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DIY Prius HV jumper cables

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Priam, May 30, 2020.

  1. Priam

    Priam New Member

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    Dear Reader,
    Here is the scoop

    purchased a distressed Gen 2 (07) prius yesterday with hopes to fix it for my sister. the ICE has an oil leak and I am reluctant to try to run it, leaving me in the dilemma where I now have 1 bar SOC (after test running it with the seller (engine stalled about 5 seconds in))

    I am searching for a reliable way to bring the SOC back up to half to stabilize the big brick for the time being while I sort out the oil leak.

    did I mention I have my own running gen2 car here too?? (see posting title)


    so after viewing the hv removal vids I am wondering, is there a better way?

    I am loath to swap the hv battery car to car just to charge it, though I know that would work.
    I will have to eventually deplete it again as I repair and test the ICE... meaning multiple swaps.


    I am considering charging the distressed battery in place using car2. Has anyone tried this or perhaps have an alternative method?

    Accessing the wiring at the inverter is much easier than at the HV battery itself, a suitably safe wire extension or 'hv jumper cable' is clearly in order.

    I would lose automatic cooling, but I could aim a blower fan down the hv cooling intake in car 1 just to be safe (were talking 2 minutes of charging max probably)

    rest assured any such thing-a-ma-jig I would build would be designed to be safe (fat wiring, isolated, insulated, housed terminals, orange plug removed for installation of course) (this will not be a true jumper cable as only one hv battery will be connected to my car, but it seemed a close analogy)


    at the end of the day this is a bit of an Achilles heel when it comes to DIY ICE repairs that may be dragged out across a few weekends!!


    Thanks so much to the people who make this forum possible!
     
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    Anything can be done, but unless you have significant experience working with high voltage DC systems and a deep understanding of how the Prius works, this could be a disaster for you. I have some experience, being a fully qualified Electronics Tech in 1987 and then a lifetime of military and industrial hands on experience. Although I'm confident I could make something like this work, I would be very reluctant to do it unless the situation was very extreme and no other options were available. You run the risk of damaging two systems, a bunch of electronics, and not to mention, yourself.

    There are threads on the forum that discuss building a low amperage high voltage charger. If you want to spend a few dollars, just buy a charger made by Prolong. Keep it forever in case you ever need it, or just sell it when you're done.
     
  3. ChapmanF

    ChapmanF Senior Member

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    Without careful control of the charging current, the result of a "jump" can look like this:

    [​IMG]
     
  4. Priam

    Priam New Member

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    Thanks for the replies! I was told to look into a laboratory power supply by EC corp, the current output is low and variable 100-750ma range.

    currently I am looking into this with a little help from ebay!!!

    My thought with the 'jumper cable' idea was that the prius knows best so let it charge the battery up, but at the end of the day yes I am reluctant to risk my car.

    in terms of me... tested working voltage detector, heavy rubber gloves, and obviously I will be hiding behind a 2" solid lead shield and press the power button with a long non conductive stick (brick on the brake pedal)

    just kidding about the last part ofc

    on a more serious note, in the event that I can get my hands on a lab power supply, is there a sensible way to charge the hv battery without removing it?

    I read about tapping into a relay panel. I understand that forum users may be reluctant to post information here that might be dangerous in the wrong hands, perhaps a personal message might work

    we have 3 gen 2s in the fam-a-lam now and I am the headmaster, so I am looking for a repeatable solution to address this exception should it arise again.
     
  5. Priam

    Priam New Member

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    I will study the wiring layout and try to do due diligence, but if someone has done this (trickle charged an installed HV battery) and has a reliable connection procedure worked out I am All Ears!

    thanks again everyone! best wishes.
     
  6. fotomoto

    fotomoto Senior Member

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    Hmm, a weak HV batt attempting to start the ICE can "sound" like the ICE is running but in fact is still being spun by the weak (and getting weaker) battery.

    I would ask the seller how long the car has been "distressed" (aka sitting) and why.
     
  7. TMR-JWAP

    TMR-JWAP Senior Member

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    A true lab grade high voltage power supply is a $3k+ device. Beware of many of the HV power supplies for auction on ebay. Many are advertised as 250v power supplies, but they are wrong. The people selling them have no clue. I've seen several that are 24v power supplies, being advertised as 250v power supplies because the data plate/label on the back of the unit says to use a 2 amp 250 v rated fuse in the protection circuit.......they're not purposely trying to shank anyone, they're just ignorant. If you decide to purchase one, you better be sure you research the part number and understand how to connect it up, as many just have a terminal strip on the back for input power and output power.

    or....You can purchase a Prolong Charger (or similar), with the correct harness and instructions for about 350. That will give you a proven, safe and reliable method to charge any 28 module HV battery. It also contains the circuitry to run the car's HV battery cooling fan to keep the battery airflow going while charging.
     
  8. ChapmanF

    ChapmanF Senior Member

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    Depending on what kind of current capacity you're looking for, you might get away for a fifth of that, less on the used market.

    Sure, a ΒΌ amp output is not going to dazzle you with how fast it brings up your 6.5 amphour battery. But as long as you've got something else to keep you occupied for a day and a half, it probably also won't give your battery the bulgies.

    I hear people mention old electrophoresis power supplies, if you happen to be near any kind of operation that that uses those and might sell old stuff.
     
  9. Priam

    Priam New Member

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    I went ahead and purchased a power supply, due to arrive in just 3 days!

    it is an EC model 570-90 electrophoresis lab supply
    variable voltage up to 500vdc, low variable current under 1A

    heads up *ebay link ALERT!!!**

    Items for sale by wazobia_ent | eBay

    this seller has a slew of similar models (university lab resale) for the reasonable price of 40$ shipped!! (many are cosmetically damaged and the seller is 'unable to test them further' the one I bought was listed as 'wont power on' however the pictures clearly show it powered on! *sigh*

    ill take a chance, at the end of the day I tinker with electronics so I doubt itll be a one trick pony.

    Get yours today while supplies last!
     
  10. ChapmanF

    ChapmanF Senior Member

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    I kinda tinker with electronics, but the number of times my tinkering has required 500 VDC doesn't take many fingers to count....

    Other than megger testing. There is that.
     
  11. Priam

    Priam New Member

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    I bought the car the day after the seller broke it down on IH35, it was a ferocious daily driver up until 'the incident' (50k in 2019). this was about 4 days ago.

    developed mystery severe oil leak on the way home... (a squirter, not a dripper)

    sellers father showed up and they added a bunch of oil (maybe too much, may have fouled the MAF) ICE would not run after that, but yes it 'sounds' like it is running when the car tries to boot up

    the car is also missing several lug nuts off multiple wheels, I am hopeful that the engine has some very loose bolts causing the oil leak but I have not got my hands dirty just yet... (busy few days)

    seller is a police cadet driving 100 miles per day to and from. He is about to graduate and its Crunch time, all the fun stuff 'mace to the face day' and even a written exam...

    he just needed a working Car asap so the poor Prius had to be liquidated instantly

    just to flesh the story out a bit.


    Thanks everyone for the replies!!
     
  12. Priam

    Priam New Member

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    the EC supply is variable voltage DC so anything up to 500...

    my thought was might be handy for EV battery pack projects. someday ill need a folding e-bike for my dream prius road trip!

    it also has a timer!! which is very handy!
     
  13. Priam

    Priam New Member

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    Update::

    Hv battery charger: complete. will post some pics in a bit!

    found crack on the bottom of the crank case (will post pics in a bit)

    right behind the oil filter, its a complex crack and looks NO GOOD!!!
    leading into my next thread... advice on fixing that!

    google says some people Solder a plate of aluminum over top (lower temps than welding)

    or JB weld magic...

    but the big question is, did this crack come from inside the engine indicating internal failure... or was it from road debris... bottom plastic fairing went Bye bye about the time of 'the incident' leading me to say its a road debris thing...

    but the crack looks suspicious!! like it was made from within...

    we booted the car today to locate the crack, powering it off seconds after the ICE tried to fire up...
    engine sounds relatively healthy... no banging knocking etc...

    more update in a bit, possible new thread, and pics!!!
     
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