hybrid battery Pre-replacement plans

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by totalimpact, Jan 2, 2018.

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  1. totalimpact

    totalimpact Junior Member

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    I have a 2007 with 222k (barely broke in), and just picked up another 2007 with 170k (like new!) for my wife that was sold (dirt cheap) due to the red triangle of death + dead MFD (already replaced). I know I wont really know anything until I get the battery pulled and isolate cells, but looking for help on a pre-game plan.

    I checked the battery using Torque app before buying, and its specs look better then my higher mile one, I am trying to figure out what route to take to get it rolling -
    - Replace the entire pack $850 refurbed
    - Replace suspect module(s) $250 installed for 1 module pack, or $40x2 if I do it myself
    - Pay someone - or do it myself. $250 vs $80 (amazon)... or the whole pack??

    I am mechanically inclined, do most of the work on my Ford 6.0 diesel (the devils work), including head gaskets and EGR. I have a good friend that runs a mechanic shop, so I also have access to $100k worth of shop grade tools.

    I have seen a few videos on battery balancing, I have a Turnigy balance charger, and I think it just needs 1 pair replaced. Torque shows the ECU readings for voltage and resistance on the 14 module pairs.

    All of the modules are pretty close to around 16 volts, accept module #2 is 13-14 volts, I *think* it just needs that one. I have monitored it while driving, under load, charging, and at rest, and that is the only one that seems really low.

    Other observations - the dash battery display goes from zero to green extremely quickly under braking, and of course depletes quickly - is this the effects of the 1 bad module that is over charging to a higher voltage than its true holding voltage and this fools the ECU into thinking it has reached a higher SOC??... or is the entire pack suspect?? Every module is currently showing .02 ohm, I was able to screenshot my phone, there are a few seconds between shots, so its not 100% consistent (need to use Torque data log next time).

    Idle voltages (ICE off):
    Mod1 16.11 / Mod2 14.74 (bad)
    Mod3 16.13 / Mod4 16.11
    Mod5 16.12 / Mod6 16.11
    Mod7 16.12 / Mod8 16.07
    Mod9 16.13 / Mod10 16.08
    Mod11 16.11 / Mod12 16.15
    Mod13 16.16 / Mod14 16.13

    Discharging on battery only from a stop sign:
    Mod1 15.28 / Mod2 13.51
    Mod3 15.18 / Mod4 15.16
    Mod5 15.10 / Mod6 15.14
    Mod7 15.10 / Mod8 15.05
    These taken 13 seconds later, still accelerating battery only:
    Mod9 14.48 / Mod10 14.55
    Mod11 14.46 / Mod12 14.49
    Mod13 14.48 / Mod14 14.62

    Charging (braking):
    Mod1 16.95 / Mod2 17.38
    Mod3 16.98 / Mod4 17.01
    Mod5 17.03 / Mod6 16.99
    Mod7 17.00 / Mod8 16.99
    Mod9 16.99 / Mod10 16.99
    Mod11 16.95 / Mod12 16.95
    Mod13 16.98 / Mod14 16.90

    Other stats noted:
    Charge 60kw
    Current 3.96amp
    Discharge 68kw
    Fan speed 6 (what the ECU reports to Torque)
    SOC 94%
    Temp 83

    Should I try getting a couple used modules off amazon and balancing them myself? Should I pay someone to do this (referred by someone else not mechanically inclined, of unknown skill), or is the whole pack suspect and I should just replace the whole thing? Can I try to just balance the new pair (probly not)? Or can I just parallel the whole pack for a day or 2? Or does every single module need to be balance cycled individually.... or should I get that $400 Grid charger thing?

    This car can sit for a couple weeks, it is not my primary, but the plan is to sell my wifes current car and use this once it is road worthy - after that I need it to run good for at least 6 months.... the goal is to eventually get a Gen3 and pass this gen2 along to the mom-inlaw who drives 2-3k per year.
     
    #1 totalimpact, Jan 2, 2018
  2. Dxta

    Dxta Senior Member

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    You've got lots of threads on battery rebuild over here. Y not search on the search box?
     
    #2 Dxta, Jan 3, 2018
  3. totalimpact

    totalimpact Junior Member

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    I have, and the recent ones the search gave out looked like nightmares... I was hoping for some encouragement for any particular direction.
     
    #3 totalimpact, Jan 3, 2018
  4. dolj

    dolj Senior Member

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    I wouldn't use Amazon/eBay. Call a reliable and trusted member like @ericbecky, he is always happy to talk to PC members about their options. He can supply good quality modules, too.
    If you have the skill and aptitude and understand working with HV DC voltage/current, them I wouldn't do this, I'd do it myself.
    Not necessarily, all modules other than #2 look ok. I think you have a good chance at getting some more out of this pack.
    You don't understand balancing, it is something that you do to the battery in its entirety, not to individual modules per se – although you will need to charge/discharge/charge cycle all modules to do a proper job.
    This is just a waste of time. It will achieve very little.
    Yes, or in pairs, as I go on to say below.
    You will need to get the charger and discharger as a pair ($650) to do a proper balancing in the easiest and quickest time. This is where a grid charging/discharging system has it in spades over your Turnigy. Even though it can probably charge a maximum of 15 NiMH cells at a time, which means you could do 2 modules at a time (12 cell in total in two modules), it will still take you about 2 weeks to do all modules as opposed to about 3-4 days with a grid charger. If time is not critical and you can cope with 2 weeks then charging with your Turnigy would be a viable option. One other advantage of using the grid charging system, is while you have everything apart, it is easy to install the charging harness. Then when you do further charging cycles in the future, you can hook up the charger and discharger to the harness without any disassembly/reassembly of the car or HV battery. Everything remains in situ.

    hope this helps.
     
    #4 dolj, Jan 3, 2018
    Last edited: Jan 3, 2018
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  5. jerrymildred

    jerrymildred Senior Member

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    +1 to @dolj.

    Check the threads on the Prolong grid charging system. It's much faster, much easier, and much better at balancing all the cells evenly. Since you need to pull the battery to replace the bad module anyway, installing the cable only takes a few more minutes, and then it's always there for future maintenance grid charging. That's your best chance of trouble free driving short of a new or near new complete battery or full set of cells.
     
    #5 jerrymildred, Jan 3, 2018
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