Smart Battery Isolator
I don't know if this is the right section to drop this in, but it seemed that most battery and isolator threads were in this category.
When istarted my CarPC build i wanted a second battery in the back to run the PC and a/v equipment off of so that if something didn't shut off or went wrong it wouldn't drain the main battery. I obviously needed some sort of isolator for this and I didn't want a traditional one because of efficiency loss of diodes and stuff. I wanted an isolator that would open up when the alternator was charging properly and shut off if it wasn't charging.
My first attempt was I bought a standard high amp solenoid and used a uSDC20D Micro Shutdown Controller to sense the voltage of the charging system and open the solenoid at 13 volts or whatever its set at and shut off when the below a certain point (hooked the sense line up to the ign wire so that it would shut off as soon as the key was off not just stay on till the voltage drops in the car).
This worked great. Or so i thought... Once the engine warmed up and the engine compartment got hot it triggered the temp sensor on the uSDC20D and it thought it was too hot to run a PC and it would shut the solenoid.
Then I ran across this! http://www.colehersee.com/pdf/hot_fe...BatteryIso.pdf
Cole Hersee Smart Battery Isolator: Does exactly what I wanted the uSDC20D and Solenoid to do all in one unit and no temperature sensors. Plus designed for automotive use.
A little pricey and most places don't stock them, but they are available from Cole Hersee if you have someone who deals their product.
I'm a diesel mechanic so I deal with a large truck parts supplier near me in north NJ and they deal Cole Hersee so I had them order it for me. Took a couple days to get and ran me $106.29. But to me the price was worth the features and ease of installation.
Just thought I'd share this with the community. I searched around and didnt see it mentioned anywhere else. Hope someone finds this helpful!
I have read up on this product and it looks great. I was wondering if you could comment on how well it has worked for you?
I'd be curious to know if you extended the remote LED into the cab of the vehicle or other details about your specific installation.
I am considering this product for my Tacoma and extra battery. I especially like the optional start assist feature which is extremely valuable for back country travelers like myself.
nice find, I bookmark this just incase I plan on installing two batts. I am sure they have others you can used such for car a/v.
I'm at work now but I'll throw out some quick opinions of what I found with this.
As a whole it is a really nice well built unit. Cole Hersee is known for its quality built electronics and this is no exception. It is sturdy and the electronics are all sealed away. Easy and straight forward to install.
As a general battery isolator is great. I wanted to use it a little different so i ran into a few issues. The voltage sensor wire is connected to the main battery side of the solenoid. I originally took that wire and hooked it up to my IGN switch in the car bc i wanted it to shut off as soon as i turned the key off instead of staying open till the voltage drops enough to shut off. The problem with this was when the voltage drops enough to shut off the solenoid it will remain off for about 2 minutes after the voltage has risen high enough to kick it back on. This may not be an issue for many people but for me it was bc i have my PSU set on voltage sense to boot up so I'd have to drive for 2 min b4 the computer would start to boot. So i wired the isolator back up how it was stock. Now the solenoid is ground activated. So i took the ground wire off of the terminal on the solenoid and ran it through a relay and the relay is activated off the IGN switch in my car. So now when i turn off the key it turns off the solenoid but the voltage sensor is still reading the voltage from the main battery so it thinks that it is still on. So now when i turn the key on and start the car the pc boots up right away. The voltage stays high enough all day and over night to keep the unit thinking its on still so other than 1 or 2 times i have not had to wait the 2 min for it to turn on.
I did not extend the status LED or the jump start wire. The LED would be useful in some situations to have in the cabin but for the most part if the PC turns on i know it on.
So I have it working pretty good how I want it and i may change my PSU setting to boot at a lower voltage just to make it easier but im still debating that. But as a whole as a straight up battery isolator is a great product.
I couldn't tell you where to buy one though... i havent seen any online distributors offering them. I live in Northern New Jersey and I'm a diesel mechanic so I ordered it through my truck parts supplier who deals Cole Hersee products. Ran me about $106.
You could do it for cheaper like how i talked about how i first did it in my first post. You would just have to put the controller in the cabin of the car so it wouldnt over heat with the engine. I dont know how it would react in the cold weather after sitting over night bc i did not test it in that temperatures.
Hope this info helps any more questions just post em up and ill help you as much as i can.
Thanks for posting your experience. Yes I would prefer the unit to isolate the batteries immediately once the car turns off. I guess if I understand what you wrote, you achieved this by connecting the voltage sense wire to the IGN wire. This worked for you, but once the car was turned on, you had to wait two minutes before the solenoid would close and voltage could then flow to the aux battery and charge it?
I think I understand.
If you only need to isolate the battery when the car is off (not provide start isolation) then a relay triggered by your engine run circuit would be enough to do the trick.
FYI - how is the mere addition of a relay as per....
?? Note that only the relay (plus a fuse at both sides to both batteries) is generally required.
For more info, see http://www.the12volt.com/installbay/...oldspark&TPN=5 for a description of a "mere relay" to connect auxilliary batteries whilst charging.
That post also refers to http://www.the12volt.com/installbay/...asp~TID~118493 (~7th post).
And I'm answering similar at http://www.mp3car.com/vbulletin/powe...ml#post1366441 where additional options are mentioned.
I've got the Cole Hersee Smart Battery Isolator in my dual-battery van/camper. It is great.
But.......from what you wrote it sounds like you simply needed a dual battery RV switch. This switch connects the twin batteries when the ignition is on and separates them when the ignition is off. This way you can never drain your starting battery. No efficiency loss or diodes or anything. About $15-20.
Except when you forget to turn off the ignition (and it isn't charging).
Originally Posted by adrianl_888
And you must ensure the link can handle the shared stater motor current! (Which can be MORE than the starter motor itself.)
But whatever the relay costs you is the price of the UIBI system (for most rotor-controlled alternators - ie, not some bikes etc and not marine).
And that ensures your batteries are only paralleled whilst charging.
Am I repeating anything?
Correct. The purpose of using this isolator w/ my modifications to it was not only to disconnect the 2 batteries when the ignition is off, but to ensure that the pc and audio system isn't draining the main battery if the engine isn't running or something goes wrong with the charging system. If I only wanted it to work with the ignition I would have just used a standard solenoid.
Originally Posted by OldSpark