Leoma batteries

[hilbert]

Compass Marine says 250 amp for small diesels. So I guess I should order two 5191 terminal fuse block and two 250 amp fuses??

Minimum fuse size for small sailboat diesel AUX engines 8HP to 35HP = 250A

I think that it is too broad a statement.

When in doubt go back to basics.
"Simply put you size the fuse to protect the wire, provided your wire is sufficiently sized." from the same article.
The wire in my circuit is 2 AWG. Using table VI from the article, the allowable ampacity of 2 AWG 75C wire inside engine spaces is 127.5 amps.
That's probably how I selected 125 amps back in 2011 (but I can't remember that far back).

My starter is rated at 1000 watts. Even with a voltage drop down to 10 volts, that would only be a 100 amp draw (1000w/10v = 100amps).
The trip delay of the fuse should be sufficient to handle the inrush current. I do remember that my measurement of the starter current was less than 50 amps in summer conditions.

For a good reference and explanation on these topics and much much more, I recommend Nigel Calder's "Boatowner's Mechanical & Electrical Manual".

[wikakaru]

Thanks Jim. I might change all mine also. Not till I understand what I'm doing. I saw that it's a lot cheaper if I buy the wire and solder the ends on myself. I found some tutorials on wire sizes etc. online. I'm still getting accustomed to using the internet.

Soldering wire connections is considered a bad idea on a boat because soldered connections are brittle and can crack and break with the vibration found on a boat. Check ABYC Standard E-11.

By all means do the job yourself, just not with solder!

Smooth sailing,

[A different] Jim

[JD-MDR]

Thanks "different Jim", I plan to get an estimate from "BestBoatWire" guys, recommended by Frenchy. Or I will get a crimping tool and do it myself .
I ordered Calders boatowners electrical manual but it never came . They sent me a refund after a couple of months. I wonder if its safe to just put the 250 amp fuses in. Trying to figure out all that amp stuff is confusing.

[Keith]

I used crimp connections as well and west marine allows you to use their crimp tools and wire cutters.

Keith

[hilbert]

I wonder if its safe to just put the 250 amp fuses in. Trying to figure out all that amp stuff is confusing.

It is difficult to answer without knowing how everything is wired.
If your battery selector switch can combines two batteries in parallel (each with a 250 amp fuse), then it can deliver up to 500 amps to the downstream wire.
So the devil is in the details.

[JD-MDR]

I cleaned it up a little. Doesnt look like much. I have only one neg cable from batt1 to bat2 to bus to engine block. Both pos bat terminal have a cable to the main switch and another to the ACR and they each have a wire to the charger and another to the volt meter. The house battery also has a wire to the bilge pump. They all have inline fuses. I wanted a cable today for the battery to bus so I bought one from a battery shop. I dont know how good it is from Maney Wire they told me it was tinned and for marine use. He said it was for welders? So unless someone tells me how to improve I will order all new cables the correct length and the terminal fuse blocks with 250 amp fuses. Time for a break. Mechanic hasn’t called yet about my reverse gear and v- drive. Cant go sailing yet. I think I will pull the starter and take it in. Im sure its 42 years old.

[tjr818]

Looks like a sweet mess to me Instead of welding cable, try;
https://www.genuinedealz.com
That have great products, fast delivery, and good information

[Keith]

I wonder if its safe to just put the 250 amp fuses in. Trying to figure out all that amp stuff is confusing.

It is difficult to answer without knowing how everything is wired.
If your battery selector switch can combines two batteries in parallel (each with a 250 amp fuse), then it can deliver up to 500 amps to the downstream wire.
So the devil is in the details.

Hi guys,

You don't need to calculate the current draw of all your electronics or how many batteries you have. The 250 AMP fuse is to protect your battery cable from melting (burning up your boat) if there is a dead short. The experts have determined that for our small diesel vessels you need a 250 AMP fuse within 7" of the positive terminal on each battery.

Keith

[JD-MDR]

I’m holding off on buying cables and fuses till I understand what I’m gonna do. I’m tracing all the wires and putting tape labels. I think I can get rid of a lot of them. The two bars in the first photo are pos and neg. The negs can go to a new bar that is inside by the distribution panel. There are three wires on the pos bar that don’t go thru the main panel: the windlass which came with a 50 amp breaker, vhf, and the switch for the Propane. I found that circuit doesn't have a fuse. I’ll fix that and get a better bar for those pos wires and move it somewhere. The bar in the second photo is the junction for the bilge pump wires. I can crimp all those wires and run them in a harness with all the others that go that direction. The 200 amp breaker is for the distribution panel. I can probably move that inside where my windlass breaker is(just on the other side of that same bulkhead) There is another bar on the port that I think is just a junction for the wire harness for the instrument panel and engine . That one doesn’t bother me now. Maybe I should turn the battery switch around. I put it that way because the old one was like that so I could access it from inside but this new system with the ACR I won't be using it much only to turn it off. It would be safer to turn it around and plug the hole that goes thru the bulkhead . I could also move the charger inside , it has plenty of extra wires. That all would make t a lot less crowded. I'm wondering if I should cut some of the bulkhead to make the battery compartment more accessible but I'm worried about cutting that bulkhead. That bulkhead is so tightly bonded to the hull. Maybe it needs to be extra strong. I was just thinking of cutting about 2-3 inches above the batteries just to make it a little more accessible. I think I will slow down and try do this nicely. Anyway my reverse gear should be ready soon and then I plan to cruise for at least a week. I want to go north maybe even as far as San Francisco. At least to Morro Bay so I can send some photos to Roberto. I know it's one of his favorite places. I've been layed up for at 4 or 5 weeks.

[JD-MDR]

OK I finally got the manual. I ordered one a few months ago but it never came. They said it was lost and sent me a refund. This time I paid for the higher priced one. I'm determined to do this electrical job nicely . The mechanic hasn't got back to me yet about my reverse gear and v-drive. I think they will say they are all backed up because of the virus and the riots etc. I want to sail. I may dive in and paint the lazerette. I'm pretty sure I got the steering systems all set.

[hilbert]

John, I hope that you find this book as helpful as I have (and I only have the 3rd edition).

It has been my repair manual on a number of projects, for example when I refurbished my starter (the pinion assembly froze and would not engage the flywheel):


or when I rebuilt my windlass:


And it is a solid reference on electrical, rigging and many other topics.

[JD-MDR]

I can see the manual will be a lifesaver in repairing things on my own especially in remote places. It's giving me some ideas on how to rewire . I found this fuse block in photo. I think it will be good to replace what I have. when I get everything all figured out I will get all new wires and heat shrink fittings. I'm kinda the trial and error type I keep doing and redoing till I get what I want. I spent about 8 hr on the electrical yesterday. I'm making progress. I'm not posting photo because It doesn't show.

[JD-MDR]

I'm slowly coming along with the wiring. Slowly. I can't wait to finish and post photos. I have a long way to go but I'm getting it figured out. I'm having trouble getting suggestions on what to do with all the wires connected directly to my batteries. I know the cables for the battery switch and ADR need to stay but I have, on both batteries, a wire for the volt meter and wires for the charger (pos and neg) and on one battery I have a wire for the bilge pump. I just thought of putting a separate pos bus for each battery for those things . There is a tag on the charger wires that says to put both the pos and neg wires directly on the battery. I had the neg wires going to a common neg bus. I changed it but I want to put them back on the bus and not on the battery. I can't see whats wrong with that. I will be removing the two ugly bus bars that in the photos and I have a Blue Seas Safety Hub 150 fuse Block. It's gonna be a lot of work . Most of the wires are too messed up with several splices and some will be too short etc. I got a spool of 16/2 Ancor form Defender. I can't wait to tear out all the old wires jammed up above that bulkhead between the deck and liner. My reverse gear and v-drive have been ut for almost two months. I guess they are having problems getting the seals. Probably out of production. The reputable Volvo dealer and his staff haven't responded to my calls. Here is a photo for your entertainment . I got a little cabinet from C-list so I modified the back access for my compass as well. I have to remember not to put anything magnetic near there. I also moved all wires away form that area.

[JD-MDR]

I'm trying. It's still way crowded. I cant get any help everybody has a different opinion. The electronic tech gave me 100 amp fuses for the batteries. I didn't argue. He said that's fine for a 40 amp alternator. He told me to put them on the switch or ADR instead of directly on the battery terminals. I haven't got new cables yet. This boat got along fine for 45 years with a little battery and a couple fuses. Now I have thousands of $ of stuff. I guess with the windlass, the motor driven uto pilot and the GPS chart plotter etc. Its good that I update the charging system. I've also added a VHF, a solenoid for the propane valve , a masthead light and probably a couple more things. Here are a before and now photo. I would appreciate any suggestions on how to improve or correct. Thanks. That harness on the far right is for the instrument panel. I moved it across from the port side. I can't do much with it till I decide where to mount the panel. I think I can loose the 200 amp breaker up on the right since I now have one in the fuse block. I like having the 50 amp one that came with my windlass( its on the inside of the bulkhead) so I can shut off the power and not have it running thru the windlass when I don't need it. My batteries posts are completely clean now only the cables to the switch and ADR and ground.

[JD-MDR]

It really helps just looking at the photo. I moved the charger inside. As I make more room I can spread everything apart more. Then i can make the wires more orderly. I think the power wire on my the harness can go thru the fuse block. No, it comes from the started motor . I guess it needs an inline fuse. I can crimp the others together and wrap the harness up neat.