Jump starting car with Clarity (you can do it)

Discussion in 'Clarity' started by DanGest, Oct 2, 2019.

  1. DanGest

    DanGest New Member

    After getting a couple claritys (one for me, one for wife) the gas-guzzling volvo had been sitting idle for quite some time, and of course when I went to start it, the battery was dead. Volvo, being stupid, requires the battery to open the trunk where my jumper cables were stored...I mean really - but that is more of a rant. Anyway, had another set of jumper cables luckily and located what i think is the larger battery on the Clarity (on passenger side of hood). Hooked everything up and went to start clarity...not being stupid.......I switched the car to HV mode and shifted into neutral and tried to accelerate to activate the gas engine/generator. Ugh, the Clarity does not let you do this, leaving in park or switching to neutral and trying to press the "gas" pedal only results in failure/some sort of warning that you are in neutral. Let the car sit turned on with the gas engine not running for around 3 minutes, and decided to just see if anything happened. Lo and behold, the charge was transferred, Volvo fired right up and I drove around 30 minutes to charge the battery (as should be done).

    TLDR: The Clarity will jump a car even if the gas engine doesn't fire up, so don't get overly frustrated as I did when I couldn't force a gas engine start.
  2. Claire Green

    Claire Green Member

    The clarity has no generator/alternator to charge your volvo. The 12v battery is charged by the "big" battery under the car from what I remember. But there is a way to start the ICE for oil change purposes I just don't have the procedure with me at the moment.
  3. Sandroad

    Sandroad Well-Known Member Subscriber

    As noted by @Claire Green , there doesn't seem to be a particular advantage to starting the ICE in that situation, provided the HV battery has enough charge to supply power to the terminals on the 12V battery. But, another user posted the ICE force start procedure last year.

    Posted by @Jeff628

    You can force the engine to turn on by doing the following steps.

    1) Make sure the car is completely off.
    Note: The rest has to be done within 60 seconds to take effect.
    2) Press the start button without stepping on the brake pedal. Then a second time after a few seconds so that the lights come on around the P on the shift lever.
    3) With the shift lever in P, press the accelerator pedal to the floor twice.
    4) Push the brake pedal and move shift lever to N, release brake pedal. Press the accelerator pedal to the floor twice.
    5) Push the brake pedal and move shift lever to P, release brake pedal. Press the accelerator pedal to the floor twice.
    6) Push the brake pedal and push the ON button to start the car. The display will show maintenance mode and the engine will start after a few seconds.

    When you are done, just push the power button to turn the car off.
    Last edited: Oct 2, 2019
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  4. DanGest

    DanGest New Member

    Wow, good to know, I had no clue there was no alternator (isn't that what the gas engine acts as in HV mode though?)
  5. insightman

    insightman Well-Known Member

    The ICE is always connected to the starter motor/generator and the starter motor/generator can send electricity to the traction motor and the HV battery. The HV battery charges the 12V battery through a DC-to-DC converter, as with all Honda hybrids, starting with the 2000 Insight. With no alternator, the HV battery has to be working to drive the car any significant distance.
    Last edited: Oct 2, 2019
  6. KentuckyKen

    KentuckyKen Well-Known Member

    Since the manual only talks about jump starting a dead Clarity and not about using it to jump off another car, I’ll go out on a limb and start the discussion on what would be best practice for this.

    Previous posts seem to indicate that the 12V battery is not kept charged up when the Clarity is not turned on. And, as stated, there is no alternator so the charge comes from the HV traction battery.

    Based on these “facts”, then I think you would want to turn on the Clarity (EV Ready, not Acces, HV, or HV Charge) for the jump which would be analogous to running a gasmobile’s engine to keep the voltage up in the 12V battery. If you have a decent SOC in the traction battery, I don’t see any advantage in forcing the Clarity’s ICE to start.
    Will the collective wisdom of the Clarity Brain Trust please weigh in, since I am not an expert on this and the manual is silent on it.

    Also note that the manual is very specific on the placement of the cables and this may not just be for safety in avoiding a spark at the battery since it specifies an exact placement location for the neg cable on the power system mounting bolt and not just on any ground away from the battery. It doesn’t say, but this implies that it also might be for the protection of the Clarity. At the risk of losing my Man Card, it’s usually best to follow the instructions.

    Or you could take the chicken’s way out like I did. I was a little leery of jumping someone off or being jumped off considering all the expensive electronics that might be affected if it was done wrong. But I still wanted to be able to help someone who needed a jump. So I bought one of those small Li-ion battery jumpers that’s the size of a paperback book after a Good Samaritan jumped my old gasmobile off with one and proved to me that they work. It stays in the cubby under the trunk mat and will even power my phone for weeks in an emergency. I paid a little more ($80) for one powerful enough to jump off even a midsize diesel that comes w all the cables, a light, and a hard shell case.
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  7. Mowcowbell

    Mowcowbell Active Member

  8. Walt R

    Walt R Active Member

    Since I know I won't remember this procedure when I actually need it, I am wondering - assuming that the EV charge is low enough, would it be simpler and just as effective to activate HV or HV charge mode to start the engine?

    Hmm, now that I'm thinking about force-starting the engine, I wonder what happens if you go in for your emissions check (which are almost all OBD II queries now) after driving 2 or 3 months on EV-only. Would they fail you because the OBD reports no emissions operation data?

  9. bpratt

    bpratt Active Member

    I have actually used my Clarity to jump start a stranded vehicle. I first pulled up, shut off my car, opened the hood and hooked up the jumper cables. There was not enough power to start the stranded vehicle until I turned my car on. My engine did not run, but there was immediately plenty of 12 volt power to then start the other car.
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  10. This makes sense. Just like an ICE vehicle does not keep the 12V battery charged, via the alternator, when the engine is not running.

    Being a LA battery, the brains of the operation must keep it properly charged while driving. It sounds like access to the voltage in the 12V battery may not be available until the vehicle is powered up.

    It certainly seems that the need to jump a Clarity would be a rare occurrence. I am also a fan of the Lithium jump starters.
  11. MrFixit

    MrFixit Active Member

    My thoughts --

    In general, you can jump-start another car without 'running' your engine.
    After all, it is effectively just using the same 12V battery that would start your own car, and it is perfectly adequate for that.

    There are 2 reasons I can think of to 'run' your engine while jumping another vehicle:

    1. If your battery is marginal, you run the risk of the recipient depleting enough energy such that your car could fail to start after rescuing the other vehicle. If your car is 'running', then you can drive away and re-charge on the road.

    2. If you have a less-than-perfect connection with the jumper cables (common), the extra couple of volts (14V wen running vs. 12V when not) can help overcome a 'poor' connection and provide enough current to crank the other vehicle when it may otherwise not.

    Item 1 is more of a concern for an ICE vehice because of the large demand when 'cranking'... The Clarity would not have this high demand when starting out in EV... When the ICE needs to start, you have likely been driving / charging for a bit of time anyway.

    One thing that would make me hesitant to jump start another vehicle with the Clarity 'running' would be this - The Clarity will be trying to charge the battery, maintaining 14V while there is a very high load from the other vehicle. This is also true with an ICE vehicle spinning it's alternator, but the old mechanical alternators are very robust and the extra load [could] but would not be likely to damage them. My concern is that the Clarity may have a relatively wimpy DC-DC converter because the 12V system does not have a high demand. It is possible that the recipient vehicle could damage your electronics with an excessive load.

    I am thinking that I would leave the Clarity off if I ever attempt to jump another vehicle because that would be less likely to damage any electronics. There might be some merit in hooking up, and 'running' the Clarity for a few minutes to 'charge' the recipient's battery a little, but then I would turn it off before attempting to crank the other vehicle.

    I agree with the Lithium jump starters, but if you have one, it is likely that it virtually never gets used. It may be dead when you need it, unless you are diligent about keeping it charged (most people aren't).

    Last edited: Oct 8, 2019
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  12. M.M.

    M.M. Active Member

    This is a bit late, but I wanted to add some clarity (ha!) based on experiments I did in prep for using the 12V system to run an inverter for my house:

    When the car is on (not accessory mode), the DC-DC converter will float the 12V battery from the high voltage system at about 14.5V, outputting up to 2300W (somewhere in the range of 160-190A) to do this. Depending on load and how long the car has been on, the voltage will be lower and it may cycle charging off occasionally (probably to maximize life of the 12V battery and/or check battery health), generally holding it a bit above 12.5V under heavy load (A/C, lights, both seat heaters on), occasionally turning off charging and letting it drop to ~11.7V or so for a brief period.

    This makes it extremely simple: If you turn the Clarity on and hook the jumper cables to another car from the 12V battery, the DC-DC converter will kick in and shove up to 150A into the other vehicle. If the other vehicle were to draw more than that, the Clarity's lead-acid battery will supply additional current up to probably a few hundred amps. In reality, due to contact resistance of the jumper cable clamps, the amount of current will be substantially lower than that, and the Clarity is unlikely to even notice. The other car will start (maybe not instantly, but as soon as there is a bit of charge in the other battery).

    If you want to be paranoid, turn off the climate control, seat heaters, and headlights in the Clarity while doing the jump, to minimize load on the DC-DC converter. The only thing you don't want to do is clamp on the wrong side of the overcurrent protection and risk blowing a fuse. Hypothetically if the other car's alternator was wonky and putting out very high voltage it could do something weird on the Clarity's end, but I wouldn't worry about that; it should get the voltage pulled down by the discharged battery on the other end before it's any sort of problem.

    As noted by the OP and others, the Clarity's ICE is completely irrelevant to this process. The 12V system is powered by the DC-DC converter and 12V battery, period. Turning the ICE on does exactly nothing to help, nor does revving it. There is no alternator. If the high-voltage battery is completely empty, the ICE will start on its own and run if needed. If the high voltage battery is not empty, if anything running the ICE may actually put more load on the 12V system (spark plugs, circulation pumps, or fans).

    I've jumped cars with my Clarity exactly as described above, and it worked exactly as expected. In fact, a friend with an older vehicle tried and failed to jump a car (either corrosion on the battery posts or a crappy alternator). They thought the car had something else wrong until I hooked up my Clarity and it started immediately.

    The real thing to be careful of is that you don't screw up the Clarity's battery posts by putting the clamps somewhere funny and melting some metal; there really isn't a good place to clamp on to the Clarity's 12V battery.
    Last edited: Nov 5, 2019
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  13. descolado

    descolado Member

    I tried this on a 2008 a couple months ago but wasn't able to get the MDX started. Their battery is much bigger, and I did let my Clarity run for about 15 mins before calling it quits.

    Was very paranoid I would damage the electronics of my vehicle but had no issues. I'm guessing their battery was too low to sustain a charge, so instead helped the other driver pickup a replacement at Walmart and did the install under the power of a cell phone flashlight. I figure I'm covered karmicly as a good Samaritan for at least another few months.
  14. Cash Traylor

    Cash Traylor Active Member Subscriber

    Since this is another duplicate thread I am going to link some possibly new information here regarding this practice. I have to agree with many that there are some inherent risks since the practice is not spelled out in the manual. However, many have been successful.

    I also like @MrFixit point about you not "having" to run your car to jump start another. My detailed answer is here and why I will not be boosting another vehicle with my car unless I can start it without running the Clarity (leaving the DC-DC converter off).




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