OMG, shortening the battery cables... Inverter in engine room.

Often the choice is not available vice design size of the boat. Assuming you don't choice then the question is which inverter. Windlass/bow thruster run an inverted A/C line to the bank for the windlass/Thruster and plug in a small charger there.
You should read the manufacturers recommendations for inverters and pay special attention to the temperature performance ratings provided, especially shutdown temperature. Victrons tolerate higher temperatures than Magnums however all inverters output degrades as temperature increases. Some are very particular and specify minimum clearances for any compartment that the inverter is placed. Work around is very good positive ventilation for the engine room/space. We had ours in the engine room and added extra positive ventilation( two Delta T 350 cfm 12 volt fans) and we were good. YMMV
Good Luck,

This is an easy one.. If the Microwave really does operate at 1000W @ 120VAC, then the load on the batteries is 1000 divided by 12VDC, which is 83 Amps, actually it works out a little bit more considering the loses in the Inverter, & other losses...say 90 Amps.. So the system is working correctly.. Changing battery cable length, etc, won't help.. You can't fight Ohm's Law.. Seeing that the Duty cycle is small, lets say you run it 2 minutes, that's. 60 minutes, divided by 2 minutes equals only 30 Watt Hours, which your charger should recover in no time.


Same for engine Start. Say that the engine draws 350 amps on starting, for 20 seconds, that' 3600 seconds divided by 20 equals 180 Watt Hours, which is nothing, & easily recoverable..



In looking at any load, always convert to Watt Hours to se how much POWER you are actually consuming............ Ken Ongemach BSEE

I have a question triggered by one of the comments in this thread. Question: if you have a cable running between a battery and a load and the load is actually greater than what that cable should be carrying is it ok to run another cable, same size as the original, parallel to the original with the result being the capacity of both cables is adequate to carry the load...is this solution ok?? Is it code compliant? Thanks

Ken Ongemach said:

This is an easy one.. If the Microwave really does operate at 1000W @ 120VAC, then the load on the batteries is 1000 divided by 12VDC, which is 83 Amps, actually it works out a little bit more considering the loses in the Inverter, & other losses...say 90 Amps.. So the system is working correctly.. Changing battery cable length, etc, won't help.. You can't fight Ohm's Law.. Seeing that the Duty cycle is small, lets say you run it 2 minutes, that's. 60 minutes, divided by 2 minutes equals only 30 Watt Hours, which your charger should recover in no time.


Same for engine Start. Say that the engine draws 350 amps on starting, for 20 seconds, that' 3600 seconds divided by 20 equals 180 Watt Hours, which is nothing, & easily recoverable..



In looking at any load, always convert to Watt Hours to se how much POWER you are actually consuming............ Ken Ongemach BSEE

Click to expand...

Yes, the microwave should be very doable, the total load after overhead and losses should be in the 100-110ish amp range at 12 volts.

It's not working correctly now, it was pulling 188 amps and only getting 10.5 volts to the inverter when I shut off the microwave.

Ken Ongemach said:

This is an easy one.. If the Microwave really does operate at 1000W @ 120VAC, then the load on the batteries is 1000 divided by 12VDC, which is 83 Amps, actually it works out a little bit more considering the loses in the Inverter, & other losses...say 90 Amps.. So the system is working correctly.. Changing battery cable length, etc, won't help.. You can't fight Ohm's Law.. Seeing that the Duty cycle is small, lets say you run it 2 minutes, that's. 60 minutes, divided by 2 minutes equals only 30 Watt Hours, which your charger should recover in no time.


Same for engine Start. Say that the engine draws 350 amps on starting, for 20 seconds, that' 3600 seconds divided by 20 equals 180 Watt Hours, which is nothing, & easily recoverable..



In looking at any load, always convert to Watt Hours to se how much POWER you are actually consuming............ Ken Ongemach BSEE

Click to expand...

"Same for engine Start. Say that the engine draws 350 amps on starting, for 20 seconds, that' 3600 seconds divided by 20 equals 180 Watt Hours, which is nothing, & easily recoverable.. "

This is exactly why I am a proponent of not having dedicated engine start batteries. The demand on a decent-sized house bank is virtually nothing. Ken cited a 20-second start as an example. My engines start within three seconds, even when very cold (40 degrees). And, no, I am not worried about a no-start if I run my batteries down in an anchorage. Who does that anyway? Even so, I have my generators' start batteries as a back-up, or, I can run the generators while I have breaksfast.

I’m considering just that - removing the individual start batteries and expanding my house bank into that space. What’s stopping me is me. One is it works fine the way it is and second my house bank at 440AH works pretty well for our usage which now includes 320w of solar.

Ken

I've had my Victron inverter/charger in the engine room for 10 years. Happy as a clam. I do have good engine room ventilation and run a couple of quiet computer case fans 24/7 to exhaust heat after the engines are off

Upgrading the cables is almost certainly a good idea. Even those that were not undersized to start will have more resistance from corrosion now. Also, clean every end terminal and treat with a good electric terminal grease. There's often more resistance is in the connection not the wire. I use this: https://www.amazon.com/NO-OX-ID-Tube-Special-Grease-Compound/dp/B00HSW341A

If you want to replace the cables yourself, I've been using Genuine-dealz for years. His marine wire quality and price is great. But better he will make up custom cables measured to the inch with your choice of end fittings and shrink tube - adding only about $2 per end.https://www.genuinedealz.com

Ken Ongemach said:

This is an easy one.. If the Microwave really does operate at 1000W @ 120VAC, then the load on the batteries is 1000 divided by 12VDC, which is 83 Amps, actually it works out a little bit more considering the loses in the Inverter, & other losses...say 90 Amps.. So the system is working correctly.. Changing battery cable length, etc, won't help.. You can't fight Ohm's Law.. Seeing that the Duty cycle is small, lets say you run it 2 minutes, that's. 60 minutes, divided by 2 minutes equals only 30 Watt Hours, which your charger should recover in no time.


Same for engine Start. Say that the engine draws 350 amps on starting, for 20 seconds, that' 3600 seconds divided by 20 equals 180 Watt Hours, which is nothing, & easily recoverable..



In looking at any load, always convert to Watt Hours to se how much POWER you are actually consuming............ Ken Ongemach BSEE

Click to expand...

That’s a great post Ken! Clear so even I can understand

Ken, but if get rid of that starting battery and associated wiring and switches, you may be able to double your house bank and help keep it topped up with your solar array. Sure, what you have works, but why not improve?

kchace said:

I’m considering just that - removing the individual start batteries and expanding my house bank into that space. What’s stopping me is me. One is it works fine the way it is and second my house bank at 440AH works pretty well for our usage which now includes 320w of solar.

Ken

Click to expand...

You’re absolutely right. Plus if my current solar setup works out well, I may be able to double it to 640W. Mostly just need to get past my penchant for extreme redundancy. Maybe when it’s time for refreshing batteries it’ll be easier. Maybe next year or so I should swap out 7 year old house and start banks. I have plenty of generator (8k) to bump the charger to 100a which would make sense with a 650ah house bank.

Hmmm, I could get rid of 2 ACRs, their wires and fuses. I HAVE been simplifying battery wiring. This would help....I’ll have to do some measuring.

Ken

ABYC

31.5.5 INSTALLATION AND LOCATION
31.5.5.1.The battery charger, inverter or inverter/charger shall be installed in accordance with the manufacturer’s
instructions.
31.5.5.2 Battery chargers, inverters and inverter/chargers shall be installed:
31.5.5.3 in a ventilated, dry, accessible location,
31.5.5.3.1 where the ambient temperature will not exceed 122°F (50°C) and
31.5.5.3.2 away from heat sources, such as dry engine exhaust manifolds and other heat producing devices.
31.5.5.4 Battery chargers, inverters and inverter/chargers shall:
31.5.5.4.1 have controls which are readily accessible,
31.5.5.4.2 be located so that hinged covers and access plates can be opened,
31.5.5.4.3 be securely fastened to bulkheads or other vessel structural parts and
31.5.5.4.4 be mounted at least two feet (0.609 m) above normal accumulation of bilge water, or protected so it is not
subject to bilge splash.

ranger42c said:

If it helps, I was eventually able to figure out that we could install our inverter/charger above the batteries, not in the engine room

-Chris

Click to expand...

ABYC
10.7.6 Batteries shall not be installed, without an intervening barrier, directly below electrical equipment susceptible to attack from corrosive gasses.

Thanks for that info boatpoker.

boatpoker said:

ABYC
10.7.6 Batteries shall not be installed, without an intervening barrier, directly below electrical equipment susceptible to attack from corrosive gasses.

Click to expand...

Good point. Leads me to clarify that our installation does have an intervening barrier, and the batteries are offset a bit, not directly above the batteries as I suggested earlier.

-Chris

Do I see fuses between the start battery positive terminal and the starter? No, no.

rgano said:

Do I see fuses between the start battery positive terminal and the starter? No, no.

Click to expand...

Yes, yes !

This is one of the very few things I disagree with ABYC.
ABYC exempts starter batteries from fuse protection but if your starter locks up, where do you think that 600amps is going without a fuse ?

Mainesail has an excellent write up on the issue
Battery Bank Fusing

I removed the fuses I had placed in the starter cable when they blew during a need-to-start-now situation, Never again! Fastest change of a battery cable ever. Never an issue thereafter. Did I say never again? Well, never again.

rgano said:

I removed the fuses I had placed in the starter cable when they blew during a need-to-start-now situation, Never again! Fastest change of a battery cable ever. Never an issue thereafter. Did I say never again? Well, never again.

Click to expand...

So what would have happened if the fuse didn't blow ... melted cables, fire, blown up battery ?

Battery switch? What they were designed for?

Don't get me wrong....I have the fuse to satisfy the girly men ( politically incorrect).....but this is a clear suggestion that boat owners are dumber than rocks. While mostly true, I prefer that I and some others are not included.

boatpoker said:

So what would have happened if the fuse didn't blow ... melted cables, fire, blown up battery ?

Click to expand...

I'll tell you what happened, the engine started and continued to start for another 23 years, every time I pressed the button. That good enough? And I have not seen fuses in any starting cable in any of the many boats I climbed around since.

rgano said:

I'll tell you what happened, the engine started and continued to start for another 23 years, every time I pressed the button. That good enough? And I have not seen fuses in any starting cable in any of the many boats I climbed around since.

Click to expand...

So what caused fuse to blow ?

psneeld said:

Battery switch? What they were designed for?

Don't get me wrong....I have the fuse but this is a clear suggestion that boat owners are dumber than rocks. While mostly true, I prefer that I and some others are not included.

Click to expand...

I guess that woiuld work if you were standing right next to the switch and knew that the cables were about to melt.

boatpoker said:

So what caused fuse to blow ?

Click to expand...

Never did know. Maybe fuse too small. So long ago, I don't recall. Just made a believer out of me that start cables be short and uninterrupted, just like ABYC sez.

boatpoker said:

I guess that woiuld work if you were standing right next to the switch and knew that the cables were about to melt.

Click to expand...

Not really....monitor start battery voltage and if it doesn't return after releasing start switch...shut down engine and turn off battery switch.....or just listen carefully.

Worked for decades before the ABYC.....but true that some modern boaters can't handle some important decisions and why the ABYC requires us all to wear diapers.

psneeld said:

Not really....monitor start battery voltage and if it doesn't return after releasing start switch...shut down engine and turn off battery switch.....or just listen carefully.

Worked for decades before the ABYC.....but true that some modern boaters can't handle some important decisions and why the ABYC requires us all to wear diapers.

Click to expand...

Around 75% of powerboats that I see, the battery switches are in the engine compartment which has always struck me curious since the majority of boat fires start in the DC wiring in the engine compartment.
I'd think thats the last hatch you'd want to open to get to a battery switch.

boatpoker said:

Around 75% of powerboats that I see, the battery switches are in the engine compartment which has always struck me curious since the vast majority of boat fires start in the DC wiring in the engine compartment.
I'd think thats the last hatch you'd want to open to get to a battery switch.

Click to expand...

Having had some starters stuck on...its no big deal if wired properly to begin with and if the battery switch is accessible without breaking into a vault.

Not every overheated wire or cable, or starter turns into a raging inferno in just a few minutes...which is plenty of time to get to many battery switches and turn them off.

Sure...like I said...some clueless boaters or really poorly laid out electrical systems are dangerous...but TF tends to focus on the extreme versus the typical.

Scott, totally agree with you on the ABYC. They have devolved into an organization in search of "problems" to solve, however remote the possibility, all to keep us safe. My pet peeve is the requirement for a metal heat shield for the plastic sight bowl on the bottom of Racor filter assemblies. Never mind that more than half of the bowl is still exposed to heat and any fire hot enough to melt that exposed portion will come from a fire so fully-involved that the boat would be long-since doomed to total loss. In my opinion this is a perfect example of the ABYC diaper mentality. But, no doubt ABYC will continue to try to stay relevant.

psneeld said:

Not really....monitor start battery voltage and if it doesn't return after releasing start switch...shut down engine and turn off battery switch.....or just listen carefully.

Worked for decades before the ABYC.....but true that some modern boaters can't handle some important decisions and why the ABYC requires us all to wear diapers.

Click to expand...

Seeing how the fire is already started. How about bilge pump fuses, breakers, or not at all? Maybe no fuse on the secondary/ back up pump?

boatpoker said:

Around 75% of powerboats that I see, the battery switches are in the engine compartment which has always struck me curious since the majority of boat fires start in the DC wiring in the engine compartment.
I'd think thats the last hatch you'd want to open to get to a battery switch.

Click to expand...

I'm a believer in both fuses and being able to turn off the power from the the outside of whatever I'm working on. Many years of working on various and sundry machines have taught me that lesson. That's why codes require the main breaker on a house is on the outside.

Somewhere in my boat's history an owner decided the battery switch (1,2,both,off) needed to be at the helm too.

That choice though was put into practice by using a start circuit that included roughly a 40' plus round trip for the start power and a fair number of other wiring choices that became 'convenient' because of that.

Battery switch availability and cable length are the big drivers that got me thinking about using relays and timers as the 'battery switches' for the start, windlass, and thruster circuits. The default setting for each battery switch (the relay) becomes 'battery off' and the cable lengths can be minimized.

One big advantage of using relays as the battery switches is that the 'battery control switches/timers' can be installed anywhere easily using small gauge wire. Cabin and flybridge and even in the engine room.

One example of why I like fuses and intrinsically off setups is that the seller of my boat had to discount the price because the windlass melted down a day or two before we completed the sale for lack of proper fusing and because of a manual battery switch at the helm being bumped into to the 'on' position, it's mounted close to the helmsman's right foot, and very likely a passenger on the boat stepping on the unprotected windlass control switch on the foredeck as they admired a beautiful day on the Hood Canal.







Stupid stuff happens when systems are poorly thought through and they don't have fail safes.

Now, who would do any of those things? What is your point?

Cigatoo said:

Seeing how the fire is already started. How about bilge pump fuses, breakers, or not at all? Maybe no fuse on the secondary/ back up pump?

Click to expand...