Reply
 
Thread Tools Display Modes
 
Old 12-22-2016, 12:15 PM   #31
Mini-Skoolie
 
Join Date: Apr 2016
Location: New England
Posts: 68
Year: 2003
Coachwork: AmTrans
Chassis: International
Engine: T444E
If I use a 4 lug Bus Bar does this make sense?

-Connect solar charger to one lug, with 60 amp fuse close to bus bar.
-Connect Inverter/Charger to another lug, with 70 amp fuse close to bus bar.
-Connect DC load center to another lug with fuse close to bus bar.
-Connect Batteries to bus bar (Do I put one large catastrophe fuse here?)
WhiteWhale is offline   Reply With Quote
Old 12-22-2016, 01:01 PM   #32
Bus Crazy
 
Join Date: Feb 2012
Location: Salt Lake City Utah
Posts: 1,321
Year: 2000
Chassis: Blue Bird
Engine: ISC 8.3
A fuse (or circuit breaker) protects only its downstream from over-current conditions. I'd put protection fuses as near to the sources of power as is practical -- rather than putting fuses at a busbar, put them near the two chargers and the battery bank. For example, if the fuse for the battery bank were at the busbar (which I'm assuming is not very near to the batteries) then there's a long section of unprotected wire between the batteries and fuse. If that were to be damaged anywhere along its length by a sudden cut, gradual abrasion, etc there would be no automatic cutoff of its power and the resulting arcing could start a fire. Fire safety is the main thing driving electrical protection.

You may not need a fuse at the input to the DC load center: if it is chosen such that its max current rating is greater than what the fused sources can provide, then it is adequately protected by those source fuses.
family wagon is offline   Reply With Quote
Old 12-22-2016, 02:28 PM   #33
Mini-Skoolie
 
Join Date: Apr 2016
Location: New England
Posts: 68
Year: 2003
Coachwork: AmTrans
Chassis: International
Engine: T444E
Quote:
Originally Posted by family wagon View Post
A fuse (or circuit breaker) protects only its downstream from over-current conditions. I'd put protection fuses as near to the sources of power as is practical -- rather than putting fuses at a busbar, put them near the two chargers and the battery bank. For example, if the fuse for the battery bank were at the busbar (which I'm assuming is not very near to the batteries) then there's a long section of unprotected wire between the batteries and fuse. If that were to be damaged anywhere along its length by a sudden cut, gradual abrasion, etc there would be no automatic cutoff of its power and the resulting arcing could start a fire. Fire safety is the main thing driving electrical protection.

You may not need a fuse at the input to the DC load center: if it is chosen such that its max current rating is greater than what the fused sources can provide, then it is adequately protected by those source fuses.
Ok great thanks. I wasn't thinking correctly about the direction of power flow from chargers to bus bar. I will put the fuses close to chargers. Any thoughts on how to size the main battery fuse?
WhiteWhale is offline   Reply With Quote
Old 12-22-2016, 06:43 PM   #34
Bus Crazy
 
Join Date: Feb 2012
Location: Salt Lake City Utah
Posts: 1,321
Year: 2000
Chassis: Blue Bird
Engine: ISC 8.3
In sizing the main battery fuse I'd first consider the "absolute max" charge and discharge rate for the battery bank. That should be available in technical data from the manufacturer. It will likely be higher than their "recommended" max rates, which are geared toward optimizing AH capacity and/or battery useful life. Don't choose a fuse that exceeds that absolute max.

Next I'd consider the actual (expected) charge and discharge rates for the extreme cases: charging at max rate with no house loads, and zero charging with all possible/reasonable house loads running. These might be different to the recommended max if, for example, loads are modest but the bank is being sized to run for days between charges. This is the current actually "needed" and is a good guide for fuse and wire sizing. Round up to the next higher standard fuse, or even one more level beyond that. Finally, balance the trade-offs: the fuse and wiring can be up-sized for future-proofing, reduced wire resistance, etc, in exchange for higher material cost and installation effort.
family wagon is offline   Reply With Quote
Old 12-22-2016, 11:32 PM   #35
Bus Nut
 
superdave's Avatar
 
Join Date: Mar 2015
Location: hills of sw virginia
Posts: 837
Year: 1996
Chassis: thomas
Engine: 8.3 cummins
Rated Cap: 11 window
the inverter/charger will require a fuse between it and the batteries. a 2000 watt inverter will use a 300 amp fuse, a 4000 watt will use a 500 amp fuse. when a inverter/charger gets pluged in to shore power the loads are transfered to shore power. then the inverter shuts down and checks the incoming power, it then becomes a converter and starts charging the batteries. my xantrex will put 100 amps into the batteries.
__________________
living in a bus down by the river.
my build pics
https://www.skoolie.net/forums/membe...albums942.html
superdave is offline   Reply With Quote
Old 12-22-2016, 11:50 PM   #36
Bus Crazy
 
roach711's Avatar
 
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,570
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
Quote:
Originally Posted by family wagon View Post
In sizing the main battery fuse I'd first consider the "absolute max" charge and discharge rate for the battery bank. That should be available in technical data from the manufacturer. It will likely be higher than their "recommended" max rates, which are geared toward optimizing AH capacity and/or battery useful life. Don't choose a fuse that exceeds that absolute max.
I was told to size my fuses to the ampacity of the connecting cable. The fuse is there to keep the cable from melting/burning from a dead short. For instance, the 2/0 cable connecting my house and starting banks has a 200 amp fuse on both ends even though both banks have well over 200 amps capacity.
__________________
The Roach Motel
roach711 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


» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:31 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.