Need a simple test for ACR...

[john61ct]

Heart Echo or DC-DC charger even better.

[mitiempo]

Originally Posted by john61ct

Heart Echo or DC-DC charger even better.

I don't really agree with that. The Echo Charge is a one way device and limited to 15 amps. It is also nowhere near as water resistant as a Blue Seas ACR. Also more expensive than an ACR.

DC-DC chargers have the same issues - limited current and one way only. They really shine however when the banks are differing voltages - 24 - 12 for example or 12 - 24.

[boatbod]

Echo Charge is limited to 14.1V, which will seriously mess up your batteries over time. (Unless you have gel)

[john61ct]

Originally Posted by mitiempo

I don't really agree with that. The Echo Charge is a one way device and limited to 15 amps. It is also nowhere near as water resistant as a Blue Seas ACR. Also more expensive than an ACR.

DC-DC chargers have the same issues - limited current and one way only. They really shine however when the banks are differing voltages - 24 - 12 for example or 12 - 24.

I meant there specifically to help where the goal is to isolate the noisy/engine circuit from sensitive house loads.

Many other use cases justify paying more, and many DC-DC chargers are waterproof.

But yes ACR/VSR is fine for most, even modern isolators for many. Too many ways too skin that category IMO 8-)

[john61ct]

Originally Posted by boatbod

Echo Charge is limited to 14.1V, which will seriously mess up your batteries over time. (Unless you have gel)

I thought 14.4-14.5

Depends on the battery, well within spec for many.

We're talking about topping up a barely cycled starter here right?

If your special expensive batteries needs precise voltage setpoints, then of course an adjustable charge source is best. Usually a bigger investment though, my comment was wrt the advantages of one-way flow control, compared to an inexpensive ACR.

I picked a new one up for $93 delivered a few weeks ago.

[tinkrman69]

Run alt to engine batt and isolate that from the house Batts with a switch . when engine batt is charged switch back to house K I S S

[Maine Sail]

Originally Posted by Rowglide

So putting alternator output on Start battery side of the ACR really guarantees a full start battery first then house second instead of the other way around.

No, it does not guarantee a “full” start battery.. The start battery is already going to be at a very high SOC, so all it guarantees is that your start battery will see 30 or 90 seconds of charging before it combines with the house bank. The Blue Sea SI ACR combines at 13.6V after a delay of 30 seconds or 13.0V after 90 seconds of delay.



You can’t even recharge a single Ah in 30 or 90 seconds, especially at a high SOC, where most of the energy put into the battery is being lost in high SOC charge acceptance inefficiency. It’s really more of an “urban myth” that an ACR prioritizes a start battery by recharging it first. 30 or 90 seconds is simply not “recharging” it is just a 30 or 90 second delay before it tries to charge the house bank.


A dual-sensing VSR/ACR/Combiner doesn't "prioritize" anything. They are bi-sensing and the delay applies to either bank.



Think of it as a voltage triggered, automated version of the BOTH position. When either battery attains the minimum combine voltage, and time (30 seconds at 13.6V for the SI ACR or 90 Seconds at 13.0V), the banks are then automatically paralleled for charging. It takes very little current to raise the voltage of a small 99% charged start battery to 13.0V or 13.6V. In the 30 or so seconds it will take to combine you are not really "charging" the start battery first you are just waiting out a 30 or 90 second delay..



At a high SOC, like 99%, that last 1% is horribly inefficient so that last 1% can take much more time to replace than most would ever assume it does. The time to replace this energy is not happening in the 30 or 90 seconds it takes for most VSR's to parallel the two banks when charging is fed to start first...

Originally Posted by Rowglide

Any reason that would not be preferred.

Jim

One reason is relay cycling, and it can limit how fast you can physically recharge your house bank. Relay cycling is affected by your charge current amperage, the depleted Ah's of the house bank and size of your house bank


On banks with disproportionate sizes, that are also deep cycling, Blue Sea recommends feeding the charge sources to the house bank first, not the starting bank.

Starting an engine uses very, very little Ah capacity usually far less than 0.5Ah. Wht waste any time charging a bank at 99%+ SOC when the house bank needs all it can get.


Another reason to feed house first is that this means the relay will see the lowest amperage across it at all times. If just charging the start battery the relay will be asked to pass only minimal current. It makes little sense to be passing a 100A charger or alternators current through the relay. On top of that you now have more terminations leading to increased voltage drop in all the added terminations. If you direct feed sources to the house bank, where is is needed most, we get better voltage a high output, faster house bank charging and minimal voltage drop to the low current requirements of the start battery..

Originally Posted by Rowglide

The main reason I would rather run the windlass from the start battery is distance. It is another 10 ft+ (X2) to the House batteries. The windlass existing correctly sized cables end near the start battery.

Buy the correct cable, it's not that much..…

Originally Posted by Rowglide

Could you explain ACR cycling?

Wayne Kelso, the designer of the Blue Sea ACR, explains it best.


Blue Sea Systems on Relay Cycling



The SI ACR does have programmed logic to minimize relay cycling but it can still happen with small current charge sources such as solar, wind or small AC chargers. In my experience it most often happens with cheaper alternative versions of the Blue Sea ACR or with solar or wind but I have seen it with small alternators too..

Originally Posted by john61ct

Cycling: The volts dropping causes open/isolate, which allows volts to rise, causes close/combine, which. . .

Can happen quickly enough to call chatter.


Delays and/or gap in the setpoints reduce the frequency so not damaging, but a bit, spaced out not a problem.

A Blue Sea SI ACR will not “chatter”, it can’t due to the programming delays, but it can still cycle and eat into the charge performance of the house bank. Some cheap VSR’s can potentially chatter because they do not have delays built in. A customer got a "good deal" on a VSR on eBay and it was set to combine at 13V and open at 12.9V. No delays what so ever. It lasted all of about two months with solar fed start battery first.



There's a actually a difference between relay chattering and relay cycling. Companies such as Blue Sea and Yandina have designed good quality combiner/VSR’s that avoid chattering. Some cheaper products can actually do what may be considered chattering but you won't find a Yandina or Blue Sea ACR doing this.

Originally Posted by Rowglide

By using house bank (my windlass is a 1200W unit) will the sudden draw drop the voltage and cause my instruments to cut out?

In a well designed & wired house bank system with an intermittent 100A windlass load, on a house bank, it should not be causing a drop out of electronics. If it is this is often a sign something is amiss or the house bank is simply too small. When using a windlass it’s a best practice to have the engine running to minimize the battery load, and to keep voltage to windlass motor higher, by supplementing the load with the engine alt. If your alt can contribute say 50A then the load to the battery now becomes only 50A and we have a higher voltage at the windlass motor and better performance.

Originally Posted by Chuck Hawley

The ACR SI has terminals which allow you to force it to connect (sort of like a remote battery switch) and to force it to not connect (override its normal operation). I don't use those terminals, but they might help you diagnose its operation.

Chuck

It should be noted that smaller 120A 7610 SI ACR series can’t be forced to combine or un-combine. That feature is found in the latching series relays called the ML-ACR.


The ML-ACR can be used in this manner. It is an excellent ACR.. The only terminals on the SI 7610 ACR are NEG/GND, START ISOLATION and LED.

Originally Posted by mitiempo

As posted above the ACR will chatter if charging is wired to the smaller (start) battery.

The ACR won't chatter but it certainly can cycle if the current source is not large enough to maintain the combine logic threshold.

Originally Posted by dw1979

Another great use for the ACR-si is protection of sensitive electronics from DC spikes. Properly configured starter motors and electric windlasses (to name a few) can be isolated.

Absolutely!! The SI feature (starting isolation) of the ACR is one of the best design features it has, yet nearly 98% of the ACR’s I see out there, installed on switch isolated dedicated starting banks, do not utilize this excellent feature. Poor marketing or just installers not understanding what SI is? I don't really know....

[john61ct]

Wow, as usual superb detailed info!

Will be looking at Blue Sea's SI implementation more closely for sure.

Apologies to all for my ignorance. . .

[Maine Sail]

Originally Posted by john61ct

Wow, as usual superb detailed info!

Will be looking at Blue Sea's SI implementation more closely for sure.

Apologies to all for my ignorance. . .

No ignorance at all. I was just trying to clean up some misconceptions, many of which can be directly related to the way some of this equipment is marketed...