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DIY harness for DIY charger/discharger

Discussion in 'Gen 3 Prius Accessories and Modifications' started by edu4prius, Jan 17, 2021.

  1. edu4prius

    edu4prius New Member

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    Inspired by @Abarnabe's thread showing his MeanWell LED driver as grid charger and a set of 230V bulbs as a discharger I'm going to show how I built my own harness to balance charge without removing any covers.

    First, I used two terminal rings that fit the modules screws. One for the positive end and other for the negative one. Wiring was made with household electric wires (1,5mm) but since they should not carry more than 2A could be thinner.

    IMG_8374.JPG

    I added a 15A fuse in the middle of the longest wire (positive in this case). Again, 15A is a lot more than what is expected to carry, but it was what at hand and, in case of short, it will break instantly.

    IMG_8689.JPG

    This is how the other end looks when the black covers are on:
    IMG_8383.JPG

    To make a safe connection to the charger I used a Schuko female marked + and - signs at each side. Later I thought I could have used the ground pins as negative and the main holes as positive, maybe next time...
    IMG_8375.JPG IMG_8376.JPG

    Next, to power the fan while balancing (very very important to prevent overheating) I used the pinout schema posted somewhere in PriusChat. I just inserted rigid wires in the female fan connector (fan side) like this:
    IMG_8379.JPG

    Purple and red end in a DC female jack that gets connected to a 12V power supply after a long enough wire. Purple and blue meet in a switch that can also be used to force ventilation when the car is on.

    IMG_8381.JPG

    That's all. I also zip-tied the battery charging wires to the fan power wires so the stay together while hidden in the tray that sits under the trunk floor, so now I only have to take them out of there and plug the LED driver (or the bulb array) and the 12V power source.

    Hope you find it useful. And if I made any foolish mistake, please, comment!
     
  2. ChapmanF

    ChapmanF Senior Member

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    What type of fuse is that? Have you checked its voltage rating?
     
  3. waldox

    waldox Junior Member

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    Tip im going to use IEC C13/C14 connectors that i have plenty of in my PC cable drawer. they are cheaper too in USA/Canada. would be good to use the c13 female end attached to the car, and c14 male end attached to your charger.
     
    #3 waldox, Jan 18, 2021
    Last edited: Jan 18, 2021
  4. waldox

    waldox Junior Member

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    Edu4prius, what type and size eyelet connector are you using? im looking to order some
     
  5. edu4prius

    edu4prius New Member

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    It is a regular ATO blade fuse. No voltage specs on it, though they are used in cars low voltage circuits. Since I was concerned about arcing at high voltage, I made a test with a broken one and I saw no arc nor spark so I guessed it was good to go. Anyway, I'm not 100% sure if harmful arcing always appears visible. Would feel better if someone could confirm that :oops:

    Not a bad option either, though C14 posts seem too exposed if not covered with a cap. I liked the Schuko because the female is well protected while moving around the trunk.

    I already had a few eyelets of different sizes and picked the ones that fit better, I guess something around 5mm or 6mm can do the job. Maybe someone in the forum knows the exact diameter of the posts if you are looking for the narrowest option.

    BTW, here you have two pics of how it looks in the trunk: trunk1.jpeg trunk2.jpeg
     
  6. ChapmanF

    ChapmanF Senior Member

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    If I understand correctly, what matters to the voltage rating of a fuse is not whether you will get an arc at X volts across an already blown one, but whether an unblown one can successfully interrupt the arc at X volts if it blows.
     
  7. edu4prius

    edu4prius New Member

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    So to be sure it is a safe choice I should try to put an unblown fuse, blow it by shorting the circuit and see if arcing occurs while keeping the circuit shorted, right?
     
  8. ChapmanF

    ChapmanF Senior Member

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    There's a saying attributed to Frank Westheimer, goes something like "a couple of months in the laboratory can save you a couple hours in the library".

    In this case, it suggests that maybe putting something like "ATO fuse max voltage" into Google is the way to go here. When you see that the answer is 32 volts, you'll appreciate that this method is probably also better for your eyebrows than trying what you suggest in #7.
     
    tungm likes this.
  9. edu4prius

    edu4prius New Member

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    :eek: Wow! Then I’ll look for a high DC voltage rated fuse ASAP. Thank you for saving my eyebrows, Chapman!
     
  10. ChapmanF

    ChapmanF Senior Member

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    (y) I'm actually very much in favor of eyebrow conservation.

    There are some older threads on PriusChat where suitable fuse ideas have been bandied about, like this one.
     
    #10 ChapmanF, Jan 22, 2021
    Last edited: Jan 22, 2021
  11. waldox

    waldox Junior Member

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    i did some research should be #10 or 5mm boltsize diameter for the terminals
     
  12. waldox

    waldox Junior Member

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    any fuses you can recommend?
    i couldnt find the previous posts about possible fuses,
    i found this one which may be suitable 300vdc 3 amp fast acting and cheap
    MERSEN A4J3 | A4J3 FUSE | Rexel Atlantic

    ended up buy ten 3amp 500vdc pack
    (10-Pack) Littelfuse KLK3 Fast Acting 3-Amp Midget Fuse 3A 600VAC/500VDC | eBay


     
    #12 waldox, Jan 24, 2021
    Last edited: Jan 24, 2021
  13. waldox

    waldox Junior Member

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    here is a gen 2 harness for inspiration
    [​IMG]
     
  14. edu4prius

    edu4prius New Member

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    I've been looking for DC fuses in Spanish shops and most of them sell fuses designed and certified for photovoltaic systems (usually tagged as gPV). In the specs of the ones I'm about to buy the breaking capacity is rated at 30kA and hold up to 1000V DC. I also seen in some general purpose fuses (gG) that specs show they can hold up to 250V DC with a breaking capacity of 15kA. Would those fuses be suitable for the harness or may still be dangerous? Does anyone know the specs of the fuse that comes with Prolong's system?
     
  15. Raytheeagle

    Raytheeagle Senior Member

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    @jeff652 will know the specs of the fuse(y).
     
  16. waldox

    waldox Junior Member

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    thanks for the inspiration to make my own harness from fellow pruischat nerds
    i have made several working looms with the following materials

    outer covering protection: 1/2 split loom

    used common old computer power supply 3 prong covered plugs (IEC 320 C13/C14)
    female end at the car (more protected), male end at the bulb discharger and led charger/power supply

    Charger: Mean Well HLG-80H-C350A LED DRVR CC AC/DC 128-257V 350MA

    Fuse: 3 Amps 500VDC/600VAC fast acting fuse (note you should use fast acting and your fuse should be greater than 250V and between 3-5 Amps, the led charger is use is max 0.350 miliAmp and discharger with two 200W bulbs is maximum 1.6Amps)
    (10-Pack) Littelfuse KLK3 Fast Acting 3-Amp Midget Fuse 3A 600VAC/500VDC | eBay

    quality scotch 700 electrical tape is key, its a pain to remove, which is great for safety.

    10-12 eye ring terminals for #10 or M5 diameter stud (5mm)

    note when soldering the fuses, took me a while to figure out that you need to sand the ends and maybe use acid flux for the solder to stick. you need to remove the oxidation on the metal. i almost gave up on the fuses. fuses are key incase of accident and your harness gets severed touching metal, you dont want the battery to short and make the car body live with 250v!

    i didnt make a fan adapter, my reasoning is that i would be using this in under 10C/50F temperature weather with the windows cracked. at 3C outside, it was 18C in the car and 32C at the battery with the cover open. as long as the battery is under 40C it should be good. so i will stick to conditioning the battery when it is under 10C/50F outside.
     

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  17. edu4prius

    edu4prius New Member

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    That’s good to hear, @waldox.
    I’m currently waiting for the fuses and holders I ordered. But instead of soldering I think a fuse holder is more convenient. The one I ordered looks like this. 73FDBC78-8890-4698-BA20-E1E2F42A2376.jpeg
    It was listed as “car audio fuse box”, but it is supposed to fit 10x38mm fuses so I guess it will be fine. I finally decided to go with a fuse per wire (positive and negative) for extra safety in any short circuit scenario.

    Let us know if you put that harness to work!
     
  18. PriusII&C

    PriusII&C Active Member

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    @edu4prius What is the objective of DIY charger/discharger vs. a commercial one? If it is cost, how much will it be?
     
  19. edu4prius

    edu4prius New Member

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    In my case, living in Europe, buying the Prolong charger, discharger and harness from USA means paying an expensive shipping and kind of abusive customs taxes. So adding that extra to the products price would cost me up to 1000€.
    The money I spent in the DIY version is no more than 100€. Of course, apart from money, you also have to take into account the hours (happily) spent learning how to make it safely, finding where to buy the right LED driver and fuses, and a morning assembling stuff up.
    Of course, Prolong devices are more complete, better constructed, look nicer and feel safer than DIY. But that, from my perspective, is not worth 900€ more.
    I also have to say that the intelligent discharger they sell seems really convenient and it’s something I would be willing to invest in if it wouldn’t require their harness and was shipped from Europe.
     
    alftoy and Mendel Leisk like this.
  20. PriusII&C

    PriusII&C Active Member

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    I did not know it costs so much more in Europe.

    I am interested in your DIY. After you are done, it would be nice if you could put out a summary.