Second Deep Cycle Options
- Thread starter k3vin
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75 GRC
Member
G'day Happy John,
The link you put up is not showing??????
but I know what the link is about and it is still a great option in my opinion.
benchrisfennell
Member
two batteries in tub
here you are mate, hj
http://www.navara.asia/showthread.php?t=31117
I was going to keep my power cable i have now running from front of car to the back hook up new agm battery, then second agm hooked up from power of first aux battery then earth them separately this should keep it 12 volt circuit and just give me double ah of what ever size batteries i have true.... My alternator and dual battery management system will have enough juice to charge them ive been
Told. Any advice fellas
Ben that depends on how you're hooking everything up. There are 3 alternatives with two batteries in the rear:
1) Batteries connected directly together (positive to positive, negative to negative - called 'parallel'). This is simple, effective and the only problem is introduced when the batteries aren't matched. An older battery of the same model will behave like a battery of a lower spec (age does that to us, too). Mismatched batteries in parallel will basically drain each other and cause the charging system to not fully charge them. This has a cascading effect as you might imagine!
2) Hooking AUX1 to the heavy cable up front, then isolating AUX2 from AUX1 which means AUX2 won't start charging until AUX1 exceeds 13.2V (typical isolator cut-in voltage). Nice in theory but AUX2 may not get a charge between stops and that's going to end the fun rather quickly. Another thought occurs with this system and that's how the charge rate of AUX1 is affected by AUX2 starting to charge. At 13.2V, AUX1 isn't fully charged at all - when the isolator switches in AUX2, AUX2 will start drawing from AUX1 as well as the alternator. This will reduce the voltage in AUX1, possibly shutting down the isolator, but at any rate it will render the battery system (on a charge cycle) more like a mismatched parallel system, so one battery will charge (the smaller capacity one) and the other won't.
3) Hooking AUX1 up to the heavy cable and then running a second heavy cable to the rear and treating the two AUX batteries as entirely separate. Can't fault this method except for the expense in cabling. It's especially good if you do run BOTH positive and negative down twice, with the two isolators up front.
If you were driving chargers for the batteries in the tub (like the D250S) you'd put the charger close to the aux batteries. If you're using isolators, place them near the power source (starter battery).
In every case you can share the earth, who cares - a circuit is created when BOTH poles of a battery are connected to something.
1) Batteries connected directly together (positive to positive, negative to negative - called 'parallel'). This is simple, effective and the only problem is introduced when the batteries aren't matched. An older battery of the same model will behave like a battery of a lower spec (age does that to us, too). Mismatched batteries in parallel will basically drain each other and cause the charging system to not fully charge them. This has a cascading effect as you might imagine!
2) Hooking AUX1 to the heavy cable up front, then isolating AUX2 from AUX1 which means AUX2 won't start charging until AUX1 exceeds 13.2V (typical isolator cut-in voltage). Nice in theory but AUX2 may not get a charge between stops and that's going to end the fun rather quickly. Another thought occurs with this system and that's how the charge rate of AUX1 is affected by AUX2 starting to charge. At 13.2V, AUX1 isn't fully charged at all - when the isolator switches in AUX2, AUX2 will start drawing from AUX1 as well as the alternator. This will reduce the voltage in AUX1, possibly shutting down the isolator, but at any rate it will render the battery system (on a charge cycle) more like a mismatched parallel system, so one battery will charge (the smaller capacity one) and the other won't.
3) Hooking AUX1 up to the heavy cable and then running a second heavy cable to the rear and treating the two AUX batteries as entirely separate. Can't fault this method except for the expense in cabling. It's especially good if you do run BOTH positive and negative down twice, with the two isolators up front.
If you were driving chargers for the batteries in the tub (like the D250S) you'd put the charger close to the aux batteries. If you're using isolators, place them near the power source (starter battery).
In every case you can share the earth, who cares - a circuit is created when BOTH poles of a battery are connected to something.
benchrisfennell
Member
Thanks for that Tony. And yes mate i will be buying two new batteries that are the exact same.
http://www.piranhaoffroad.com.au/product/dual-battery-management/management-systems
I have the first one i t the link. If i were to run two cables up from the front i would need a second one of these? Is that what you mean pal?
Cause i was going to go with your option (1) in your last post cheers
http://www.piranhaoffroad.com.au/product/dual-battery-management/management-systems
I have the first one i t the link. If i were to run two cables up from the front i would need a second one of these? Is that what you mean pal?
Cause i was going to go with your option (1) in your last post cheers
happy john
Member
Sorry here was the link I was looking for.
http://www.navara.asia/showthread.php?t=22631
http://www.navara.asia/showthread.php?t=22631
For option 1 (parallel aux batteries in the tub) you'd only need the one cable pair from the front. If you were using chassis for earth you'd only need the one cable, but I like to run BOTH positive and negative just to avoid any problems with earth points front and rear.
The device you're pointing to is an isolator that can handle around 100A. That's a LOT of power, hopefully your chosen batteries can handle a 50A charge rate. The cranker will supply all the power it is asked for (and the alternator tops the cranker back up later). You'll need at least 8Ga cable, preferably 4Ga. The isolator should be mounted up front near the cranker - the cranker voltage is what it's designed to protect.
Putting a pair of identical batteries in the back isn't a problem, once connected you'd treat them like a single battery of larger capacity. Just keep the cables between the two batteries as short as possible (under half a metre if you can manage that, and preferably 0Ga or 2Ga at the smallest).
The device you're pointing to is an isolator that can handle around 100A. That's a LOT of power, hopefully your chosen batteries can handle a 50A charge rate. The cranker will supply all the power it is asked for (and the alternator tops the cranker back up later). You'll need at least 8Ga cable, preferably 4Ga. The isolator should be mounted up front near the cranker - the cranker voltage is what it's designed to protect.
Putting a pair of identical batteries in the back isn't a problem, once connected you'd treat them like a single battery of larger capacity. Just keep the cables between the two batteries as short as possible (under half a metre if you can manage that, and preferably 0Ga or 2Ga at the smallest).
benchrisfennell
Member
Thanks tony. Yes the isolator is up the front and im running 10mm thick cable from front to rear what ever that is in guage. The guys at pirahna here in Melbourne have pointed me in the direction of this stuff and the batteries ill need to match the isolator... Thanks for all your help it has been more than greatful.
Your a trooper Old Tony ��
Your a trooper Old Tony ��
Those guys at Piranha in Melbourne sound like they're on the ball.
benchrisfennell
Member
I hope they know what they are doing
benchrisfennell
Member
One more quick one Tony.
If i run power and earth from front to rear aux battery number one. Then power from battery number one over to battery two. Can i go from earth on one over to earth on number two or should i earth aux battery two separately? Should i even earth both from the front?
Cheers heaps
If i run power and earth from front to rear aux battery number one. Then power from battery number one over to battery two. Can i go from earth on one over to earth on number two or should i earth aux battery two separately? Should i even earth both from the front?
Cheers heaps
Let's talk about positive and negative separately because together they can confuse things.
Negative - earth - can be done ANY way you like, hook them all in together, use 50 cables or one great big one it doesn't matter. Hook them up in either order, no drama, as long as negative goes to negative it's all good. Power DOES flow through the cable so you can't use a 2A cable for negative and expect it to survive long when 50A is being pumped down from the front - so pick a cable big enough and just do it whatever way you want that looks neat and serves your porpoise.
Positive is different. If you run positive power through an isolator to aux1, and then directly from aux1 to aux2 (no isolator or anything else, just one big cable) then aux1 and aux2 can be treated as a single battery (as long as they're closely matched) and you won't have a problem.
Negative - earth - can be done ANY way you like, hook them all in together, use 50 cables or one great big one it doesn't matter. Hook them up in either order, no drama, as long as negative goes to negative it's all good. Power DOES flow through the cable so you can't use a 2A cable for negative and expect it to survive long when 50A is being pumped down from the front - so pick a cable big enough and just do it whatever way you want that looks neat and serves your porpoise.
Positive is different. If you run positive power through an isolator to aux1, and then directly from aux1 to aux2 (no isolator or anything else, just one big cable) then aux1 and aux2 can be treated as a single battery (as long as they're closely matched) and you won't have a problem.
benchrisfennell
Member
Sweet i got it all now Tony. Thank you ever so much for your help. ��
I know how in going to go about it.
Again thanks heaps
I know how in going to go about it.
Again thanks heaps
benchrisfennell
Member
So apparently my model nav has something built into the wiring or alternator that once it charges the main battery it stops charging. So my isolator was apparently not good. So i had to buy a c-tek battery charger isolator thingy.... This sound correct
happy john
Member
Your alternator will have an inbuilt regulator that reduces the available oomph in an attempt to save the alternators load on the motor. You can cut or remove the green sensor wire and that will see it putting out above 14volts again. The DC-DC is probably a better option anyway.
benchrisfennell
Member
The dc-dc charger is what i decided. Didn't want to. with wires like that. Plus ill take it out for my next car etc etc... Might call the place Monday where i got my isolator and let them know they sold me a product that was not ever going to work in model car. I told them what car it was. Very frustrating
So long as your redarc dcdc if that's the one you got says LV that's low voltage
Short of that, disconnect the green wire from the negative terminal at the battery and the alternator will run as it was intended to
benchrisfennell
Member
So long as your redarc dcdc if that's the one you got says LV that's low voltage
Short of that, disconnect the green wire from the negative terminal at the battery and the alternator will run as it was intended to
Nah i just decided to part with the isolator and im installing a c-tek dcdc charger.
Not really a fan of disconnecting wires that were put there from factory.
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