Charger - Cellpro Multi4

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Having had to deal with many dead NiCD's over the years due to incorrect charging most caused by the wall wart the manaufacturer supplied, I have been eagerly awaiting an opportunity to get a 'real' charger. Thus Fedex delivered a Cellpro Multi4 to my door along with the Polyquest balance plug adapter.

Besides the LiPO's for the planes, I have various NiMH/NiCD and Pb batteries that need charging. A first test was to connect the suspected dead 8 cell NiCD pack from the FF6 radio and let it run with the ball. Surprise! Charge terminated normally, radio shows 10.8v and the battery ran down to 10.2v when left one for about an hour. Seems the pack is not so dead after all but was not getting a proper charge off my constant current charger. To me, that means the Multi4 just paid for itself even though it cost a lot more than a new 8 cell pack, it is the peace of mind.

Having tried it on a few packs and even gel cells I decided that the socket where the balance adapter plugs in will not last long if that plug is moved often. Dry solder joints on pc board mounted sockets like that are well known to me, as I fix things like that often in lab equipment at work.

I decided to mount the whole lot on a piece of clear plastic sheet, so the balance adapter cannot wave around. I then added a set of banana sockets so that batteries without balance plugs can be plugged in using various adapter cables with standard banana plugs on the ends.

So far this setup works very well. The backing panel is cut 10mm smaller than an A4 sheet so that it fits into a standard A4 paper box, which is what I use for storage.

Having just received the USB adapter I will fit it to the upper left corner (yes, I left space for it), using the RS232 socket for the cable detach and leaving the little 3 pin connector permanently connected to the charger. Of course the software is WinXP only which gives me a problem as my main machine runs Linux and the older machines are fit only for Win98. I'm stuck with using the office laptop to talk to the charger.

General layout of the mounted charger.

The banana sockets (will accept 4mm bullet connectors) from the top. Yeah, it took a while to polish the plastic parts, but it does look nice all shiny.

The rear of the panel showing where the banana sockets are connected to the balance board.

Being an IT technician I have a number of old PC power supplies lying around, too good to throw away, too old to actually use. This was one of the older AT type with a real power switch on a cable allowing the power switch to be mounted on the front panel of the PC. I ripped all the wires out and mounted a power switch into the case as shown. The banana sockets are similarly wired to the 12 volt (yellow) wires, all other wires being clipped short and safely heatshrinked so they cannot connect to anything. To the 5 volt line I connected a 6 volt car tail light (you can see it through the holes at top left), which glows from inside the case acting as a pilot light and also helping the circuit to regulate by providing a constant load. This PSU can supply 8 amps on the 12 volt line, so it is plenty for the 4 amp charger, the fan runs slowly and quietly and it is generally a pleasure to use.

Gratuitus extra image showing what I did to the voltage monitor that will go temporarily into new planes (esp with new ESCs that may or may not cutoff correctly) . The monitor comes with 4 pins on the edge that are the wrong spacing for the Polyquest. kindly supplied a female PQ socket with wires and a female socket that plugs to the monitor. Since the monitor had a broken pin anyway, I removed all the pins and soldered the PQ connector directly to the board. This will now plug directly into any Polyquest battery pack of 2 or 3 cells. It shows green lights when cell voltage is above 3v, but shows red lights and squawks quite loudly when it hits 3v or below.

I ordered some adapter plugs and soldered them together to make a 5 pin Polyquest extention which allows me to recharge with the battery still in the plane. Oh I know about the fire hazards, but I don't charge unattended, I don't charge at more than 1C (in fact about 1.1A instead of 2.1A) and I keep checking for heat etc. Doing this saves me a cable tie and the fiddle of remounting the wheels each time.

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Last modified: February 18 2013 16:03:31.