Supermate and Transformer

I bought a 12v 5amp power brick for about $10 on eBay. The plug actually fit the Supermate DC6.

JeffD

12 Volt 5 Amp (12V 5A) DC Supply AC Power Adapter LCD | eBay

Looks like an equivalent unit (I think that it is the same one I bought). I would buy 4 DC6s plus power supplies to speed up the process. It takes over a day to balance one module with a DC6 and there are 28 modules.

 

Just remember to not overheat the modules during the charging cycle. Don't charge adjacent modules simultaneously and allow for some air flow during the process. Set the DC6 charging limit to 7200-7500 milliamp hours to avoid over charging the cells.

JeffD

 

Sorry to hijack the thread here.

Jeff,

Sorry to hijack the thread here.

Jeff,

I have two questions that I've yet to get straight answers on and maybe you can shed some light on them. I'm looking into buying the B6AC charger/balancer because it has four channels (50W per) and uses 110VAC or 12VDC as a power source. The user manuals look like the same person wrote them. Any comments regarding the comparison between the DC6 and the B6AC?

About the rebalancing, the charge/discharge cycle takes a couple of hours or does it really take 1.5 days. I thought that you charge/discharge a module and let it cool. While you are letting it cool or "rest," you can do another module. So while it may take 1.5 days to complete one module, you could charge/discharge them one after the other and then start from the beginning again. Am I way off?

 

I assume that you are talking about the B6AC "Quatro" charger. I looked it up and it appears to be the same as packaging 4 SuperMate DC6 units in one case with an AC power supply. This is a nice find as it also has templates for LiFe and LiPo battery cells (the DC6 only supports LiOn), if a bit more expensive than 4 DC6 units.

Yes it does for a three cycle rebalancing since a full discharge is about 52 watt-hours of energy and a DC6 is limited to 5 watts (as is each part of the B6AC - the 50watt rating is for the charging cycle - about 10-12 hours for a discharge, much faster in the charging cycle).

I let my DC6 automatically manage and document the three cycle rebalance before going on to another module.

Two additional suggestions:

• You can leave the modules in the battery clamps for this task, but don't work on adjacent modules to avoid over heating.
• Putting the setup on a UPS (battery backup) avoids loss of data in case of a short power loss during the process.

JeffD

 

Thanks for the info. This could be a dumb question but I'm assuming you can't increase the load on the battery during the discharge cycle because the charger has to account for the energy dissapated and use that in its final numbers for the Ah rating?

With 14 chargers, I can complete a battery in 3 days. Man, that's a long time. I guess that's the max since you don't advise working adjacent modules.

 

Yes you would need units with more heat sink to go faster. There are such units available (e.g. link below), but at a higher cost.

14 at a time is what Selierts does when rebuilding a battery. The next time I have a battery problem in a Prius, I will work on a salvaged battery (while the Prius is still drivable), then swap batteries and fix up those modules at my leisure for resale.

JeffD

Turnigy Accucel-8 150W 7A 8S LiPo/LiFe/NiMH​/NiCAD Battery Balance Charger | eBay

 

You need to supply up to 200 watts for a reasonable amount of time to bridge a short power hit. The sneaky approach is to use a car battery and an automotive charger to reliably supply 12 volts to the DC6's. A 50 Amp-Hour battery would hold up in this use for about 3 hours if there were an AC outage during the charging cycle. A deep discharge battery like those used in an EV would double that run time.

JeffD

 

Jeff,

What is a normal amount of time to let the modules rest between charging and discharging? Do you check the temperature and when the module cools to a certain point then you start the charge process over again?

 

Most of my work was on individual modules (clamped of course). I only let the module rest for 5 minutes and saw no heating problems. The discharge with a DC6 is low wattage (5w) so that time can count as resting for a module rated at 6.5 amps. I put the charging limit at 7200 milliamps to prevent overcharging stronger cells.

JeffD

 

Thanks!

 

Jeff,

What do you suggest as far as mV sensitivity and time (minutes) as far as cut-off parameters?

 

Time should be set (for charging) to just a bit longer than needed to pump in the 7.2 amp-hours. I let the default values for NiMh modules alone for determining when discharge should stop.

JeffD

 

Something must be wrong or I have a very bad module. I wasn't even able to get 2 amp-hours on my final discharge (2 cycles). The two cycles took around 12 hours.

 

What voltage is the module at after the full charge cycle? What voltage does it drop to after a couple of days rest? Pull an amp from the module and measure the voltage drop at the terminals (separate voltmeter) to determine the effective series resistance. But yes, you may have a bad module.

JeffD

 

This is my first one so I'm not even sure if I'm doing it correctly. Although, everything was pretty straightforward. I put the module back on the charger a little while ago with three cycles so we'll see how that goes. The end mA hour rating was 1391 so I was pretty much disgusted and didn't record anything. I will stop this module at 1 Ah and measure. It's almost there now.

Am I looking for a zero ESR? What is a "good" range?