Cycling battery modules - do these results make sense?

What kind of charging and discharging systems are you using?

In general, you need lab grade equipment to measure true mAh amounts because more primitive devices won't measure that accurately. Once a module is fully charged, the amount of voltage loss after 2 minutes on a 12v 50w bulb is good way to match a batch of modules. Also a thermal camera can help you find cells running hot that are soon to fail. And measuring voltage loss after a fully charge module has sat for a few days or longer is essential too. What you're looking for in all this is not precise numbers, but a sense of all modules being similar in behavior.

As for reconditioning results. Some packs respond really well, some packs don't...

What are your discharge thresholds for reconditioning? I prefer down to 5v, then down to 3v, then down to 1v.

 

There is nothing wrong with those modules that have the low discharge numbers. Your problem is that your charge cycle is stopping too early. Most likely due to a false deltaV trigger or too low of a setting in the parameters.

You will never discharge more energy from a battery than it had put into it from the previous charge.

How are you cooling them while under charge? Temp will affect how the charger detects a fully charged condition. What gauge wire are you using for the cables? How are they connected to the modules? many things can affect the voltage (and voltage change) read by the charger, which is used to trigger a detection of 'fully charged', whether true or false.

For the purposes of DIY, you can use even the most inaccurate charger/discharger ever manufactured, as long as it's consistent. If all you're looking for is improvement and then a plateau, it's all relative.

 

I have (7) of the CQ3 4x100 models manufactured by EVPeak. Had 'em for a few years and they just roll right along. Work great for me.
I use a max of 8200, charge at 2 amps and discharge 1.5 down to 5.8 volts. I also use 16 gauge wire, which is heavier than what you're using, even though my current level is lower. I also use spade connectors crimped to the wires and fastened to the terminals using the busbar nuts. I do not use alligator clips, as they are too unreliable. You're probably getting double my voltage drop between the charger and module during the charge cycle.

You're not going to feel any heat generated in the modules until after they are at full charge. Once fully charged, any additional 'charge' is going to be converted to heat, instead of stored energy.

 

The delta V and the discharge voltage are totally different items. The discharge voltage is where the CQ3 will stop drawing current from the battery and start its rest period prior to starting the charge portion. The delta peak is a change in voltage the CQ3 algorithm is looking for when it does its charge routine. During the charge portion, you'll notice the charge current will frequently drop to 0 amps. During this time, the charger is monitoring the module voltage, looking for voltage changes that would be consistent with a battery reaching a full charge status. If that threshold isn't satisfied, then the charger will continue the charge again. Over and over, until either the threshold is achieved, or a max limit (like 7500 mah) is reached.

In the 'user set' menu, just set the mv to 20, which should be the max iirc. This helps to ensure the charge goes the full distance based on the mah limit. Even then, sometimes the threshold is reached and the charge will stop.
After you select NiMH, step through the menu until you reach the screen for setting the discharge current level. That screen also has the lower voltage setting.

 

Hi PriusOwner428, I'm reading through the forums to get as much info as I can find before I start reconditioning my Aqua(Prius C) HV battery. I also just got one CQ3 4x100W EV Peak charger. I'd like to know how long it took you to cycle all your modules after you set the charger correctly? Also kindly highlight if you had success with your HV battery, did you get consistent results after the changes?

 

Yea, I've noticed this as well, especially when trying to do a top balance (300 mA, 16 hours). Even at such a low current and with the delta peak sensitivity set to 20mV/cell, these CQ3's would still detect a peak and terminate the program. If I keep restarting the program everytime it detects a peak, it seems like it's less likely to detect one and just let the program run. I'm guessing this happens because not all the cells top off at the same exact time.

 

I read on Battery Universe that a NiMH battery will self discharge 20% in the first 24 hours after charging. That seems high. But, play it safe. After running a discharge-charge cycle, repeat any subsequent discharge-charge cycles immediately. As mentioned, the discharge that you measure is determined by the previous charge, which might be inadequate or may have self-discharged too much. I charge to 7500mah and retest ASAP. You need to watch youtube videos to see how to set the discharge cutoff voltage. I use 6.0 volts. And, as mentioned, the battery will only heat up after a full charge at the end of the chargee cycle. I think that 7500mah is a good balance of minimum heating and assuring a full charge. Do not trust alligator clips-use ring terninals.

 

That's more because of how high of a voltage you can charge NiMH up to... They're very tolerent of too much charge because the chemistry allows it to quickly self discharge to normal levels without damage. Lithium on the other hand doesn't have that self-discharge problem, but will be ruined if even slightly overcharged.

Once at normal voltage levels NiMH does self-discharge down to zero over many, many years but nothing like the rate it does in first 24 hours after a charge and balance, which is a form of low amp overcharging.

 

Hey guys new to Prius chat! Working on cycling the cells on my Gen 2. I'm using a Hitec X4 charger with an interface very similar to the CQ3. It is what I had because I also do Radio controlled car stuff too. I have almost cycled all my cells 5 times. 3A charge 1A discharge. 7500 mah upper cut off and 6.0volt min discharge. I have only one cell that is discharging over 5000, one that is 4700, and the rest are in the 2500-4000 range. Am I doing something wrong or are my cells actually that weak?

 

Those numbers look similar to what most folks are getting Mine are even weaker, most are somethere around 550mAh to 800mAh. Only one cell of mine broke 1000. I'm also wondering if I'm doing something wrong, or if my cells can really be this weak.

I'm using the EV-Peak BGUAD CQ3 and discharging at 1 amp to 6v, charging at 3.0A. I've done 8-10 cycles on each cell and still seeing consistently low capacity numbers.

 

The numbers look normal, keep on going with this and you will be able to keep using this pack. Just need to sort out the truly worst modules from the pack and replace them.