Battery Banks and Charging

[Rustic Charm]

Thanks Everyone, and Dockhead, that link to the Smartguage information pages is brilliant. It's given me really comprehensive information on just about everything in an easy to follow explanation. Thanks all. I'll start designing a new box and putting it all back together now.

[batkins61]

I have a question about using an Echo Charger and putting all charging sources on the house bank, including the alternator. Is it possible that a house bank, particularly as it gets older, might require so much energy to recharge that there is not enough left over to activate the trickle charger to the starter battery?

I could envision a situation where the house bank is not getting fully recharged during daily running time or other charging regime, and repeated starts is slowly depleting the start battery, until you don't have enough to fire the engine in either bank.

Am I being paranoid? Is that a 1000:1 shot? Of course, proper monitoring and vigilance would be the best answer, but is it something to worry about, or at least consider?

I like the idea of the alternator being the primary charging source for the starter battery and, through an appropriate relay, feeling the house bank with any excess, and the reverse for shore/solar/wind power (house bank first, with excess going to the starter battery). That way, as soon as you've started the engine, the starter battery is immediately replenished, and then the house gets charged.

Our situation is much like the OP, weekend sailing with shore power charging during the week. But I worry about the above scenario on an extended cruise, where we are no longer on shore power to top everything up, and are relying on the alternator to keep everything functional.

[btrayfors]

You needn't worry! As batteries age and lose capacity, they still require the same charging voltages. And, under most any scenario, the required cut-in voltage for the EchoCharge (13.0VDC) is reached in just a couple of minutes whatever the charging source: alternator, battery charger, wind or solar panels, etc. Also, keep in mind that the energy consumed from the start battery for the typical startup of a small-to-medium size diesel is less than 1AH. It doesn't take long to replenish the start battery! Bill

[msponer]

Originally Posted by mikefossl

Here's what I have. Just re-done in the last 6 months.

I feel the electrical system, as drawn, is a little odd, and am wondering if that is some new idea of how to do it-- is it tuned for a set of scenarios that a book, the ABYC, or someone else is really concerned about?

My preference is for the switches to make sense without knowing any detail of the wiring behind them, and I don't see a clear mental model for how these switches work. For example, in an electrical fire the House Bank would be set to 2 and the Engine Bank set to Off, which seems arbitrary. And it's missing basic functionality -- there's no way to disconnect all electricity from the engine, to work on it, without pulling the alternator fuse (and setting House to 1 and Engine to Off, also not obvious and half opposite from a fire). And there's no switch configuration that makes the starter battery function as a 'backup bank' to get you home -- you can power the distribution panel to run a minimal electrical load (GPS/propane solenoid/a few lights) with the starter battery, but it won't charge from the solar or alternator, and it won't power the bilge pump. You'd have to hotwire the starter battery to the fuse block to do that keep the 'reserve' system running for more than a day, or to drop the anchor when you get there.

I believe some of the common (or dogmatic) details in boat electrical systems are misguided for voyaging boats. These details are clearly made with an idea of a weekend sailor who wants to "Turn Off" the entire boat at the master switch, while still leaving the battery charger and bilge pump on. I think that in the context of cruising, what you really want is complete and redundant fire safety, and a very straightforward mental model combined with easy operational flexibility that allows the sailor to reconfigure the system to gracefully handle a variety of failure modes. Anyways, I don't think you get that by using what's in the books as a recipe, and I'm really interested in other people who have thought along these lines and designed this kind of detailing into their systems. Maybe there is a past thread here I should be searching.

Also, Dockhead, I take exception with your idea that it doesn't matter if the starter and house banks are the same type. In almost every case both battery banks should be the same type. One needs a separate charging system for each bank to have different types of batteries.

And I also believe that a completely separate alternator and dock side charging system for the starter battery is of dubious benefit, and is a needlessly complex solution to a problem that can be solved in a much more straightforward way than doubling the amount of charging wires, fan belts, DC fuses, AC breakers, charging boxes...

[goboatingnow]

If you go down the echo charge route, which in my view is the best. Then you can mix starter and domestic battery types as you wish. You could have AGMs on the domestic and a sealed VRLA on the starter. It's always best to have the correct battery type per application.

Dave

[Kettlewell]

msponer, there is no single right way to wire your boat, but there are many wrong ways! I spent much free time last winter sketching out various wiring scenarios on pieces of paper--I ended up with a thick folder. It is very worthwhile to do this. When I had purchased the boat six years previously as always I had to rip out a ton of bad old wiring and set it up quickly before I took off on a two-year cruise to the western Caribbean where parts and wire etc. weren't readily available. Considering I had rewired in haste things didn't work out too badly, and I think things were reasonably safe but I still didn't like the configuration. I'm still tweaking the system and I'm on about the third iteration of it. Take your time and work things out. In a nutshell, here is what I have at the moment:
1. A big house bank of deep cycle batteries and a single starter battery.
2. All charging sources connect direct to house bank through appropriate fuses (big one on alternator). This is so that when I leave the boat and turn all systems to off the solar still charges the batteries, and when I am running the engine I can't disconnect the alternator. To work on the alternator it is a matter of one minute to pull the fuse.
3. I have a 1, 2, Both switch that controls where the power comes from for the starter. Position 1 is the normal position connected to the starting battery. Position 2 allows me to start on just the house bank. Both allows me to connect the two banks for starting. Normally I leave this switch Off unless I am actively using the boat.
4. There is a separate On/Off switch (high-amp) next to the 1,2, Both switch. This On/Off switch just turns off or on all the normal loads on the boat, so that when I leave the boat, even for just part of the day, I usually flip this switch to off. Return, just flip it on.
5. I have a Trik-L-Start (cheap version of Echo Charge) that connects with three wires between the house and start bank and keeps the start battery topped up whenever there is charging going on.
6. I also have a small group of items that are basically hard-wired to the batteries through their own small fuse panel. I have found that some things I never want to disconnect: bilge pumps, GPS, VHF radio, and my stereo. The latter electronics lose memory over the winter if they don't remain plugged in, and I have found keeping them plugged in also seems to prolong internal battery life. I think having these things always "on" power is a small risk I am willing to take to avoid worse problems, like sinking from a small leak after turning off the bilge pump circuit.

This system works for me, but it is by no means ideal for you. Just an example. There are many other good ways to do this.

[msponer]

Originally Posted by Kettlewell

msponer, there is no single right way to wire your boat, but there are many wrong ways!

Yes, you're right, I was being a bit pedantic. I do have a completely different idea of what the electrical system should do, so I was a bit quick to think of the drawing as 'wrong' when it just has a much different philosophy.

[goboatingnow]

Msponer

I would suggest an alternative approach, I don't like the 1.2.3 switch stuff

What I have is a battery disconnect on the starter a separate disconnect on the domestic and a third emergency paralleling switch to bring both banks together in an emergency to start the engine.

In normal use I just switch on and off the two switches. ( They are actually remotely operated from the control panel). I also have a small disconnect switch ( manual) and local breakers for contact power feeds. ( I like to have a switch in case I need to disconnect things fast). In the wintertime when she's laid up I kill all three switches.

Charging sources are fed directly to the main battery bus bar, fused and cannot be disconnected by switches. ( to be pernickidy all power sources to battery lines should have fuses at each end of the cables.)

Dave

[Kettlewell]

Go Boating Now, that sounds like a good approach, though I like to be able to start using either the start battery or the house bank, and to be able to run the house with either the house bank or the start bank, without having to connect the two banks directly. The reason for this is that if you get a bad cell or a bad battery in one bank or the other you can instantly cut it out of service and go with the other bank without having to move batteries around or reattach cables, etc. I have had one battery short out internally offshore for some reason, and I was able to instantly switch over to running on the other bank while I sorted out the problem.

[mitiempo]

It's never a good idea to combine a dead bank with a good one, better to have switching that lets you use each bank for either house loads or engine starting.

[btrayfors]

Originally Posted by Kettlewell

Go Boating Now, that sounds like a good approach, though I like to be able to start using either the start battery or the house bank, and to be able to run the house with either the house bank or the start bank, without having to connect the two banks directly. The reason for this is that if you get a bad cell or a bad battery in one bank or the other you can instantly cut it out of service and go with the other bank without having to move batteries around or reattach cables, etc. I have had one battery short out internally offshore for some reason, and I was able to instantly switch over to running on the other bank while I sorted out the problem.

You can do that by connecting the third "jump" switch to the load side of each of the other switches. That way, you can isolate either bank as desired and you can use either battery bank to power the panel and starter. Bill

[Kettlewell]

Bill, I suppose you could, but for some reason I have had less reliability from the standard single switches with the red flag-like removable handles than I have with 1,2, Both switches, which are somewhat sealed. I suppose it just depends on the quality of the switches you can get. But I like the idea of what you propose. Do you have three switches set up like that?

[goboatingnow]

I don't use the cheap red flag handles I use BEP Marine in the past my current remotes are industrial rated relay battery disconnects stated at over 1000 amps.

The 1-2-3 switch is commonly used on sports boats with two batteries, in my experience its two easy to forget to set it right and run the worn set down, especially if one set is smaller then other.

It's never a good idea to combine a dead bank with a good one

now not in general, but in most cases the other bank is not dead dead. ( see jumping car batteries !!)


As to emergency paralleling you can do the post load switch idea, but in reality the vast majority of uses for such switch is that you've run down the domestic and you need a bit of emergency use.

[mitiempo]

Usually it's a 1/2/both/off switch and it is used on most boats from the factory. In a cruising sailboat there is most often a house bank of multiple batteries and a single start battery. If the start battery is down too much to start the engine switching to the house bank works. I can't think of a good reason to combine a good with a drained bank - unless the switching doesn't allow it.

Jumping a car is a different issue, and usually the donor car is running and therefore charging so no problem.

Interesting reading about switch wiring here:1/BOTH/2/OFF Switches Thoughts & Musings - SailboatOwners.com

[btrayfors]

Originally Posted by Kettlewell

Bill, I suppose you could, but for some reason I have had less reliability from the standard single switches with the red flag-like removable handles than I have with 1,2, Both switches, which are somewhat sealed. I suppose it just depends on the quality of the switches you can get. But I like the idea of what you propose. Do you have three switches set up like that?

I've found that the Blue Sea Systems #6006 ON-OFF switches are great. Low cost, very robust, small, and can be flush or face mounted.

No, unfortunately my boat doesn't have this setup. I've tried to pretty much make an existing not-so-favorable situation better. My house bank is split between port and starboard sides, with two T-105's on the starboard side and, about 10' away, four T-105's on the port side. These are each connected to a very robust 1-2-Both-Off switch with 1/0 cable. The switch is left in the Both position to run the two banks as one. Not the best arrangement, but it's worked for me for almost 20 years.

My Group 31 engine start battery battery also goes to a 1-2-Both-Off switch. Normally, it's used in the #1 position when using the engine. The #2 position jumps the start battery to the house battery circuit in emergencies. I've only needed to use it once in many years, but it was convenient when I did have to start the engine with the house batteries.

I do favor the use of simple ON-OFF switches, though, since they're easier to understand and help to avoid user errors. One for the engine starting circuit. One for the house circuit. Depending on the battery locations, a simple jumper cable might be kept handy for emergencies, avoiding the need for a third switch or a 1-2-Both-Off switch.

I have implemented this system on a number of client boats, and they tend to like it very much.

Bill