Economical battery isolator?

[zuren]

I'm preparing to sell my van and removing equipment I want to keep for my next build. When I put in a house battery, I installed a Hell Roaring isolator to keep the house separate from the starting battery. Considering the Hell Roaring isolator is around $200, I would like to keep it and see if there is a cheaper, recommended replacement.

The mounting location is not easily accessible, so it needs to be automatic. As of 2019, what economical isolators would you go with?

Thanks!

 

[rayra]

Been ~3yrs with a PAC 200A-rated isolator, no measurable voltage drop across it, using the fat cables I made. Only problem has been a bit of corrosion on the top of it because some idiot installer (me) initially used steel washers instead of copper, on the terminal studs. That's since been corrected and some dielectric grease toothbrushed on the top around the various stud connections and those connections themselves coated with liquid electrical tape. 'A' No. 1 Good now. Pic pre-corrections.

$38 dolla, it love you long time.
https://www.amazon.com/PAC-PAC-200-...0amp+isolator&qid=1563483845&s=gateway&sr=8-1

 

[plh]

There is a thread on here about the $50 dollar solution

 

[zuren]

The thing I'm realizing about these isolators is that you need a low voltage connection to energize the isolator...which I don't have with the current setup, unless I run a new wire. I'm trying to avoid running more wires.

I'm reconsidering the automatic part, and looking at manual marine switches like this:

Amazon.com : Blue Sea Systems m-Series Mini Selector Battery Switch - Red : Boating Battery Switches : Sports & Outdoors

Amazon.com : Blue Sea Systems m-Series Mini Selector Battery Switch - Red : Boating Battery Switches : Sports & Outdoors

www.amazon.com

The downside is that it is manual, but I think I can make it work for access. The up side is that you (I believe) could combine the batteries. In the event of a dead starting battery, you could combine them and essentially jump-start yourself, correct? I'm just trying to figure out which one I need. I believe the "4 Position Selector" would do what I need.

If I'm understand the diagram in these directions (link), is this what the dial selections would equal? I would bring the starter battery into #1, rather than to the Output/Load as they show:

• Off = No power from any battery to the House Output/Loads; I'm not isolating the Starter battery from the engine, so the engine and the non-house loads would still function
• 1 = Starter battery routed to the House Output/Loads
• 2 = House battery routed to the House Output/Loads
• 1+2 = Starter and House batteries combined to each other and the House Output/Loads; I would need this setting to charge the House battery when rolling down the road, and to "jump start" myself in the event of a dead starter battery

I just want to make sure I'm thinking about this correctly.

Thanks!

 

[dreadlocks]

Low voltage? everything is ~12v..

w/a relay setup, you just need to wire it up to a keyed ignition source.. same as your radio and other accessories, so when you take key out.. the relay disconnects everything.. its self jump starting because it'll combine the batteries right before you fire up engine.

 

[rayra]

... providing you don't kill the starter battery so badly that you can't energize the solenoid. Which I did by leaving a peltier six-pack cooler plugged in for ~3 days while the vehicle was parked. I used small wire alligator-clip cable to connect the Aux (+) to the solenoid activation to combine and got the vehicle started, but the backfeed blew the fuse on the factory aux circuit I had the solenoid connected to.
The next time I had a dead starter battery I used a regular set of jumper cables to connect the two. Both times were in front of my house and I could have used a regular battery charger but was experimenting.

OP, you're not 'thinking about this correctly'. Vehicles have aux fused circuits. It's expected to add a new wired device or two. Identifying a keyed power source is a simple deal and running the wire (and the associated grounding wire for that) is likewise not difficult. Don't get hung up on the simple stuff when you are trying to accomplish something bigger.

A manually switched system means you'll be screwing around under the hood every time you want to do something, and more often than not you'll leave it in the wrong config and wind up with a dead battery.
The whole point of the solenoid setup is to keep your Aux battery connected / combined while your vehicle is running in order to give it a maximal re-charge. And then when you turn the key off /
'camp', the Aux/House battery is separated from your Starter battery and you can run whatever you like even to the point of abuse of the battery, without impacting your Starter battery.

 

[dreadlocks]

Yeah true, if you wire a diode up to that feed branch coming off main circuit breaker it'd stop any back feed into the rest of the system.. If you want to get real fancy you can hide a momentary switch under the dash that powers the solenoid from the aux/house battery and have a push-button jump start option for a completely mucked-up starter battery.

If all your circuits are done well, so all loads are coming off house battery.. chance of your starter battery going flat and ever needing a jump would be greatly reduced.. you'd have to leave the headlights on or something and even then most modern cars will handle turning all that stuff automagically.. my radio will even shut off every 15mins if engine's not on.. I use it as a timer to tell me my vape break at work is over.

I'd still carry jumper cables tho, none of this would help you start another vehicle or get a boost from another vehicle if something goes sideways.

 

[rayra]

All true.
I've been intending for several months to change the wiring on all my 12v power receptacles in my Sub to run them from my Aux (which is also being topped by my rooftop solar setup) so I don't have another unintended drain-down of my starter battery.
But I need to pull everything apart to do it and have 4-5 related electrical changes and backup camera replacement to do at the same time and have been putting it off.