Building many smaller A123 packs (NO BMS) and add them together

Batteries, Chargers, and Battery Management Systems.
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Pota
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Building many smaller A123 packs (NO BMS) and add them together

Post by Pota » Jan 10, 2018 4:06 pm

I was thinking of making several A123 ANR 26650 packs. (3,3v nom and 2300mah, each battery)

Im considering having 6 packs, each of the battery pack with 6s10p.

1 pack would then give around 19.8 nom volt and 23AH.
I want to connect lipo low voltage alarm to the 6 packs, so i can hear the alarm if some of the cells are low. Instead of using a BMS system.

I also want to connect them all together in series so i have up to 118.8 nom volt.

Couldent each of these packs be charged as a lipo pack with balance plug?

Is this possible?

Pota
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by Pota » Jan 11, 2018 9:04 am

Noone got a clue :)?

thunderstorm80
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by thunderstorm80 » Jan 11, 2018 9:57 am

Pota wrote:
Jan 10, 2018 4:06 pm
I was thinking of making several A123 ANR 26650 packs. (3,3v nom and 2300mah, each battery)

Im considering having 6 packs, each of the battery pack with 6s10p.

1 pack would then give around 19.8 nom volt and 23AH.
I want to connect lipo low voltage alarm to the 6 packs, so i can hear the alarm if some of the cells are low. Instead of using a BMS system.

I also want to connect them all together in series so i have up to 118.8 nom volt.

Couldent each of these packs be charged as a lipo pack with balance plug?

Is this possible?
I am pretty sure there are small digital volt meters, that can measure all your cells in real time via the external port, if you make one.
Where do you plan to buy the cells from?

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fechter
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by fechter » Jan 11, 2018 10:08 am

It would depend on your charger. Lipo is a different voltage than your A123 cells. If the charger has a LiFePO4 setting, then it would work.

36s 10p would be a very large, heavy pack. 131.4v at full charge.
"One test is worth a thousand opinions"

StinkyGoalieGuy
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by StinkyGoalieGuy » Jan 11, 2018 5:00 pm

You would want the voltage alarms to be configurable. Those A123 cells cells are good until about 2 volts before they drop off a cliff. I would think most lipo voltage monitors would trigger much before 2 volts.

999zip999
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by 999zip999 » Jan 12, 2018 12:53 am

2v Maybe the cliff that you already fell off of try 2 6v or zero.
3.50v -2 60v
Typo sorry fixed.
Last edited by 999zip999 on Jan 12, 2018 4:28 pm, edited 1 time in total.

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dogman dan
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by dogman dan » Jan 12, 2018 7:53 am

Yes it should work fine, if you plan on using a 6s RC charger for charging. Most have settings for lifepo4, NiCad, nimh, etc.

You could also go with 8s packs if you wanted to, with an 8s charger.

Re the lv beepers, some can be set to the lv warning of your choice. Many are 6s, but I think some are 8s.

You can't leave those beepers on the pack permanently though, they will drain one or two of the cells.

Get to know your pack, and which section has the lowest capacity cell in it. Then put the beeper on it only when you need it. What I mean is, if your pack will take you 20 miles, you simply don't need the warning for a 10 mile ride. Watch the whole pack voltage, and if you need to drain it all to get home, put the beeper on it when you need to, as you limp home slow on the nearly dead pack.

999zip999
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by 999zip999 » Jan 12, 2018 4:30 pm

Get a C.A. great help

999zip999
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by 999zip999 » Jan 12, 2018 5:01 pm

What do you plan on using them for as fecter said it will be big and heavy. Could last a very long time.

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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by StinkyGoalieGuy » Jan 12, 2018 7:42 pm

999zip999 wrote:
Jan 12, 2018 12:53 am
2v Maybe the cliff that you already fell off of try 2 6v or zero.
3.50v -2 60v
Typo sorry fixed.
My bad, I misread the chart. Though if you were to pull 40 amps, the discharge curve sits pretty flat at 2.6 for most of your usage. Your alarm would be buzzing the whole time. I think 2.5 is right about where the cliff starts. That's one of the strength/weaknesses of these cells. It's a very flat discharge, but when it's done, it's done real fast.

999zip999
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by 999zip999 » Jan 12, 2018 9:26 pm

The problem with A123 cells they don't like the be bought to the cliff with no bms. I can only test mine after I get off my bike. So they have time to bounce back. So I don't know how low the voltage is under load. But have run them down to quit with no BMS. Still just bluck charge @ 16amps and all 3.46v - 3.51v most all the time 24s. 1,101 cycles 4.5 years. The A123 20ah pouch.
So what you running ?

Pota
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by Pota » Jan 14, 2018 3:59 pm

Was thinking
6x 6s10p and combine them in series for 36s.

Im using it on electric gokart. Pushing around 600amp @ 130v.

How thick should the wires then be on each battery pack?
Need to be able to handle 600amp for 10sec. Will be alot of bursts.

Pota
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Re: Building many smaller A123 packs (NO BMS) and add them together

Post by Pota » Jan 16, 2018 11:36 am

I think i would need some massive 50mm2 cables on each pack

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