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Stock alternator sanity check

Discussion in '2nd Gen. Tacomas (2005-2015)' started by ac2ndGenTacoma, Aug 13, 2022.

  1. Aug 13, 2022 at 12:01 PM
    #1
    ac2ndGenTacoma

    ac2ndGenTacoma [OP] Well-Known Member

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    I'm looking at adding an stereo-amp and a second (house) battery. The amp takes a 50amp fuse and the house battery charger (25 amp solar/alternator charger) takes a 40 amp fuse. The plan is to run 4awg on a 100 amp fuse to the rear passenger area of an access cab (about 15 ft. where the 4 awg will split into 2 8 awg at a fused distribution block; grounded to chassis under the passenger seat).

    If I go off of the fuse amp rating that's 100 amps which is cutting it really close to the 130 amp stock alternator capacity. However the real draw of the amp is going to be closer to 15 amps (https://www.crutchfield.com/S-SRv5o4BEXkb/learn/car-amplifier-installation-questions.html#9) and I assume the charger will likely draw run around 20amps or less.

    Looking for a sanity check and ideas on when it's worth the $$ to upgrade the alternator and/or big 3 upgrade. Thanks.
     
  2. Aug 13, 2022 at 10:33 PM
    #2
    Chuy

    Chuy Well-Known Member

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    I would do the big3 upgrade but you don't need to spend a lot of money on a kit. When you add the second battery, grounding it correctly will take care of the ground wire(s) in the kit. You only need to address the alt to fusebox wire, and the fusebox to battery wire. The use of a junction block will minimize dealing with the fusebox. I would keep the stock alt to see how it handles the new duties and upgrade it accodingly.
     
  3. Aug 13, 2022 at 10:59 PM
    #3
    Bivouac

    Bivouac Well-Known Member

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    Remains to be seen I bought the tires and wheels the rest came along
    You would need to have all the electrical loads on plus winching to exceed your alternator output.

    A big 3 upgrade is always a good idea in older trucks.
     
  4. Aug 13, 2022 at 11:02 PM
    #4
    6 gearT444E

    6 gearT444E Certified Electron Pusher

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    Calculate the demand factor of your loads and wire as such. If you want to be overly conservative you can add up all loads and size accordingly but you’ll be wasting money for wire gauge that you’ll never need or use.
     
    TnShooter likes this.
  5. Aug 14, 2022 at 12:35 PM
    #5
    ac2ndGenTacoma

    ac2ndGenTacoma [OP] Well-Known Member

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    Thanks for the replies.

    I can see a big 3 upgrade in the future but for now I'm just trying to get to a 50Wx4 amp installed and house battery in as few steps as possible. Calculating real world load is the difficult part, just adding up fuse ratings on various accessories apparently exaggerates practical load by a lot. The main fail-safe is to fuse to protect the wire.

    My previous van build (was some 10 years ago) had an AGM charged by VSR fused at 80 amps...worked until I added a sub / amp at the point the alternator could not keep up (amps ran off of house battery, not doing that again...maybe the amp was going bad from constant load?) and the VSR started to chatter.

    I had some 4awg left over from that build but it's not long enough - looks like I'll need about 20' to go through the passenger grommet to the rear - so if I'm going to be buying more wire anyway I might go with 2 awg for future proofing but apparently the preferred OFC (supposedly corrosion proof) does not come in 2 awg (jumps from 4 to 2/0 as far as I can tell) so I suppose I'll go with welding cable and heat shrink it the best I can.

    Any recommendations on marine heat sink? The wirefly brand recommended on Amazon is no good IMO.

    Any idea what the largest awg will fit in the ~1" grommets on the firewall? Looks lie the passenger grommet is easily drilled larger and covered with primer but, again, trying to avoid any unnecessary stuff if I can.

    Also anyone have experience with keeping a lithium battery in the cab full time (hot and cold weather)? My only reason for holing out on lithium over AGM is concern with heat in the cab.

    It's all part of a rear seat delete, I'll post some pics when (if?) I get it done.
     
  6. Aug 14, 2022 at 2:59 PM
    #6
    shmn

    shmn Well-Known Member

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  7. Aug 14, 2022 at 4:13 PM
    #7
    deanosaurus

    deanosaurus Caveman

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    The Big 3 link in my sig has a big bold link at the top to my DIY thread, which has links to suppliers for quality wire, marine heat shrink, and ordnance terminals, as well as some info on OFC (tl;dr on OFC: what is sold to consumers as OFC is usually not proper OFC, OFC isn't corrosion proof, and it offers no benefits in audio applications beyond standard copper welding cable)

    Re:lithium, I live in VT and keep a jump pack in my truck year round. No real issues.
     
  8. Aug 15, 2022 at 12:27 AM
    #8
    ac2ndGenTacoma

    ac2ndGenTacoma [OP] Well-Known Member

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    Good deal, I was just looking at your big 3 post but the link to ac/dc got lost between photos, thanks for pointing that out. It's on my to-do list.

    Looks like phase one (the amp) will be a blue sea battery terminal 125amp fuse, 20' of 2 awg wire to a 2 output fused (50 and 60 amp) distribution block. Phase 1.5 will be a sub speaker. Putting a 125 amp fuse on an accessory power wire running of a 130amp alternator is a bit counter intuitive but my understanding is that these accessories (amp and charger) will not be pulling anywhere near their fused amperage and the house charger does not even turn on until the starter battery is charged.

    At the time of this writing phase two will be a Wise 100 amp lithium battery (in the floor of the cab) with a redarch 40 amp duel DC to DC charger...not exactly clear at this time how I'm going to afford phase two but I'll be wired for it. Was originally considering the 25 amp charger (uses a 40 amp fuse) but the 40 amp charger is "only" $65 more so I figure I'd run wire for the 40 amp dc-to-dc charger which has a 60 amp fuse.

    I should probably budget for my 100K maintenance before doing phase 2. Also the dealership's 4 for the price of 3 tire sale is in October so yeah...phase two might be on hold for awhile.
     

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