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150/180 Watt Electronic Dummy Load under-voltage fix
#11
^^^ Yes, you can also use RC hobby chargers, but they are notorious for quickly dying if you use their internal loads much (even with higher end junsi iChargers). That may be less of a concern if you use them with external loads (or regenerative), but that's a bit of a pain to set up (and you can fry the charger if you are not careful). I've lost count of the number of complaints I've seen about chargers dying due to nontrivial use as discharger. It's better to put the wear and tear on a $25 load vs. a $250 charger.
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#12
I just ordered one of the linked 10A dummy loads.
It's annoying to wait another 6 - 8 weeks till I can start testing, but I think it is the best way I have to test a complete akkupack
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#13
^^ Good luck. Be sure to order from the known-genuine Aliexpress seller I linked there. 

Btw, this youtube video shows the DL24 frying in only a few secs at 20V/8A (start at time 13:50).  He says it blew a fuse and the IRFP260 mosfet (which he thinks was fake). It's in Russian but you can turn on subtitles and auto-translation.

There are many similar reports of such failures on these clones. So don't believe the specs. It may not even handle 150W (which the genuine unit handles with ease).
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#14
(08-01-2020, 06:51 PM)gauss163 Wrote: ^^^ Yes, you can also use RC hobby chargers, but they are notorious for quickly dying if you use their internal loads much (even with higher end junsi iChargers).  That may be less of a concern if you use them with external loads (or regenerative), but that's a bit of a pain to set up (and you can fry the charger if you are not careful).  I've lost count of the number of complaints I've seen about chargers dying due to nontrivial use as discharger.  It's better to put the wear and tear on a $25 load vs. a $250 charger.

I have owned RC chargers for 15 years and I have yet to nuke one using within its capabilities.  I find a lot of value being able to monitor the individual cell groups, which is why it is still my preferred tool.

Another solution I like a lot is the West Mountain Radio - CBA
http://www.westmountainradio.com/cba.php

I also like having nice tools.  I don't mind spending on stuff like that.  If you are budget constrained then sure... for $25 seems decent.  That said, if you want cheap, you can just any load that has a constant draw and a stopwatch.
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#15
(08-02-2020, 01:41 AM)Crimp Daddy Wrote: I have owned RC chargers for 15 years and I have yet to nuke one using within its capabilities.  I find a lot of value being able to monitor the individual cell groups, which is why it is still my preferred tool.

You're likely very lucky then. I've lost count of the number of such failures I've heard about. Most RC hobby chargers aren't properly (thermally) designed for discharging, so using them heavily for such will greatly decrease their lifespan. 

Note that we can also monitor cell voltages using an electronic load and a BMS (or similar device).

(08-02-2020, 01:41 AM)Crimp Daddy Wrote: Another solution I like a lot is the West Mountain Radio - CBA
http://www.westmountainradio.com/cba.php

The WMR CBA has far poorer price/performance ratio than said $25 load. The cheapest version cost 7x more ($175), has less power (only 100W continuous), has fewer features, and is more cumbersome to use (requires a Windows PC to control it), to mention a few of many deficits.

The $25 load is completely programmable using a serial interface. So not only can we control it manually by its buttons, but we can also program it on almost any computer (e.g. an Arduino) to do all sorts of handy functions. Below are a few of infinitely many possibilities:

(1) DIY CC/CV charger: turn any normal (CV) power supply (e.g. wall warts, laptop bricks) into a CC/CV charger. Furthermore, we can completely control the charge algorithm, e.g. we can easily implement fast-charging algorithms such as multistage CC/CV algorithms used by Tesla and bleeding-edge cell phones (e.g. Qualcomm's 50% charge in 5 minutes). [If it's not clear how to combine a CV power-supply + CC discharger into a CC/CV charger then I can elaborate].

(2) Regenerative charging, i.e. use one battery as power source to CC/CV charge another (same as (1) with a battery replacing the power supply)

(3) Balance charging (up to 60V/10A/150W), same as (2) but with balance as termination condition.

(4)  CC/CV discharging: program discharges to have a final CV phase, e.g. to discharge to exact storage voltage, or to any target voltage (e.g. for determining SOC at exact voltage). Such discharging with a final CV phase is the symmetric reflection of CC/CV charging (called reducing discharge "D-reduce" on the SkyRC MC3000).

(5) Variable load testing (to see how power sources respond to load changes, as in industry standard testing of power supplies and batteries).

(6) IR testing: we can program different kinds of tests for internal resistance, both DC and AC.

The sky is the limit once we have complete computer control of the load - which is not possible with RC hobby chargers or the CBA (they are limited to a few built-in programs).

(08-02-2020, 01:41 AM)Crimp Daddy Wrote: I also like having nice tools.  I don't mind spending on stuff like that [...]

If you like having nice (proper) tools then I highly recommend that you get a real (programmable) electronic load. For $25 the above load is a great deal (even a steal). A good load is an absolute must-have for any power user. The longer you procrastinate buying one the more time and money you will end up wasting (as I know too well from experience - both mine and colleagues).
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#16
I do have an electronic DC load... but still tend to gravitate to my iCharger 4010 Duo with an external resister load-bank. I also regularly use regenerative charging/discharging.

I do a lot of EV module testing and still prefer this as I can log cell group data in bulk without too much hassle and increased saftey since the charger has various ways to terminate the charge/discharge which is pretty important when you have to leave it unattended.
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