ok, very appreciative of the help I received from Henrik through the review link you gave me, so thank you for your help as well Wayne. I truly appreciate it.
my friend ordered the opus as an impulse buyer after I mentioned I was looking for an analyzer. but as your recommendation and Henrik also confirmed, the Powerex was what I ordered.
im happy. thanks so much guys. youre all wonderful!
Those are exceptional and excellent reviews, showing information not available anyplace else. One or two little things though, perhaps something gets lost in translation, maybe I read something he didn't write.
He does not like the Opus doing pulsed current charging, yet it is required in sophisticated chargers doing dV/dt.
And he has a thing about charging more mah than cell capacity. Yet this is always a requirement, it always necessarily happens, it is an efficiency thing. The significance of the IEC spec for 16 hours at 0.1C charge is 60% overcharge, to insure full charge. The cells can easily handle it if at the low 0.1C rate (200 ma for 2000 mah Eneloops). This is all that some cheap chargers do, no monitoring, just long and slow for a fixed time. Other cheap chargers go fast, and just wait for high temperature to stop. The good ones have a computer to monitor current and voltage of each cell individually. The irony is that cheap chargers overcharging fast might be seen to do better charging.
However, that certainly can affect your battery life in years (so your 1.5 year question might be about which chargers you use?)
He says the Maha C9000 does not do either pulsed current or dV/dt, yet he shows clear graphs of the pulsed current, which is done for dV/dt, so it is very puzzling what he meant. And the Maha definitely does implement dV/dt (it has been discussed for years), but dV/dt is problematic in every case for NiMH (worked better for NiCD). Often the cells hit the voltage limit before dV/dt, so Maha will stop then. I think charge rate affects how easily dV/dt is seen (Maha says stay between 0.3C and 1C charge. and 0.5C is default). The Maha will stop on dV/dt, voltage, or temperature, whichever occurs first.
I drive a Toyota Prius, which has NiMH batteries in it (around 180 D cells in series for about 200 volts at 7.2 amps). Also has a gas engine used normally, but tuned for economy and pollution instead of power. So the purpose of the electric motor is that it used for added acceleration and power torque, as instantly needed, at any speed). I just bought at 2016, and not yet very familiar with it (it sure drives better), but I had a 2008 for 8 years.
The point is, the Prius computer limits NiMH charging to about 80% capacity, and limits discharge to about 40% capacity. It is continually discharging and charging all the time, but charge will not exceed those limits. They guarantee the NiMH cells for 8 years (10 in California), and sometimes there are reports of one failing, but the general idea is that the batteries should last for the life of the car.
So my guess is that you might be using some cheap hot shot fast charger for your NiMH that last only 1.5 years? And your intense use might make it a good choice, replacing the batteries periodically might not be a big deal for your use?
