Our long term readers may have noticed that we don’t really talk a lot about battery chargers on this site. The reason is simple: if you buy a quality charger early on in your career, you will never have to upgrade. For example – the charger I have been using has been with me for over a decade. It’s easy to sideline such a tool. Anyhow – we’re looking to improve that with a series of battery charger reviews in the near future. First up is the miniature iSDT SC-608 charger, provided to us for review by our friends at Gearbest.

iSDT Charger Fundamentals

The selection knob on the iSDT chargers is a really cool interface element I’d like to see on other chargers.

iSDT chargers have a pretty unique design compared to other chargers on the market. They all share a similar user interface, which is accessed using a nice big wheel on the side of the charger. I’m a big fan of these wheels for any type of user interface – they are way easier to use at selecting things than buttons. This is one of the reasons I adore my Spektrum DX-18, for example.

The iSDT charger we are looking at, the SC-608, is the smallest charger I have ever used. It is not much bigger than the 1300mAh batteries I am charging with it. Aside from the selection wheel, it has three ports. The XT-60 port on the top is for DC power input – it runs off of anything from 9V to 32V of power. I like that it is an XT-60 port – that means you can use a big battery like the ZOP 8000mAh 3S LiPo to power your charger. This big battery will hold enough enough to charge up four of your 1300mAh 4S batteries at the field.  A second XT-60 port on the side is where you plug in your battery to be charged. Finally, there is a balance port which supports up to 6S batteries.

Since we started reviewing the SC-608, iSDT has released an updated model onto the market – the SC-620. The big difference with this new charger is the ability to charger at 20 amps instead of 8 amps.

Here are a few relevant specs for the SC-620:

  • 1S-6S battery support.
  • Supports almost every battery type: LiHV, LiPo, LiIon, LiFe, NiMH / NiCd, Pb.
  • Charges 4S batteries at up to 20Amps. 500W power output max.
  • Supports all the standard charging modes: Charge, Balance, Discharge, Storage Charge.
  • Calculates internal resistance while charging.
  • $80 at the time of writing.

 

Operation

Supplying Power

The first thing you have to figure out is how to supply wall power to the charger. You can buy dedicated power supplies that were specifically built for chargers, but my recommendation is to look for retired server power supplies. These can often be picked up for less than $30 on Amazon or eBay and can provide more than enough power to charge many batteries at once. We recommend using power supplies built for HP proliant servers as they are cheap and readily available. Here is one for $20. It should be capable of charging 4S batteries at the maximum 20A of the iSDT SC-620.

Basic Charging

Pressing the selection wheel will open the “Task Setting” screen which allows you to configure a charging session.

The iSDT user interface is extremely intuitive – I was able to charge my battery very quickly without consulting the charger manual. Simply press the control wheel once to access the charging menu, configure the various settings, and hit “Start”. If you plug the balance port in, the charger balances the cells as well as charges them. If you don’t plug in the balance port, the charger will do a basic charge. The battery voltage setting gets pre-selected when you plug the battery balance plug in – nice feature.

Once you start charging, you are shown a screen that displays a ton of useful information:

  • The charge time
  • Current battery charge state in percentage
  • Amp level
  • Amount of mAh put into the battery
  • Cell voltage of each individual cell

The last readout was particularly valuable to me. Looking at the split between cell voltages is one of the best ways to watch how your batteries are wearing. One of the primary ways our LiPo batteries die is by one cell slowly losing capacity relative to the others. Before using the iSDT, I regularly watched my cell voltages by plugging the battery into a special device before each charge. With the iSDT, I no longer have to do this – the information is ready for me to read immediately after starting the charge. Note: this won’t work very well if you are using a parallel board – this is not a fault of the iSDT charger, just a limitation of that charging method.

An important feature on these single-battery chargers is how much power they can put out. When charging batteries for miniquads, you’ll often want to charge 4-8 batteries at once using parallel charging. To charge 6 1300mAh batteries at 1C, you’ll want to use a setting of 7.8 amps on the charger – right at the current limit of the SC-608 (although not even close to what the new SC-620 can do). Most chargers, including my old one, cannot actually put out their rated power above 12V. I was pleased to find that the iSDT charger did not have this problem:

I also plugged in one of my 4S batteries with a dead cell to see what would happen. I was pleased to see that the iSDT immediately recognized the problem and stopped charging. It also would not allow you to charge in 3S mode, which some charger would.

Internal resistance can be accessed by scrolling down on the main screen. I found the values very inaccurate, though.

The other neat feature this charger offers is the ability to calculate internal resistance while charging – if the balance lead is plugged in. I was pretty disappointed by this feature, though. I tested it by plugging the same battery in multiple times and the internal resistance values that it spat out varied wildly. There was not even consistency across which cells were “good” and which were “bad”. I’m not terribly disappointed – it’s hard to expect a $50 charger to accurately perform a function that most $200 battery testers struggle with, but it would have been pretty neat.

Conclusion

All-in-all, I am very pleased with the iSDT charger. It has the best user interface of any charger I have used and I love how small it is – it makes it really easy to slip into my backpack with a big battery for field charging. It meets all of the advertised specs and has adequate safety features. The only thing that disappointed me was the inaccurate internal resistance reading.

If you are getting into the hobby, the iSDT-620 would be my current recommendation for a first charger.

 

 

 

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