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Old 08-22-2018, 04:37 PM   #1
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Project creep now encompasses all new battery wiring

Iíve redone the house wiring and the AC system, but the battery wiring to the primary switch is original. And after wasting most of a day yesterday just trying to run it all down, Iíve decided to rip it all out and start fresh. This whole thing was precipitated by my purchase of an arch and 600w of solar panels to alleviate engine and generator run time on the hook.

The current battery situation is 3 sets of Trojan T-105s, sort of set up in the ď2 for house, 1 for startĒ type configuration, except thereís tons of random stuff just tapped off in random places (of course, unfused.) The two sets for ďhouseĒ have a 1-2-off switch mounted between them. That runs through an unlabeled fuse through a run of unidentified wire and to another 1-2-off switch to join with the ďstartĒ bank (on position 2) which is run with what looks like welding cable (either way itís black for positive.) Iíve just been running everything in the ďallĒ position and pretending itís fine because it works.

The wiring is a hodge-podge of different gauges and types. No two of the battery connects is the same, neither in gauge nor wire type nor length.

So, my current plan is this:

All new battery cables with proper crimps and heat shrink. Each bank will run to an ďon-offĒ switch (through a 150 amp fuse at the battery), which will then join at a covered primary bus bar. This will give me the ability to isolate any one battery pair should there be a problem (bad cell or whatever.) Phase 2 will involve a dedicated starting battery with an echo charger, but for now Iíll just start off the one big bank.

All charging will land on the primary bus bar. Alternator is new (blew up another rebuilt auto one so broke down and upgraded), and so is the 100amp charger (Magnum inverter/charger.) The arch for mounting the solar arrived today, so Iíll have 800w of solar (200w now) when Iím done. Thatís 2 each of 300w panels with their own controllers, and my current 2 each 100w panels in parallel to a third controller.

All cabling will be 2/0 except the run from the inverter/charger, which will be 4/0. I have a nice hydraulic crimper for the ends and a fair amount of experience in using it. I got a smoking deal on two spools of Ancor 2/0, so even though the math works out for 1 gauge, it was cheaper to go this route. Plus I already had the terminals in 2/0 so that saved even more.

House usage has been between 85 and 100 amp hours per day. I am three reading lights away from being all LED lighting, and Iím adding a deep freezer unit which should add another 40-45 amp hours depending on ambient temperature. Iím estimating 150 amp hours per day draw for planning.

The current plan is to cruise down to the Sea of Cortez this winter. Weíll need to be back in a marina every couple of weeks because my sonís school will require him to check in via video-conference regularly. So figure two to three week cruises at a time. The longest weíve done so far was two weeks, and thatís why we ordered the freezer...

Any advice, or anything Iíve missed? Iíll try and take pictures, but sometimes I get on a roll and forget.

Josh
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Old 08-22-2018, 04:45 PM   #2
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Sounds like you have a good handle on the situation. I, therefore suggest you go to Lithium based batteries to challenge yourself.

Or, at least do a wiring diagram on Visio or something for us to poke at.
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Old 08-22-2018, 04:46 PM   #3
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Never a bad choice to go oversize on battery cable. Sometimes it is really easier to just start over. My boat had a really strange charging setup so I understand where you are coming from. Good luck.
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Old 08-22-2018, 04:54 PM   #4
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Greetings,
Mr. q. Project creep?






You've just discovered my middle name. I've come to realise that any project is simply an exercise in adding to "the list". As to your last sentence: "...on a roll" is a GOOD thing.
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Old 08-22-2018, 05:17 PM   #5
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Would think you need at least a couple of more batteries.
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Old 08-22-2018, 05:32 PM   #6
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Is that 150 amp fuse before the starter?
Also check what fuse the Magnum requires between bank and inverter.
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Old 08-23-2018, 02:20 AM   #7
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Fusing the start battery will be a mistake unless its huge - 150 amps is not enough.
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Old 08-23-2018, 09:19 PM   #8
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Fusing the start battery will be a mistake unless its huge - 150 amps is not enough.


Why? The upgraded starter for my motor is rated at 3kw, and the standard one at 1.7kw. Those are worst case numbers, so I should easily be able to start the engine on two of the three sets. As far as I can tell from the data sheet, it seems the 1C current for the T105 is 250amps, so I am hesitant to fuse above that number.

The max rating for 2/0 cable with a 105C temp rating in an engine room, where these will live, is 270amp. I could see bumping up to 250 amp fuses, but not above.

Even that seems like overkill because thereís a bunch of 2 gauge wiring thatís there now. The only large draw items I have are the inverter (267a for five second surge), the SSB (25a transmit max carrier), and the horn (15a when sounding.) Assuming I donít use the microwave and the starter simultaneously, I should easily be under 300a draw, and way below 450a.

I guess there really isnít a reason not to go with the 250a fuses, as it still protects the wire. Iíll go for it.
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Old 08-23-2018, 09:31 PM   #9
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Would think you need at least a couple of more batteries.


Why? Before I added the first two solar panels I could easily go three days in between charging sessions. We run the engine every other day for hot water, so we end up charging about 40-45 amp hours during that. I noticed after I added the 200w of solar I was putting back about half my daily draw just with the panels.

Iím adding another 600w of solar and a freezer. It should be total overkill, even when itís overcast. At 40% depth of discharge Iíll have two full days of discharge capacity at worst case. Why would I need more?
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Old 08-23-2018, 11:32 PM   #10
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The moment you push the starter button the current inrush is significantly higher than 150 amps until the motor reaches its operating speed. You haven't mentioned your engine type, but here's something for you to digest.

That's why.
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Old 08-24-2018, 12:02 AM   #11
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I put 300 amp fuses on a previous boat but that boat had gas engines. I couldnít start my diesels on 300 amps.
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Old 08-24-2018, 06:22 AM   #12
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" 3 sets of Trojan T-105s, sort of set up in the “2 for house, 1 for start” type configuration"


I thought the T105 was a 6v golf cart deep cycle battery , seldom a choice (even paired) as a start battery?
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Old 08-24-2018, 10:40 PM   #13
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" 3 sets of Trojan T-105s, sort of set up in the ď2 for house, 1 for startĒ type configuration"


I thought the T105 was a 6v golf cart deep cycle battery , seldom a choice (even paired) as a start battery?


It is. And it usually isnít...

The project is on hold for a few days as the fates have decided that instead of having days off to work on the boat, I really need to work the next five straight. The good news is that this will fund the project and the addition of a dedicated start battery. Itís the usual story, when you have the time thereís no money, and when you have the money thereís no time...

So the new plan is to use the three sets of Trojans for the house, with 250 amp fuses on each. A dedicated starting battery with an echo charger. Iím thinking a group 31 battery. I can reuse the switch that is currently in between two of the sets of Trojans.

I guess Iíll be able to run the microwave and start the engine after all...

Josh
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Old 09-25-2018, 10:30 PM   #14
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So, the fates decided to really delay this project, as I got deployed up to Northern California for almost three weeks for work. But I got back home yesterday and back to boat work today. It was a pretty good day.

I laid everything out to make sure I had what I needed. With the exception of leaving the new battery monitor at home, everything is here. I measured out the longest of the three positive battery cable runs, and then made all three cables that length. I did the usual label and clear heat shrink, so each end is labeled with whatís on the other end.

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Hereís one of the finished cables. The hydraulic crimper got a workout today, as the interconnects between the 6V batteries were crap, so I made new ones. I also made the short cables that will go between the switches and the positive bus bar. Everything got glue lined heat shrink as well.

Then I started removing the old wiring. I disconnected the battery positives and started back pulling. And thatís when I discovered that all of my loads were on the wrong side of the one existing fuse. Turns out that everything was on the supply side, and the only wire on the fused side was the alternator. It looked right at first, and even the surveyor missed it. Got lucky on that one.

I ended at a good stopping point this evening. I have tomorrow off as well, so my plan is to remove the old alternator, alternator controller, and the rest of the wiring. Iíll mount the new switches and bus bars. I did a dry run mount of the inverter and I really donít like it under the stairs. I think Iím going to try moving it into the storage locker (used to be the shower.) itís the same cable length away, and a bigger air volume for cooling. So hopefully Iíll get the charging system installed, although thatís a pretty ambitious day.
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Old 09-26-2018, 06:23 AM   #15
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"and the only wire on the fused side was the alternator. It looked right at first, and even the surveyor missed it. Got lucky on that one."

You bet a blown fuse while charging usually would cost the alt its diodes .

Be sure to only use rotary switches with field cut offs , so a bad move wont cost the alt.
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Old 09-26-2018, 07:20 AM   #16
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"and the only wire on the fused side was the alternator. It looked right at first, and even the surveyor missed it. Got lucky on that one."

You bet a blown fuse while charging usually would cost the alt its diodes .

Be sure to only use rotary switches with field cut offs , so a bad move wont cost the alt.
I have the one wire 12SI Delco alternators, I think if the single wire comes disconnected nothing will happen to that alternator as it becomes unloaded. I also think some type alternators are more likely to self destruct. I know the old Chrysler car alternators were like that, they fried instantly if disconnected from the battery, but my knowledge is going back a few decades on that.
I have 80 amp blue sea red fuse boxes on the 80 amp alternators. There is no interrupting rotary switch, they are hardwire connected at the rotary switch to the lug that goes to the batteries. I have never seen these alternators need to output more than 50 amps by looking at the ammeters. And they are reliable. The inline fuse protects the wire if it inadvertently shorts to ground. I suppose it also protects the alternator from a dead output short if running.
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Old 09-26-2018, 06:09 PM   #17
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Update as I take a little break from boat yoga in the engine space...

So far, this is the wiring that Iíve removed today:
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Actually, thereís a bit more than that now, as I took that shot before lunch and before I pulled the last battery positive run.

Hereís what the positive switch/ bus bar looks like now. I havenít done the cable management yet, so thatíll be cleaned up. Iíve also been taking the time to remove the sheet metal cable anchors that came original from Taiwan, and Iíll be replacing them with proper cable management.
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That one little guy heading off to the right is the original supply for the house panel. Iíll be replacing that shortly.

Now Iím going to try and get the negative cables made before I have to leave. Doubtful, but Iím off again on Saturday, so I should be able to have house power back by then. Luckily the fridge is dual power so the beer stays cold...

Also, if anyone wants the Heart Interface and alternator regulator, theyíre free (you pay shipping or pick up in SB/Channel Islands) to a good home. Both the battery monitor and regulator shunts are included. Everything works, Iím just going with a different solution.

Josh
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Old 09-26-2018, 07:07 PM   #18
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Greetings,
Mr. q. Atta boy. Looks pretty sweet. Nothing quite as satisfying as cleaning up and upgrading boat wiring. I look forward to pictures of the finished masterpiece.



In spite of the fact that I'm weak on electrics I usually have no problem replacing one wire at a time which is what I did with a previous 1974 MT. I ended up with two, one cubic foot boxes, packed fairly tightly, of redundant/poor/undersized wiring. An unwanted legacy from several DPO's.


Seems I'm going to have some time this winter so I may attack our current vessel's rat's nest...


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Old 10-03-2018, 02:14 PM   #19
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Nice work, Josh! You're rebuilding the electrical backbone of your boat. That will make a huge difference with all the upgrades planned.

FYI, I can start my Perkins 4.236s with a 300A fuse no problem. Each starts from the same single Gp 31. Since it charges from the port alternator, I always start the port engine first and verify the oil press and charge before second (stbd) engine start.

YMMV.
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Old 10-03-2018, 03:47 PM   #20
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I once tried to measure the starting current on a small two cylinder Yanmar with a 200A clamp on meter. It pegged the meter, not just inrush current- it stayed pegged while cranking.


If an alternator that is still turning is quickly disconnected from its load, the voltage will momentarily shoot up and it will fry the diodes. All marine 1,2,all,off switches are make before break to help avoid this. Field current disconnect switches as FF mentioned are probably better.


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