Reconditioning the HV battery

Hello everyone,
I felt a bit adventurous with the Covid-19 isolation and thought I will try to recondition the batteries of my Prius although there was no issue with them. Dr Prius gives me a rating of 59% on the battery condition, which I was hoping I can improve. I got a skyRC Q200 charger, and took the battery out, but when I put the charger to work on the batteries, I get some weird behaviour.
First of all my settings are to perform 3 charge-discharge cycles, at 3A charge and 1A discharge. I setup the cell number to 6, and cutoff voltage to 1V (I think it does the multiplication itself for 6 cells). The dV setting is at 4mV. I put that for each of the 4 channels.

I see the charger going from around 12V to 14V while charging. Which from what I have seen on videos, or charging NiMH batteries is too high. It should not be much higher than 9.5V at maximum voltage. This really worries me, so I have stopped the process but could not find more information. I am also worried about the charging cables, since they feel quite thin. Not sure if they are the reason of the high Voltage. When the charger measures resistance, it find it at 1300 - 1500mOhm depending on the module. I know the internal resistance is at around 22-24mOhm in my cells according to Dr Prius.
Also I see that the charger is stopping the charging stage early, so it does not go to a full charge. When starting to charge again it keeps going happily. It is happening it to the first 2 modules I tried. I am wondering if there is something with my settings.
Any thoughts or advise on the above?

Thanks

 

I was on a tighter budget, plus I play around with drones so it was two birds with one stone. That is if this charger can do a proper job and this high voltage is not dangerous

 

So you guys think the skyrc Q200 charger is playing up on me, and this high voltage is not appropriate for NiMH batteries.. Misreading something about the module probably. I ordered some AWG 16 cables anyway in case they help. I will keep looking at and contacted the manufacturer, but it looks like I may need to send it back and get something else. I don't see how to get a prolong charger in the UK, and don't wont to mess with the delay and expense of customs. I may have to go for some of the cheaper chargers other people have used which seem to work fine.

 

I actually figured it out yesterday night, the cables were to blame. I borrowed some AWG 16 cables from work, and the voltage dropped to normal levels, plus they don't get that hot. I just need a permanent setup to complete the work. Thanks for the help and information guys

 

Hello guys,
just reporting on the results. The car starts!
I went for a quick spin, and all look good, no complain or error codes coming up. The one worrying thing is that the internal resistance (according to Dr Prius) went up from 23-24mOhm to 26-27mOhm. Its like I did more damage than good! I am wondering if cleaning the bolts from the dried electrolyte increased the resistance or maybe I did not tighten the bolts enough. I put the bolts on Vinegar to clean, and used a tooth brush at the end to scrub. Some rust was still on when I put them back on the battery, but thought its good enough.
I will do a life expectancy test with Dr prius and see how it goes. It was at 59% before.

 

To answer the questions.
I tightened the bolts with a ratchet wrench up to the level it started to require a quite bit of force to tiwst more.
No more vinegar then, baking soda it is. Vinegar is considered good at cleaning rust so I went for it.change from being at 80-90% to 40% so I am wondering what the deal is.

I run the battery test, and here are the results.
The old one first

and the new one


It makes me wonder if there is any merit to these tests, and how reliable they are. 101.28% sounds too good to be true. I am wondering if the starting charge level was too high, and confused the battery controller given I fully charged the batteries before putting the unit back. I did a little drive about 20 minutes before, and not sure if this discharged the batteries or not. I will do another test later, wondering if I will get anything around that range