found these guys while looking for Li-ion cells with tabs to make my own pack:
https://xpresstekstore.com/7-4v-7000...tected-8a-pcb/

seem to be pretty good considering li-ion cells by panasonic sell for 6.00 in bulk (real ones not the fake)

also has a pcb protection circuit, its a generic one I have seen in various components works ok.

But $35.00 shipped for 7000 mah 2s.

I ordered 2 and will let you know what I found, however, I didn't see talk about this on rcg or fg so I figured I post.

That's a pretty good price.

Got the batteires in, so far so good, I ran a test charge and they appear to have taken 3800 mah to charge up to 8.2 volts so based on the starting voltatge of 6.9 they appear to be rated capacity.

The one issue I noticed was that the included wire is quite small appears to be 18 gauge wire. I would have liked to seen 16 gauge at least.

Other than that seems to be good, they are about 1/3 of the price of duralite batteries of the same capacity. We will see how they work I'm going to be using them to setup a plane which usually involves keeping the plane on so it would be a good 30-45 min draw and we will see how many mah it uses.

However at the rated capacity of 14 amps (2 batteries) that is a lot of flying.

Please keep us updated. These would be great for an ignition battery.

To thin of wire, needs 16ga min

18 gauge can safely do 8 amps continuous and 16 amp peak. 2 of these are ok for a 100cc. But for a 150cc or using more than 8 servos 16 would be nice, I emailed xpresstek to see if he as a 16 guage version.

Ok so update,

The owner emailed me and said he will send me some batteries with 16 awg wire. This is good, so I'm actually going to send back the 18 guge wire and see how the 16 awg are. Should be the same but these would be good for a 150cc as well.

Originally Posted by Alkaline

Ok so update,

The owner emailed me and said he will send me some batteries with 16 awg wire. This is good, so I'm actually going to send back the 18 guge wire and see how the 16 awg are. Should be the same but these would be good for a 150cc as well.

Thank you, I would like to use their batteries.

The 3500 is out stock!

Originally Posted by Alkaline

Ok so update,

The owner emailed me and said he will send me some batteries with 16 awg wire. This is good, so I'm actually going to send back the 18 guge wire and see how the 16 awg are. Should be the same but these would be good for a 150cc as well.

Very nice. Good way to generate more business.

I read this on the specs ''Over-current protection ～10A''

if memory serves me right the Duralite cell balance circuit is limited to 1A only.

New batts came in, these have 16 gauge wire, but it appears to be copper wire and not the silicone based stranded wire. Ok I suppose as the main thing it needs to do is carry current which it should be able to handle without issue.

Added deans plugs and twisted the wire, I will put on charger and see what it takes to do a full charges.

I'll do a load test on these batteries and see what we can safely draw out of them before the pcb based BMS decides to cut-off.

Well after doing some testing unfortunately I can not recommend these I performed charged / discharge test on these batteries and starting from a discharge state of about 3.0 volts/cell to 8.4 volts cell I was only able to get about 4400 mah, not any where near the 7000 mah claimed.

2ndly 1 of the packs appears to be damage as it would only take about 2550 mah.

So based on these it appears xpresstech is not using genuine 18650 cells or using Chinese fake cells that are not the stated capacity. I was hoping these were LG, Sanyo, Panasonic, or even Samsung (unlikely) but they are not.

Further more they are not able to provide the stated output as many of them browning out when a load of 7 amps is applied. The PCB actually cuts off and needs to be awakend to start working again, if not awaken it will not send out any power, very dangerous for R/C aircraft.

The charge / discharge cycles were done using my hyperion charger using the LION 7.4 volt profile.


Having fooled with this has gotten some ideas stiring in my head, I think I'm about to order some geniune Samsung INR18650-30Q cells, these are 20 Amp capable 3000 mah batteries used in powertools like dewalt/mikwauke and cell for about $5

This with a basic spot welder may be the way to go in making my own packs.

I will forgo using built in BMS/PCB as I believe they have more downsides than up.

Excellent research and story.

Keep doing your research and you will find quality lion cells are expensive. That’s why fromeco and other name brand lion packs like durallight are expensive. They are not getting rich making battery packs.