Just find one of your oldest battery pack and your newest one.
Charge them with the same settings/charger and you'll see which pack peak at higher voltage.
To me, my newest pack always peak at lower voltage but i live in New Zealand so things may work a bit different here
DPD vs CTX-D
I've got a DPD and i've borrowed my friend's CTX-D 2 and used it for a week or so.. and here are some comments:
I got very similar results when i discharge my batteries using both discharger. (e.g. if DPD tells me my battery pack 1 cell #2 got 15% lower capacity than other cells, cell#5 got highest IR...etc, then the CTX-D would tell me same result too)
-Doesn't need external power so can use it anytime anywhere.
-Display is large and clear
-The clamp system is faster/easier to install/remove the battery
-Display capacity as mah/internal resistance as ohm
-Has Dynapulse function
-Can discharge stick packs
-I got some error and it refuse to do anything if the battery pack voltage is too low when you start or the internal AA batteries power is low.
-Looks much cheaper/plastic compare to CTX-D
-I got some rattling noise from the unit/fan just after a few use...
-Discharge faster than the DPD
-Looks very nice. Usual muchmore quality feeling
-The "screws" hold the battery better. (but takes a longer time to secure/remove the batteries)
-Can deadshort battery (but then most latest cells don't like deadshort)
-IT'S REALLY NOISEY!!!!! i thought my muchmore cellmasters are loud but it's louder than my 2 cellmasters running at the same time. I can't use it in the late evening.
-Need 12V external power.
-Depends on which discharge mode you choose, it only shows you the IR or Average Voltage .. but not both.
-The IR and capacity displayed are not in ohm and mah.
If the CTX-D and DPD are same price, even there are a few things i don't like about the CTX-D (noise, can't display IR and average voltage at same time, need external power), i would get the CTX-D just because i love Muchmore products and it "looks" much better on your pittable
But since the CTX-D is quite a bit more expensive than the DPD, it is a much harder decision as i think both are great products