Gen II Prius Individual Battery Module Replacement

I just received a Thunder T6 and did my first 4 modules. I'm not sure if I have the settings correct. Discharge 1a/6.0v, charge 2.5a, 7350mah, dp 5, wait 5 min, charge/discharge 480 min. When cycling all the modules the charge stop at 7350, should that be set higher? On discharge even though the setting is 1a it does .7 and one sometimes flickers .8. I would appreciate some help.

Thank you

 

Your settings are fine, but you need to increase the charge rate to 5 amps (clamp the module to avoid bursting the sides) so that the delta-v threshold will be detected. Do a three cycle balance watching the discharge milliamp-hour readings. Your first discharge will read low as the module starts out partially discharged, but the second will be a valid reading and the third should show some improvement.

JeffD

 

Discharge is fine, mine never hit more than 0.7A with 4 modules connected at once.

Charge side, you should turn off the charge time limit.....charge rate seems fine to me.

 

All looks good to me, my charger had a max 2 amp discharge rate. The charger will only do this on the right module, probably an rc battery with less cells or something. With the setting at 2, mine were floating between 1.0 and 1.2 discharge rate. Just have confidence the charger knows what its doing.

X2 on what MTL said, turn the timers off, let them max or delta. And your max is fine. Many go to 7500, I conservatively would have gone 7000 to 7250 had my modules even taken it. Looks like your on your way to a good pack though. See my previous posts on this thread, 53mpg on a degraded pack. Key to my success was matching and eliminating modules with bad cells I guess. Didn't get much balancing. Oh and heres one 18 mile average after a reset from the 50+ avg. This is also after a learning curve on how to drive a prius.

 

X2 on the charge rate as well. I got better results at 3 amps than 1 amp. I set at 1 because I assumed id be better off "taking my time and doing it right" this method evidently didnt apply to the charge portion of rebuilding. Heed this method in your math and other areas though...

 

Thanks guys for the help. I'm on my third set of four modules and I have turned the timer off, upped the mah to 7500 with the delta at 5 and the first charge the mod that I saw went to the 7500 I set. I have the charge set at 3 amps and on auto. Should I change anything?

Thanks

 

Hi everyone. I have a few data sets recorded and every time I try to step outside of the 1.0 amp discharge/ 2.0 amp charge rate, I end up with degrading results. i.e., the third cycle yields less capacity than the 2nd cycle. And so I only run 1 amp discharge/ 2 amp charge at most. I'm assuming this happens because the cells are heat soaking, so to remedy this, I'm considering building a cooling cabinet that can maintain ~60 degree Fahrenheit environment. Is this a bad idea? Is there some other issue that I'm not addressing? I would appreciate the feedback. Thanks guys and gals.

 

What kind of charger are you using and how is it getting its power to the charger ?

 

I'm using Hitec H4's running on a 12 volt, 80 amp variable power supply

 

This is exactly why unless you are doing this process in winter (ie low ambient temps that help cool the modules at high SOCs) you are best off keeping charge rates lower (2A or less)......discharge rate doesn't matter at all so use the max charger setting.

 

I think he meant Hitec X4s......(they also have an AC Plus version with built in power supply too).

 

Someone had asked how GenI and GenII modules and blocks were numbered. I don't know about the GenII, but the GenI starts from the ECU end.

"Nineteen block(s) of battery modules are arranged in the order of 1 to 19 from the ECU side." pg 295 DIAGNOSTICS - HV BATTERY CONTROL SYSTEM

 

I agree, but the discharge rate does matter when ambient temperatures are high and heat dissipation becomes an important variable. Even though the discharge rate doesn't generate heat (or at least not to my knowledge), a 1.0 amp discharge rate that takes ~3.5 hours per cycle gives the battery ~3.5 hours to cool before the next charge cycle starts to generate heat at a high SOC. So when I turn the discharge rate up to 1.5 amp, or even 2.0 amp, followed by a 2.0 amp charge, then the results degrade because there wasn't a long enough break for the module to cool off. I also use a 5 minute break between cycles but I think that helps more with giving the charger a normalized voltage reading rather than cooling, but that's just my hypothesis.

 

I use Hitec H4's. The chassis makes a great heat sink and I think they can charge and discharge at a higher rate than the X4 model (even though that has proven unnecessary). X4 seems to work great for everyone though. I just wanted to check this charger out and so I spent a little more for it.

 

My apology, didn't know there was an H4 too.......does look pretty nice from what I can see.

http://hitecrcd.com/files/H4_Manual_V2.pdf

If you are seeing a full 2A on the charger during the discharge cycle then yes, you're well above what the X4 was able to handle from what I saw. Even at a full 1A (settings maxed out) with 4 modules discharging at once the max discharge rate I actually saw was around 0.7A so I agree when you are doing this with higher ambient temps, it's a benefit to keep it lower on both the charge and discharge cycles (ie minimize heat at all costs).......I'd suggest doing it where you have air conditioning and fans if at all possible too.

 

To be fair, the most I've seen Hitec H4 discharge was at a rate of 1.7A when it was set to 2A discharge, but like I said, any discharge rate higher than 1A gives some odd numbers. Those X4's are a safe bet. Indoors with the air conditioning set to 70 F and a fan in front of the pack creates an efficient environment.

 

The discharge rate is limited to 5 watts, so that's why you only see .7a on the discharge.. As the module voltage drops you should see it go up to .8a. Fans and AC are definitely a good idea. Don't freeze them though, the plastic becomes brittle and the module fails catastrophically (this was just some dumb experimentation I was doing on charge efficiency.)

 

I have checked the temp while charging at 3-5 amps and I don't see a temp rise more than 4 degrees. Why would I need a fan?

 

To keep that four degree rise in check to help keep your method consistent and therefore your final discharge numbers are more reliable resulting in a well balanced pack. As temperature goes up charge acceptance goes down. Often you'll see discharge numbers like this:
D1: 3500mah
D2: 4000mah
D3: 3800mah

It always seems to happen on the third discharge cycle where you see a reported drop in capacity (in my tests at least). I see it as two things combining to cause this (and why you don't typically see it on the second discharge).
First the temp of the modules has slowly crawled up, lowering charge acceptance. Second, by the time you get to the third discharge the "growth" of the capacity is less pronounced, so the loss in charge acceptance (energy going in) is greater than the "gain" in capacity.. Yes you'll also see the loss of charge acceptance on the second cycle, but the module is still conditioning rather generously so the loss doesn't overcome the gain.. If you're hitting mah cutoff then the temperature becomes even more important.

If you're doing a whole packs worth of modules at once these differences don't really matter as the method is the same so the results are comparable to each other. But if you're doing four modules at a time then you really want to normalize all the variables as much as possible. Reported discharge capacity will vary quite a bit depending on charge rate and temperature and discharge rate and temperature. You're obviously keeping the rates the same, so getting the temperature the same is a nice bonus. Following conditioning the modules capacity is what it is.. but the variables while measuring it will change what is reported, and alter the balancedness (new word) of the pack. In reality will it matter a whole lot? Probably not.

 

Thanks for the reply. I seem to be hitting the mah cut off so where should it be. I have tried 7250, 7350, 7500 and my overall readings don't seem to vary too much. Where should the dp be set? I have mine at 5. Most of my discharge mah are 5500-5600. On some I did notice a slight drop from the second cycle to the third.