Jump to content
Sign in to follow this  

Isolator pros and cons

Recommended Posts

I am tryin to figure out if i should install an isolator in my setup and have been reading a LOT of info about this and have came across a LOT of things that i have never read about before from others.

I've read things like-

Not using an isolator can hurt the starter by it receiving a superior CA load and may kill it quicker.

Showing off with car off will kill starting battery.

Now, i've been on Stinger's site and i gotta call them about some things because they got some products and descriptions that are just begging for answers!

Such as their SRVG which shuts off power altogether in the rear to prevent front battery from dying.... really? How?

And also, their 200A relay solenoid...

This is ridiculous, i have never seen this before.

Is this really necessary?

Stinger recommends running a solenoid in between EVERY aux battery in the rear!

Reason - batteries may not have the exact same charge and batteries are never perfectly identical...

Um... ok but when the car is on, the solenoid can do nothing but let power be sent to all batteries at the same time for charging...

When the car is off, it will allow an independent discharge for each battery but... the alt will charge them back up when car is on so do not understand that recommendation at all.

Share this post

Link to post
Share on other sites

i never show off with my car not running,...... i dont think i ever have. or have even wanted to... but i did put one on my pearl lincoln.... a few things happen.....

1 . i found out i had 1 of two of my batts were bad!.. turns out the cell under the hood was bad.... the whole car had been running on the rear cell.

2 i found out i was drawing more then 200 amps to the rear.... AFTER i replaced the bad cell.. so what ended up happing was my isolator slowly burned.. and the bolt came off the damn job,

what am i sayin here.... o yeah.. you have to have a HUGE FIN isolator if your gonna pull power to the rear..... i used a blue one... ummm... i wanna say hurse or rease.. but i have been drinkin......

Share this post

Link to post
Share on other sites

There are two types of isolators, the mechanical type which is cheaper and the electrical type which is smarter but now out of production.

Both do the same job which is allow you to drain only the AUX battery, (bank), so that when you're ready to start your ride, the main battery has been, ISOLATED, (not drained) and is ready to start your engine.

The mechanical type comes in two flavors, straight honking relay, (solenoid is just a big relay), and cheap relay with a heat sink.

Usually the sink is blue since they all get them from the same place. These can still be found in AutoZone, PepBoys and the like.

The other type, my fave, is the electrical type. The first on the scene was the70A isolator, the MBR-70 from Orion Industries. Later the same guys designed a 200A version for Lightning called the SSR-200. Then after Rockford acquired Lightning they made two compact versions since they have the robots there in Tempe. They were SMT versions with Rockford's MEHSA heat sink method. The products were identical but pricewise were different since RF treats the Lightning brand like its dirty bitch. These were called the Rockford CPSR and the Lightning Audio SSR2002. Both were rated at 200A constant current transfer.

The electrical type has some brains involved. The mechanical simply switch ON or parallel the AUX batteries every time you start up. You can delay this load by running a switch inside the cabin and switching on only when you want to charge the AUX battery bank.

The electrical isolators do this automatically. They won't charge the AUX bank until the front battery is fully charged. They use devices, (same type used in your amplifier's power supply), to do the switching instead of a mechanical switch like the solenoid.

Now big feature about using the electrical type besides being smart was the fact that the electrical type had no voltage loss. This of course isn't totally true but true enough. The solenoid types would get hot and when they get hot they build up resistance and resistance = voltage loss.

Now they just build them really beefy and say they have no voltage loss, which is true but they have to be within certain parameters. The solenoids are certainly cheaper to build and you can line up multiples in parallel to increase the current passing capabilities.

My only beef is that companies like Stinger charge a big toe for one of these. There are several generics that you can get from other companies that work just the same... And remember, they're all made in China anyway. Not that the quality is bad, just that Stinger pays the same low price as everyone else, but because you bought it through a dealer network and it has a cool decal on it, you pay $200+.

Dealer price for the Stinger SR-80 is around $12 and around $38 for the SR200 so hunt for those bargains!

The other down product of using a solenoid is that it wants to charge your AUX bank all the time. This can really put wear on the alternator. Like I mentioned before, you can add a switch in the cabin so you can charge it when you want. To keep tabs on it, you can have a digital volt meter for the starter battery and a second for the AUX bank. That way you can decide when to load down the alternator and recharge that AUX bank from 4hrs at the river playing Back In Black over and over.

As for cheapie DVM

Share this post

Link to post
Share on other sites

couldnt ask for a better explanation, thanks.

So, i was looking and you're right, electrical versions are discontinued and VERY hard to find.

So, i'm forced to look into a Relay-type Solenoid.

Well, since they come on when the car is on, then they will act like they are not even there...

If i were to only play music with the car on, would i not need one?

At the least, if that's true, Stinger's SRVG looks like a nice little device. It's only $37 and says it will shut off all aux battery power to ensure starter battery is charged. I don't know how it works since all the wires coming out of it are very small. It doesn't look like you feet the main power line through it at all which makes me wonder how it works.

Share this post

Link to post
Share on other sites

The solid state isolators are nothing more than a pair of really big diodes. They are still in production but have fallen out of favor with the car audio community because of the voltage drop that they cause. They function by having a single input feed a pair of diodes that only allow current into the the batteries (one for the starting battery and the other for the audio bank). Because current only flows one way in a diode, the batteries are isolated from each other completely but are still able to charge from the alternator. You can still get really big ones from RV and marine suppliers. There is a voltage drop involved of about .7V.

Solenoids don't cause a voltage drop to speak of. The high current doesn't flow through the relay coil, it's a low current device. The high current only flows through the switched leads. It only isolates the batteries when the ignition is off.

The SVRG is only a controller for a solenoid or relay. It triggers an output once voltage reaches a certain threshold and can either trigger your isolation solenoid or turn off your amps. Nothing special and not at all needed if you only run the stereo with the car on.

Share this post

Link to post
Share on other sites

okie dokie, thanks.

Looks like i'll be gettin 4 200A solenoids...

Gotta call stinger tomorrow(even though i'm gettin PACs 200A solenoid) and see if 200A solenoids are enough...

I'm pretty sure they are but just in case they arent...

Got 3 batts in the rear, so 2 solenoids go in between each batt.

then the other 2 solenoids get wired in parallel which are between the front and 1st rear batt.

Those PAC 200A solenoids are almost half of Stingers 200A.

I'm assuming the ground lead off of these solenoids doesn't have to be large correct?

I noticed the terminal was small so i'm guessin 8 awg is plenty?

Share this post

Link to post
Share on other sites

OK, i got done talkin to Stinger about my setup.

He said for me to put 300A fuses at each end of the main power line running from front battery to rear battery bank.

So, i am taking it that 2 200A solenoids wired in parallel is not a good idea on this line, correct?

Would i be better off running a 200A and an 80A in parallel?

I am assuming too much relay is like too much fuse which is bad, correct?

Too little relay will just damage the solenoid, correct?

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this