Reply
 
Thread Tools Display Modes
 
Old 05-25-2014, 12:28 PM   #41
Guru
 
City: Tuckerton, NJ
Country: USA
Vessel Name: WIRELESS ONE
Vessel Model: 36 Gulstar MarkII
Join Date: Mar 2011
Posts: 937
That's why 1000 amp shunts are manufactured so the entire vessel including start and engine loads can be used.
Bill
__________________
Advertisement

Billylll is offline   Reply With Quote
Old 05-27-2014, 11:34 PM   #42
Senior Member
 
Brent Hodges's Avatar
 
City: Seabrook, Texas
Country: USA
Vessel Name: Friendship
Vessel Model: Albin 43 Sundeck
Join Date: Oct 2007
Posts: 138
[QUOTE=FF;236369]This way the starting loads don't go through the 150 amp rated bus bar but rather through the higher rated 500 amp shunt.

The starter loads should NEVER be run thru a shunt.
1. too small a load over time,

2. a shunt is basically a measured resistance,

A FUSE is a measured resistance .

Just do what 100% of the boats do and forget about measuring start amperage on the OC.


Timjet is correct. FF is pretty much wrong on on all counts.

It is just fine to run starter loads through a shunt provided the shunt is rated to carry the current. A shunt is a measured resistance, but so small of a resistance that an engine starter will never see it. A 500 amp, 50mv shunt like most all of these monitors use only cause a 50mv drop with 500 amps of current. If you are starting from this house bank, and don't run the start current through the shunt, you have lost accurate measurement of the battery bank. I've started my 135 Lehmans through a 500 amp shunt for almost 13 years with no ill effects. Mater of fact, I've installed many, many shunts in starter circuits (properly sized) and have NEVER seen a shunt failure.

A fuse IS NOT a measured resistance. It is a fusable link.

100% of boats DON'T forget about measuring start current. I've seen many that do, including mine. Generally, if they have a separate start battery it doesn't get measured, but if they are started from the house, and they have a properly wired battery monitor installed, they do.
__________________

Brent Hodges is offline   Reply With Quote
Old 05-28-2014, 06:04 AM   #43
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
Generally, if they have a separate start battery it doesn't get measured, but if they are started from the house, and they have a properly wired battery monitor installed, they do.

To what purpose?

With a dedicated start batt , only in an emergency would a boost from the house be required .

A few seconds of cranking is hardly going to change the house recharge requirement.

So why bother?
FF is offline   Reply With Quote
Old 06-01-2014, 06:26 AM   #44
Senior Member
 
City: Green Cove Springs, Florida
Country: USA
Join Date: Feb 2012
Posts: 210
Send a message via Skype™ to bglad
Quote:
Originally Posted by Billylll View Post
That's not a breaker/ fuse I would use it won't handle high inrush currents.
Bill
They are used quite often for just that. Most inverters have control circuits. You wouldn't be switching it on and off with a load. What is not good is to have an inverter connected to the DC battery bank without a switch to shut it down if it starts smoking or other silliness. Much quicker to toggle a switch than find your tools or fuse puller...

Bill Too
bglad is offline   Reply With Quote
Old 06-01-2014, 05:43 PM   #45
Senior Member
 
Brent Hodges's Avatar
 
City: Seabrook, Texas
Country: USA
Vessel Name: Friendship
Vessel Model: Albin 43 Sundeck
Join Date: Oct 2007
Posts: 138
bglad wrote: What is not good is to have an inverter connected to the DC battery bank without a switch to shut it down if it starts smoking or other silliness. Much quicker to toggle a switch than find your tools or fuse puller...(endsnip)

Exactly correct. As I mentioned before, I've installed dozens of inverter / chargers, mostly 2000 to 3000 watt. I always install the proper size fuse and wiring, based on the Inverter manufacturer's recommendations, and always install a dedicated switch just for the inverter where you can switch it off without interupting the house circuits. I also only use the class T fuses because of the high current capacities of the battery banks normally associated with inverters, and the chance of an inverter failing with a direct short. An inverter is the only high current device that I've ever seen fail that way (direct short) and I've seen it happen twice.
Brent Hodges is offline   Reply With Quote
Old 06-01-2014, 05:54 PM   #46
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,864
Quote:
Originally Posted by Brent Hodges View Post
bglad wrote: What is not good is to have an inverter connected to the DC battery bank without a switch to shut it down if it starts smoking or other silliness. Much quicker to toggle a switch than find your tools or fuse puller...(endsnip)

Exactly correct. As I mentioned before, I've installed dozens of inverter / chargers, mostly 2000 to 3000 watt. I always install the proper size fuse and wiring, based on the Inverter manufacturer's recommendations, and always install a dedicated switch just for the inverter where you can switch it off without interupting the house circuits. I also only use the class T fuses because of the high current capacities of the battery banks normally associated with inverters, and the chance of an inverter failing with a direct short. An inverter is the only high current device that I've ever seen fail that way (direct short) and I've seen it happen twice.
what in the inverter direct shorted?
and did the manufacturer suggested fuse work?
psneeld is offline   Reply With Quote
Old 06-01-2014, 06:25 PM   #47
Senior Member
 
Brent Hodges's Avatar
 
City: Seabrook, Texas
Country: USA
Vessel Name: Friendship
Vessel Model: Albin 43 Sundeck
Join Date: Oct 2007
Posts: 138
I have no idea exactly what direct shorted, but they blew the Class T 300 amp fuses both times. One inverter was replaced under warranty. The other was out of warranty and was replaced with a new, different brand of inverter/charger.
Not sure what you mean my suggested "fuse work". They were properly fused in both cases, and the fuses did their jobs.
Brent Hodges is offline   Reply With Quote
Old 06-01-2014, 06:36 PM   #48
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,864
So why recommend additionl switching..which the manufacturers don't always recommend when the class "T" fuses did their jobs?
psneeld is offline   Reply With Quote
Old 06-01-2014, 07:21 PM   #49
Guru
 
City: North Charleston, SC
Country: USA
Join Date: Sep 2010
Posts: 4,390
Quote:
Originally Posted by FF View Post
A FUSE is a measured resistance ..
Nope, a fuse is a conductor sized to melt in a controlled environment at a certain current flow.
rwidman is offline   Reply With Quote
Old 06-01-2014, 08:00 PM   #50
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,864
In electronics and electrical engineering, a fuse (from the French fuser, Italian fuso, "spindle"[1]) is a type of low resistance resistor that acts as a sacrificial device to provide overcurrent protection...........

http://en.wikipedia.org/wiki/Fuse_(electrical)
psneeld is offline   Reply With Quote
Old 06-02-2014, 07:09 PM   #51
Senior Member
 
Brent Hodges's Avatar
 
City: Seabrook, Texas
Country: USA
Vessel Name: Friendship
Vessel Model: Albin 43 Sundeck
Join Date: Oct 2007
Posts: 138
psneeld wrote: So why recommend additionl switching..which the manufacturers don't always recommend when the class "T" fuses did their jobs? (endsnip)

Well, this has been explained several times, but the switch is to isolate the inverter incase of a fault, or just for maintenance / testing. If you don't want to pony up the extra $25 on a $2,000 job to make it a better, safer installation, don't. I'll continue to do things right.................

Good grief, this thread is getting ridiculous. I think I'm done.
Brent Hodges is offline   Reply With Quote
Old 06-02-2014, 07:43 PM   #52
Guru
 
Moonstruck's Avatar
 
City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,848
It is a good idea to have a "lock out" on the inverter because even with 120 volt power off the inverter can still be making it. There should be a warning in the AC panel that such a situation exists. It can kill you.
__________________
Don on Moonstruck
Sabre 42 Hardtop Express & Blackfin 25 CC
When cruising life is simpler, but on a grander scale (author unknown)
http://moonstruckblog.wordpress.com/
Moonstruck is offline   Reply With Quote
Old 06-02-2014, 08:43 PM   #53
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,864
Quote:
Originally Posted by Brent Hodges View Post
psneeld wrote: So why recommend additionl switching..which the manufacturers don't always recommend when the class "T" fuses did their jobs? (endsnip)

Well, this has been explained several times, but the switch is to isolate the inverter incase of a fault, or just for maintenance / testing. If you don't want to pony up the extra $25 on a $2,000 job to make it a better, safer installation, don't. I'll continue to do things right.................

Good grief, this thread is getting ridiculous. I think I'm done.
What's ridiculous is not answering a simple question...

IF the fuses did what they were supposed to....then why the extra switch when not called for by the manufacturer?

Not hard to understand or explain.

And yes I'm probably as good with hooking up equipment as you are and just as safe.

I'm not an electrical engineer or inverter manufacturer so there might be something I am missing...it's not a trick question or trying to bait you into something...I'm just curious what I am missing....

If not..then "right way" is only a matter of opinion.
psneeld is offline   Reply With Quote
Old 06-02-2014, 08:46 PM   #54
Guru
 
City: Tuckerton, NJ
Country: USA
Vessel Name: WIRELESS ONE
Vessel Model: 36 Gulstar MarkII
Join Date: Mar 2011
Posts: 937
I am not sure who's high current inverter's battery switch costs $25.00? I like the BlueSea gray high current battery switch to shut down the inverter's DC feed as well as installing the properly sized Class T fuse in the 12VDC feed to the inverter. I want to install a 1, 2 on and off switch so I can effectively shut down the inverter when needed, use all 4 batteries in the house bank to feed the inverter, or charge off the inverters charger or split half of either bank if needed to feed or charge.
Bill
Billylll is offline   Reply With Quote
Old 06-02-2014, 09:08 PM   #55
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,360
After all this discussion, I'm still curious as to why a simple stand alone 12V starting circuit is felt by some to need "protection" beyond good wiring and logical cable runs.

It seems I'm not alone.
sunchaser is offline   Reply With Quote
Old 06-02-2014, 09:15 PM   #56
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,864
Quote:
Originally Posted by sunchaser View Post
After all this discussion, I'm still curious as to why a simple stand alone 12V starting circuit is felt by some to need "protection" beyond good wiring and logical cable runs.

It seems I'm not alone.
even ABYC agrees if done correctly...
psneeld is offline   Reply With Quote
Old 06-03-2014, 11:17 AM   #57
Guru
 
City: North Charleston, SC
Country: USA
Join Date: Sep 2010
Posts: 4,390
Quote:
Originally Posted by psneeld View Post
In electronics and electrical engineering, a fuse (from the French fuser, Italian fuso, "spindle"[1]) is a type of low resistance resistor that acts as a sacrificial device to provide overcurrent protection...........

Fuse (electrical) - Wikipedia, the free encyclopedia
Wikipedia is a source for school children to find information without doing actual research themselves. It is not a reliable source for technical information.

While a fuse does have some electrical resistance, it so small that it is not generally considered when designing an electrical circuit. The resistance of the circuit conductors is likely to be far greater than the resistance of the fuse. Professionals in the trades do not refer to or think of fuses as "resistors".

Also, a "fuse" does not necessarily open ("blow") on excess current. If you use a hair drier for a heat gun, you may overheat it and blow the "thermal fuse" (activated by excessive heat). These are also sometimes found in transformers and small motors.

A fuse (fusible link) may also be used to hold mechanical devices in a certain position and release them at a set temperature. Fire doors are an example.
rwidman is offline   Reply With Quote
Old 06-03-2014, 11:25 AM   #58
Guru
 
City: North Charleston, SC
Country: USA
Join Date: Sep 2010
Posts: 4,390
Quote:
Originally Posted by psneeld View Post
What's ridiculous is not answering a simple question...

IF the fuses did what they were supposed to....then why the extra switch when not called for by the manufacturer?
An appliance such as an inverter needs a positive means of being disconnected for the safety of anyone working on it (and possibly for convenience). While removing the fuse is a positive means of disconnecting the appliance, it's often not the most convenient or fast way of doing so.

In my case, removing the fuse means getting out the tool box, removing four screws to swing out the electrical panel, removing the plastic cover over the fuse, then finding the correct socket and handle to loosen the nuts holding the fuse in place. The option is to reach down and turn a knob on a switch.

BTW: An inverter, even one with a remote power switch will still draw a small standby current when connected to the battery. A switch in the DC circuit will eliminate this standby current when turned off.
rwidman is offline   Reply With Quote
Old 06-03-2014, 11:28 AM   #59
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,360
Quote:
Originally Posted by rwidman View Post
Wikipedia is a source for school children to find information without doing actual research themselves. It is not a reliable source for technical information.
Yeah, but it is a lot easier to post a link from Wikpedia than scanning those 50 year old EE text books on my shelf.
sunchaser is offline   Reply With Quote
Old 06-03-2014, 11:39 AM   #60
Guru
 
City: North Charleston, SC
Country: USA
Join Date: Sep 2010
Posts: 4,390
Quote:
Originally Posted by sunchaser View Post
Yeah, but it is a lot easier to post a link from Wikpedia than scanning those 50 year old EE text books on my shelf.
I used that stuff for many years on a daily basis. Of course I updated it when necessary.
__________________

rwidman is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 11:55 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012