Isolator vs Solenoid

[r2m]

I have two Odyessey PC1200 Batteries that I purchased about 3 months ago for a dual battery set up (in my '98 LC). One is in my rig and currently being used, but have not had a chance to install the second one yet, so it's still sitting in it's box in the garage.

I'm now to the point of getting the "things" needed for the install but am confused regarding what "things" to get. Basically my question is:
Which is better, using an isolator or a solenoid for a dual battery system?

On one one hand I have read that isolators will draw as much as 1 volt from the system (I believe from the accessory battery). On the other hand I've read that Solenoids will fail also.

I suppose I have one more ancillary question about wiring: on a solenoid, the two large posts are for the (+) positive battery terminals, one small one for ground and the last one?? Does that go to the ignition or accessories? Do you have to separate the wires (or separate that black box attached to the positive cable at the battery terminal) from the vehicle to the positive post?

I have looked at quite a few of the other posts but there are too many posts regarding "dual battery" and I have too little time to scan through them all to narrow down to this simple question of which is a better system to go with. So my apologies if this particular topic is redundant.

 

[CappyKD]

Take a look at the IronMan 275 Amp DBS, it comes with everything (wiring terminals etc) you need except battery terminals.

 

[r2m]

At almost $350.00 dollars, I can by an isolator AND solenoid with all the cabling for both my LC and my wife's!

Seriously though, I'd like to buy the components separately and and build it myself to help keep costs down.

Thank you for your thoughts CappyKD!

 

[Tapage]

pretty simple setup ..

 

[r2m]

I don't mean to seem like an idiot but is that a solenoid or an isolator? Also, could you label your cables? I see the one red on the left to your aux battery and I assume the one opposite with the black wire wrap is the positive to your stock location battery, but what is the third wire?

Thanks for the pic!

 

[FJ60Seth]

I don't mean to seem like an idiot but is that a solenoid or an isolator? Also, could you label your cables? I see the one red on the left to your aux battery and I assume the one opposite with the black wire wrap is the positive to your stock location battery, but what is the third wire?

Thanks for the pic!

I think this is what Tapage is using, although I don't see the switch in his setup.

 

[rusty_tlc]

The third wire goes to an ignition hot wire, the solenoid is only closed when the ignition is on. Make sure you install a thermal breaker as close as possible to the battery on the supply side.


I have yet to hear a compelling reason to go with an isolator over a solenoid. I've been using the traditional solenoid set up with RV's for over 25 years and it is pretty bullet proof. This also has a substantial cost savings.

With the money you save you can start your next cool upgrade.

 

[r2m]

With the money you save you can start your next cool upgrade.

You mean like actually starting to save for some armor??

Seriously, thanks! The MUD is starting to clear and I'm beginning to see how this thing is to work.

 

[mobi-arc]

My first comment: call Odyssey and ask the engineers what they recommend for use with their batteries.

My second comment is in regards to the terminology: people use the term isolator, solenoid, and relay interchangeably and for most of us, it all boils down to the same basic concept....how to manage multiple batteries on a platform where you may have a single source (the alternator), or multiple sources (alternator, solar, shore-power). Generally speaking, if you're trying to manage batteries, you can do it with moving or mechanical parts (solenoids, relays, knife switches), or you can do it with solid state parts (battery isolators, rectifiers). There are benefits and detriments to each style. Mechanical parts are cheap, easy to source, and easy to understand. Like all mechanical parts in power switching applications, they degrade with use over time. Solid state devices have no moving parts, but the early early device constructed of silicon diodes had (have) a relatively high voltage drop and because of that , they get quite hot. There are some devices on the market that use MOSFETS instead of silicon diodes and the voltage drop is significantly less than the older silicon diode technology. A lot of choices out there and the information can be conflicting so first you have to determine what you're trying to accomplish by installing a second battery. How do you plan to use it. Then determine if you are more comfortable with a mechanical option or a solid state option. Mechanical will be moderately priced while solid state will cost more. Then you have to wade through the information, ask lots of questions, and hopefully you'll focus in on what looks to be the best fit for your application.

 

[ntsqd]

My suggestion is to break out of what people commonly use on 4x4's and look into what is used on boats intended for deep sea cruising. Those parts are a lot more robust than the typical off-road part. Tencha's device is a Blue Seas product. Another similar vendor is BEP Marine.

Search "VSR" (Voltage Sensing Relay) and/or "ACR" (Automatic Charge Relay). Just within this forum they've been mentioned a lot.

My own preference is a ACR/VSR in parallel with a high quality marine battery switch. Leave the switch set on one or the other battery (not "Both") and let the relay do it's thing. Then if you need to for some reason use the switch to combine both batteries. Simple redundancy.

 

[MANUCHAO]

I used this
http://www.bluesea.com/products/7622

Going on one year now with no issues.
I did not want to do a pre package deal either, so I shopped around for the best prices and put it all together.
I found this info on ExPo
https://forum.ih8mud.com/attachment.php?attachmentid=647936&d=1340605148

 

[rusty_tlc]

..... Mechanical parts are cheap, easy to source, and easy to understand. Like all mechanical parts in power switching applications, they degrade with use over time.

Even cheap solenoids (relays) are rated in terms of hundreds of thousands of cycles. I've never worn out or noticed any significant increase in "ON" resistance in a solenoid designed for continuous "ON" duty in automotive applications. This is probably the weakest argument against solenoids.

Solid state devices have no moving parts,

Solid state devices have a rated number of cycle times (same as solenoids), in addition they are more susceptible to damage from voltage spikes and other insults (shock and vibration) than mechanical devices.

My suggestion is to break out of what people commonly use on 4x4's and look into what is used on boats intended for deep sea cruising. ...

Good advice, there seems to be a prejudice against relays in the 4WD world, in favor of much more expensive solid state devices.

 

[mobi-arc]

Even cheap solenoids (relays) are rated in terms of hundreds of thousands of cycles. I've never worn out or noticed any significant increase in "ON" resistance in a solenoid designed for continuous "ON" duty in automotive applications. This is probably the weakest argument against solenoids.

Huh...I guess I'm doing something wrong.....I've replaced my starter solenoid twice, but I'm sure you're right....no wear-and-tear is taking place every time it slaps open and closed. Seriously, they use solid state switches in automation by the gazillions and you're going to argue that solenoids just don't wear out. Come on.....now you're just being silly. They do wear out, they do degrade in performance, and they do increase in "on" resistance as a function of physics. That's just what they do and any mechanical relay engineer will concede that point. It doesn't make them evil components, it's just how they are. Many ways to skin the battery isolation cat.

 

[george_tlc]

Huh...I guess I'm doing something wrong.....I've replaced my starter solenoid twice, but I'm sure you're right....no wear-and-tear is taking place every time it slaps open and closed. Seriously, they use solid state switches in automation by the gazillions and you're going to argue that solenoids just don't wear out. Come on.....now you're just being silly. They do wear out, they do degrade in performance, and they do increase in "on" resistance as a function of physics. That's just what they do and any mechanical relay engineer will concede that point. It doesn't make them evil components, it's just how they are. Many ways to skin the battery isolation cat.

A starter solenoid/contactor sees huge current draw right at the moment of contact and at break. Those events are what creates contact wear.

A solenoid in a dual battery system MOST of the time sees little current flow at the moment of contact and at break unless the aux battery is flat every time and even then we're not talking hundreds of amps

I do like the mosfet solution for isolation (just my EE side talking), it's just a huge whack of $$ more than a solenoid and provides minimal true world advantage for a dual battery system that has a marine switch for jump starting or winching use.

With 15 years in my 80 the solenoid is still functioning perfectly to keep my aux battery charged and isolated. I've had one in my patrol in oz for coming on 10 years and it's never failed to perform. In both systems when I winch, the act of rotating the marine switch to select power to the winch automatically disconnects the solenoid from the 'puzzle'. So, ONLY charging current and non-winch (fridge, ham gear etc) current flows through the 200A rated solenoid. The contacts will last a LONG time...

cheers,
george.

 

[mobi-arc]

If you've discharged your auxiliary battery with the fridge and ham gear, you are creating a high current transfer as that solenoid closes and we can agree, that IS what creates contact wear. Why would you NOT run winch current though the solenoid? Because it will get hotter than hell and as an EE, you know heat cycling ain't good for it, and you know that breaking that winch current will cause the solenoid to wear quickly....of course quickly is a relative term. Warn tried to go solid state to switch winch current, but they had issues trying to accomplish that, but it was interesting that a company that sells a crapload of solenoids was attempting to create a more reliable winch by go to a solid state method. Not sure if they still have a MOSFET pack or not...I believe they had technical issues they caused them grief, and I'm sure the cost of a solid state solution factored in there somewhere.

And as an EE, MTBF favors a non-mechanical solution albeit more $$. To each their own...I think there are tradeoffs to anything chosen. Solenoids have been around a long time and they'll be around for a long time.

A starter solenoid/contactor sees huge current draw right at the moment of contact and at break. Those events are what creates contact wear.

A solenoid in a dual battery system MOST of the time sees little current flow at the moment of contact and at break unless the aux battery is flat every time and even then we're not talking hundreds of amps

I do like the mosfet solution for isolation (just my EE side talking), it's just a huge whack of $$ more than a solenoid and provides minimal true world advantage for a dual battery system that has a marine switch for jump starting or winching use.

With 15 years in my 80 the solenoid is still functioning perfectly to keep my aux battery charged and isolated. I've had one in my patrol in oz for coming on 10 years and it's never failed to perform. In both systems when I winch, the act of rotating the marine switch to select power to the winch automatically disconnects the solenoid from the 'puzzle'. So, ONLY charging current and non-winch (fridge, ham gear etc) current flows through the 200A rated solenoid. The contacts will last a LONG time...

cheers,
george.

 

[cody c]

So, solenoid: this refers more to the coil used to stroke a mechanical linkage. There is a solenoid on a relay, there is also solenoids on electrically actuated valves and dampers for fans or vents...

Relay, with regards to electrical components, this is an electrical contact, operated by a solenoid, small current to throw a bigger switch, I think you already know what this is...

Isolator, this can be many things, but it is usually just a switch or manual disconnect, often a dial switch with regards to this forum, though I've seen folks use it to refer to electronically disconnecting components which preserve one battery.

What's the difference: essentially the first two are used to describe the same thing on here and use some amount of power to maintain a contact, the latter is usually a manual disconnect which isn't usually accesible from the cab.

 

[george_tlc]

If you've discharged your auxiliary battery with the fridge and ham gear, you are creating a high current transfer as that solenoid closes and we can agree, that IS what creates contact wear.

Yes, I agree. But your original statement of changing out your starter motor solenoid due to contact wear 'implies' that a dual battery solenoid sees similar usage - which is stretching things by a long shot.

Every engine start is basically a full high current cycle to the starter solenoid contacts. Start the vehicle say 2 times per day x 365 days and over 10 years... That's 7000+ full current cycles. My first starter solenoid went out after about 10 years and it say a heck of a lot more than 2 starts per day average over that time.

I'd imagine you may agree that 7000+ cycles of an aux battery solenoids is very unlikely WITH a discharged aux battery each time....

Anyhow, both mosfet and solenoid scheme will work fine over many many years. I can't justify the expense of a mosfet based system that will provide no appreciable benefit. Given I've got 15 years on the solenoid in my 80 it would seem to have provided plenty of durability so far.

cheers,
george.

 

[rusty_tlc]

Yes, I agree. But your original statement of changing out your starter motor solenoid due to contact wear 'implies' that a dual battery solenoid sees similar usage - which is stretching things by a long shot.

Every engine start is basically a full high current cycle to the starter solenoid contacts. Start the vehicle say 2 times per day x 365 days and over 10 years... That's 7000+ full current cycles. My first starter solenoid went out after about 10 years and it say a heck of a lot more than 2 starts per day average over that time.

I'd imagine you may agree that 7000+ cycles of an aux battery solenoids is very unlikely WITH a discharged aux battery each time....

Anyhow, both mosfet and solenoid scheme will work fine over many many years. I can't justify the expense of a mosfet based system that will provide no appreciable benefit. Given I've got 15 years on the solenoid in my 80 it would seem to have provided plenty of durability so far.

cheers,
george.

There you have it, two out of three EE's agree that solid state isolators do not have enough of an advantage over mechanical islolators to warrant the increased cost.

 

[rusty_tlc]

....
And as an EE, MTBF favors a non-mechanical solution albeit more $$. ....

As a EE who has worked in Hi-Rel applications for the last 25 years I'd like to see the MBTF numbers that support this. Unless you are using space rated components ($$$$$$$$) I find it hard to believe.

 

[mobi-arc]

I think getting 15 years out of a solenoid is terrific, and I suspect some people achieve greater longevity while most likely get far, far less longevity. After all, if relays didn't suffer from wear-n-tear, there would be no market for solid state relays. It's funny how we prioritize things: we all spent more money on Land Cruisers subscribing to the concept that better engineering and better components would yield greater longevity. I happy to carry that philosophy over to the batteries I install, and products I use to connect to, and manage those batteries. Just as I suspect you don't use dirt-cheap, flakey LEDS and likely stick to manufacturers with solid quality control. We all go through this cost-benefit analysis process: for me, if I can get the job done with no moving parts, and get comfortable with the idea I'm deriving additional benefit, or at least a higher probability of greater performance, it's a no brainer. That said, I do use relays for low current applications on my motorcycle and on the LC, primarily because solid state is more pricey. So to each their own.

Yes, I agree. But your original statement of changing out your starter motor solenoid due to contact wear 'implies' that a dual battery solenoid sees similar usage - which is stretching things by a long shot.

Every engine start is basically a full high current cycle to the starter solenoid contacts. Start the vehicle say 2 times per day x 365 days and over 10 years... That's 7000+ full current cycles. My first starter solenoid went out after about 10 years and it say a heck of a lot more than 2 starts per day average over that time.

I'd imagine you may agree that 7000+ cycles of an aux battery solenoids is very unlikely WITH a discharged aux battery each time....

Anyhow, both mosfet and solenoid scheme will work fine over many many years. I can't justify the expense of a mosfet based system that will provide no appreciable benefit. Given I've got 15 years on the solenoid in my 80 it would seem to have provided plenty of durability so far.

cheers,
george.