Saturday, 2 January 2016

LiPo battery rebuild - Almost done

After wiring up the low voltage alarm module to the 25-way D female socket, as shown in the last blog entry, Several more steps were needed before finally attaching the LiPo battery pack.

First, the low voltage monitor module required modification. This is because in its original form it was impossible to mount correctly due to the presence of one of the rivets on the casing. Both the alarm LED and the sounders were taken off the PCB and wired onto trailing wires, again a lot of heatshrink was used! Second, an LM35 precision temperature sensor was added, a length of 3 way ribbon cable connecting this to the last three pins of the lower row of the connector.

A 3mm hole for the alarm LED, and a rectangular cut-out for the 7-seg LED display were provided. With the 25-way D type bolted in place, and the LED hot-melt glued in its hole, the main body of the low voltage module could be glued into place. This was a little tricky due to the restricted space to get the glue gun in.

With these sorted, the two alarm sounders were glued to the side wall of the case, using impact adhesive. The photo to the right here shows all the wiring in place, and a layer of foam at the bottom of the case ready to install the battery pack.

Here the battery is finally installed. The main power connectors have been refitted to the case and plugged into the battery, as have the balancing connectors. The temperature sensor is on top of the battery ready to be secured. At this point I tested the output voltage, and using the 'personality' plug, checked that the low voltage alarm module was working.

Now, more foam packing was placed either side of the LiPo pack. The battery is fairly secure now, but I wouldnt trust it as is. A light-weight plywood framework will be created to secure the battery and prevent it moving into the empty space above.

A blob of hot-melt glue and the last task, securing the temperature sensor to the body of the battery, was completed.

 And thats it almost completed. The photo above shows it all in its final configuration, and with the 'personality' plug attached allowing the low voltage monitor to check the battery. I now need to make a charging cable up, complete the framework, and secure the lid. Oh, and add the necessary safety warning labels!

Meanwhile, whilst all the glues were setting, I turned a £1.50 coal shovel into a beach sand scoop for metal detecting, by simply drilling a shit load of 5mm holes into it!

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