Multiple house banks
- Thread starter Dblbld
- Start date
If the charger you are talking about is a shore power charger, then the ACR will defeat your attempt to use a multi-output charger for each battery. As soon as the charger is turned on, then ACR will combine the batteries and your charger will just be providing half it's output to each battery, but they will all be connected together anyway.
You want something that is the inverse of an ACR. When the charger is on, then the two batteries would be disconnected and the charger could charge each battery according to it's own need. Once a charging source goes away, the batteries would be combined again.
That's probably a bad idea, and unless you alternator has multiple outputs as well, because it wont work when you're charging with your motor.
Anyway .... if your 2 house batteries are a matched pair, same age, etc., and they're both in good shape, then charging them as a single bank should be just fine, and a lot simpler. The only time you might want to charge them independently would be if they were different types, different ages, or in different conditions (one dying, one good), but you shouldn't be using them in a single bank if that's the case.
BTW, I use an ACR between my starter and house banks. My alternator only has a single output. But, my shore power charger has multiple outputs, and I have wired it up so that when my shore power charger is on, then, via a relay, my ACR is disabled so the shore power charger can charge and maintain the two bank independently.
Chris
You want something that is the inverse of an ACR. When the charger is on, then the two batteries would be disconnected and the charger could charge each battery according to it's own need. Once a charging source goes away, the batteries would be combined again.
That's probably a bad idea, and unless you alternator has multiple outputs as well, because it wont work when you're charging with your motor.
Anyway .... if your 2 house batteries are a matched pair, same age, etc., and they're both in good shape, then charging them as a single bank should be just fine, and a lot simpler. The only time you might want to charge them independently would be if they were different types, different ages, or in different conditions (one dying, one good), but you shouldn't be using them in a single bank if that's the case.
BTW, I use an ACR between my starter and house banks. My alternator only has a single output. But, my shore power charger has multiple outputs, and I have wired it up so that when my shore power charger is on, then, via a relay, my ACR is disabled so the shore power charger can charge and maintain the two bank independently.
Chris
The only advantage is in maintaining a backup as the two batteries when connected together will operate more efficiently and provide a longer useful life. The most common instalation is with the use of a 1,2,Both, Off battery switch. This way you can manually combine or separate the two. The way most use it is to only use one battery at a time alternating their use with every outing to exercise both of them. This way you always keep a battery in reserve to start the diesel. In cold weather or when one battery is down then you can switch to Both to get the extra power. The alternative would be to combine the two together and keep aboard a fully charged portable battery pack for emergencies. Make sure your batteries are the deep cycle type.
A single bank will last longer for a given load scheme. This is due to the total AH taken from a small bank is a greater percentage of the bank total then the same AH taken from a bank that is twice as big. So you don't discharge the bigger bank as deeply and it lasts longer. It also makes the charging two banks with two or more sources issues go away.
The disadvantage is that, as Andy indicated, you don't have a backup. I find that having a written down check list for anchoring, closing up, opening up etc makes this pretty unlikely. You just have to think through how you want to use the bigger bank so you never get into the "can't get the motor started" situation, write it down and when you anchor out or close up the boat you pull out the check list and follow it.
Also helps if the brother-in-law uses the boat and is not as salty as you might like.
Alternately and to give you some additional options, you could wire the two banks with a 3-way switch and leave it on both until you run into (for instance) that long weekend where the sailing was GREAT and you didn't motor much but did make lots of dacories with the 110 AC blender and now don't KNOW if having 1 bank is going to cut it but don't want to run the motor for 3 hours now that you are in that nice little snug harbor and the sun is going down and the first mate is........ you get the idea. In that case just switch to 1 or 2 and you have a reserve for the morning to get the iron spinnaker fired up.
The disadvantage is that, as Andy indicated, you don't have a backup. I find that having a written down check list for anchoring, closing up, opening up etc makes this pretty unlikely. You just have to think through how you want to use the bigger bank so you never get into the "can't get the motor started" situation, write it down and when you anchor out or close up the boat you pull out the check list and follow it.
Also helps if the brother-in-law uses the boat and is not as salty as you might like.
Alternately and to give you some additional options, you could wire the two banks with a 3-way switch and leave it on both until you run into (for instance) that long weekend where the sailing was GREAT and you didn't motor much but did make lots of dacories with the 110 AC blender and now don't KNOW if having 1 bank is going to cut it but don't want to run the motor for 3 hours now that you are in that nice little snug harbor and the sun is going down and the first mate is........ you get the idea. In that case just switch to 1 or 2 and you have a reserve for the morning to get the iron spinnaker fired up.
Are these your only two batteries on-board? Gorup 24's are awfully small for a Catalina 350? They normally come from the factory with two 4D's, if I recall correctly...
Multiple charger outputs to two banks defeats using the ACR between them, so you could wire only one charger output to one bank and let the ACR do the second bank.
An ACR between two separate house banks with a single alternator output to the C post of the 1-2-B switch will charge the second battery when the switch is on #1 or #2. It is the same as putting the switch on the B position.
If your 1-2-B switch is wired as a charge selector switch, with the alternator output (AO) going to the C post, you don't need an ACR, just use B.
You would do much better in combining your two batteries into a bigger house bank, installing a small reserve bank, and using the ACR or an echo charger between the two banks, removing the jumper between the starter and the AO, and removing the AO from the C post and moving it TO the house bank.
Like this: http://forums.catalina.sailboatowners.com/showthread.php?t=137615
Most all battery chargers, until you get into very expensive ones, are still "single output" in terms of the voltage settings. Each output is connected to the same charger/charging algorithm but has a diode or FET that prevents one battery from draining back into another. They are all still "single" in terms of voltage output.
One battery is not going to get 13.2V while the other gets 14.8V unless you have two separate chargers in one case..