Combiner or Isolator

All,

Looking for some advise on what is better, and isolator or combiner.

On my 40ft Mainship, I have a isolator downstream of the output on the engine alternator. Voltage going in is fine, voltage out on one leg is poor and the other leg is good. Suspect a failed isolator and will replace.

The combiner won't have the slight voltage drop that the isolator has, but are there other advantages or disadvantages?

One side note: I can't figure out what the good side of the isolator is charging. It's not charging the house, starter battery or generator battery. Volts measured on the batteries. Ideas?

I love KISS , so chose a selinoid isolator as the seamless method of automatically seperiating and joining the two systems as needed. Engine Key switch ACC operated.

No thought required , no effort required and no voltage drop between systems when combined.

Nice that it costs under $20.00 too.

With an external 3-4 stage V regulator , and a SOC meter a boat is ready to cruse well for little cash, or effort.

KISS

Regarding isolator versus combiner, they both can fail. The continous duty solenoid works well bet they do have a finite life, keep a replacement on board. When I used one on my charter boat, they typically lasted 3 or 4 years. Isolators seem to work ok, but need to be rated well above maximum amperage of the alternator. Had one fail where the primary diode failed which spiked the voltage to the secondary battery way up. This was a function of how the alternator sensed battery voltage. There may be a better way to wire them into the system, but this spooked me away from using them.

Ted

A combiner works just like a battery switch but it's automatic. There's no voltage drop or loss. An isolator uses diodes to separate the batteries and there's a one half volt drop. You don't want that.

Battery combiners are much more popular and are made by several different companies. I think the "under $20.00" quote above is way too low. The price for name brand marine battery combiners is more like $80 - $150 depending on capacity. Still, they are worth it.

From Victron energy site....

https://www.victronenergy.com/battery-isolators-and-combiners/argo-fet-battery-isolators

"Argo FET Isolators are High Efficiency - Low Voltage Drop!

Victron Energy FET Battery IsolatorsSimilarly to silicon diode type battery isolators, FET isolators allow simultaneous charging of two or more batteries from one alternator (or a single output battery charger), without connecting the batteries together. It allows discharging of batteries independently of each other without effecting the other. Popularly used on Rv's, Boats, Commercial vehicles where both starter and house batter banks exist.

In contrast with diode battery isolators, FET isolators have virtually no voltage loss. Voltage drop is less than 0.02 Volt at low current and averages 0.1 Volt at higher currents. "

​ https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A

Super robust and reliable.

"I think the "under $20.00" quote above is way too low."

Not for a solenoid , I think even a Cole Hersey can be had at that price.

Electronic stuff is pricey , esp if sold on the boat market , but solenoids are 70+ year old tech , with lots of competition.

The isolator or any PN junction is a .6 volt drop. I once had a motor home that had lots of toggle switches with no labels. Well after the battery went dead, I discovered that there was a few solenoids in the battery charging system. Then there was 3 fuel tanks that had solenoids valves to isolate the tanks. Well they averaged 3 amps when on. So the switch to shut them off is a great idea, but it has to be like the ign or start/run switch. I also borrowed a car from a guy and he said the battery went dead over night. So when you disconnect the battery and it arcs when you hook it back up you would think there is a problem. Well I climbed into the trunk and said close the lid. The trunk light was on. I was the hero. After the owner had paid several people to fix it. So you gota be vigilant. gary

The solenoid is to accomodate a bad starting battery. And, I like and use them. The iso vs combiner is different mission. Charging. What I like about the mometary emergency solenoid is that it is manual, reliable, and doesn't connect a good and a bad battery together for long. Bad things can happen if you do (like using that evil 1, 2, both off switch).

I believe the new genetation of "isolaters" are wuite different than their older cousins.

Read up on them, they have advantages in terms of no moving parts or arcing contacts if what I have read is accurate.

Not to say other stuff might not be better, but dont didmiss the new ones based on older models.

Yes, not only ArgoFET, also these guys

​ http://www.perfectswitch.com/isolators/

When you really want a one-way only flow.

Personally I'd go B2B intelligent DC-DC charger once things get that expensive.

Here's a link to what I did on our MS 34HT

See charging system mods.
http://dkloeber.wixsite.com/bacchus/project-pg-4

It includes a link that compares several good combiners.

FF said:

"I think the "under $20.00" quote above is way too low."

Not for a solenoid , I think even a Cole Hersey can be had at that price.

Electronic stuff is pricey , esp if sold on the boat market , but solenoids are 70+ year old tech , with lots of competition.

Click to expand...

A marine battery combiner is not just a solenoid. It contains circuitry that monitors the voltage and switches the batteries together for charging or apart for use when not charging.

No human intervention is necessary for use.

"It contains circuitry that monitors the voltage and switches the batteries together for charging or apart for use when not charging."

Great , but why bother, with costly complex electronics??

There is no charge unless the engine is running , so joining the house to the start batt , after engine start is all that is required .

FF said:

"It contains circuitry that monitors the voltage and switches the batteries together for charging or apart for use when not charging."

Great , but why bother, with costly complex electronics??

There is no charge unless the engine is running , so joining the house to the start batt , after engine start is all that is required .

Click to expand...

All true. But lots of folks love automation[emoji847]

Then there are those that hate automatic chokes on lawnmowers.

As for the automation... I could lean toward KISS, however, I need to figure out what I'm going to replace my failed isolated with.

And there's a ton of good info on this thread, just need to digest, but leaning toward a combiner (or similar).

I don't understand how the solenoid protects the batteries, is there a diode built into these? And are they manual or automatic?

FF said:

"It contains circuitry that monitors the voltage and switches the batteries together for charging or apart for use when not charging."

Great , but why bother, with costly complex electronics??

There is no charge unless the engine is running , so joining the house to the start batt , after engine start is all that is required .

Click to expand...

Maybe because a VSR can work with multiple charge sources, does not require key on excite, and some, like the Blue Sea version, are extremely reliable.

I can't even count how many Blue Sea ACR's I have sold or installed over the years but it is many, many hundreds and I have yet to see one actually fail. Sure a few of them got miswired (only three wires but still that can apparently get messed up) and the owners claimed they were not working but in the end it was a DIY wiring mistake and the ACR was actually fine.

The Blue Sea ACR in-particular is one of the most reliable pieces of gear I have come across in the marine market. I say this when I currently have two failed Mastervolt Battery Mate low volt drop mosfet isolators in my trash bin as well as an old school diode isolator..

Rather than using gimmickry, in an attempt to protect a cheap relay, like some VSR makers try, Wayne K. spent a long time working on the actual contacts for that relay so they could handle the abuse of the designed duty.

The "solenoids" used by most builders (Cole Hersee etc.) are quite often not up to that duty and I replace a quite a lot of them that have failed. Builders such as Hunter, a number of Downeast builders and numerous others used cheap solenoids over the years that have cost a number of my customers some good money on towing when they failed without warning.

I have a customer with a thruster circuit that burned up five paralleling solenoids over a few year period. This all at total cost to him, from various boat yards, of well over 1.5K in repair and trouble shooting bills. None of the yards ever solved the problem because they kept replacing a relay that could not handle the amperage or duty cycle.

When I was called in the problem was obvious and solved in about three or four minutes of glancing at the system and builder schematic.. His Blue Sea ACR has been plugging away now for over 8 years, in this same system, with zero issues. It also charges both banks, via solar, when his boat is on the mooring at his island house.

While those relays are certainly inexpensive they can be less than reliable with the current that can be expected to pass through them on many boats.

For a few dollars more you can get excellent reliability, start isolation, charging from multiple sources etc. with a product actually designed from the ground up for the task. One of the first things I noticed Marlow did when they bought Hunter Marine was to do away with the unreliable Cole Hersee key-on solenoids for paralleling. I can't even recall how many of those I have replaced that have failed, but it is far more than I ever should have..

Seevee said:

As for the automation... I could lean toward KISS, however, I need to figure out what I'm going to replace my failed isolated with.

And there's a ton of good info on this thread, just need to digest, but leaning toward a combiner (or similar).

I don't understand how the solenoid protects the batteries, is there a diode built into these? And are they manual or automatic?

Click to expand...

Simply put, a "battery combiner" or "automatic charging relay" ( Blue Sea ACR is one brand) senses a charging voltage from the engine's alternator or battery charger and connects both batteries together so they both receive charging current. This is what the "Both" position of a typical battery switch does. When the charging voltage goes away (engine stops or the charger is unplugged), the combiner disconnects the two batteries from each other. Hopefully, you have wired your house loads to one battery or bank and the starter to the other. Now, you can run your house loads with no danger of draining the starting battery and not being able to start your boat.

"a charging voltage from the engine's alternator or battery charger and connects both batteries together so they both receive charging current. This is what the "Both" position of a typical battery switch does."

The problems come up when the BOTH switch is not rotated to seperiate the batts after engine shut down,

OR when rotated to OFF with the alt operating , and the switch was installed with out hooking up the usually built in field cut off .

"I don't understand how the solenoid protects the batteries, is there a diode built into these? And are they manual or automatic?"

No diode is used as the solenoid is open when the engine key is off.

The signal that operates the unit to close is power from the ACC position on the engine key switch.

A secured engine will usually have a low oil pressure alarm , which is enough to trigger the boat operator to turn off the key.

"The "solenoids" used by most builders (Cole Hersee etc.) are quite often not up to that duty and I replace a quite a lot of them that have failed."

The better boat assemblers will read the stamping on the units.

Most are rated 80A cont. duty , so they spring a second $20 cost and install 2 in parallel, if a 135 A truck alt or other big amp unit is installed.

A DN 50, 24V up to 300A is not usually a small boat item, and $20 units are not suitable.

FF said:

"a charging voltage from the engine's alternator or battery charger and connects both batteries together so they both receive charging current. This is what the "Both" position of a typical battery switch does."

The problems come up when the BOTH switch is not rotated to seperiate the batts after engine shut down,

OR when rotated to OFF with the alt operating , and the switch was installed with out hooking up the usually built in field cut off .

"I don't understand how the solenoid protects the batteries, is there a diode built into these? And are they manual or automatic?"

No diode is used as the solenoid is open when the engine key is off.

The signal that operates the unit to close is power from the ACC position on the engine key switch.

A secured engine will usually have a low oil pressure alarm , which is enough to trigger the boat operator to turn off the key.

"The "solenoids" used by most builders (Cole Hersee etc.) are quite often not up to that duty and I replace a quite a lot of them that have failed."

The better boat assemblers will read the stamping on the units.

Most are rated 80A cont. duty , so they spring a second $20 cost and install 2 in parallel, if a 135 A truck alt or other big amp unit is installed.

A DN 50, 24V up to 300A is not usually a small boat item, and $20 units are not suitable.

Click to expand...

I'm having a hard time understanding this post but I will address the first three paragraphs:

No switch is required when a battery combiner is installed. The combiner takes the place of the switch. In most cases the switch should be removed. The wiring instructions furnished with the combiner will show the correct wiring.

FF said:

There is no charge unless the engine is running, so joining the house to the start batt, after engine start is all that is required

Click to expand...

Perhaps in a particular scenario, but most setups do also use a shore charger, and many have solar for living on the hook as well.

ACR is a good idea. I though went with the cheaper continuous duty relay as it was a lot cheaper, bought off Amazon rated at 80 amps.

I have an inline manual switch and when ignition is on for the starboard engine, power is sent to the manual switch, then to the relay. So I can turn it off if I wish. I put this in so that both alternators from each engine can simultaneously charge both battery banks. I have a starter battery as bank 1, and 2 house batteries as bank 2. So with a combiner relay, the port alternator gets to share the load with the starboard alternator. The starboard bank 2,house bank is always running down, so it helps charge it more quickly with less alternator stress combining the output of 2 alternators together.

I have ammeters on both banks, and turning on the relay, bumps up the output of port alternator to 30 amps and drops output of starboard alternator from 50 to 30 amps.
So in lots of ways it works fine for me.

The alternators are Delco 12SI, internal regulator, single wire.

An ACR or battery combiner is as simple as it gets. No switches, no buttons, just install it and forget about it.

john61ct said:

Perhaps in a particular scenario, but most setups do also use a shore charger, and many have solar for living on the hook as well.

Click to expand...

Those can be connected to the house bank as the start battery in good condition can go for months if you shut down and it is fully charged.

Jumper cables or a jumper to the solenoid could cover those rare times the start battery is low.

Having something simple and cheap is good for remote areas over a combiner unless you carry a spare or backyard engineer a fix.

For most cruising near West Marine stores have no worries...

With that specific ML series Blue Sea ACR, there is no need to carry a spare.

With a cheap solenoid there definitely is.

I happen to use quality batteries for starting as well as House, so for me letting it go months without a charge is not something I would do intentionally.

The 7622 model has a manual switch to use for self-jumpstarting off House if needed, I don't think it's worth paying for and storing the massive heavy long cables for just that purpose, likely never needed if your system is designed and installed properly.

Note the cranking amps rating on the ML unit is 2500A, that 500A rating is continuous.

I personally would never try cranking through a device rated at 80A.

A bit off base in my opinion.

Any piece of eqipment can fail.

Inexpensive doesnt mean cheap and prone to failure.

Jumper cables are not massive or hard to store.

The solenoid concept isnt meant to try starting through unless you have one rated for it.

It is simple and definitely workable and way less expensive...

You are trying to convince people to go with something nice but pointing out negatives tbat just arent true to the KISS principle wint convince me.

ACR to me is 100% within KISS

You just heard from CMS that **that one** doesn't fail, and there is no more reliable an expert out there IMO, based on servicing hundreds of boats over the years.

Plus keep in mind this isn't mission critical functionality anyway - assuming it failed closed, or your alt is still servicing the Starter batt anyway.

Show me, link to, what you consider a good reliable high-amp solenoid, on par with that ACR, I bet the price difference is less than a nice dinner out with the family.

And to me the fact that the design only accounts for **one charge source** is the fatal flaw, but the way some use their engines all the time, don't live on the hook for extended periods, maybe that aspect is fine for many in this forum.

.....there are always other possibilities.

Also, while I respect the input from CMS, if man made it, it can fail...after 1000 years or new out of the box.

You arent dealing with wannabe, almost boaters and cruisers with FF and me....while combiners are a nice setup...they are not lightyears better than ancient tech in this case.

I dont even use a solenoid. I use an on/off switch next to my oil dipstick so a one second turn of the switch works for me when I check the engine right after start each day.

Yep, lots of reasonable ways to skin a cat in boat systems...none are "right", only orefered by a particular owner.

Here is the relay I bought. It has worked fine since 2016 when I installed it.

https://www.amazon.com/gp/product/B00KGID0X0/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

It never has a full cranking load running through it.
And the wire size limits the current flow. I used #4 wires about 4 foot in total length to join the two battery banks.

Looking up that part number, it is 90 amp continuous, 150 amp surge.

Product Description
BRAND NEW HEAVY DUTY
12 VOLT UNIVERSAL CONTINUOUS DUTY SOLENOIDS
Winch Solenoid Combo from DB Electrical
Quanity of 4 Solenoids Included

4 Terminals (2 large and 2 small)

Continuous Duty Solenoid
12 Volt, 4-Terminal, Insulated Base Flat Bracket

Ratings : 90 Amps continuous - 150 Amps surge

Used On:
Golf Carts, Industrial & Marine Applications where Solenoid is to be
engaged for extended periods of time

Notes:
To replace 3-terminal solenoid, connect wire from one small terminal to mounting bracket

This universal continuous duty solenoid is used on thousands of winch and
hydraulic applications and can be used almost anywhere a continous duty solenoid is needed.
It is fully insulated which makes is adaptable to many applications.
It is guaranteed to perform equal or better than the solenoid it is replacing.

1 YEAR WARRANTY -- Don't be fooled by cheap imitations!

Click to expand...

Question....
My buddy says an inverter can take the place of all of the above, combiner or insulator or solenoid. He says to split the house battery and have at least two inputs and two outputs for the inverter.

If so, how is this wired.