4.2V 1A LiPO charger in use

Here's how I'm using the 4.2V 1A LiPo charger to charge the 25.9V LiPO pack with the low 4.2V cell. It looks very kludgy, but it works! :-)

4.2V 1A LiPO charger

I thought these would be handy to charge 4.2V LiPO cells once in a while so I ordered a few. They are meant to charge 18650 sized cells but could easily be used for any LiPO cells. I used a wood dowel with two screws for battery contacts. That along with a couple of alligator clipped leads and you have a single cell LiPO charger!

http://dx.com/p/4-2v-1-x-18650-battery-charger-black-2-flat-pin-plug-168948

Replacement 3.7V 10Ah LiPO pouch cells arrived

I ordered 3x3.7V 10Ah LiPO pouches to replace the defectives ones on my LiPO packs. They have markings on them that they are 37V and 10000mAh, however, the plastic sleeves are marked as being 3.7V and 1.4-1.7mOhm and ~3000 mAh. I wonder why the discrepancy. I'll test one tonight to see how it does...

Here are some pics of the cells:

Cell-log 8M on the 7S 25.9V LiPO pack

I took a few minutes and soldered a set of JST-HX connectors to the 7S LIPO pack last night. The first cell in the pack is a bit low. I plan on charging it using a small single cell LiPO charger. Here's a picture of the Cell-log connected.

I tested the 2nd 25.9V LiPO pack and found a similar problem

I unwrapped the pack to get to each cell tab and measured all 7. You'll notice a similarity to the first video...

I'm beginning to see a trend.

Fixing the 1st 25.9V LiPO Pack.

I took apart the first of the defective 25.9V LiPO packs I got recently to try and see what was happening inside. If you just want to find out, then watch the video below. If you want to know the gory details then check out the pictures below the video.

First outer wrap of plastic and tape removed. Feline creature checks out the wiring.

What I thought was a dent in the outer casing of the pack was actually the first cell! This could be very dangerous if it should short out.

Close-up of the damaged cell.

Close-up of the BMS with the individual leads going to the cells.

The BMS leads connected to each cell under the cargo tape.

Double-sided tape holds the BMS to the pack. You can also see the black plastic foam pieces separating the tabs.

The black foam pieces are supposed to hold the tabs in place to prevent them from shifting and shorting out.

The BMS leads are soldered to the tabs which are folded over each other and then soldered in series.

The solder quality isn't great. But it did seem to work. 

You can see the globby look of the solder. It should be smooth and rounded.

Uneven and inconsistent soldering.

More of the same.

Crystalyte 35 series motor/controller/batteries for my M-750X build

The motor/controller/batteries for my M-750X build came in yesterday thanks to Scratch1973. It's quite a kit for the price. I checked all 3 batteries and they were out of balance. Two of the packs are somewhat damaged but it looks as if they are held in a metal outer case under the thin shrinkwrap plastic cover. They do not have balance leads which is surprising. So I'll be disassembling the packs, adding the JST-HX balance wires, testing each cell of each pack, and reassembling it perhaps into a different configuration.

I liked that the battery had a pre-charge resistor. This eliminates the possibly huge ZAP that happens when you hook up a large voltage to a controller.

Here are the pics.