Battery chargers might not seem like the most exciting thing to read a review on but trust me this one is different and has a lot of neat features to geek out on. ISDT is an established brand in the Hobby charger market. They have historically been focused more in the RC market but the C4 I have in front of me today is targeted to more common battery sizes such as AAA, AA, and 18650s. This is my first formal charger review, so let me know in the comments what you would like to see in future charger reviews. Thanks to Banggood for sending this to me to take a look at it, this review has not been influenced by the manufacture or seller.
Full Image Gallery: https://imgur.com/a/QpI7Z
Video Review of the ISDT C4:
The body of this charger is constructed with a high density gloss white plastic, with the inner carrier where the cells go being a black semi gloss finish. ISDT claims this is a fire resistant plastic, which is nice but one thing I obviously didn’t test. On the rear you have the fan exhaust, power in, USB port for charging a phone or powerbank, and a MicroUSB in for firmware updates. The bottom has slots for cooling air to enter the charger. The front has a nice fairly large color LCD display thats 2.4” IPS display with a wide viewing angle. Itself isn’t touch screen but the touch panel is to the right and contains up and down arrows and a select.
The C4 doesn’t use the standard spring loaded contacts instead the contacts are hard mounted and have a bit of flex to them. Compared with most other battery charges I have (Nitecore, Xtar, etc) it’s a much less flexible in the size of cells that it will accept. I will go as far as saying it’s very picky.
18650 that are any longer then 650mm just will not fit. So most protected batteries are a no go. Unprotected Flat tops, or unprotected button tops seem to fit. Here are a selection of cells I tested fit with.
Sony VTC6 Flat Tops – Fit
LG HG2 Flat Tops – Fit
Samsung 30Q Button Tops – Fit
Sanyo NCR18650B Protected – Too Long
*Nitecore NL1894 *- Too Long
Xtar Protected 10440 – Too Long
I didn’t have any trouble with the KeepPower 14500’s, Eneloop AA, Ikea Ladda AA, Duracell Rechargeable AA. Amazonbasics AAA, and Duracell Rechargeables AAA seem to fit.
Input power is via an included AC Wall adapter. The one in my package has a 2 prong European design and an adapter was included in the shipping package. Having to use the adapter means it’s not the most secure connection with the wall wart hanging off the plug. The charger itself is capable of a 12V or 24V input from an automotive source too and displays incoming voltage in the top right corner of the screen.
Modes and UI
In all modes when the charger is doing its thing you get lots of metrics on the display. You get the mAh that has been put in or discharged from the cell, The time it’s taken, The current voltage, and requested charge rate, the resistance, and temperature. Each bay has its own temperature probe and I believe they are at the positive end of the termal. So it might take a little time for heat to radiate to the sensor if the battery does get hot. It also plots a graph in real time as battery are going through their cycle. This graph scales in real time as time increases.
The C4 is compatible with a wide variety of battery chemistries including NiMH, NiCd, NiZn, Eneloop, Li-Ion, LiHv, LiFePO4.
The main modes of this charger are …
Discharge – Does exactly what the name describes, it discharges the cell in the slot at the rate you choose. 1A seems to be the default speed. Depending on the chemistry the charger will discharge down to 0.9V for NiMH, 1.2V for NiZn, 3.1V for Li-Ion, 3.3V for LiHv, 2.9V for LiFePo4, and 0.9V for eneloop.
Store – This mode charges the battery to the optimal voltage for it’s type of chemistry. This is particularly useful for Lithium batteries who are happiest if they are not going to be used for a while to be stored at between 50-80%. I tested it on an 18650 and it stopped charging at 3.70V. Depending on the chemistry of your lithium battery it could be 3.8V or 3.2V. Storage mode will automatically charge or discharge the cell to get it to the optimal voltage. It’s only available for the Lithium based batteries.
Cycle – Will charge and discharge a battery a given number of times at your given speed. This could be useful on older NiHM or NiCad batteries. Default cycle here is 3 times but the charger will allow you to do this up to 99 times.
Analyze – Analyze will charge the cell up to 100% at the rate you choose, then do a full discharge at that rate, and then charge the cell up to full once again. During it’s run it tells you time, cell resistance and capacity in mAh.
Activate – This is used to activate a cell where the voltage has fallen below specs or on protected lithium batteries to reset a protection circuit. It uses a small amount of current to “wake” the battery up prior to charging. Caution should be used if using this mode.
UI(Video is best for this) is pretty clear and easy to understand. To the right of the screen there is a touch panel with an up, down and select button. They are pretty self explanatory, the up and down allow you to scroll and when you are on an option you want to change you touch the gear selector and then use the arrow keys to make a choice and then the selector to confirm. By default the charge goes to charge mode, in auto detection at 1A when you insert a cell. It gives you 3 seconds (Configurable) to make changes before charging begins. If you want to change modes of a slot while in use the only way to do this is to remove and reinsert the cell. It has a audible alarm and a very large flashing error message if you put a cell in reverse polarity.
The C4 also has the ability to charge another device via USB while charging the batteries in the bay. What’s a little strange is that it seems to prioritize this USB and it will limit current to the batteries instead of limiting the current to the USB port, just something to be aware of. ISDT lists it as 2.1A at 5V for USB charging.
I have some Thorfire 14500’s that this charger doesn’t seem to like. I can’t tell if it’s a bad battery or something else. I know they are not a great battery but they are also not terrible either. My other chargers like the Xtar VC4 charge it without a problem. This charger however will stop charging these at around 75% and act like there isn’t anything in the bay. If it was a bad cell I would expect an error message of some type.
My charger analyzer setup that enables me to graph charging curves isn’t friendly with this charger. The charger is too smart for it and the graphs that I have gotten are not accurate to what the charger itself is doing. I have some new parts shipping from overseas so hopefully that helps a bit for future chargers.
Firmware Update Process
This charge has a microUSB port on the rear that’s used for updating it’s firmware. When my unit arrived I checked the ISDT website and found there was a firmware update available. I was able to download the firmware which came with a windows only flashing program. I had to use AC to power up my charger then plugged it into my PC via USB and then started the program. It was recognized and I clicked the Start flash button in the application. The charger rebooted into a bootloader mode, transferred the file and rebooted. I do wish the log notes were more detailed about what changes between each firmware version. I didn’t notice a tone of difference but there are still a few bugs in the firmware it seems.
One firmware bug I have encountered is sometimes when I have a battery charging already and I go to insert another one the screen almost goes 100% white, It’s like the user interface locks up. I can’t make it happen regularly but it seems to only happen on the 2nd or 3rd battery insert. I also get some odd percentages as it guesses how charged the battery is at first. This seems to stabilize after about 10 minutes. This was new and I only noticed it after the firmware update I did. Hopefully a future firmware update will fix these issues.
In the Box
The box is nicely constructed and rigid with foam in the bottom and lid. The charger itself was housed in a plastic try with the Euro AC power adapter underneath. I like that they included a glass screen protector like you would put on a smartphone for the screen. It’s should keep the screen free from scratches.
- Ton’s of advanced features and options that are all pretty easy to get to on the IPS display with the side touch interface.
- It’s fast with a maximum of 25W of charging power and 10W discharge power.
- Easily Upgradeable Firmware on a PC.
- Well built plastic construction that’s fire retardant.
- Super obvious reverse polarity alarm
- Comes with a plastic screen protector you can apply.
- Limited to what cells can be charged by it’s design. No protected cells as the design doesn’t allow for anything longer then the standard 650mm in length. This also holds true for protected 14500 and 10440’s.
- Small fan is loud and seems to come on based on the power level your charging at not the ambient temp.
- Shipped with a European power adapter and requires a plug adapter to work in other countries (Included).
- No manual listed online yet.
This is an advanced charger that has just about every option one would want, but it would be hard for me to recommend this to the flashlight community as someone’s only charger to do it all, because of inability to accept protected cells (Especially protected 18650). Protected batteries are popular on flashlights because they give an extra layer of safety. However for some reason ISDT choose a design that was less flexible on battery length which really compromises the offering in my opinion. I have had a few querkey issues too, mainly with the UI. These should be fixable in future firmware updates.
There are good things about this charger despite that though. It’s easy to use, with a relatively large, easy to read color display. The UI is easy to navigate. It has a wide variety of modes to handle your basic and advanced battery charging like charging, discharge, storage and activation needs. I like that the more batteries you put in it, it doesn’t slow the others down. It also has the ability to charge fast or slow if you want. The charger gives you a lot of data if if your the type of person who likes that thing, and I am.
For charging AA size NiMH batteries this is really a nice charger. It has the ability to cycle, charge, discharge, and analyze cells at pretty quick rates. It can fit 4X AA sized cells at once but only 2x AAAs at once.
For me this is my new AA and AAA charger. I will use it with 14500’s and flat top 18560’s that fit. It won’t completely replace my XTar VC4 as a do all charger but it will supplement it. I really like it’s storage mode for batteries that fit and wish protected cells fit too.
My hope for the short term is that ISDT continues to bring out more firmware fixes for the software bugs that I have noticed. It would be awesome if they had a email list you could join to be notified of new firmware. In the long term I hope that ISDT revises their design for the C4 and comes out with a model that can charge a wider selection of cells including protected batteries, and popular shorter batteries such as 18350, 16340, etc. It would also be nice to see a future model be able to charge 4X 18650 or 2× 26650 at a time. Since this model would most likely be physically larger I would prefer a larger, lower RPM fan to make it a quieter charger.
Thanks again to Banggood(link is external) for sending this to me to take a look at. They did provide a coupon (coupon Code “C48100”) that takes 8% off the price if you are interested in picking this up.