Charging a older HV battery that has been sitting..

It's VERY unlikely your old battery pack is in any type of condition to function, and is most likely about completely discharged after sitting 2 years. At a minimum, there will be several modules that are completely discharged, making the battery useless for installation. Remember, the HV battery is the power source for starting the engine. If the ecu detects any failures of the HV battery, it won't even allow the main relays to close, so the HV battery never even gets put into the circuit. If you don't have a way to charge the pack all at once, it's possible you can do 1/2/3 at a time with a hobby charger. Charging them is in no way guaranteeing the modules are still functioning properly.

 

I would just be curious to know what your voltmeter tells you on DC volts sitting right there right now 196. ? That should only take a second to read. Then after that you look at the bus bars and nuts and look for the copper getting the patina on it looks nice but not good for electricity conduction frosted nuts All of those things If I saw 125 plus volts I might put my hobby lamp on it and let it discharge somewhat and then put my charger back on it and charge it back up with my charger when there's no change in voltage for 5 minutes charging up then you disconnect the charger but it stands a while to recheck the voltage and then do another discharge and then another charge and so on and see what happens obviously you have time so that's not the issue.

 

It's more like 4 to 6 hours, not 5 minutes.

 

No what I'm saying is is when I hook up my Venice hybrid pack charger to a hybrid pack depending upon where the battery is when I connect the charger I run the charger until there's no change on the chargers voltmeter which is reading the battery in 5 minutes so if I look at the charger and it says $230 volts in 5 minutes if it doesn't go to 231 I disconnect the HV charger as the battery is accepted the voltage it's going to accept That's the recommendation from the manufacturer of the charger. No the battery will not charge in 5 minutes typical though if the battery is sitting at 150 volts 157 volts or something like that usually in about 2 hours I'll be sitting at 2:11 2:30 somewhere in there I have not tried to charge a pack that's sitting at zero DC volts that I know of

 

This is charging it 300 volts at 2.4 amps

 

Yes, I understood that's what you meant. There is no way you can charge past ~ 220 V by waiting only five minutes. If you look at the graph below which shows a typical charge session it takes progressively longer to raise the battery voltage by 1 volt.

The recommendation from the Hybrid Automotive is that when you do not see the voltage rise within 4 to 6 hours then you stop the charge. If you do not do this, you will not top balance the battery.

On the graph (below), the two rightmost solid vertical lines denote 6 hours. The dotted vertical line (between them) is 4 hours.

The next pair of solid vertical lines to the left is ~ 40 minutes and marks the time the voltage took to rise from 235 volts to 236 volts.

If you can raise the voltage by 1 volt (above 235 volts) in less than 5 minutes, your battery is pretty cr4p. The healthier the battery the longer it takes and also the lower the top ceiling voltage.



Detail matters.

 

Like I said this is very common so clean up the mess see if you got any leaks anything swollen look under the modules on the tray with a flashlight and go from there That's what I expected you to find pretty much a good show.

 

This is just what the manufacturer of the Venice hybrid charging system Raj is his name said to me when I got the system from him when it's connected and it's working when it reaches voltage and doesn't change in 5 minutes you should disconnect the charger You can leave it on a while if you want see if the battery pack starts to heat up and then disconnect it once you start generating heat you're pretty much done with charging so I think his advice seems pretty reasonable that was not going to happen that 5-minute change until the battery is pretty much charged up to 80 85 87% somewhere in there That's probably what it works out to be You're not trying to blast it up to 100%

 

I guess it all depends on what you're trying to achieve.

I'm just trying to highlight for readers coming along later that using that 5-minute criterion is not adequate to top-balance a pack and if you're trying to top-balance a pack, that is good to know.

If you apply that 5-minute criterion, you are likely to be around 55% to 60% SoC. If you look at the graph I posted above, using the 5-minute criterion I would stop the charge at 217 V. As I didn't stop the charge at that point I can see that the next two voltage rises from 218 to 219 V took ten minutes each; The next three voltage rises from 220 to 222 V took 15 minutes each. From 223 V onwards to 241 V it took progressively longer (25 min, 30 min, 50 min, 60 min, etc) where the final voltage of 241 V was achieved with no change in four to six hours. In total, the elapsed time to top-balance was some 28.5 hours.

The point of charging for this length of time is to top-balance the battery pack.

Like I said earlier, it depends on what it is you're trying to achieve.

I don't know what the charge current is on your Venice charger, but it should be 350 mA maximum. If you're getting heated modules at that current rate, then I'm thinking your modules are pretty much done for. Even if you don't get any noticeable heating it is a good idea to apply cooling the battery.

If it is your intention to just add a few volts to the pack to get it to 60% or 80%, then yes, that is sufficient. However, if you are reconditioning the pack, an important step in that process is top-balancing and to do that you do need to get the pack to 100% and keep going until it won't take any more voltage, not blasting it, but a very gentle, slow, 350 mA or less.

 

Yes of course I'm usually applying the charger to a battery that does have some juice in it like one I've walked up to wherever it is and I put my test leads on it and it says there's 120 volts in there 150 196. I hook up the Venice hybrid charger turn it on the 300 volt mode which the manufacturer suggests for this $211 volt system The battery is not connected to the car generally while I'm doing this and I turn the charger on and it says whatever number I just spouted above whichever what it was let's say $150 It says it's 150 volts in the battery I have the charger on It's steadily starts to rise 150 155 157 whatever when it gets to 230 volts or whatever it is and there's no change on the battery chargers display for five solid minutes that's a long time when you're standing there. And it doesn't change the manufacture of the Venice hybrid charger recommends you remove the charger from the battery... That's it I'm not talking about it's going to take 5 minutes to charge your battery up holy Christ that has nothing to do with this conversation nothing in this world is going to take 5 minutes to charge anything at least not yet. 5 minutes is not the total time it will take the charge any battery anywhere that I know of. The 5 minutes is the time that the display on the charger itself does not show a voltage change That's all this has nothing to do with where I'm carrying the battery as far as state of charge goes 80% and 90 none of that. I think this is generally acceptable methodology when charging some of these batteries I don't think somebody just pulled this out of their rear end because they had nothing better to do The guy who made this charger is really not that kind of guy you know. I've seen other similar things mentioned with other charging devices and so on so it seems reasonable 5 minutes is not anything to do with battery charging time I would say it's more battery voltage changing time.

 

Well since we're getting into the super common stuff it's really super common for these battery problems more than it is for the break actuator problem. So there's that I see a lot more battery problems than break actuator problems generally speaking when I'm working on these things that's usually your number one call and whatever is something's wrong with the battery and usually that is the case because they haven't been touched for 8 to 10 years and well it's time I don't know why people some people especially think that this battery will just last forever my like ask people right to their face I mean you've never seen a battery in your life last forever You've bought batteries for flashlights and major Matt Mason toys and all that stuff for the last 50 years what in the world would make you think a battery shoved in the back of your car not the 12 volt to run some electric motors in a transmission is just going to last forever No with the last till you're tired of the car maybe which you should be by now Why aren't you in another one? And then all the dialogue starts well we were hoping we could exactly It's always a hope and a dream you know

 

It would have to be a heck of an accident to smack into the car and create enough shock and what have you through the system to literally compromise the prismatic cells racked in the HV battery I guess a side impact in either of the rear corners or a direct hit in the back of the car pushing the spare tire well almost into the back of the HV battery could do it but most of the Prius I see are light dinks to the sides of the front end on the front part of the car and when I walk up to most of these things when there's a battery sitting in them which is rarely I'll give you that unless I'm at a tow lot. But regardless when I walk up to one of these cars it has a battery sitting in it even if it still connected I put my test leads on it shockingly I'll see over a hundred volts pretty regularly. And usually right on the spot out pull the cover off lift the cover up take a look under the hood of that battery and decide whether I'm going to slide it into my rolling cart and wheel it back to the front of the junkyard or not.

 

Just because it is fully discharged and 5 years old doesn't mean it needs to be replaced. I'd try fully charging it and then testing it first before condemning it.