Recharging Traction dead Battery

There are two ways of approaching this problem dependent on your level of skill with electrics.

(1) Long winded but best. Charge each module in the battery individually with a Suppermate DC6 charger balancing each module as you go. Expect at leased a month to accomplish with one charger.

(2) The possibly quick but risky method of using your 230v mains supply through a bridge rectifier then charging the battery through a 40watt light bulb. This should give a charging current of no more than 175 ma.

 

I'd rather pay Toyota than the above; or buy a second hand one.

 

As a retired EE I would have no problems with either method, but I would always advocate working within one's capabilities. To me it would seem a waste to discard a high value item without trying to refurbish or simply charge.

After all if you flatten your 12v battery you would try recharging it before buying new. There is fundamentally no difference between the two.

 

If the OP doubts his capabilities, he might want to try Re-Involt.

Remanufactured Hybrid Vehicle Battery Packs

Unfortunately, we can't tell where he is, because he has not stated and he has not filled out his profile.

 

It might not be illegal to disable the "sound," but you might be opening yourself up to legal liability, if you should have an accident with a predestrian.

The "sound" essentially, as I recall, is mandated by Federal Regulation. That's probably why a Toyota dealer won't do it.

 

There is no problem with using a step up transformer from 120v to 230/240v.

Bridge rectifiers can be bought for pennies at electrical suppliers suggest minimum rating of 2amps at 400v (4amp or above would be better) or 4 diodes in a bridge configuration, again of similar ratings.

The bulb should be rated at around 230v if rated at 120v use two in series. A variac (variable voltage transformer) can be used to advantage but few people will have access to one of these.

Permanently monitor the battery voltage when you hit about 210v you should be good to go. Do not try to charge to quickly, if you can measure the charging current suggest you keep it below 1/4 of an amp 250ma. to reduce current use smaller wattage bulbs.

Take sensible precausions against shock risk use the HV battery safety plug when connecting and disconnecting charging device.

NiMh batteries do not suffer from the same problems as lead acid when fully discharged and left in that state so with luck your battery will be ok.

John (Britprius).

 

Once charged it would be sensible to check the voltage of each module to make sure the modules are at at the same voltage "or state of charge".

If you need a circuit diagram let me know and i'll see what I can do.

Just one point to clear up did you check the battery voltage with the safety plug installed and at the terminals where the wires are connected that come from inside the battery case not on the output of the contactors.

John (Britprius).

 

Steve,

There are 28 modules (all in series) and each module has 6 1.2v NiMh 6.5 Amp-Hour cells (again in series). All in all a very simple layout. The battery ecu monitors the modules in 14.4 volt pairs.

JeffD

 

The wiring diagram I meant was for a charger but I think you seem to be ok with that.

Unfortunately I do not have a diagram that shows the HV battery internal wiring. It is purely a series battery of 168 cells arranged as 6 cells to a module (at nominal 7.2 volts, 1.2 volts per cell) and 28 modules totaling 201.6 volts nominal.

The modules are paired in the battery purely for monitoring purposes.

There is no logical reason why the whole battery cannot be balanced as one unit. The theory behind balancing is that over time for various reasons some cells will have less charge than others. Meaning that if they are all charged in series some will reach full charge while others may only be charged to say 70% because they start from a lower base charge.

If you continue to charge the battery after the some cells are fully charged, those cells will not charge any more and will give off the excess charge as heat. While this is happening the cells with a lower state of charge will begin to catch up. A fan to keep things cool when doing this is a good idea.

Fully discharging the battery helps to condition it, so cycling the battery through a few slight over charges and discharging a few times (usually 3 but can be more) brings all the cells into line. Remember the amp/hr capacity of the whole battery is the same as the lowest capacity cell,"weakest link in the chain".

Do not try to charge individual modules unless they are clamped on either side with timber in a vice or with G clamps, and do not charge the battery unless it is in it's chassis and has the clamp rods in place. These modules can blow up like balloons unless clamped.

When you have initially charged your battery you can check module voltages, they should all be the same within .1 volt or better if outside this figure they should be balanced.

In use in the car the battery only ever gets charged to 80% capacity and discharged to 40% this increases the service life of the battery but does little to keep the cells balanced. The total amp/hr capacity of the battery is 6.5 amp/hr.

John (Britprius).

 

When you reinstall the orange traction battery interlock, you must first insert the interlock, then pivot the handle 90 degrees. Finally, slide the handle to lock it in place. The last step is frequently overlooked.

I suggest you try that. If you still measure less than one volt I would think it is likely that your battery has at least one failed module out of the 28. When you open the battery case then you can measure voltages across each of the 28 modules.

 

Thank you Patrick for your advice. I was not happy that such a low reading was given the reason for my comments in post "10". This is for a gen2 battery that has 28 modules.

I agree that if the interlock is not properly in place the reading would be zero but the chance of having a module completely open circuit "that is several 10s of megohms" so that no voltage is registered off load is highly unlikely. Even a badly corroded buss bar would give a reading.

I think the sensible option is as you imply to measure all of the modules to see if there are any with charge rather than trying to check the complete battery. I will ask the OP to do this before going further.

 

Steve, you have probably read the above post and would ask that you remove the cover (after removing the safety link) and check the voltage of each individual module and report them back to us.

The reasons for my questions in my post "10" was that it would be unusual for such a large pack of cells (168) to have as low a reading as you are getting. So just trying to dot all the I's and cross all the T's before progressing.

I am in the process of drawing up the charger circuit.

John (Britprius)

 

It is true that the fuse needs to be checked.

Note that the interlock is not connected between the two halves of the 2G traction battery. I don't recall exactly where it is wired, but you will find that one section has more modules and therefore voltage, than the other.

 

I believe the link is one module pair off center in the battery giving voltages of 115.2 and 86.4 volts nominal. It would still be help full if you could measure the individual module voltages if you have the battery out of the car.