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Dual battery setup question - starting from aux battery...

yeah, hey, I shoulda prefaced that with an" isolators have worked fine for years" line... obviously a system setup for an isolator is fine... been around a long time now, tried and true..

I know all the regulars have heard me talk about em., so I make sure to try and warn unknowing of the "investment" factor and a need to "understand" the system, not just a diagram of "cut here, splice here"...

there ya go, William, a debate on 2 styles of systems, among 100 options... :wink1:
 
I thought the one drawback to the isolator system is the second battery is not used to start the vehicle. The second battery is used for storage for the accessories. The only way to use the second battery to start the vecile (if the primary is dead) is to move to connections between batterys or to add a battery switch parrallal to the primary battery.
 
ryoken said:
i would just pull the 12v from the permanently hot side of that solenoid, or get a 4 post isolator... like this....

3356.jpg


and no, you wont have any issues with the deep and cranking in parallel as far as charging goes.. as long as they are within reasonably the same condition..
Click to expand...
I'm confused with something here. The "New #14 wire" is the excite wire which usually goes to the idiot light. Right?
Then how come the voltage sensing wire, which usually goes to parallel to charge wire, is going to ground?
 
JDNobodi said:
I thought the one drawback to the isolator system is the second battery is not used to start the vehicle. The second battery is used for storage for the accessories. The only way to use the second battery to start the vecile (if the primary is dead) is to move to connections between batterys or to add a battery switch parrallal to the primary battery.
Click to expand...

That is correct. Even if using an ACR though if your primary battery goes dead you can parallel the AUX battery and still start the vehicle but that puts a huge strain on both batteries by the "unloading/loading" of voltage from one battery to the other that occurs when you parallel a good battery to a dead battery. This will significantly shorten the life of the batteries.
 
4X4HIGH said:
That is correct. Even if using an ACR though if your primary battery goes dead you can parallel the AUX battery and still start the vehicle but that puts a huge strain on both batteries by the "unloading/loading" of voltage from one battery to the other that occurs when you parallel a good battery to a dead battery. This will significantly shorten the life of the batteries.
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Thats one of the reasons why I have a marine switch... it adds that flexabilty and control to the system with the ability to swap the primary bank from one to the other in an emergency, isolating a bad battery, in addition to the ACR's paralleling capability and the marine switches mechanical paralleling capability...

one other thing here guys...

not that either product, isolator or ACR has a high failure rate, I have a much more thorough "evaluation" of isolator durability... been servicing them in boats for 15 yrs..

The ACR tech is much newer, thus the data pool for that is much smaller.. Tho I've yet to see one go bad, it is still a form of a switch.. It may inherently have a higher fail rate than diodes, due to that... may.... I have no evidence of that, but it's just something I thought I should say.. Someone may put out a version of it that isn't the quality of the BlueSea stuff and lose some of the ruggedness..
 
What I don't like about setups like this is that the solenoid closes whenever the ignition switch is on. If either battery is dead, the good one begins to lose charge into it as soon as you turn the key. You could kill the second battery before you get the truck started.

Why not run a relay from the oil pressure switch to pull the solenoid in?

Does anybody make a smart system that measures the voltages of each battery and monitors the charging currents?




attachment.php
 
Does anybody make a smart system that measures the voltages of each battery and monitors the charging currents?
Click to expand...

From what i read about the ACR i'm pretty sure that the ACR does that.
 
what he said...

its a voltage sensing relay....
 
Acr

After talking with BlueSea yesterday, the tech told me the main difference between a solenoid and the ACR is protecting a good battery if the other shorted out for whatever reason (no voltage so no parallel connection using the ACR).

That seems to be reason enough to go with the ACR instead of the solenoid. Concerning the isolator, the issue (for me at least) is the voltage drop across the diodes.

The only issue of the ACR seems to be the cost ($200+-). Would probably be glad i spent the $'s if I was stuck in the back country with two dead batteries...

Again, thanks for the help. I'll draw up a final diagram of my very simple dual battery setup for future consideration.

William
 
if you do go with the ACR, shop around...

2 yrs ago, I could get them for $100... now, we LIST them for customers at about $275... :eek1: you can still get them online here and there, at older rates (must be older stock or something) for $150... thats actually cheaper than I get them, think I'm paying about 160 for em these days...

http://www.wmjmarine.com/c16580.html
 
ryoken said:
Not that one would parallel continuously, but what are the ratings of the ACR in this state? I didnt find this on Blue Sea.

OTOH Ryoken, do they make Bosch style on-off-on relays?

Thanks
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crank rating, 450 amps. continuous, 250.. with 1/0... it goes up with beefier wire...

http://bluesea.com/files/resources/instructions/6693.pdf

ya lost me on the "on-off-on" relay thing, not sure what you mean?
 
ryoken said:
what he said...

its a voltage sensing relay....
Click to expand...
OK, I was thinking of something that would control the charge rate (i.e. active power electronics) to slowly bring a dead battery back to voltage, but this is certainly better than just a solenoid wired to ignition.
 
ryoken said:
ya lost me on the "on-off-on" relay thing, not sure what you mean?
Click to expand...

To me this means they don't make one. Regarding 12 volt electrics, if Ryoken hasn't heard of it, it probably doesn't exist.

Later,
Buddy
 
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Parallel switch on ACR

Not sure i understand the parallel switch on the ACR... Seems like it automatically puts them in parallel if both batteries have voltage. Maybe it is a switch to turn that off...

Anyone?

William
 
Blue85 said:
OK, I was thinking of something that would control the charge rate (i.e. active power electronics) to slowly bring a dead battery back to voltage, but this is certainly better than just a solenoid wired to ignition.
Click to expand...

the ACR's are "smart" to a certain extent.. one drops under 12.6, switch closes.. 15v, automatically opens it to prevent overcharging.. which is nice when when you have a regulator go bad, it wont nuke both batteries, unattended.. but yes, it wont alleviate the one dead, one full battery equalization issue.. tho, it wont allow the full battery to sh*t the bed too, it will keep that at full charge, no matter how bad the other is trying to kill it..

for me, my background, or I should say daily 12v dc life, is a little different with the boats, as opposed to the average car guy.. I deal and design systems with the boats that have upwards of 14 batteries, battery chargers, parallel/series switches, etc.. It can be very involved...

cars are generally much simpler... that being said...
 
BUDDY said:
To me this means they don't make one. Regarding 12 volt electrics, if Ryoken hasn't heard of it, it probably doesn't exist.

Later,
Buddy
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thanks for the props man.. :bow:

what I know, I'm pretty confident in... but even us on HIGH HORSES, don't know everything.. :rolleyes: I am not overly familiar with what Kenny is investigating.. power window relay setups... a reversing relay is what I believe he was asking me about? an off/up/down gig if I was interpreting his pm correctly? somebody who knows that system, chime in and help me out please... :confused:
 
william_7900 said:
Not sure i understand the parallel switch on the ACR... Seems like it automatically puts them in parallel if both batteries have voltage. Maybe it is a switch to turn that off...

Anyone?

William
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it manually puts then in parallel... trigger that post, it closes the switch...

one battery drops to less than 12.6, closes the switch, parallels them...
 
ryoken said:
the ACR's are "smart" to a certain extent.. one drops under 12.6, switch closes.. 15v, automatically opens it to prevent overcharging.. which is nice when when you have a regulator go bad, it wont nuke both batteries, unattended.. but yes, it wont alleviate the one dead, one full battery equalization issue.. tho, it wont allow the full battery to sh*t the bed too, it will keep that at full charge, no matter how bad the other is trying to kill it.
Click to expand...

What I would do in this case is have 2 volt meters OR have a switch on the single voltmeter so that you can check either battery's voltage.

That way you don't have a dead battery and not know about it.

http://www.fjcruiserforums.com/foru...-tech/42683-onboard-air-dual-battery-mod.html

http://www.nationalluna.com/newproduct3.htm

http://www.nulime.com/Blue-Sea-8015-DC-Analog-Voltmeter-Panel/p241575

Later,
Buddy
 
What I would do in this case is have 2 volt meters OR have a switch on the single voltmeter so that you can check either battery's voltage.

That way you don't have a dead battery and not know about it.
Click to expand...

:D


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