Many users may need the discharge function on chargers to test their batteries’ real capacity. Or they can discharge their full batteries to optimal storage level. For example, xtar vc8s charger has the battery capacity grading and storage function, which can discharge 8 batteries at 300ma each without getting hot.
Some people told they would need a separate discharge function mode. If they need to discharge a battery for some reason, they want to select the discharge current manually, choose the permitted voltage to stop at. Will you also need such discharge function? And how about the discharge current do you think it’s suitable? Welcome to comment below!
Hi Xtar team!
Yes, it would be nice! For different purposes, I might set different target voltage level. Make it compatible with TUYA so user can control it online(Yes, I know it is unsafe to leave house with charging batteries) and it will be great charger !
There may be a few applications for a dedicated discharge function. I might use this to prepare a battery for disposal / recycling. Unfortunately, I have not found out what voltage batteries destined for recycling should be discharged to … or if it even matters.
Being able to set the charging current manually for each slot independently would be much more important. Also maybe an option to set the maximum voltage in case you don’t want to fully charge a battery, but for example just to 4.0 V for longer battery life.
I own the VC8S and love it, but I wish it could discharge faster. The existing functions (grade and storage) are perfect but I wish I could press the current button and select discharge current, at least up to 1A. In a perfect world, I’d like 3A discharge for 2 cells, 1.5A for 4 cells, and 750ma for 8 cells. Much like how the charger can do 3A max charging (and less when doing more than 2 cells at once).
Grading 21700 and 26650/26800 cells takes a long time at 300ma!
Also, Xtar should be proud and boastful that the XC8S can work with 26800 cells. You’ve done something awesome, take some credit for it!
One other feature I would love is a “Grade/Storage” - charge the cell to 4.2v, discharge to 2.5v, then charge to 3.6v for storage. I just got my XC8S 9 days ago, but if you released an XC8S v2 with those features tomorrow I’d be the first one to buy it.
It would be good if a charger had a discharge feature that allows the user to select the discharge current between 0.1A and 3A and the target voltage (e.g. 0V to 4.19V).
The user interface could display the capacity.
A heatsink and fan might be required.
Before doing that, it’d be better if each slot can be individually controlled instead of having 4 slots grouped together.
E.g. ISDT C4 Evo has such a feature (0.1A to 1.5A) but the target voltage is limited (2.9V) and it only accept certain cells.
I currently have an original VC8 and considering an upgrade to a VC8S.
I think it would be better if you could control each slot, instead of groups of 4. I think the slot selection could be done using another button, to choose each slot to be controlled.
Also, the option to select the battery grading/discharging current, maybe options of 300mA, 500mA, 1A, 2A. It might need a fan and heatsink for 1A and 2A though.
I really like that idea, it would help so much when buying new batteries.
Controlling each individual slot independently and being able to set arbitrary max charge or discharge termination voltage would significantly increase the complexity of the charger. It would push it well into SkyRC MC3000 territory. The existing scheme of dual control - you can control the 4 ports on the left side or the 4 ports on the right side, but not individual ports, is a reasonable compromise. The features that would push the XC8S near to perfection are:
Grade + Storage combined mode - Fully charge the cell, then fully discharge it to test its capacity, then charge it to storage voltage. The grade feature and the storage feature already exist, but they cannot be employed together automatically in the current version. This would allow someone to pop a new cell into the charger, test its IR and capacity, and have it charge back up to appropriate level for long term storage.
Higher current discharge. Being able to select discharge current (for grade, storage, and grade+storage modes). This will obviously require a heatsink and/or fan, which will increase size, weight, and price of the charger, but it is a huge time saver for those that are grading or discharging for storage many cells.
If you’re going to make it bigger and add a fan, make each slot slightly larger so that 8x26800 or 8x26650 fit at the same time. A few mm overall larger design would double the usefulness of the charger for those using bigger cells.
Future proof it! Offer a cable that plugs into the charger (taking the place of either the left or right ports, disabling them when in use) that can do 3A charging and at least 500ma discharging. This would essentially make it a universal charger for any new battery that is released that is larger than 26800. A simple magnetic charging solution cable would be a powerful selling point as people explore these new and less common battery sizes. XTAR could even offer it as a separate accessory if there is concern that it would inflate the base unit price beyond their target market.
I agree, even my 20€-chargers from Opus and Skyrc can do that
They do also discharge, I use discharge also for capacity test.
It´s annoying that some chargers have no direct discharge function, the chargers which can only discharge via a test-function not my favorites.
Also because I can not directly set the discharge current with these chargers, mostly I can choose nothing or the discharge current is selected from the charger depending on the charging current (VP4 Plus)
A big charger like the VP4 Plus with these features and discharge currents =>0,75A would be very nice
I have also chargers which are mostly used to test capacity and the voltage stability with bigger discharge current, the advantage is with discharge I can also use a cell which I can charge in one of my other chargers.
I can also control how big the pause is between charging and discharging (capacity test)
Maybe you should take a look at chargers like the Vapcell S4+, LiitoKala Lii-600, Opus BT-C3100, these ones have good features which should be common for every charger in the 40$ price range
Discharge with a range of currents would be very nice. I think a charger like the dragon can do 4x1A or above with NiMH and 4x0,75A with LiIon without fan.
And individual slot configuration should be normal
Other improvements:
Display with some values for all cells like VC4SL but please use good readable digits instead of the awful analog voltage display
Possibility to switch through the values: Voltage/Capacity, Time/actual current, actual task Charge/discharge etc
or cycle the values like Skyrc do
currents like 700-800mA, and some between 1A and 2A
voltage is more interesting than %
I think the Dragon or a similar charger would be a good base to include these features
I think 3A discharge, especially with LiIon, isn´t interesting for most ppl. The MC3000 can max. do 4x1A and 1x2A. Maybe the other guys have a hobby charger for things like that.
I prefer a fanless design, Vapcell S4+ can discharge 2x1A and 2x0,5A, LiitoKala Lii-600 can discharge 4x0,75A. Maybe a chrager like the Dragon can also do 4x1A fanless.
I cleaned my VC4SL from dust and used the Grad-function for a cell with around 5000mAh.
I moved the charger and accidentally the cell loose contact after discharging/grading 2332mAh. With a separate discharge function I could continue to discharge and add the two results to have the capacity.
With Test/Grad-only I´m damned to charge the cell again to full and start the Grad again, lots of time wasted
The VC4SL have a real discharge rate of 283,5mA, that means 5000mAh need for the discharge-section only needs more than 17,5 hours.
So please add discharge mode and allow different discharge currents up to 1A
Another point is with Grad-function of the VC4SL I can´t see which capacity was charged, only discharge capacity is shown
BTW, I like the LED/slot-state CHx-display with red/green but it confuses me sometimes that finished cell and no cell have the green state, with no cell it should be off
Yes, a configurable discharge mode sounds like a great addon. Storage mode is better than nothing but I’ve found that sometimes it ends up with a lower voltage than I would ideally like, especially with smaller batteries that will drop over time more quickly than 18650 or better, where I’d ideally like to get them to 3.8V or so for storage.
We will share all these suggestions to our products department. 
