Isolator vs Solenoid

[rusty_tlc]

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.

I don't think a 15 year life for a charging relay is exceptional, probably not even average.

The market for solid state relays is driven by speed, not some inherent flaw in mechanical relays. The fact that mechanical relays are still around indicates that solid state relays are not the best solution in every case;
The first solid state relays I worked with were built with discrete components on PTH circuit boards. We designed them for use in traffic controls where the ability to switch an AC voltage during the zero crossing extended the life of the incandescent bulbs used back in those days (1985 ish). AFAIK AC switching with zero crossing is still the biggest market for solid state relays. Mechanical relays cannot match the speed needed to switch states during the zero voltage crossing providing a "soft" start for AC loads. There are some DC applications where the speed of a solid state relay is desirable, however charging circuits do not benefit from speed. Just because a solution exist does not mean it is the best for every application.

Less expensive does not correlate to cheap, more expensive does not correlate to better. But as you say to each their own, if a person wants to spend more to get identical result that is their choice. I prefer to apply my cash where it yields the most bang for the buck.

 

[ntsqd]

Going back to the OP's first post, as "isolator" is used in that post the inference to me is a diode isolator. Those do cost about one volt across them. Unless the voltage regulator samples voltage downstream of the isolator or is offset up to compensate, the batteries will likely never reach a full state of charge. The general trend is away from this type of battery separation device. It is possible that a device is marketed as an "Isolator" that doesn't employ diodes, but I would caution that if the mfg can't get that terminology correct then what else haven't they got correct?

A relay of any type has a far smaller voltage drop across it and the batteries will get a full charge providing that the voltage regulator has an appropriate max voltage for that battery type.

The ACR/VSR's that I mentioned have circuitry in them that senses when the alternator is charging and will switch on. And they sense when the alternator is no longer charging and will switch off. Some of these can sense a charge on one post only (single sense) while others can sense a charge on either post (dual sense). A dual sense ACR/VSR would be a good call if you have solar and want it to charge both the house battery and the starting battery.

As a matter of personal preference I don't particularly care for the "all in one" solutions. I would rather have redundant solutions. I'll not likely ever buy a ACR/VSR that has a remote controlled combining function. I prefer to put a marine battery switch between the batteries, cabled such that they can run winch or starting loads without issue. Then I wire the ACR/VSR across the battery terminals on the switch. With a dual sense unit the switch can be set on either battery and the other will charge. Turning the switch to "Both" effectively by-passes the relay for starting, winching, or charging (in the event that the relay has failed). This yields simple redundancy at a small cost in footprint.

 

[mobi-arc]

Going back to the OP's first post, as "isolator" is used in that post the inference to me is a diode isolator. Those do cost about one volt across them.

Not completely accurate. Silicon diodes "cost" about a volt across them. While Schotky diodes are about half that, and then you've got MOSFET-based "diode" isolators which are a fraction of a volt. So unfortunately, just like most people use the term "isolator" as a catch-all for battery management, it's tough to make a blanket-statement and say ALL "diode" isolators drop a volt.

It is possible that a device is marketed as an "Isolator" that doesn't employ diodes, but I would caution that if the mfg can't get that terminology correct then what else haven't they got correct?

If a device isolates batteries from each other, if not an isolator, what would you suggest engineers or manufactureres call it?

As a matter of personal preference I don't particularly care for the "all in one" solutions. I would rather have redundant solutions. I'll not likely ever buy a ACR/VSR that has a remote controlled combining function. I prefer to put a marine battery switch between the batteries, cabled such that they can run winch or starting loads without issue. Then I wire the ACR/VSR across the battery terminals on the switch. With a dual sense unit the switch can be set on either battery and the other will charge. Turning the switch to "Both" effectively by-passes the relay for starting, winching, or charging (in the event that the relay has failed). This yields simple redundancy at a small cost in footprint.

I like smart solenoids and I like redundancy. But I do think that solenoids aren't necessarily the best choice for higher current switching applications, but that falls into a Ford-Chevy debate and everybody has their own opinion.

 

[ntsqd]

Be they diodes or not I do not consider MOSFET's to be a "diode isolator", only the isolators of old that most are familiar with that typically had a couple diodes encased in potting compound on a heat sink are "diode isolators". Arguing semantics goes nowhere and serves no purpose.

Those quality vendors that make them tend to call them "Battery Combiners" or use similar terminology.

Best choice defined how? Absolute best at high speed switching? Absolute lowest price? Absolute highest current rating? Absolute best MTBF?

For me it means best ROI, and so far that isn't solid state. Oddly enough Gigavac doesn't seem to think that solid state is the correct solution either. Looking at their customer list it would appear that a lot of savvy folks agree with that.

I've never cared for Perfect Switch's advertising or stance. Always seemed like a bit of smoke and mirrors combined with an "I'm the guru" attitude. The tone of your posts has only reinforced this impression. I'm sorry to the OP, it appears that your thread has successfully been derailed in spite of my attempt to bring it back. So with that I'm out.