So, I've finally got my plan. I'm going to use 2 Lifeline group 31's (GPL-31T) in parallel for a house bank and a Lifeline GPL-1400T for a dedicated starting battery. The small size of the 1400 will allow me to get all 3 batteries in the space that's sort of reserved for batteries in my Cal 28-2, under the port settee in the cabin. This will give me a 200 AH house bank and a very adequate starting battery for my little Westerbeke W13A. With my BlueSea "on-off-combine" 2 pole battery switch, this allows dedicated house and starting banks which can be combined if needed. I've read Nigel Calder's "Boatowner's Mechanical and Electrical Manual" and Charlie Wing's "Boatowners Illustrated Electrical Handbook" as well as perusing many different forums, and I still can't find the answers to a couple of questions. 1) Should the paralleling cable between the 2 house battery positives be fused? If so, how big should the fuse be? 2) Where does the fuse go? The ABYC apparently says the fuses should not be in the battery compartment, but this cable never leaves the compartment. 3) For that matter, what wire size should the paralleling wires be? I'm assuming the ABYC has spec'd all this, but I can't find this information anywhere. The ABYC wants $130.00 (non-member price) for a downloadable copy of the spec.
Parallel batteries
- Thread starter Smitty
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OK, here ya go.
1. NO 2. See #1 3. I think you're thinking too much. What size is your cable leading to the starter motor? That'll work. P.S. And ABYC rules do not require a fuse on the starter cable because there is no practical way to do it.
1. NO 2. See #1 3. I think you're thinking too much. What size is your cable leading to the starter motor? That'll work. P.S. And ABYC rules do not require a fuse on the starter cable because there is no practical way to do it.
Battery Maintenance
Fuses are good for maintenance - you just pull them and your battery is isolated. If you are going to fuse - put it on the positive from each battery. Fusing on motor starting is very difficult because of the huge current your starter draws (locked rotor current can be 10x nominal) Personally I would not fuse - 3/8 spin lugs are very easy to remove for maintenance. The following wirring technique should be used - battery 1(+) to the load, battery 2 (-) to the load. Use the same cables for all interconnects. This technique will ensure good current sharing between batteries. Wire size - use the same wire size throughout - this way if one battery looses capacity, the other battery can supply the load through its wires. Do not assume that batteries will share current and go with half the wire guage!
Fuses are good for maintenance - you just pull them and your battery is isolated. If you are going to fuse - put it on the positive from each battery. Fusing on motor starting is very difficult because of the huge current your starter draws (locked rotor current can be 10x nominal) Personally I would not fuse - 3/8 spin lugs are very easy to remove for maintenance. The following wirring technique should be used - battery 1(+) to the load, battery 2 (-) to the load. Use the same cables for all interconnects. This technique will ensure good current sharing between batteries. Wire size - use the same wire size throughout - this way if one battery looses capacity, the other battery can supply the load through its wires. Do not assume that batteries will share current and go with half the wire guage!
Thanks GuyT
Thanks for this information. I'm definitely planning on fusing the positive of the house side. I was not planning on fusing the engine side. Thanks again, -Smitty
Thanks for this information. I'm definitely planning on fusing the positive of the house side. I was not planning on fusing the engine side. Thanks again, -Smitty
Smitty stop a second.
Why 'fuse' coming off of your batteries to the distribution panel? The supply wire to your panel should be protected against abrasion and resultant shorts. What good is a fuse going to do except fail because it's too small or fail because a fastener wiggled lose? Then you've got NOTHING. On a fiberglass boat a 'short' is really hard to do. ABYC used to allow 6' of un-fused panel feed wire. Don't know what it is now, but if you follow good installation procedures, you'll be fine. Now that should fire-up the masses!
Why 'fuse' coming off of your batteries to the distribution panel? The supply wire to your panel should be protected against abrasion and resultant shorts. What good is a fuse going to do except fail because it's too small or fail because a fastener wiggled lose? Then you've got NOTHING. On a fiberglass boat a 'short' is really hard to do. ABYC used to allow 6' of un-fused panel feed wire. Don't know what it is now, but if you follow good installation procedures, you'll be fine. Now that should fire-up the masses!
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