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Author Topic:   Battery Chargers, ACR, and Maintenance Charge
pcrussell50 posted 05-20-2011 11:55 PM ET (US)   Profile for pcrussell50   Send Email to pcrussell50  
My (new-to-me) Alert has a dual battery setup. I have a Battery Tender, float charger whose positive lead is hooked to the COMMON terminal of the OFF-1-BOTH-2 selector swtch, and the negative lead is hooked to the negative battery terminal [bus].

Right now, I have the battery selector on BOTH, and the charger is charging away. I am on the road for a week now, and I can't go back and make any changes, but I'm guessing that if I put the selector switch to OFF, as I would like to do, then the continuity would be broken to the positive battery terminals and I would get no charging. I know the float charger keeps the batteries charged while not in use; I've used them for years on my race car and single-battery boats with no electrical systems. I guess what's stuck in my craw is the idea of leaving the electrical system "live" or BOTH, such that I have to make sure all my accessories, (lights, radios, GPS, SONAR, etc.) are all each individually off. I know that it is good practice to do so, but I consider that keeping the selector switch OFF to be a good failsafe. But as it is now, I can't do that or I will get no float charging. I don't like to be without a failsafe.

Is there a standard way to connect up a float charger to a two-battery setup with an OFF-1-BOTH-2 switch?

I also have a West Marine Battery Combiner 50 that I removed while doing a little clean-up of the wiring:

www.yandina.com/acrobats/C50Data.pdf

I do not know what, if any, use I can make of this hombre. It says this:

"The West Marine Combiner 50 is a voltage-sensing relay (13.3 volts) which connects two batteries together when either is receiving a charge. When the charging ceases, the relay opens so that each battery operates independently."


*I hate the way the term "common" in used in this case, because I'm used to it being used in the sense of ground, the way you see the abbreviated word "com" on a volt meter.

-Peter

jharrell posted 05-21-2011 05:31 PM ET (US)     Profile for jharrell    
Yes using a automatic charging relay will allow this. I just installed the [Blue Sea Systems] add-a-battery kit with on-off combiner switch and ACR. The combiner switch still allows emergency starting off house battery if needed, and it has a optional terminal you can connect to the starter circuit to force the ACR to break while starting, avoiding voltage fluctuations for house equipment.

I also installed an onboard Guest charger which is has it's negative attached to the the negative bus bar and the positive attached to the house battery side positive terminal on the ACR.

The ACR senses charging voltage on either terminal and combines batteries if either the engine is running or the charger is active.

When in my garage I simply plug in a self retracting extension cord into the weather proof plug on the console I mounted, keeping both batteries maintained. This setup works very well I highly recommend.

jharrell posted 05-21-2011 06:26 PM ET (US)     Profile for jharrell    
Here is a link to my photo album of the project in which I have some pics of the switch/ACR/charging system:

https://picasaweb.google.com/107007622155886602752/ WhalerProject?authkey=Gv1sRgCOHiqYL_38ejFw&feat=directlink

jimh posted 05-22-2011 08:57 AM ET (US)     Profile for jimh  Send Email to jimh     
As described in the narrative, it sounds like the charger output is connected to the battery selector switch output. If the switch is in the OFF, the batteries are not connected to the charger. To charge both batteries, you have to leave the switch in BOTH, as you properly conjectured.

The simplest solution is to get a battery charger with dual outputs. You wire the charger directly to each battery, and the charger charges each battery independently. In this way you can leave the primary power distribution switch set to OFF when you are away from the boat.

jimh posted 05-22-2011 09:01 AM ET (US)     Profile for jimh  Send Email to jimh     
The use of an automatic combiner relay (ACR) or voltage sensitive relay (VSR) to combine two batteries in parallel automatically whenever there is an excess of charging current available and the controlling battery is fully charged is another method to approach the maintenance charging of two batteries from a single source of charging current, but I do not think it is the most simple method for keeping a float charge on two batteries.

Also, since you already have one float charger, it might be simpler to just buy a second float charger and wire it to the second battery.

jimh posted 05-22-2011 09:17 AM ET (US)     Profile for jimh  Send Email to jimh     
I recommend the PRO-SPORT 1.5 ON-BOARD BATTERY MAINTAINER

http://www.pmariner.com/productFeature.php?ProductNum=10116

as a good precision-voltage-regulated float charger. I have been using one of these on my bench to maintain a float charge on my bench 12-Volt battery for over a year with good results.

When applying a long duration float charge to a battery it is important to limit the charging voltage to avoid creating an out-gassing of the electrolyte.

pcrussell50 posted 05-22-2011 06:51 PM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
quote:
The simplest solution is to get a battery charger with dual outputs. You wire the charger directly to each battery, and the charger charges each battery independently. In this way you can leave the primary power distribution switch set to OFF when you are away from the boat.

I'm beginning to see that and ACR with a single float charger, while it may work, is sub-optimal. A single float charger with dual outputs sounds ideal, but may be pricier than just getting another float charger. I'll look into the more expensive option, as that's what my aesthetic sensibilities would prefer. Any recommendations for dual-output, float-maintenance chargers?

-Peter

jharrell posted 05-22-2011 07:30 PM ET (US)     Profile for jharrell    
Unless your engine has dual charging outputs the ACR is a better solution in my opinion as an engine with a single charge output will still keep both batteries charged while running.

Even with dual charging outputs if you have the batteries in the console like I do on my montauk would require double power runs from the engine through the rigging tunnel.

pcrussell50 posted 05-22-2011 08:58 PM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
I will definitely put my ACR back on, for charging while underway. Also, I have my dual batteries under the console of my Alert or Montauk--Peter
jimh posted 05-23-2011 08:40 AM ET (US)     Profile for jimh  Send Email to jimh     
The problem that I see with the ACR approach is that the auxiliary components needed in the ACR circuit cost more than the ACR. If you install all of the fuses that the ACR manufacturer recommends, the circuit become quite complex. I cannot imagine that on a 15-foot open boat there would be a good place for all the fuses, leads, connections, and switches that the ACR circuit suggests. Of course, you can ignore all the suggestions for the fuses and other components and just wire the ACR directly to everything.
jimh posted 05-23-2011 08:41 AM ET (US)     Profile for jimh  Send Email to jimh     
For a dual-output AC-operated battery charger, I like the PROMARINER chargers with 4-Ampere or 5-Ampere output. They typically are selling for about $100 on promotion this time of the year. I have one installed on my boat, and I have found it to be a very valuable addition to the electrical system. My routine for use of the boat typically has the boat sitting idle for several weeks between service. Before heading out with the boat, I always let the charger run for several hours to make sure the batteries are at full charge. If I had a storage location with access to AC-power, I not sure I would leave it plugged-in all the time. Usually a few hours is enough to top-off the battery charge.

Here is a link to one of the typical models available:

http://www.pmariner.com/productFeature.php?ProductNum=31310

These same type of charger seems to be sold at big outlets like CABELA'S or BASS PRO SHOP with a private label branding, too.

jharrell posted 05-23-2011 11:26 AM ET (US)     Profile for jharrell    
From what a I gathered doing research on the [Blue Sea Systes] add-a-battery system, the only fuse they really consider required is the 10amp inline from the ground to negative, which was not included in the kit and cost under $10 I believe for wire lead an fuse. This prevents an internal short to ground from starting a fire. I also had to make short 12" #4 leads from the switch to ACR, although #6 would have been sufficient.

The large fuses that are recommended on the positive leads because it would be wise to have them only if the ACR is installed some distance from the switch/battery and those leads have the potential to be shorted to negative say on the metal frame of an aluminum boat as it passes through rigging openings etc.

Putting those large fuses on short leads from the positive of the battery would be akin to putting large fuses on the main leads to the switch and starting circuit. It technically is safer, but the odds of a short to negative over such a short distance with proper securing of wires is almost non existent and about the same as the possibility of the main leads shorting.

I purchased a single bank 6amp Guest intelligent charger: http://www.marinco.com/product/6-amp-single-output-ics-battery-charger which so far has worked very well in this setup.

I plan on adding a green LED in the dash that plugs into a status LED lead on the ACR, this would illuminate when teh ACR is engaged letting me know the engine charging circuit is functional while underway and that my charger is functional while in the garage.

pcrussell50 posted 05-23-2011 01:12 PM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
quote:
If I had a storage location with access to AC-power, I not sure I would leave it plugged-in all the time. Usually a few hours is enough to top-off the battery charge.

Here is a link to one of the typical models available:

http://www.pmariner.com/productFeature.php?ProductNum=31310

These same type of charger seems to be sold at big outlets like CABELA'S or BASS PRO SHOP with a private label branding, too.


Thanks Jim. The price on those is more reasonable than I expected, too. I am considering going for it, as I do have the ability to keep AC power on it while in storage.

Jharrel, I'm not blowing off your "system" either. I've been viewing your photo gallery multiple times. It and your posts are very informative. It's just that for maintenance charging, (thanks to Jim's explanation), I like the idea of having a charging source for each battery, whether it's from a single charger with dual outputs or two small chargers. That's just maintenance charging. For charging while underway, you have convinced me to put my ACR back on. I had initially removed it to simplify the wiring situation, since I was not sure what it was for, or if it even worked. Now, I know it does. My outings are 5 minutes from my house, and usually no more than a couple of hours at a time, so the demands put on my batteries are slight. In fact, if I keep the batteries charged in my driveway I probably don't even need a working alternator on the motor, the way I use this boat.

-Peter

jharrell posted 05-23-2011 01:27 PM ET (US)     Profile for jharrell    
I don't believe a dual bank charger and a ACR are compatible. You either have to do a single bank charger with ACR or dual bank with no ACR.

If you do a dual bank charger with an ACR, the ACR will combine when the charger is on effectively creating a single bank and might be damaging to the charger or at least nullifying the dual bank design.

The only way to do a dual bank charger and ACR would be to put in a manual disconnect switch on the ACR leads that would have to turned off when the charger is plugged in.

The ACR essentially makes two batteries into on big battery as far as the charger is concerned.

I went with the ACR and single bank charger because I wanted the two batteries charged with the engine or the charger without having to manually set any switches.

I don't believe any engines in the 90hp range have dual charging circuits, my old inline 6 certainly does not, so the ACR was the best solution.

pcrussell50 posted 05-23-2011 03:17 PM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
Well, shoot. That throws a bit of a wrench into what I thought I had figured out.

Frankly, I'm shocked that with all the other Montauk owners on here, that either so few use dual batteries, or are too apathetic to post up what solution they use. :(

-Peter

newt posted 05-23-2011 04:25 PM ET (US)     Profile for newt  Send Email to newt     
I have dual batteries, each with a selector switch. I installed a dual bank battery charger wired direct to each battery with a fused connection. It is very simple. I plug the charger in and both batteries get charged regardless of how the selector switches are set. I suppose the only downside is that a malfunction in the charger could somehow connect the two batteries, but other than that the system is simple and works.
pcrussell50 posted 05-23-2011 04:42 PM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
Newt, thanks for pitching in. Couple of questions:

- Does that mean each battery's selector switch choices are, ON or OFF?

- If both batteries are selected to ON, are they connected to each other in parallel?

OR

- Are the batteries each dedicated to a single purpose, one for starting, and one for powering electronics like SONAR and GPS, and they cannot be combined?

Thanks.

-Peter

jimh posted 05-23-2011 08:59 PM ET (US)     Profile for jimh  Send Email to jimh     
Most of the ACR devices have an input which prevents the ACR from operating. You just need to wire a 120-VAC relay across the input to the dual battery charger power input. When the relay is energized by application of 120-VAC to the battery charger the relay contacts are wired to suppress the ACR from operating. This solves the ACR and battery charger problem.
jharrell posted 05-23-2011 11:50 PM ET (US)     Profile for jharrell    
Seems overly complicated to do an ACR and then another relay to control the first just in order to use a dual bank charger when you could go with a less expensive single charger and not try and wire in a high voltage relay.

Is there some great advantage to a dual bank charger that I am missing that would justify the double relay setup?

jimh posted 05-24-2011 07:27 AM ET (US)     Profile for jimh  Send Email to jimh     
In all ACR systems, when the ACR closes the two batteries are wired in parallel. If the goal of the electrical system design was to maintain separation between the HOUSE branch circuit and the ENGINE START branch circuit, this goal is lost when the batteries are put in parallel.

With a single low-current charging source, two batteries, and an ACR, the charger will first charge the primary battery until the voltage of that battery rises above the threshold of the ACR. At that point the second battery is connected in parallel. If the terminal voltage of the second battery is lower than the primary battery, the parallel combination of the two will tend to drag the paralleled battery bank voltage down toward that of the second battery. If the resulting voltage is below the ACR threshold, the ACR drops out. Now the primary battery voltage rises, going back above threshold. The cycle repeats.

What will stop the cycle is the charging current from the charger. If the charger has enough capacity, it will supply the charging current needed by the second battery, which will tend to maintain the combined battery voltage above threshold. However, if the charger has only the capacity to supply an ampere or two of current, as would be typical for a maintenance or trickle charger, the charger may not be able to maintain the combined battery voltage above threshold. This will result in the ACR cycling on and off.

ACR manufacturers usually mention the chance for this problem to occur and caution that the charging current source must be able to provide sufficient charging current to prevent the problem. In the case of a low-current maintenance charger, the problem may occur when the battery charge is low in the second battery. If the second battery is the HOUSE battery, it might be common for its state of charge to be low because it has been running the HOUSE loads while there was no charging current available from the engine.

As I have described above, this is the problem with using a low-current charging source with an ACR.

bluewaterpirate posted 05-24-2011 08:22 AM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Like newt, I have my Guest battery charger connected directly to each battery. I could have wired thru my BEP 716 but chose not to.


Install is on my 210 Ventura.

http://i676.photobucket.com/albums/vv129/bluewaterpirate/ Batteries%20545%20BEP%20716/BEP7162.jpg?t=1306239340

http://i676.photobucket.com/albums/vv129/bluewaterpirate/ Batteries%20545%20BEP%20716/BatteriesConfig-1.jpg?t=1306239287

http://i676.photobucket.com/albums/vv129/bluewaterpirate/ Batteries%20545%20BEP%20716/BatteriesConfig1-1.jpg?t=1306239309

I've changed battery brands to Odyssey/Sears.

http://i676.photobucket.com/albums/vv129/bluewaterpirate/ Batteries%20545%20BEP%20716/Odessey2.jpg?t=1306239391

http://i676.photobucket.com/albums/vv129/bluewaterpirate/ Two%20of%20a%20Kind%20Electronic%20and%20Fishing%20Upgrades/6. jpg?t=1306239543

Guest charger ......

http://cdn-2-service.phanfare.com/images/ 4892322_2160096_31023135_WebLarge_3/ Image-4892322-31023135-3-WebLarge_0_858092937b15aa0df60ce7fffabfb139_1

http://cdn-2-service.phanfare.com/images/4892322_2160096_31023604_Web_3/ Image-4892322-31023604-2-Web_0_34f0dfcc2dfb59f684cf12c608406386_1

http://cdn-2-service.phanfare.com/images/4892322_2160096_31023602_Web_3/ Image-4892322-31023602-2-Web_0_86a58abf584e4e62447a8090d83535b5_1

Tom

jharrell posted 05-24-2011 10:41 AM ET (US)     Profile for jharrell    
jimh,

quote:
What will stop the cycle is the charging current from the charger. If the charger has enough capacity, it will supply the charging current needed by the second battery, which will tend to maintain the combined battery voltage above threshold. However, if the charger has only the capacity to supply an ampere or two of current, as would be typical for a maintenance or trickle charger, the charger may not be able to maintain the combined battery voltage above threshold. This will result in the ACR cycling on and off.

The low current battery maintainer you linked is listed as being able to maintain a battery up to 250 amp hours in capacity, the two group 24 AGM I have are 79Ah each, so when paralleled through the ACR they create a single battery of 158Ah which is easily within the low current chargers specifications.

To exceed the small chargers capacity you would have to go larger than two typical group 31 AGM, this would be unlikely in a smaller boat but something to consider if planning this setup.

ACR such as the [one made by Blue Sea Systems] typically have a certain amount of hysteresis to prevent short term voltage fluctuation from causing relay chatter.

Even so I would recommend a larger capacity charger such as the 6amp Guest I used if going with a ACR as it will go into a "bulk" mode until both batteries a fully charge then fallback to "float" mode to maintain. I have never seen the ACR cycle in my setup.


bluewaterpirate,

It is interesting that you are using a dual bank guest charger and the BEP cluster with ACR/VSR.

Do you have some provision to prevent the ACR from paralleling the two batteries when the charger in on, or does the guest charger simple act as a 20 amp single bank charger?

bluewaterpirate posted 05-24-2011 12:36 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
The guest is a 20 amp charger. It has two seperate charging leads 10 amps going to each battery. The normal position for the BEP is Off/Off/Not Paralleled. Even if I have both the start/house battery on the Guest will charge at 10 amps per battery. Now if I set the BEP Parallel switch to on the VSR works as advertised.

Tom

jharrell posted 05-24-2011 01:10 PM ET (US)     Profile for jharrell    
It looks like the BEP cluster ties the ACR to the engine side of it's separate engine on off switch.

http://www.bepmarine.com/media/product/pro4c27c7b7be28f.pdf

This would prevent paralleling so long as the engine switch is in the off position. The other side of the ACR is tied to the battery side of the house switch, so that switch has no effect on the ACR.

In doing so this does prevent one from using a single bank charger with the BEP cluster unless you leave the engine switch on. So it looks as though they prefer you to use a dual bank charger.

I did look at the BEP cluster instead of the [one made by Blue Sea Systems] I liked the fact that it was an all in one unit, so no leads need to be made between the ACR and switches (and no large fuses are even possible let alone recommend between them).

However I liked the single switch design and general build quality of the [products made by Blue Sea Systems] more.

jharrell posted 05-24-2011 01:21 PM ET (US)     Profile for jharrell    
It is interesting that BEP mentions charger hookup in the install manual:

"Battery Charger:
Connect the battery charger positive output to terminal A. The house battery switch can be off but the engine battery switch must be on when leaving the boat. This allows the VSR to engage and charge both batteries."

http://www.bepmarine.com/media/product/pro4cd73148082df.pdf

They do no mention a dual bank charger hookup.

bluewaterpirate posted 05-24-2011 01:34 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
My BEP 716 has been running strong for over five years now & has never missed a beat. Not one issue. BlueSea stuff is good too.
pcrussell50 posted 05-24-2011 01:34 PM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
I hate to throw out a post with no tech value, in a tech-oriented thread, but this has been a GREAT read for me. Thanks, and keep it up, guys.

-Peter

newt posted 05-25-2011 09:07 AM ET (US)     Profile for newt  Send Email to newt     
My batteries are wired similar to this diagram:

http://continuouswave.com/whaler/reference/graphics/wiring485x347.gif

Either engine can be started from either battery. The house loads can be drawn from either battery and the batteries can be combined if needed.

pcrussell50 posted 05-25-2011 10:58 AM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
That diagram is for the case of dual outboard motors. Do you run dual outboards? If so, I missed it.

-Peter

themclos posted 05-25-2011 11:08 AM ET (US)     Profile for themclos  Send Email to themclos     
I have mirrored Tom's (bluewaterpirate) approach with my 22 Outrage Cuddy, partly because we share the same motor, but primarily because I viewed his entire electrical setup as the best documented, most easily maintained system for a small boat which I have found.

This winter, I rewired the entire boat, and added a second battery, while moving both batteries to the console.

I am using the BEP 716, as well, and a Blue Sea Systems fuse box.

I have the Guest 2620A, wired directly to both batteries.

Like Jimh, I trailer my boat, and it may sit for a few weeks between outings. I run an extension cord to the Guest outlet, and leave it powered on overnight before I head out.

The addition of the Guest battery charger, has greatly facilitated battery maintenance for me.

Dan

jharrell posted 05-25-2011 11:41 AM ET (US)     Profile for jharrell    
I believe I was incorrect in stating that a dual bank charger is incompatible with an ACR. Blue Sea Systems has some excellent technical documents on their equipment including one specifically related to dual bank chargers:

http://bluesea.com/viewresource/94

I don't know how well this would apply to two independent low current "maintainer" chargers however.

However in another document they do discuss that it a single bank charger is a good solution with an ACR:

"Why do I need an ACR? An ACR allows two battery banks to be connected so that they can share the output of a single charge source, allowing the user to charge more battery banks than the number of charging outputs. For example, an ACR can be used with a single-output charger, resulting in a simpler system at lower cost than a dual-output charger."

http://bluesea.com/viewresource/1366

DeeVee posted 05-25-2011 12:57 PM ET (US)     Profile for DeeVee  Send Email to DeeVee     
One thing I have always kept in mind when connecting both batteries to one charger, is that the batteries should be identical for good charging results to both batteries.

In other words, a deep cycle house battery may not charge at the same rate as a starting battery.

I have my house battery isolated completely from the starting battery using the BEP switch/voltage sensing relay cluster. The two batteries are never connected together for charging purposes. The BEP switch cluster incorporates a third switch which could provide emegergency power from the house battery to the starting battery if I should ever need it.

I have a two bank on board charger/maintainer that is always plugged in while the boat is at home on the trailer. While the boat is in use, the BEP voltage sensing relay ensures that the starting battery is always charged first. Once the VSR senses that the starting battery is at full voltage, then it allows voltage to the house battery.

I have not experienced any electrical problems with this set up (knock on wood) since installing it 3 years ago.

Doug Vazquez

jharrell posted 05-25-2011 03:19 PM ET (US)     Profile for jharrell    
It is correct that different battery types respond better to different charge profiles. In fact it is noted that gel batteries should not be connected with flooded or AGM batteries because of their special charging needs.

However it's seems Flooded and AGM's can be mixed without issue.

I went with matching dual purpose AGM's for my setup.

As far as deep cycle and starting needing different charge rates, most dual bank chargers do not have separate charge profiles for each output, instead the last battery to reach capacity will dictate when the charger goes from bulk to absorb to float, so it has little value over a single bank if using an ACR.

Remember your engine is essentially a single bank charger unless you have an engine with two outputs(or two engines). A single bank charger will act just like a running engine in the system.

newt posted 05-25-2011 04:19 PM ET (US)     Profile for newt  Send Email to newt     
Peter, yes I run dual outboards.
jimh posted 05-26-2011 04:32 AM ET (US)     Profile for jimh  Send Email to jimh     
jharrell make the following observation regarding low-current battery chargers in regard to use with automatic battery management devices:

quote:
The low current battery maintainer [jimh] linked is listed as being able to maintain a battery up to 250 amp hours in capacity, the two group 24 AGM I have are 79Ah each, so when paralleled through the ACR they create a single battery of 158Ah which is easily within the low current chargers specifications.

I believe jharrell is making an incorrect inference. Because the manufacturer of the low-current charger says it will be useful in maintaining a precision float charge on a battery of up to 250-Ah, one should not infer that this means such a charger will always keep the terminal voltage of such a battery above the threshold of an automatic battery management combiner system. If you connect a deeply discharged battery to a 1.5-Ampere charger (such as the one I mentioned previously) I would not expect that it will immediately pull the terminal voltage above the ON threshold of the automatic device. Exactly what will happen with the combination of a deeply discharged battery, a freshly charged battery, and the 1.5-Ampere charger is difficult to predict. Typically the manufacturers of automatic battery management devices give specifications about the amount of charging current which is needed to produce reliable operation without excessive ON-OFF state chatter. I would consider those recommendations in selecting the current capacity of a charger to be used in conjunction with an automatic device.

jharrell posted 05-26-2011 01:07 PM ET (US)     Profile for jharrell    
perhaps I misread your statement on the low current charger, you said: "However, if the charger has only the capacity to supply an ampere or two of current, as would be typical for a maintenance or trickle charger, the charger may not be able to maintain the combined battery voltage above threshold. "

I interpreted this to mean the low current charger might not be able to maintain terminal voltage above the disconnect threshold causing and endless cycle in the ACR.

Since the lower current charger has the ability to maintain a 250 Ah battery at 13.4v float, it should have no trouble preventing a VSR with voltage only hysteresis from chattering after the short equalization period, whereby a more deeply discharge battery that is paralleled through a ACR will pull a large current from the other charged battery.

During this short equalization period even a large 20amp charger may have trouble keeping up with current a discharged battery will pull through the ACR from the other battery which could be over a 100amps.

This is why I like the Blue Sea Systems ACR, it's hysteresis forces it to stay closes for at least 10 seconds, and for another 20 seconds so long as the voltage is above 12.35v. This gives the system a time to equalize without chatter even when one battery is much more discharged than the other regardless of charger size.

It seems the BEP VSR only has a voltage based hysteresis and would suffer from chatter if one battery is more discharged than the other and could be exacerbated by a low current charger. However after the system equalizes the BEP VSR stop chattering even with a low current charger.

jharrell posted 05-26-2011 01:36 PM ET (US)     Profile for jharrell    
Blue Sea Systems does provide a detailed document on the cycling phenomenon with an ACR if anyone wishes to research further: http://bluesea.com/viewresource/527
jharrell posted 05-26-2011 01:37 PM ET (US)     Profile for jharrell    
http://bluesea.com/viewresource/527
jimh posted 05-26-2011 03:25 PM ET (US)     Profile for jimh  Send Email to jimh     
A low-current precision float voltage charger connected to a deeply discharged battery will eventually bring the battery terminal voltage to the fully charged float voltage (around 14-Volts), but it will take a while to get there, perhaps many hours if the battery is deeply discharged and has a high Ampere-hour capacity. I think when the charger manufacturer said it would "maintain" the battery, he meant it would keep it at the fully charged float voltage, once it got there.
pcrussell50 posted 05-28-2011 12:20 AM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
I've used my float chargers on deeply discharged batteries before, in a pinch. It can take days, IIRC. That's often ok with me, as in my line of work, I'm gone for 2-4 days at a time, and I'd just as soon, not have high-current devices running unattended.

-Peter

ericflys posted 10-31-2011 01:07 AM ET (US)     Profile for ericflys  Send Email to ericflys     
I spoke with the engineers at [Blue Sea Systerms], and, if you are running a dual output charger, a good option is to wire the ACR to the house/engine leads side of the switch--yes, you will end up with two terminals on one stud)--instead of directly to the battery. That way when you are charging your batteries while your boat is out of the water, you just leave the switch in the "off" position and let the charger do the work without the ACR being involved, no manual disconnect is required. In some installations, this method of connecting the ACR has other advantages, such as allowing much shorter cable runs if the ACR is connected in close proximity to the switch. I also asked about the fuses, and as jharrell has said they are not necessary. The Blue Sea Systems ACR has internal protection in the advent of a short, however the ACR will be ruined.
jimh posted 10-31-2011 07:15 PM ET (US)     Profile for jimh  Send Email to jimh     
Does Blue Sea Systems have an installation diagram that shows the wiring you describe in your narrative? It is much easier to see wiring in a schematic diagram than to describe it in a narrative. If there is a drawing, we should have a link to it , please.
jharrell posted 11-01-2011 12:56 PM ET (US)     Profile for jharrell    
My ACR is wired to the battery side of the switch instead of the battery terminals. I did this to have just two wires to each battery. This is identical to the factory wiring on the BEP Marine 716 cluster, including the lack of fusing, except for the fuse on the ground wire for the ACR which the BEP system lacks.

The Blue Sea ACR and Switch have large 3/8 studs which have no problem accommodating two terminals per stud.

I have the ACR on the engine side so that I could easily use a single bank charger, the ACR's purpose is to bridge batteries when charging voltage is sensed regardless if the source is an engine or charger, it has worked flawlessly for me in this capacity, allowing me to keep the batteries charged fully in the garage while keeping the electrical system in the boat off on the master switch.

jimh posted 11-01-2011 02:22 PM ET (US)     Profile for jimh  Send Email to jimh     
In order for the ACR to be able to be wired to two batteries on the LOAD side of the switch, you need a double-pole switch. Can we have a diagram of these arrangements. One diagram would be helpful.
jharrell posted 11-01-2011 02:40 PM ET (US)     Profile for jharrell    
The Blue Sea e-Series Dual Circuit Plus™ Battery Switch which is part of the Add-A-Battery kit is in fact double-pole with a third position that bridges the poles as show in it's instruction manual:

http://bluesea.com/files/resources/instructions/5511e_web_version.pdf

Unfortunately I don't have any decent diagramming software installed on this computer or I would put together a quick diagram of my setup. I will try and do that later.

I did however use BEP's 716 cluster as inspiration for my setup and therefore the wiring is identical to their installation diagram on the last page which shows the factory wiring configuration:

http://www.bepmarine.com/media/product/pro4cd73148082df.pdf

The A-B and C-D lugs of their separate single pole switches would be equivalent to Blue Seas 1-2 set of lugs on their double pole switch. The third switch in the 716 with the exposed bonding bars for paralleling is replaced by third position on the Blue Sea switch with and internal bonding mechanism, so the back of the switch simply has 4 3/8 lugs exposed.


jimh posted 11-01-2011 02:59 PM ET (US)     Profile for jimh  Send Email to jimh     
The BEP diagram shows the ACR wired to the battery side of the switches, not the load side (as has been suggested).
ericflys posted 11-01-2011 11:01 PM ET (US)     Profile for ericflys  Send Email to ericflys     
An ACR doesn't care how its wired so long as there is a path to each battery, if that path goes through a switch, or in-between the batteries and the switch, so be it. As per my verbal conversation with the tech support people at Bluesea, there is no downside to such an installation, its more a matter of whether you want the ACR to operate with the the battery switch in the "off" position or not.
jimh posted 11-01-2011 11:46 PM ET (US)     Profile for jimh  Send Email to jimh     
Let me ask again: can we have a sketch or drawing or a link to a formal drawing from Blue Sea Systems that will show how the ACR, the two batteries, and the very necessary two-pole battery switch ought to be wired?

I believe I have gained an understanding from all the narrative explanations, but there is no real substitute for describing a circuit with a diagram. If we had a diagram we could see what is being suggested.

If Blue Sea Systems engineers tell customers how to connect the ACR, the batteries, and the switch over the telephone, you'd think they would be able to send them a diagram or a link to a diagram of the circuit.

ericflys posted 11-02-2011 02:22 AM ET (US)     Profile for ericflys  Send Email to ericflys     
I've seen a bunch of different schematics from Bluesea involving their ACR but they are all pretty basic and don't show the configuration I describe...

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