Disconnect the charger and try to start the car and let the computer manage the battery for a while. The engine should start. If you drive it around for a while the Hybrid system should replenish the battery. If it stays that way, you're fine.

 

Sure.. I will try that in the morning… the current voltage is at 328V

Thanks Alex

 

You should follow directions.

Consider:

0.5 h * 0.35A = 0.175Ah

0.175Ah/5.5Ah = 3.2% charged.

Even worse, a deeply discharged "dormant" battery needs what I call "activation capacity". It's going to take 5-10% charge to get it to 0%.

340V after only 30 minutes strongly suggests the battery is still in the "dormant" phase where resistance is higher.

There's a reason I recommended 3-4 hours.

 

Hello Keith,

I will keep the charging for 3 hours today and then install the battery.

When I checked the voltage today morning it was 315 V, the minimum charge for the car to start is 320 V right? Do you think there is a problem with my battery?

Sorry for the noob questions. Im trying to understand whats going on...

Thanks for everything
Arun

 

I don't know what the minimum VOLTAGE is. I've seen cars attempt to start as low as 285V.

As I demonstrated above, 30 minutes of charge at 350mA is a trivial amount of input. The subsequent 20V drop overnight again supports the idea that the cells are still in a dormant state and need more charging just to get to 0%.

If you have this outside the vehicle, and you have to go through the hassle of installing, I'd recommend a longer charge - a total of 6 hours.

The cells have a capacity of 5500mAh. You are charging at 350mAh. The car operates at about 50% SoC. Thus, it would take 5500mAh * 50% / 350mA = 7.9 hours to get to 50%. I'm not saying you need to do that, but it's to provide perspective on how little current the 350mAh chargers provide.

When NiMH sits and deeply discharges, it enters the dormant state where it can't pass current at high rates with low resistance as needed by the vehicle in operation. It requires an input of about 5-10% of the total capacity of the cell to restore the chemistry to be high current/low resistance capable. With this type of charging, it is common to see a rapid voltage increase early in the charge. Once the chemistry transitions to normal, the voltage typically drops - sometimes substantially. Alternatively, the voltage may not increase substantially, but it may "hang" at a seemingly acceptable voltage where it doesn't increase for an hour or two. Once "normal" is restored, voltage will increase very slowly as it charges. When either of these occur, the chemistry is essentially restored to "normal" and is at 0% SoC - all charging prior to "normal" does not count towards the total capacity. When I recommend 3-4 hours, this ensures the first 1-2 hours can overcome the dormant phase and then one gets another 5-10% of actual charge - should be more than enough to spin the ICE several times.

I don't have a technical reference for this phenomenon. I have simply observed it dozens of times, and I have confirmed similar observations made by other battery builders confirming the phenomenon.

If one is going to go to the trouble of manually charging their HV battery, it's best to spend more time charging rather than trying to rush it.

 

Thanks Keith for the detailed explanation.

Yes I'm charging outside of the vehicle, so just want to be sure before installing it back.
I will keep the battery on charge for the next 6 hours and install it back.

 

Hello Guys,
I have charged the battery for 6 hours and then started the car, its running smoothly now.
Thanks to Keith for putting up this awesome thread and saving thousands of dollars.

 

Glad to hear it. If possible, run the Forscan battery balance function.

 

Great! Glad to hear. Another successful procedure at General Hybrid Hospital under the direction of Chief Surgeon SKeith, with commentary by "Dr. Bob" AlexK. I assumed you had already charged it for several hours when I said to disconnect and attempt restart.

This is my wing of the Hospital:


SKeith's is run much better, and these days he's involved in a deep debate with ShadyEscape over replacement Chinese battery cells, a subject of unhealthy interest to me and for which angst I am deeply indebted to both for engaging in, I'm sure.

 

Good news. Now use FORScan and command a battery pack balance procedure.