realise my van already has one. I then swapped the relay to see it it made anything any better. But nothing changed.
I then got some thicker cable and ran it from the battery to the starter to reduce the voltage drop, and it made the world of difference. I'm now running some pretty fat cable, but i might try some thicker again, the motor turns over alot faster than previously.
I still haven't go around to fitting the dual battery setup yet, but haven't had alot of time between building motors for race cars.. hopefully over the coming weeks i'll have some time to dedicate to the bedford.
Anyway, cheers for the advice on the relay mark, i'd still recommend it to others that aren't running one, but i highly recommend reconsidering how thick your battery cables are and how thick they should be.
Shane, i'm keenly awaiting this dual battery setup.. more to come......
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had voltage drop on a car once due to length of cables, replaced with cables of an old arc welder. they did an awesome job!
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Good to hear Matte ;D Yes, i cannot believe the amount of difference it makes. Cranks so strong, i love it ;D Enjoy mate and glad to be of assistance! Have fun with the dual battery system - i really really appreciate when I'm camping in the middle of nowhere and i have all the accessories i could need :D let me know if you need any further assistance