Page 1 of 4 123 ... LastLast

Thread: Basic wiring question

  1. #1
    Join Date
    Apr 2010
    Location
    Pacific Beach, Ca
    Posts
    373

    Default Basic wiring question

    Hi, I am afraid of electrical fires, and every thread goes in different directions with this section, so can someone use ms paint and show me how to wire my system cause I am an idiot, and on the road headed to south america, so doing my research is tough, thanks! I will figure out the proper gauges with the calculators posted around here once i figure out the distances, I just dont want to do something stupid.

    What I have

    2 diehard batteries
    arb fridge
    blue sea acr 7622
    blue sea fuse block
    cameras, netbook, laptop, etc
    Think that is it

    My biggest weakness is a 200 watt inverter I had laying around, though I may try and upgrade in Lapaz, I never had time, and its probably too late now. I have seen some say to ground both batteries to 1 point others say not to, etc. I realllllly appreciate it guys.
    2Guys1Truck: 2004 AWD Chevy Astro through Central and possibly South America happening NOW!

  2. #2
    Join Date
    Nov 2010
    Location
    Middle of Nowhere, Outer Skin of Space Ship Earth, 1 A.U. from Sol, Outskirts of Milky Way.
    Posts
    2,226
    Is one or both of those batteries the engine battery? Or are they both intended to be auxiliary batteries?
    ...
    ...
    Current: 76 E-250, bubble-top, self-contained|couple of old Yamaha enduros
    Previous wheelers: 41 Willys|78 FJ40|78 Bronco|84 Bronco|74 Ramcharger|78 Ramcharger|79 D150 PowerWagon|77 D100|79 D400 dually, converted to 4WD, utility bed, 10' Lance|75 Westy|69 Scout, RHD|bunch of others|bunch of bikes|couple of boats|couple of motorhomes|blah blah|so what|not my idea|just doin' what I'm told|wank wank|this space for rent|candy is dandy|but liquor is quicker

  3. #3
    Join Date
    Apr 2010
    Location
    Pacific Beach, Ca
    Posts
    373
    1 engine, 1 auxillary, we shouldnt need much power.... i hope.
    2Guys1Truck: 2004 AWD Chevy Astro through Central and possibly South America happening NOW!

  4. #4
    Join Date
    Jul 2009
    Location
    San Diego, CA
    Posts
    831
    I'm doing a similar "house battery" install in my Astro right now, too.

    The main thing to think about when figuring out where to put fuses, etc. is this: Assume that ANY wire, at ANY point along the wire, can get chafed or pinched such that it shorts to the chassis or anything else nearby. With that comforting thought in mind, start putting fuses in the places where they can actually DO something about the above scenario. In general, your big main fuse(s) should be close to the batteries, so that every bit of the wire "downstream" from that is protected should there be a short.

    In my case, I have a dual-battery solenoid in the engine bay and a house battery in a box near the mid-rear of the van, so I put a big fuse (actually a 150A breaker) between the starting battery and the solenoid, and another at the other end, right next to the house battery. That way, if there's a short ANYWHERE along that run of wire between them, both ends are protected (because otherwise either or both batteries would be shorted!)

    The same goes for your load-side fuses, they should be as close to the battery(ies) as is practical, so that the entire run of wiring is protected. I'll be putting a main circuit breaker between the house battery and BlueSea fuse box, (very close to the house battery), then all the loads of course tied to individual fuses. In your case, each "load" would be a jack for your dc fridge, or charger cables, etc.

    Other general best practices:

    1) Of course, you always size the fuse to the WIRE. If you wouldn't dump 20A into a thin wire, it shouldn't have a 20A fuse on it, right? If you need a big fuse for your load, you had better run big wire to go with it. In my example of my main cable from front to rear battery, I'm planning for the possibility of adding a winch, etc. later so I ran 2-gauge cable, hence the big breaker - use a smaller fuse/breaker if you use a smaller cable. Same goes for the load side.

    2) I would say definitely ground both batteries together, and specifically connect the house battery ground directly to the starting battery ground. This sounds like a pain, but dumping big current through the chassis is a "works for now" scenario at best, a likely intermittent or oddball problem most of the time, and a serious hazard at worst. Beyond the safety issues of using the chassis as a "wire", there's a practical effect too: Using the chassis as a ground can create a voltage potential between the two batteries. If you're charging the house battery from the alternator, you're robbing yourself of charge voltage. If you're using any of the automatic charging relays, etc., they can misinterpret this voltage difference and shut off charging too early (or worse, not early enough), risking damage to either or both battery.

    You're already running one big cable from front to back, the effort for the second isn't that high. In my case, I just bought a set of 20ft, 2-gauge jumper cables from Autozone and cut off the clamps. I separated the cables in order to cover them with braid and for ease of clamping down, but you could leave them mostly connected too, and then really have no excuse because you're basically just pulling one cable at that point.

    Like the convenient (and relatively cheap) Jumper cables, I also purchased the 150A breakers and all of my 2-g lugs, etc. at Autozone, because I was figuring out what I needed and implementing all on a single weekend. Might have saved money going online), but since it sounds like you might be on the road, it'd be good for you to know that you CAN do this with mostly "auto parts" type supplies.

    The only specialty tool I needed that you're not likely to have is a BIG effing crimper for the 2-gauge lugs. The one I used actually looks like bolt cutters, except it has crimping dies on the end. It's like a $150 tool and I borrowed it from a friend. If the auto parts store you use can make or service battery cables, starter leads, etc., they might have a similar crimping tool on-hand, and might loan it to you or at least crimp your ends for you, especially if you bought the parts from them. I have soldered 2-gauge cable lugs in the past using a propane torch, but I'm not sure I would swear by that method even though some do. Crimping is your best bet.

    This is the method I used when soldering:
    [ame="http://www.youtube.com/watch?v=Ph7h6rYZnVI&feature=related"]Solder method[/ame]. You can see some commercial companies sell kits to do this:[ame="http://www.youtube.com/watch?v=SXDkNMDDrBs&NR=1"]solder kit[/ame], but consider it at your own risk.
    Herbie - K6ZMB
    San Diego, CA
    2003 Chevrolet Astrolander/ZMB - GTRV PopTop, 4" Lift, 4WD Conversion
    1995 GMC Safari GTRV - Organ Donor for the Astrolander
    2002 Subaru Impreza WRX "Outback" - a.k.a Frankenstein's WRX. Mild Lift via Outback Sport Springs, WRX-TR 4piston/2piston Brake upgrade, WRX STi Seats + More

  5. #5
    Join Date
    Nov 2010
    Location
    Middle of Nowhere, Outer Skin of Space Ship Earth, 1 A.U. from Sol, Outskirts of Milky Way.
    Posts
    2,226
    Quote Originally Posted by Wiley View Post
    1 engine, 1 auxillary, we shouldnt need much power.... i hope.
    Alright. Lemme look at the 7622 manual and see what I can whip up for you as a diagram. Probably post it tonight or tomorrow.
    ...
    ...
    Current: 76 E-250, bubble-top, self-contained|couple of old Yamaha enduros
    Previous wheelers: 41 Willys|78 FJ40|78 Bronco|84 Bronco|74 Ramcharger|78 Ramcharger|79 D150 PowerWagon|77 D100|79 D400 dually, converted to 4WD, utility bed, 10' Lance|75 Westy|69 Scout, RHD|bunch of others|bunch of bikes|couple of boats|couple of motorhomes|blah blah|so what|not my idea|just doin' what I'm told|wank wank|this space for rent|candy is dandy|but liquor is quicker

  6. #6
    Join Date
    Mar 2011
    Location
    Alaska
    Posts
    73
    When I need heavy gauge cable I usually go with welding cable. It's the stuff you use to wire up welders. It's cheap, the insulation seems to last indefinitely, and it has a really high strand count too, so it's very flexible, and cheap.

    https://weldingsupply.securesites.co...R:terms::PA#A2

    All the heavy gauge wiring I've done in the last few years has been using the same 25 foot reel of 2-gauge I got a while back. I've completely rewired the charging systems on three trucks (all with independent grounds), made new cables for a Jeep, and re-did the house batteries on one RV. I still have a few feet left over and it only cost me about $40.

    I don't have much else to add, I think Herbie touched on most of the major points I would have.

    One important one is this. If the batteries are being charged off of a diode isolator they can be different. If they are connected using a solenoid isolator, or simply wired in parallel they must be identical. Same CCA, same reserve capacity, brand, age, if you can find batteries from the same batch of batteries or else they'll fight thus shortening both of their lives.

  7. #7
    Join Date
    Nov 2010
    Location
    Middle of Nowhere, Outer Skin of Space Ship Earth, 1 A.U. from Sol, Outskirts of Milky Way.
    Posts
    2,226
    Quote Originally Posted by 2500ak View Post
    When I need heavy gauge cable I usually go with welding cable. It's the stuff you use to wire up welders. It's cheap, the insulation seems to last indefinitely, and it has a really high strand count too, so it's very flexible, and cheap.
    I'm a big fan of welding cable myself. I generally just go to the welding supply shop and have them make up what I need. They've got the connectors and the tools to crimp them.


    One important one is this. If the batteries are being charged off of a diode isolator they can be different. If they are connected using a solenoid isolator, or simply wired in parallel they must be identical. Same CCA, same reserve capacity, brand, age, if you can find batteries from the same batch of batteries or else they'll fight thus shortening both of their lives.
    That is not quite correct.

    Batteries which are tied together in a -permanent bank- DO need to be identical.

    However, for vehicular use, where the main and aux batteries are only tied together during charging - they only need to have identical charge voltage ratings, such as 14.4v,13.5v,13.2v (bulk, absorb, float).

    You would not want to connect a GEL, which requires 14.2v bulk to a charging system that puts out 14.4v.

    But any two batteries which require 14.4v, such as different sized AGMs, or an engine starting battery and a deep cycle aux battery bank, can be tied together while charging without ill effects.

    The charging system will bring the voltage of the entire bus up to the set point. At that time, all the batteries - of whatever type and size - will be at 14.4v and they'll all be fully charged.


    There is some potential for a problem if charging different sized batteries with a -constant current- type charger. For instance, if the big battery is full before the smaller battery, then the entire output of the constant current charger will end up flowing toward the smaller battery - and could be more than that battery could handle.

    But automotive charging systems aren't constant current type - they're constant voltage type.
    ...
    ...
    Current: 76 E-250, bubble-top, self-contained|couple of old Yamaha enduros
    Previous wheelers: 41 Willys|78 FJ40|78 Bronco|84 Bronco|74 Ramcharger|78 Ramcharger|79 D150 PowerWagon|77 D100|79 D400 dually, converted to 4WD, utility bed, 10' Lance|75 Westy|69 Scout, RHD|bunch of others|bunch of bikes|couple of boats|couple of motorhomes|blah blah|so what|not my idea|just doin' what I'm told|wank wank|this space for rent|candy is dandy|but liquor is quicker

  8. #8
    Join Date
    Nov 2010
    Location
    Middle of Nowhere, Outer Skin of Space Ship Earth, 1 A.U. from Sol, Outskirts of Milky Way.
    Posts
    2,226
    Okay, try this on for size...

    I may not be online much the next few days to a week, so if anyone catches a goof in the diagram then sound off!

    Mad Paint Skillz!


    EDIT: Crap! Just realized I didn't do the aux fuse block!

    Wiley, you tap off the AUX battery + to feed the aux fuse block. Put a fuse in the wire that feeds the aux fuse block. Like a 30a if you use #10 wire. You get the idea. Then you feed your aux power ports from the aux fuse block. For an inverter, tap off the AUX battery + and - and use a suitably sized fuse in the + wire.


    EDIT AGAIN: As regards Note 1 - the bloody big fuses should be rated higher than the max output of the alternator, but less than the wire. So if your alternator is rated at 100a, then you'd use 125a fuses and 150a wire.


    EDIT YET AGAIN!: CRAP... ABORT ABORT ABORT
    I just realized I goofed. Not a major goof, but a minor and subtle goof...and I don't have time right now to redo the diagram...

    Here's the error: The two little red 2a power feed wires to the switch should be connected to the AUX battery, NOT the engine battery (more correctly, they should be connected to the aux battery fuse block). The reason is simply that you don't want any part of the setup drawing power from the engine battery - if it were to have a problem (highly unlikely, but still possible) and drain one of the batteries, you want it to be the aux that gets drained, not the engine, so you can still start the vehicle.

    And that's what happens when you get in a hurry, and this morning I'm in a hurry...


    If you look at the ACR manual, you'll see basically the exact same drawing. Take out the two remote controlled battery switches, and the optional wire to the starter switch and you'll see that the aux fuse block is tapped off the aux (house) battery, and the ACR switch gets power from that fuse block.

    Sorry for the confusion.


    AND ONE MORE EDIT! You can fix my SNAFUed drawing by simply renaming the two batteries. Make the one of the left the aux and one on the right the engine and then the drawing is correct.

    Gotta run.
    Attached Images Attached Images
    Last edited by dwh; 03-25-2011 at 05:00 PM.
    ...
    ...
    Current: 76 E-250, bubble-top, self-contained|couple of old Yamaha enduros
    Previous wheelers: 41 Willys|78 FJ40|78 Bronco|84 Bronco|74 Ramcharger|78 Ramcharger|79 D150 PowerWagon|77 D100|79 D400 dually, converted to 4WD, utility bed, 10' Lance|75 Westy|69 Scout, RHD|bunch of others|bunch of bikes|couple of boats|couple of motorhomes|blah blah|so what|not my idea|just doin' what I'm told|wank wank|this space for rent|candy is dandy|but liquor is quicker

  9. #9
    Join Date
    Jul 2009
    Location
    San Diego, CA
    Posts
    831
    Since dwh helped me out a couple of weeks ago, I've augmented his awesome Paint sketch with my own mad skilz - updated to add fuse block and inverter:



    I have attempted to continue portraying relative wire size via line thickness. As stated previously, use appropriate size wire for the load and size the fuse to the wire.

    EDIT: You didn't state which model of Blue Sea fuse block you were using, but I assumed it was one with a negative bus, so you can make the power and ground connections together directly at the fuse block.
    Herbie - K6ZMB
    San Diego, CA
    2003 Chevrolet Astrolander/ZMB - GTRV PopTop, 4" Lift, 4WD Conversion
    1995 GMC Safari GTRV - Organ Donor for the Astrolander
    2002 Subaru Impreza WRX "Outback" - a.k.a Frankenstein's WRX. Mild Lift via Outback Sport Springs, WRX-TR 4piston/2piston Brake upgrade, WRX STi Seats + More

  10. #10
    Join Date
    Nov 2010
    Location
    Middle of Nowhere, Outer Skin of Space Ship Earth, 1 A.U. from Sol, Outskirts of Milky Way.
    Posts
    2,226
    Quick reply before I run.

    Herbie, nice job! But see my post edit about my goof.

    Also, the inverter fuse will likely be large. Say a 400w inverter - that would be 400w / 12v = 33.3a - it would need a 40a fuse and wire.
    ...
    ...
    Current: 76 E-250, bubble-top, self-contained|couple of old Yamaha enduros
    Previous wheelers: 41 Willys|78 FJ40|78 Bronco|84 Bronco|74 Ramcharger|78 Ramcharger|79 D150 PowerWagon|77 D100|79 D400 dually, converted to 4WD, utility bed, 10' Lance|75 Westy|69 Scout, RHD|bunch of others|bunch of bikes|couple of boats|couple of motorhomes|blah blah|so what|not my idea|just doin' what I'm told|wank wank|this space for rent|candy is dandy|but liquor is quicker

Page 1 of 4 123 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •