moving batteries forward

THATAWAY had two AGM's on the port side at the back of the hanging locker aft of the dinette.
 
The previous owner of my boat moved the batt's to under the aft dinette seat. I cleaned up the install, and added the windlass solenoid relay.

DSCF0303.jpg

This configuration is very easy to access and work on and provides great weight distribution.

jd
 
Very nice. Is the water tank under that?

Charlie
 
Yes. The factory-installed water tank is under the battery shelf.
 
I have a question related to this topic. Right now I have my house bank (one Group 31 battery) in the starboard lazarette, along with the start battery, battery switch, ACR, busses, battery monitor shunt, main fuse, trim tab electrical unit, etc. Basically just about everything electrical except for the helm bulkhead stuff.

I've been considering moving the house bank forward, for a few reasons:

1) My boat is stern/starboard heavy, and there is not much else to move.

2) While the Group 31 fits, it's so tight that it's a pain to get the battery in and out.

3) I'm okay by ABYC guidelines, but I would still like to fit a fuse to the battery at the post and I don't have the clearance above it to do so.

4) I would like the option of adding a second house battery (once I have the means to charge it properly).

I think I would move the house bank to the storage bin under the port forward seat. I actually could move it to the port aft seat, and then move the water tank forward, but it would not be that big a savings in cable/run length, so probably easier to just keep the water fill/tank as is, and put the batteries forward. In any case, my question is the same either way (yes, I'm getting to it :lol: ).

The question:

What and how much of the "other stuff" that is in the starboard lazarette do I need/want to move? I don't see that compartment ever being used for anything else, because the start battery is there, amongst other things. So it's not like I'm going to clear it out and suddenly have a useful locker. Given that, do I "have" to move anything but the house battery(ies)? Presuming I use the proper sized cable for voltage drop, etc...

A) Can I just have the house bank and its fuses in the new locker, and then let that (long but properly sized and fused) new cable run back to the switch in the lazarette and proceed "as usual" with everything else where it is? Same question with the negative cable: Can I just leave the bus bar, etc. in the lazarette, and electrically "pretend" the battery is nearby presuming adequate cabling?

B) When something like my new windlass calls for the breaker to be "as close to the battery as possible," well, of course even now it would actually be on the downstream side of the switch, not on the battery (although they are close together now). But in my new setup the downstream side of the switch would be a long way from the battery. Presuming the cable size is proper, does that still count as being "near the battery," electrically?

C) I do also have an unswitched power post (between the battery and the switch) for the bilge pumps and battery monitor, so technically the incoming new/big cable would stop there, then to on to the switch. Is this still fine?

I guess the real question is this: If I size the cable/fuses properly, and then put the house bank 12 feet away from everything in the lazarette, then does the system "think" the battery is nearby, because the large cables prevent voltage drop? The other alternative is to move everything, as the photo above shows, but I'd like to know my options first.

Thanks,
Sunbeam
 
There is always some voltage drop--maybe not enough to be significant. When you put batteries into a storage area, this not only decreased the amount of storage, but you have to encase the battery, switches etc--and if you store things above that there are a number of precautions which may have to be taken. Storage area is precious in a C Dory 22. How much difference in the list etc will moving a 58 # (or less) battery. Consider you may also put in some substantial cable, which will be distributed all along that side, and increasing the total weight of the boat.

If you have the battery only 3 feet from the helm, does it make sense, to run cables 12 feet back (the large cable) and then the 16 feet up to the console, or do you run another circuit to the helm directly?
 
Thanks for the info. I'll add some notes/questions:

thataway":3rcwate9 said:
There is always some voltage drop--maybe not enough to be significant.
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Understood. I figured it would be a given that I would size the cable to get the down to an acceptable level.

thataway":3rcwate9 said:
When you put batteries into a storage area, this not only decreased the amount of storage, but you have to encase the battery, switches etc--and if you store things above that there are a number of precautions which may have to be taken.
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True. I have AGM batteries, so from what I can tell, it is okay to have them in the cabin. I would probably build "false floor" above them (that I could pull out at will) so the remaining storage would be useful. Right now it is one very deep "cavern."

thataway":3rcwate9 said:
Storage area is precious in a C Dory 22. How much difference in the list etc will moving a 58 # (or less) battery.
Click to expand...

Well, part of this is that I would like to add a second house battery and solar panel(s) plus controller. So that means more like #140 pounds of batteries. That's about like a person sitting there, and with a person sitting the boat runs better. Also, access where I have the one battery now is difficult, and there is no room at all for a second house battery. Maybe I should have explained that a bit more.

thataway":3rcwate9 said:
Hence Consider you may also put in some substantial cable, which will be distributed all along that side, and increasing the total weight of the boat.
Click to expand...

I initially wrote this idea off for that very reason, but then when I did a rough calculation, I came up with #2 cable (this may not be big enough, it was only a napkin sketch), and it really doesn't add that much weight (proportionately). So I put the idea back on the table. Especially if adding a second battery.

thataway":3rcwate9 said:
If you have the battery only 3 feet from the helm, does it make sense, to run cables 12 feet back (the large cable) and then the 16 feet up to the console, or do you run another circuit to the helm directly?
Click to expand...

Good question. I'm really not sure. There are a lot of components back in the lazarette, and some of them would have to have long cables added because they come from astern (start battery/switch/trim tab components). I'm all for tackling the big sucky project if the outcome is good (I only have to do it once, I always figure), but if it's a horse apiece... well, they are already in place, that lazarette is sort of "fake" anyway (no bottom etc.), and it's a handy place to "one stop shop" for the switch etc. My starting battery would stay there anyway, so I'd not be making it into a propane locker or something else useful. The other thing is that even though it's further, it seems easier to run wires aft from the helm (where there are easy/hidden channels) rather than go "across the stream" to the port side.

So my thought was, if I could properly install two AGM house batteries (around 140#) under a sub-floor in the port seat locker, that would get the weight right where I need it, and my solar controller and cabling could just go right there from the roof. The only "connection" needed (IF this can be done correctly, which is why I'm asking) would be my two honking cables (still a lot lighter than the batteries), and then everything else could stay at "command central" in the lazarette.

Or maybe it doesn't work that way, and I can't have the batteries situated remotely, no matter the cable size? That's what I'm not sure about. I thought maybe that as long as I negated excessive voltage drop with heavy cables, and proper fuses protected that cable run, then everything would "think" it was right by the batteries, and not 14' away (?)

Sunbeam
 
Good points from Bob. If you are moving power forward, and that is the house battery, how much amp movement ability do you need running back again. If the loads are not huge you might be able to use lighter wire such as 4-6g.

I moved all batteries out of our rear hatch and although there are still many wires and connection running through that space, I have moved them all to the walls and the rest is usable for storage. I currently store some waterproof hard and soft containers full of spare parts and rags in there. Lots of space left but could be a damp area if you don't have good hatch seals.

Greg
 
Aurelia":2fda8kta said:
Good points from Bob. If you are moving power forward, and that is the house battery, how much amp movement ability do you need running back again. If the loads are not huge you might be able to use lighter wire such as 4-6g.
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I still have to figure this out. I think I have to account for the possibility of "combining" and starting the engine through these wires, so that is probably the largest draw? I have to get my head back "into" the electrical system on the boat to figure that out (been away from it for some months).

Aurelia":2fda8kta said:
I moved all batteries out of our rear hatch and although there are still many wires and connection running through that space, I have moved them all to the walls and the rest is usable for storage. I currently store some waterproof hard and soft containers full of spare parts and rags in there. Lots of space left but could be a damp area if you don't have good hatch seals.
Click to expand...
That's about what I have, but my batteries are there too. I have the improved (dry) hatch covers, although moisture can still "waft" in from below, potentially. No liquid wet though. I had a goal of having nothing attached to the bottom of that locker (except the battery hold downs) so everything runs around on the "walls" - I have a rounded plastic container in the middle that stores my small battery charger when not in use. It can't really move around and/or destroy anything. With the AGM batteries I was able to keep them off in one corner, which is one reason I chose them.

However.... it is a bit difficult to get to the power posts on them. I could fix that by turning them 180º (and then protecting the exposed terminals, which are now tucked under the edges of the lazarette). I still have two other "things" though: One is that I desperately need weight forward and to port. I could solve that somewhat that by going from my Honda 8 to a Honda 2, but not sure I want to do that (might rather just go to a 6 or something, which will not take off as much weight). The other is that I want to add a solar panel and, potentially, a second house battery. I probably would hold off on the second battery, but I want to have a plan in mind before mounting the solar panel, wiring, and controller. I can't add a second house battery in the lazarette.

So that's a bit more about the whys and wherefores. I just don't know enough to know what I can and can't do. It's like when I designed my cabin: I only came up with designs that I knew how to build (as opposed to someone who could utilize more materials and techniques and would thus be able to think of them and design them). I couldn't plan what I didn't know though (luckily I didn't mind in that case).
 
Sunbeam - regarding your fuse on the battery post dilemma - an inline fuse holder is available that can be mounted anywhere. I have one to protect the Trace invertor on my offgrid system. It is made by Connect Energy - Grass Valley California (530-271-1919ph.530-271-1914fax). The lugs will handle the double aught wire used in my system. The replacement fuses I have been using are a class T 250amp made by Edison part # TJN250. Not sure if they can supply the holder as well. When making your connections do not use dielectric grease until after a dry metal to metal connection has been made and torqued to the required torque. Dielectric compound is designed to prevent the flow of electrical current hence if connections are coated before assembly the resistance can cause excessive heat buildup to the point of a fire at periods of high/prolonged amperage draws.

As for the wiring dilemma - some boaters move their house bank forward to be closer to a large draw such as a bow thruster, windlass, or the galley. If you are only using it for small draws and won't be charging it at large amperages - consider my earlier post. If you are worried about having to "combine" - I carry a small lightweight 8' set of booster cables - if necessary it does not take long to unhook and carry a battery aft for boosting. I guess I'm old school - I still prefer switches over the ACR - I have made them part of my docking/undocking procedure. Tie up - check all gauges - check hours and mileage from the chartplotter - shut off engine after cooling at idle for a few minutes - switch battery from start to house - then readjust dock lines and fenders.

Regards, Rob
 
Thanks, good info.

In thinking about it, if I could isolate my question to one thing it would be this:

If I had my house bank in the forward seat base, and if I had cables large enough to avoid any more voltage drop than I have now with the house battery in the lazarette, then would my components in the lazarette (switch plus everything else) "think" the battery was right there next to them, like it is now? Is there any difference, electrically? (Again, provided cables can be large enough, and of course with fuse at the battery to protect the cable run.)

This is what I can't quite figure out, not being an electrical guru.

Thanks.
 
Your electrical goods in the rear of the boat would be none the wiser. I moved the house bank of two large batteries in our 25 from hatches in the rear transom to the cabinet under the passenger seat on the port side. I put a breaker in the cabinet with them but otherwise just ran large cable rearward to busbars I added next to the other electrical gear and used many of the existing bits and pieces back there. I might call it a "remote" or "offset" house bank for a C-dory.....
 
Thank you, Greg - this is exactly what I was trying to figure out. It *seemed* right, but electrical things are not always as they seem (to me anyway).

I can see a case for moving "the rest of the stuff" up there too, because after all a lot of the electrical goes to the helm area, but then.... the engines and start battery are still aft (plus trim tab HPU and brain), and that lazarette is somewhat inferior to the port seat for many types of stowage. Plus of course all the wiring is already back there. And running it aft from the helm under the gunwale is easier and more roomy than going "across the pond" to the port side. I guess one could make a case for either, if starting from scratch.

I'll have to think about it, but I could see a few positives to moving the house battery forward in my case. This would be under a "sub-floor" in the port seat, so most of it would still be readily available for stowage. I would have the option for a second house battery, and it would help balance the boat (as long as I then don't get a "portly" co-pilot ;)). I would also then have room in the laz for a charger, if I ever decided to add one. Something to think about, anyway.

I guess the next thing would be to calculate cable size from the switch to the batteries. I know how to calculate draws for all of the "normal" things (just did most of them to figure out what size to upgrade my helm feed wire to), but how do I know how much the main engine would draw if I combined the batteries? I'm thinking that is one of the larger loads. Also, for the new windlass, for example. That says it draws 35 amps, so I am sizing my wire accordingly (around a 42 foot round trip, #6 wire). But... do I then have to add the round trip to the batteries and back to that distance, and hence suddenly #6 is not good enough for the run from the switch to the windlass? Or doesn't that "count" for some reason, and so I have to, say, size the windlass wire for a 64 foot round trip instead? This probably is totally obvious to those in the know, I realize.


Since you seem interested in batteries and electrical, have you been following about the LiFePO4 batteries? They certainly look very interesting. Shoot, with one of those at 100 amp hours (which I think are somewhat lighter than an equivalent lead-acid battery), and the ability to discharge to 80%, I wouldn't need a second battery, nor would one contribute as much to my starboard list. I note that AM Solar is now testing them for future sale to "normal people" (vs. techy early adopters). Any thoughts? Input welcome from anyone else too, of course.

Sunbeam
 
Sunbeam":3ib1z01o said:
...and the ability to discharge to 80%...
Click to expand...

Oops, I stated that backwards: Meant to say ability to discharge to 20% (without great harm; of course any battery CAN be discharged that far).
 
If you are connecting your windlass to the battery through the rear set of equipment then look at that round trip and 4-6g wire could work for you. I would also consider just going straight from the forward moved battery directly to the windlass even if you connect the battery rearward for everything else. That would take your largest load and shorten the distance also minimizing the wire loads/size for the run rearward. Just be sure to follow guidelines on required fusing/breakers for the short forward run to the windlass as well.

I don't have personal experience with the LiFePO4 batteries but the potential is something I am watching. The price for larger units is still ridiculously high and the specialty charging requirements are just an added cost. I currently maintain (6) 2 cell Lipo batteries in two sizes for another hobby and while I am impressed and happy with their performance in general, the safety issues during charge and discharge cycles are hard to ignore. Any battery that should be charged in a fire resistant bag or other fuel deprived arrangement, is a little suspect for use in my boat.

Greg
 
Aurelia":1bahe9fi said:
If you are connecting your windlass to the battery through the rear set of equipment then look at that round trip and 4-6g wire could work for you.
Click to expand...

I can't quite figure out the answer that I'm sure is contained here.... So if you don't mind, I'll ask again (perhaps more clearly). I do see what you mean about going straight to the forward batteries with the windlass, and I would probably do that in actual fact; but I still want to get the concept of when wire runs are "on their own" and when they would "add up."

So let's say I still run the windlass wire aft to the starboard lazarette (where I put the Lewmar breaker, and go to the positive bus, and the negative cable to the negative bus). And then let's also say I have the house bank up in the port locker with appropriately heavy cabling leading to the lazarette with all the other electrical gear. Let's say the round trip run from windlass to lazarette and back is 43', and 50' is the limit for #6 cable. So I'm good with #6, but without a lot of distance to spare. And then let's say it's an additional 24' round trip to the batteries (with appropriately heavy cable). Okay, so my question is, does that windlass cable run then "become" 67' round trip, so I then need to use #4 for the run from the windlass to the lazarette? Or does the windlass round trip distance calculation somehow "stop" at the lazarette (I'm not sure I see why it would, but that's why I'm asking). I guess I can't see why the whole thing would not be counted as the windlass run, but of course it would be nice if it didn't! Anyway, I want to understand which it is and why.

Interesting to hear your take on the LiFeP04 batteries. I had wondered about the fire angle. A friend is using similar (not sure if the boat type would be any different) batteries in RC airplanes, and yes, a "fire bag" was in evidence. Of course a lead acid battery can have problems too, but I would like the fire hazard of the new tech to be equal to or less than before switching. Sounds pretty promising though!
 
There have been several threads on THT with moving batteries and wire size (happens at least once a month). One recently involved a 30 foot round trip (fairly close to what Sunbeam is going to have). I looked up the cable size for a 90 hp (both Suzuki and Merc) and #2 AWG wire was fine. Another post was thus, calculating the precise voltage drop by wire surface area:

24 feet run of #2 copper @ 200a will drop 1.862 volts ( down and back ); 1/0 gets you down to 1.171 voltage drop; 2/0 is .928 voltage drop.

It is unlikely that you will be using 200 amps starting--more like 125 to 150 on a 90. The person asking went with #1 wire, although most felt that #2 was fine. Don 't forget about fusing--and in this case at least 200 amps.

As far as the windlass, definitely take the cables along the port side of the boat, and use the current wire. You can put the contractor on the port side also, and just run the smaller (#16 to #18 wires from the up/down switch) wires from over the entrance to the forward cabin, along with the single two wires from the battery (+/-) for the console bus bar. (you can tie in your wireless remote any where along the way--either under the console or on the port side of the boat.)

The engine running draw, is pretty well covered because the alternator is running, and voltage will be up--with #2 AWG (or #1 if you wish) there will be minimal voltage drop.

Now you may decide to move the shunt for the Victron, and many of the other items, but leave the bilge pumps etc aft.

One other possibility--and that is to leave your starting battery aft, and move the house battery forward. As I recollect, you have a small starting battery. If you do this, you only need large enough wire to carry the charging current--probably #12 will be fine. (But this done not allow combining the batteries, if the cranking battery dies--if you want that option, you are back up to #2AWG. The other option is to put two group 31 AGM forward, and not use the smaller starting battery.

As for Lithium ion batteries. The Torqueedo has a lithium ion battery, Of course most of the good laptops, and smart phones etc have li ion batteries. On of the RVers (Dr Ron Jones), has his entire house bank of Li ion batteries. His installation is enough to completely run off solar and batteries (including air conditioning) and is experimental. His battery pack is torn down yearly (was every 6 months), and each cell tested. If a cell was low, then it was replaced. Ron is about 4 years into the project now and doing very well. They figure 10 year life span, with good maintenance. One of my neighbors has built a twin trolling motor 16 foot cat, using li ion batteries and solar panels. He has about an 18 mile range, and at 3 knots during daylight, the range becomes unlimited, because the solar energy equals the demand of the motors.

Here's your battery: 12.8 Volts, 160 Amp Hr, 2000 Cranking Amps, 14.750" X 8.186" X 10.813" 50 lbs and cost is only: $2156.00, plus delivery. This is from Summit Business Group. If you want to build your own, from single cell batteries, my neighbor says you can do it for less than half of that--of course you have to figure out a case, hook ups etc….

My personal feeling is that they are too expensive still, but it is getting better. Why not do an experiment for the C Dory clan?
 
Thataway,

Thanks for that information - very, very useful! I would love to try out the LiFeP04 batteries (and would report back of course, presuming I was not on fire ;)). When I was reading I partly got the feeling that this was (now anyway) something for someone who is very "techy" and gets how to build their own battery, figure out a BMS, etc. etc. It was way over my head. But if someone like AM Solar would sell a "pre-boxed" 100 ah battery (or similar) and there was not more likelihood of it bursting into flame than my current AGM batteries, I would love it. And granted, $2500 would be a bit of a choke, but I would certainly pay more than for my AGM (which is around $300 already, since I don't have access to those Sam's Club AGM's, darnit). So if I need two (since I can only run them down to 50%), I can instantly halve the cost of the Li battery, because I can use a smaller bank and run it down to 20%, and then I can maybe halve it again (or more) for the many more cycles they will withstand (presuming I got this all correctly). Plus much less weight and space - I wouldn't even be talking about moving the house bank forward if one, 50# battery could give me 80 amp hours on the hook, for example.

(I did see the 100 ah LiFeP04 battery on display at AM Solar a couple of weeks ago. They are testing it for possible sale to "regular people" like me, and said that so far all looks positive. I didn't specifically ask about fire risk though, and many of the details are over my head, electrically. It really made me start thinking about the possibility of using one on the C-Dory though.)
 
Here it is. Two separate round trips.

The distance from the forward positioned battery back to the rear connections is one round trip. Lets say its 25ft total. If your total loads being demanded from that length are 35 amps, you could use 6-12g wire depending on the % voltage drop you can live with.

The distance from the rear connections to the windlass is another separate round trip assuming there is a "break" in the wire above before connecting forward to the windlass. That break could be a panel or busbar or other post connection of some sort. Lets say this section is 35ft total. If your total loads being demanded from this windlass length are 35 amps, you could use 4-10g wire depending on the % voltage drop you can live with.

You can treat each individual run of wire between connections as a separate round trip when you fact load and distance. But I would personally err on the side of larger for less voltage drop and I think many folks also end of using oversize wire on some intermediate sections because it is what they are already working with. (from battery, 6 inches to breaker as an example)

A repeated point for clarity, So if you had your house bank very close to your rear connections, you could get away with a smaller set of wire from the bank to the rear connections, than you could get away with on the longer round trip to the windlass forward from that location. Longer lengths equal more resistance for the same amp demand.

Not that you would want to skimp, but you could install just the minimum wire gauge needed for each continuous run on a boat, micro-managing each run requirement for maximum cost savings and minimum weight not that I would recommend it.

Please, someone correct me if I missed a detail here.

Greg
 
Another point I always consider but is less often mentioned when determining wire size/length is duration of amp draw. If I will have a high amp draw for very short durations such as shallow water windlass use, I might err on the side of thinner but adequate wire. However, if I was supplying big amps to an inverter for running a toaster oven to cook a pizza for 20 minutes, I would personally oversize that wire to minimize heat buildup over the duration of the draw.

Greg
 
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