Which battery is the bilge pump hooked up to?

[elk]

I'm thinking it's battery 1, and that it's hooked up to battery 1 even when the battery switch is in the off position. Which means to me, that I could hook up my solar controller to the battery switch common and it would always be connected to a battery, even in the switch off position.

Am I wrong?

thanks,

[R.B.]

I just rewired my switch so my guess is that it would be similar to mine. It was wired directly to the 1 2 Both Off battery switch. The lug behind the number 2 which is the number 1 (arrow on selector points to 1). It is one of the smaller gauge wires attached to the lugs on the back of the switch. The other small gauge wires are for the battery test (amp and volt meters) on the panel.

An easy way for you to test this is to disconnect the positive wire from a battery (one at a time) and then switch the bilge pump to manual while only one battery is connected. Which ever battery runs the pump is your battery. And yes it doesn't matter where the switch is set since the battery wire and the bilge pump wire are attached at the same lug on the switch.

[jonnjones]

Mine is hooked up to battery #1.

[TBOT422]

A related question for all you electrical experts:

Can you wire the bilge pump to multiple DC power sources? Our boat has a DC power supply that runs all DC circuits from the shore power connection when we are at the dock. Consequently we do not run the battery charger all the time since the batteries have no power draw other than the bilge pump if water ends up in the bilge. If left unattended for long periods and the bilge pump runs a lot, battery 1 could theoretically get run down since it is not being constantly charged. I'm thinking of re-wiring the bilge pump to the + bus bar behind the battery switches as well as directly to battery 1. The bus bar receives power from either the DC power supply or whichever battery banks happen to be ON. My thinking is that as long as we have shore power and the DC power supply is on and functioning, the bilge pump could not run down battery 1. However, if we loose shore power, then battery 1 would take over as needed. I'm just not sure whether this would actually accomplish what I am looking for. Would a connection to 2 possible DC power sources actually eliminate the power draw on battery 1 from the bilge pump since it is also connected to it directly? Wouldn't a multiple power source (whether something like our DC power supply or a second battery bank) be better than just hardwired to Battery 1? If the bilge pump is hardwired to Battery 1 and it happens to go bad with a short, wouldn't the bilge pump fail to work?

Thanks

[wolfe10]

Gary,

Sounds to me like you would be "connecting" the DC power supply to the battery bank through the bilge pump wiring UNLESS you use a diode to prevent "back-feeding" the battery.

Most modern 3 stage/smart battery chargers are designed to be left connected to the batteries 24/7. Said another way, they will not over charge the batteries if set up for the batteries in your boat.

That is the way we store our 350 and also how we do the batteries in our diesel motorhome.

Brett

[TBOT422]

Thanks Brett,

I knew there must be some kind of means to 'isolate' the 2 possible power sources. A diode seems to be the right approach if I decide to go that way.

I'm not sure how 'smart' our charger is. It is a Charles 5000SP C-Charger. A few weeks ago, I left it on for 24 hours since we had been out for awhile and I needed to fully charge the batteries. When I checked in the next day, the batteries were pretty warm. I'm not sure whether that is a problem or not, but I know newer chargers have battery temperature sensors. I'm not sure what if any harm would be caused by the batteries being that 'warm' 24/7, but my guess is that it probably isn't great for longevity.

Then there's the issue of outgassing from lead-acid batteries. I have to disable my CO alarm when charging the batteries overnight. I know you are not a big fan of lead-acid batteries in the first place, but that's what most of us are stuck with until it becomes time to replace them.

Am I correct in my assumption that the way the present bilge pump is wired on most Catalinas the bilge pump would not work if there was a failure (short) on Battery 1 (or whichever battery bank the bilge pump happens to be hardwired to)? It seems that we have a single point of failure in only one pump connected to another single point of failure (one battery). I would be more accustomed to having more boot staps than that on something as critical as a bilge pump.

Thanks

[wolfe10]

Gary,

Be sure your Charles charger is properly set for your batteries: http://www.charlesindustries.com/marine ... argers.pdf

Voltage is adjustable depending on battery technology-- see page 6.

Excessive out-gassing is a sign if high charging voltage OR a bad cell in a battery.

What voltage does your charger provide AFTER 24 hours (i.e. float level)?

What batteries do you have?

Brett

[TBOT422]

Brett,

I haven't checked the switch on the Charger, but assume it is set for the lead-acid batteries that were originally installed in the boat at the factory. I guess I should check, but I doubt that it is set incorrectly. It appears that I have to dismount the charger from the wall and look at the switch on the underneath (back) side? I'll look into it over the weekend.

Per the Charles manual (pg 12) the float voltage for the lead-acid setting is 13.6 V @25 deg C (77 deg F). Who knows what it is at near 85 deg F which is where the cabin generally is sitting at the dock. The Charles charger does not monitor the battery temperature itself. I don't see it being adjustable in any other fashion.

Batteries are the 2 original 4D lead-acid batteries installed by Catalina, plus another bank comprised of two 6-V golf cart lead-acid batteries (new Aug 2011), and a forth dedicated 12V lead-acid starting battery (new May 2012). Since the Charles Charger only has 3 charging outputs, there is a SPDT switch installed on one of the Charles outputs that directs the charging to either the starting battery or the golf cart bank. The 4D batteries seem to operate fine, but they are now 6 years old and may not have much life left.

[wolfe10]

Gary,

With a separate 12 VDC starting battery, another option is to combine the two 4D's (connect in parallel) so they become one battery bank and the 12 VDC starting battery is the other.

This is a particularly good option if you run heavy loads on the house batteries http://en.wikipedia.org/wiki/Peukert%27s_law

Brett

[TBOT422]

Brett,

I like that option. It will eliminate my SPDT switch to charge 4 banks, and will let me charge all the batteries at once rather than switching. It will also eliminate one A-B Switch I presently have and simplify my operational procedures. However, I don't see any difference in battery discharge rates per the Wikipedia reference. It seems to me that wiring 2 185 AH batteries into a single 370 AH bank would be no different than having both of the batteries ON via the A-B switch. The load 'sees' a single well of 370 AH in both cases.

Are there any issues with the banks having different capacities? If I combine the 2 4Ds they will have about 370 AH and my golf cart bank will be about 230 AH. Will the Charles Charger be smart enough to put more charge into the larger bank in order to keep the banks balanced? As it is right now, the 3 house banks are similarly sized 185, 185, and 230. Or will the batteries more or less balance themselves when the charger is removed if they are all turned on? (i.e. the bank with a higher charge voltage will essentially 'charge' the bank with the lower voltage until they reach equilibrium).

Thanks

[wolfe10]

Gary,

Basically, Peukert's law says that the higher the amp draw (rate of battery discharge), the fewer amp-hrs a battery bank can provide.

From the link: Peukert's law, presented by the German scientist W. Peukert in 1897, expresses the capacity of a lead–acid battery in terms of the rate at which it is discharged. As the rate increases, the battery's available capacity decreases. If the battery is discharged in a shorter time, with a higher current, the delivered capacity is less.

Said another way, you will get more usable amp-hrs from a larger battery bank than running the same draw on two smaller batteries of the same total capacity. The extreme where Peukert's law comes into play is powering an inverter. Under high-amp inverter conditions, a battery is able to provide substantially less total amp-hrs.

And your charger should bring all batteries (both banks) to the same VOLTAGE-- charge rate (amps) to each will be dependent on depth of discharge.

Brett

[russp]

Hi Gary, one way of thinking about your question is to see the batteries like buckets of water connected to a single tap. If you cross-connect all the buckets the levels will equalize with the more full buckets emptying into the less full. If you turn the tap on they will all fill and keep same level but a big bucket will take more water than a small one.

This only works when the batteries are all of same type an condition. If you connect up a new one in parallel with a nearly dead one the good one will keep trying to charge the dead one.

Russ Peel
Avalon #150

[TBOT422]

Brett,

I seems to me that Peukert's Law would be applicable to a load connected to 2 batteries sequentially not 2 batteries connected simultaneously. It state's that a high current draw will draw down a single battery in less time than it's rating might imply, then swithcing to the second battery it would also draw down in less time. The combined 'life' of the 2 batteries sequentially, would be less than the life of the 2 batteries simultaneously. My point is that it doesn't matter whether the 2 batteries are hardwired into a single bank, or they act as a single bank through the A-B switch. If the A-B switch is set to ALL, the the capacity of BOTH batteries is connected to a single draw point, the main 135 A circuit breaker, through the DC Bus Bar behind the battery switches.

The difference with the Charger is that the Charger does not go through the A-B switches, It is hardwired directly to the positive post of each battery 'bank'.

Using Russ's analogy, assuming there are 2 buckets of water. Each has it's own fill and drain. You could interconnect them directly so that their water levels are the same and run a sinlge drain, or you could connect each drain to an A-B switch before the single drain line. With the A-B switch, you have the choice of draining each bucket independently, or simultaneously. Set in the BOTH position, the water levels will equalize and drain down at the same rate. On the fill side of the equation (the charger), new water is added to each bucket until it is full. Apparently the 'charger' has a 'float guage' to determine how much water is in each bucket. From what Charles has told me, it will charge the most empty bucket until all buckets are equal, then split the charge equally to all buckets until all buckets are full.

Combinging my 2 4D batteries into a single bank will help me resolve the problem with charging my 4 battery banks from the 3 outlet ports of the Charles charger, and simplify some operational confusion as to switching, but it will cost me the flexibility of isolating a specific battery from the system. i.e. If one of the 4Ds developed a short, I would have to switch both of them out of the system rather than just the one bad battery. Last spring I happened to have this problem with my 12V starting battery. It developed some type of problem, that when it was ON, my GPS would kick OFF and ON, other gauges were erratic. I quickly solved the problem by just switching it out of the system, and ran on the other battery banks until I replaced the bad battery.

[wolfe10]

Gary,

Yes, as you suggest, Peukert's Law says you can draw more total amp-hrs from one large battery bank than from the two batteries making up the bank if drawn on separately. And yes, you can make that "large battery bank" with the battery switch to ALL or by hardwiring them in parallel.

And, were one battery to go bad, if hardwired in parallel, you would have to disconnect/rewire to remove the bad battery from the good one.

Again, Peukert's Law is less critical for small electrical loads such as just the refrigerator, but as amp draw goes up, it makes a larger and larger difference in how much total amps you can draw.

Brett