Victpower A123 pre-made pack review

[999zip999]

Yea it goes over a black sense wire and solder close togethere and I don't like it. ? That other pack is a fisher pack reject from victpower with cells already doon up in this pack ? And you put a new bms for the 3p7s or something. are all these cells we have B grade ??? What's up ? Where is A123 Michigan going ? Sorry getting off. ??? Charge it with cell level count. befor and after with a little note for time and E.S. It sounds like the way to go. Icewrench that's a nice start for a car battery or ? Yes it's clean how's the balance ? Thanks for sharing.

 

[cwah]

Yes all wires are well connected and all cells are around 3.264 and 3.265V. But I suppose it was the BMS job to balance the cells.

Can I get this tape to wrap it up? http://www.amazon.co.uk/Black-Self-...fing-Connections/dp/B000KH9UHM/ref=pd_cp_ce_0


And how can I charge with cell level count? I have 2 hyperion 14s but they won't work with this pack as this is a 20s pack

 

[cwah]

Did they solder directly onto the tabs, or is there mechanical connections too in addition to solder? Also, where balance wires connect too?

There seems to be a lot of excess solder and/or flow for series connections, so I'm wondering about overheating of tabs transferring into the cell pouches? Looks like series tabs are folded & soldered?

Looks like the in-series tabs are isolated/separated by very thin fiberglass board???

I think they did solder directly into the tab board (the green one) with the balance wire in it.

They are not separated via fiberglass board but rather with very thin black foam. Not sure what material it is.

 

[deVries]

Can you tell us if the tabs were full sized tabs that were folded & soldered together? Full tabs are about 1" inch "high" from the base of cell pouch.

Can you describe how the tabs are bonded/connected together for the main series connections?

And how can I charge with cell level count? I have 2 hyperion 14s but they won't work with this pack as this is a 20s pack

You can bulk/balance charge with two 14s Hyperion *IF* you can bypass the BMS safely??? That's 3.55v x 20 cells which is 71v the usual "safe" bulk charge amount. You *must* use two different Power Supplies -one PS per Hyperion charger to charge/balance w/2 in series.

But! Can you even bypass the BMS??? Why? ...you need to charge faster than the BMS can, or why do you want to do this? Why not just use the charger for BMS that came w/battery?

Reference the tape you linked to: that stuff seems super strong, read reviews, so be prepared to have a very difficult time to remove the tape if you have to. In other words, make sure the razor blade doesn't cut the pouches or cause shorts when you remove the tape. :lol:

 

[cwah]

It seems that it's full tab and not folded tab. They are bonded together via the green board. I can't see wire coming out of it, so it should be connected directly between each green board.

Hyperion doesn't allow bulk charging individual pack over 14s. That means that if I want to bulk charge my 20s pack with my 2 hyperions, I would need to divide my pack into a 14s and 6s pack. BMS isn't an issue, I can bypass it easily. But hyperion wouldn't allow me to do that unless I severly re-wire my pack.

So for now, I can't bulk balance/charge all cells unless someone know a way to do that.


ps: I can still use the charger provided to charge the pack but it wouldn't display the voltage on the cell level.

 

[999zip999]

Charge with the charger that came with it. Then when charged check the cell voltage at 3.65v after the bms bleed down or off charger what is the charger set at voltage ?. The hyperion needs balance wires added and maybe the bms disconected with the jumb wire in between the chargers ? Or ? I'm quessing ??? I run a set up balance wires extra. Hyperion 3-7s sense wires maybe there are from hyperion @2usd. that way ? If no loose wires and all looks good charge it. And jut tape with ribbed packing tape, duct tape ect. That tape is self sticking and I use it for wires. Works good. My 24s is split as 2-12s and charged on the 1420 one at a time. I say these things and someone will jump in to correct me Good luck. Zip

 

[deVries]

Hyperion doesn't allow bulk charging individual pack over 14s. That means that if I want to bulk charge my 20s pack with my 2 hyperions, I would need to divide my pack into a 14s and 6s pack.

You can divide equally at 10s each.

 

[999zip999]

4-5s balance wires ?

 

[cwah]

Yes I plan to use the charger provided by them to charge my pack.

And I won't divide my pack into 2x10s because I would need to re-work on all the connections and divide the main plug for that. That's a lot of work lol.

So for now, I can't see a way to individually monitor the cells. Unless someone can tell me a way that would take less than 1 hour to arrange. (re-wiring the pack is a minimum of several hours)

 

[cwah]

I tried to measure individual cells from the bms board while charging:

And there was spark and the charger stopped. My multimeter red and black stick became hot.

How come measuring cell voltage would lead to spark and heat?

 

[deVries]

I tried to measure individual cells from the bms board while charging:

And there was spark and the charger stopped. My multimeter red and black stick became hot.

How come measuring cell voltage would lead to spark and heat?

Obviously you were shorting something to trip the charger & have your probes get hot. I would not manually check voltage while charger is running.

 

[ohzee]

Yea agreed id only test voltage when the cables there are unplugged while being VERY careful not to touch the 2 leads together.

hopefully it's ok

 

[cwah]

Yeah I hope it's ok. Will see when I'll test the pack when the charge will be complete

Finished charging: It's strange, it charges only up to 72V?

 

[cwah]

Finally had my polycarbonate box completed:

I used 5 cm of noise isolation foam in order to attenuate vibration. Should be much better than standard foam


I tried to covered the side with foam where I could:

Not enough room for foam here :lol:

I can put my box directly inside my brompton bag 8)

All included (battery cover + foam + bms), the battery now weight 11.2 kg!


I don't have a top cover yet, I'm thinking of a waterproof cover... Will see after I test my battery on my brompton 8)

 

[deVries]

Finished charging: It's strange, it charges only up to 72V?

Do you take that reading immediately at end of charge?

72v @ 20s is 3.6v so it is a "safer" conservative number. If you develop a weak cell, then this will help it. Does it balance by bleeding off the high cells?

 

[cwah]

Devrie, I took that reading immediately after charge. I tried to measure again the cells with my multimeter on the balance wires but there was again spark. So I stopped. Don't know why it happened but I don't want to kill my pack. I already killed so many electric component that now I prefer not to touch anything when it works :lol:

My brompton with the A123 pack:

When I started cycling, the pack voltage dropped very quickly to 66V. I dropped within 2 mn or something like that. I thought the pack had a problem. Then the voltage remains at a very steady 66V. I have around 1.5-2V sag at 1500-2000W power. My 30C zippy sag a little less than that. But I think that's a new pack so it should get better over time.

For now, I did 400wh, will see later how much power I can get from it

 

[999zip999]

I to had a big voltage drop on my 24s on the first 2 rides. I hope I just have to cycle once I get the box setup.

 

[deVries]

When I started cycling, the pack voltage dropped very quickly to 66V. I dropped within 2 mn or something like that. I thought the pack had a problem. Then the voltage remains at a very steady 66V. I have around 1.5-2V sag at 1500-2000W power. My 30C zippy sag a little less than that. But I think that's a new pack so it should get better over time.

For now, I did 400wh, will see later how much power I can get from it

For 20s 66v is exactly nominal voltage @ 3.3v ... that's "perfect".

Now, you can understand why just charging to 72v is no biggie.

 

[999zip999]

What's your target of end of ride voltage ? Not total AH just where is it best to stop as end voltage ? As what make it the happest ?

 

[thedarlington]

id say either no lower than 50 or 52v but it would be interesting to know what that BMS board uses

 

[cwah]

I'll probably end the voltage at 3V or when the BMS cut-off. For now I've used 800wh and the voltage still was at 65V. I'm waiting for the strong voltage drop to stop. I believe the Lifepo4 are very on their nominal voltage, and when they are not anymore at that voltage, there isn't much power left. And it's time to stop

 

[cwah]

id say either no lower than 50 or 52v but it would be interesting to know what that BMS board uses

Yeah, also maybe 50V few time to check the pack capacity. But I wouldn't do it most of the time.

 

[cwah]

Tried a full charge today. On my cycle analyst the voltage went up to 73.2V, then go slowly down to 72.7V. On my multimeter I have 71.8V... :?

I almost have 1 V difference between my multimeter and the cycle analyst. Who's right?

 

[999zip999]

Do you have a second MM ?

 

[ohzee]

Just charged up one of my 20s A123 packs I made from victpower cells. It has a ping high power BMS which evens out all
the cells.. Testing all the cells they are at 3.47 pack voltage is 71.5.

So id say yours is looking good as well.