Advocate I
Dual battery question ( equipment based)
- Thread starter Red_Leaf_Overland
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Influencer III
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- Rex
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- Drake
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19540
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I bought one those cheap, but it turned out there are two versions. One for smart alternators and the other for old school alternators. Their website is pretty helpful figuring out how to use it.
Advocate I
I'll have to look at the modle number and see what I can find. It was free so if I can made it work it would be awesome lol
Member III
That's really going to depend on your intended setup. I believe these kinds of isolators are for separating banks of batteries while charging via a single alternator and they do not offer any mechanism to link the two banks together. Modern smart alternators can also be weird with charging larger capacity fully (looking at you Toyota) so I'm not sure this is going to be an ideal unit for a vehicle.
Advocate I
So looking into the model of this thing it looks like I have 2 options if I really want to stick with using it.
1. I pull the voltage regulator off of the alternator and use this at the new regulator.
2. I put power from the first battery to the "alternator" post and see which side has power and charge the second battery off of that side.
I am basically using stuff I have in the garage and have got no money invested in this at the moment so I'm kinda just tinkering. If I can get it to work I may put it together in my TJ because it is the vehicle that gets out off grid with Noone anywhere close to help if something goes wrong.
I have a battery sitting on my work bench that I managed to bring back to life so it will be battery #2 ( which is also the old battery out of the TJ).
1. I pull the voltage regulator off of the alternator and use this at the new regulator.
2. I put power from the first battery to the "alternator" post and see which side has power and charge the second battery off of that side.
I am basically using stuff I have in the garage and have got no money invested in this at the moment so I'm kinda just tinkering. If I can get it to work I may put it together in my TJ because it is the vehicle that gets out off grid with Noone anywhere close to help if something goes wrong.
I have a battery sitting on my work bench that I managed to bring back to life so it will be battery #2 ( which is also the old battery out of the TJ).
Advocate I
So weird thing. Just ran a bench test on the spare battery to the center pin of the isolator and it came out with even voltage on both sides. I suppose next step is to run a ju.per off the alternator and see what happens lol .... that's not a tonight challenge....
Member III
If you give the center pin power both the others should show battery voltage (as this is simulating the alternator). If you give power to the left or right, the others should read zero.
Advocate I
When I was reading through about this model it was talking about working for alternators with no internal voltage regulator, which I kinda figured meant that it was converting from AC power to DC power itself. Which made me think that if I out power to center I would only have power to one side at a time. But I really don't know anything about this kinda stuff I'm kinda leaning on the fly.
I believe the original manufacturer for this one was bought out by littlefuse and is being remanfactured by them now. It was hard to find info on it and some of the information didn't really line up 100% so I was guessing a little.
Member III
So the alternator generates an AC current but it has rectifier circuitry to convert that to DC before the output terminal. The voltage regulator is strictly to maintain a usable voltage in the 12.5v to about 14.5v range. Dumb alternators are more RPM dependent with a slightly lower idle voltage than at cruise but a modern smart alternator will vary greatly. If you have a vehicle with a smart alternator, this isn't a great device to be using because the vehicle will be trying to adjust voltage for economy and won't see the changes. Someone mentioned there is a smart alternator version but I have no idea how that would interact with some vehicle systems. This is an older tech which works great on simple systems but likely won't interact so well with modern vehicles.
This device likely has a regulating circuit that caps voltage at a flat 14.x or something to prevent over-volting and blowing up a battery. It's unlikely do be dynamic so I'm not sure how well it would work on a newer system and would suggest a Blue Sea ACR or Redarc for that route.
Advocate I
To be honest I don't really do anything that would require a second battery other than to have a backup in case mine goes dead. I don't usually run a whole lot of electronics but have toyed with the idea of a fridge in the future.
Also I don't really want to spend any money at the moment on doing a dual setup, but was tinkering with stuff I have in the garage lol. I'm not sure how it would react with my TJ but a can probably do a temporary install to test it out and see what happens I suppose lol
I'd say get something like a jackery for camping, or if you don't even need that just get a lithium jump pack so you have a backup in case you need a jump start.
Advocate I
Member III
@LostWoods hit the way an alternator works pretty well. Let me chime in on the regulator part.
A little "alternator 101" first (without getting too involved)
The rotor (center) is a magnet. It spins inside a series of coils (stator).
The output from the stator is controlled by turning the rotor on and off.
The regulator controls the rotor.
That's the basic.
The difference in regulator design is pretty simple. Old school regulators will sample voltage from "somewhere" and are built to bring that voltage up to what their set to. If its set to 14.2 volts and sampling from the fuse block, it will raise output voltage until it sees 14.2 at the sample.
The "smart" alternators are in two categories.
1. Old school sampling but the regulator is in the PCM (Jeep TJ)
2. More like a smart charger to properly maintain. These are not common and are tuned for lead acid batteries.
Isolators can also be diffrent types as you now know. The better ones will monitor diffrent batteries and control the voltage and amperage properly (battery management systems). The lesser ones are just power transistors separating the two batteries (isolators). That is what you seem to have.
The issue with the isolator types is they create a small volt drop and depending on where your alternator is sampling from can change the charging voltage. This may or may not be an issue.
I personally don't use transistor isolators, I use a high currant relay to isolate my batteries. Almost no volt drop and good charge rate. I wont bother with a management system because I run AGM's, their not that picky and my alternator runs at 14.4v at the batteries. Lithium's are another story.
A little "alternator 101" first (without getting too involved)
The rotor (center) is a magnet. It spins inside a series of coils (stator).
The output from the stator is controlled by turning the rotor on and off.
The regulator controls the rotor.
That's the basic.
The difference in regulator design is pretty simple. Old school regulators will sample voltage from "somewhere" and are built to bring that voltage up to what their set to. If its set to 14.2 volts and sampling from the fuse block, it will raise output voltage until it sees 14.2 at the sample.
The "smart" alternators are in two categories.
1. Old school sampling but the regulator is in the PCM (Jeep TJ)
2. More like a smart charger to properly maintain. These are not common and are tuned for lead acid batteries.
Isolators can also be diffrent types as you now know. The better ones will monitor diffrent batteries and control the voltage and amperage properly (battery management systems). The lesser ones are just power transistors separating the two batteries (isolators). That is what you seem to have.
The issue with the isolator types is they create a small volt drop and depending on where your alternator is sampling from can change the charging voltage. This may or may not be an issue.
I personally don't use transistor isolators, I use a high currant relay to isolate my batteries. Almost no volt drop and good charge rate. I wont bother with a management system because I run AGM's, their not that picky and my alternator runs at 14.4v at the batteries. Lithium's are another story.
Advocate I
So I basically would use a secondary battery to charge random equipment around camp like a radio or a phone. All of my main power comes off the primary battery on the jeep. Do you think it would s be a viable option since it's basically free just to have a little extra power around?
Member III
I run dual batteries because of my "extra" stuff. The second battery is also tied straight to my winch. I can jump across if I need but my solenoid will flow 300 amps (more than enough to start my vehicle). If ya got it already, the worst thing will be you take it off later. soon your garage looks like mine.
remember, this is how it all starts.
1. buy 4wd.
2. add small free mods
3. go off road
4. more mods
5. go more places
6. mortgage house and sell kidney to support your habit.
remember, this is how it all starts.
1. buy 4wd.
2. add small free mods
3. go off road
4. more mods
5. go more places
6. mortgage house and sell kidney to support your habit.
Advocate I
Lol ya I know. I've been working on the TJ for almost a decade ( and I've had many before it). I'm waiting on some steering parts to come in so I was looking around my garage while doing some organizing and thinking about what I could do with stuff I have lying around lol.
It's my second vehicle ( not including the wife's car lol) and sees most of its time offroad on trails tough enough that I don't see anyone else for days when I get to camp. It's nice to just have some peace and quiet for a while.
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Member III
Nice TJ, I wish I would have found the extended one.
On mine I just ran a single odyssey battery. It powered my winch just fine. I did do a ton of electrical mods. The only thing I didn't like about the TJ compared to my old CJ's was the lack of storage space. I still don't understand how a vehicle that's bigger has less cargo than the older models. I would put all my gear in an M-100 trailer and drag that around.
On mine I just ran a single odyssey battery. It powered my winch just fine. I did do a ton of electrical mods. The only thing I didn't like about the TJ compared to my old CJ's was the lack of storage space. I still don't understand how a vehicle that's bigger has less cargo than the older models. I would put all my gear in an M-100 trailer and drag that around.
Advocate I
The back seat hasn't been in this in years and I usually pack everything into totes that I want to keep clean/dry and I made cross bard to run under the top across the tub and mounted a universal roof basket to add a second layer of storage/tie down points. It works great for keeping everything in place of some of the tougher trails.
