Can discharged Headways be saved?

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mizlplix
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Can discharged Headways be saved?

Post by mizlplix » Fri, 03 Aug 2012, 04:17

Greetings: I have 8 10AH Headway cells that are averaging 1.5 volts ea. I received them that way.

Has anyone successfully "saved" any and gotten them recharged?

TYVM, Miz

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Can discharged Headways be saved?

Post by zeva » Fri, 03 Aug 2012, 05:09

They should be fine, in my experience LiFePO4 are only damaged from discharge if they get driven negative (all the way to zero and then some more) - and if that had happened they would be showing zero volts now.

(Hopefully some others will chime in in agreement so you don't have to trust just me Image )
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lithbattboss
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Can discharged Headways be saved?

Post by lithbattboss » Sat, 04 Aug 2012, 02:17

The question is if they are new cells why did you receive them "new" and only measuring 1.5V?
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Can discharged Headways be saved?

Post by Johny » Sat, 04 Aug 2012, 02:39

Provided they are over 1 volt they should charge up with no problem - but I'd do it sooner rather than later.

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Can discharged Headways be saved?

Post by mizlplix » Sat, 04 Aug 2012, 14:17

They were dropped off UPS during the day when I was at work.
Anyways, the UPS driver will not stand around while you unpack and test the cells. They must keep on schedule.

The friendly people I bought them from just keep saying "We not sell bad cell." " Our cell all good." "We sell many cell and not have any bad one."

About 6-7 email exchanges of that and I got the picture. I was stuck with them.

I am currently charging them one at a time on a small one amp charger built by Tenergy. I have 6 of them that are 3+ volts and have held there for a week sitting.

Two charged up but dropped over night to 1.5 volts. I am giving them another cycle to see if they improve.

I have one that will not take a charge at all.

I was just wondering if there was any tricks to recharging them.

Thanks , Miz
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Johny
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Can discharged Headways be saved?

Post by Johny » Sat, 04 Aug 2012, 14:40

I think you have your own answers. I had 2 out of
384 that went to zero volts (my fault) and every attempt to recover them has failed. They draw zero current regardless of applied voltage - up to 20v.
If they don't take a charge then I'm afraid they are lost. As you see, keep cycling the other maybe-bad ones and. They might recover. I'm not optimistic though. If they don't hold a charge first time.....

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Can discharged Headways be saved?

Post by lithbattboss » Sat, 04 Aug 2012, 19:47

It sounds like they sold you defective cells. I thought Headway destroyed and recycled the 25% of cells they manufacture which are faulty / don't meet spec. But I suspect they onsell many of the poor cells in the hope the customer is "none the wiser".
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Can discharged Headways be saved?

Post by jackhyq » Sun, 11 Nov 2012, 03:46

lithbattboss wrote: It sounds like they sold you defective cells. I thought Headway destroyed and recycled the 25% of cells they manufacture which are faulty / don't meet spec. But I suspect they onsell many of the poor cells in the hope the customer is "none the wiser".


Yes,you're right.
There is some manufactories destroyed the marketing of lifeop4 battery with the so lower price and poor quality.
Portable AC/DC/Solar UPS;
3D BirdView,RearView,A.I System;
1C~90C LFP/LiPo Battery ;
BatteryShow@126.Com;
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Can discharged Headways be saved?

Post by jumpjack » Thu, 20 Mar 2014, 00:17

Johny wrote: I think you have your own answers. I had 2 out of
384 that went to zero volts (my fault) and every attempt to recover them has failed. They draw zero current regardless of applied voltage - up to 20v.
If they don't take a charge then I'm afraid they are lost. As you see, keep cycling the other maybe-bad ones and. They might recover. I'm not optimistic though. If they don't hold a charge first time.....

Same happened to me:I incidentally overdischarged an headway cell, which reached 0V.
Unfortunately, such cells are completely lost, because such an underdischarge triggered the safety mechanism:
Image

No matter how many volts you apply, cell is now disconnected for ever Image (for your safety).
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Can discharged Headways be saved?

Post by Johny » Thu, 20 Mar 2014, 14:31

jumpjack wrote:Unfortunately, such cells are completely lost, because such an underdischarge triggered the safety mechanism:
I don't think that's correct. It's more like all the Lithium Ions have propagated out of the electrolyte. It doesn't really matter why - they're stuffed!

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Can discharged Headways be saved?

Post by Richo » Thu, 20 Mar 2014, 20:17

Yeah I was under the impression when under extreme load causing the internals to gas out and pop the valve.
continuously discharging to 0V is different and wont pop the valve.

I have had poorly treated headways still recover from over discharging.
I have had only 1 pop the valve and go open circuit.
I use it now for measurements with metal rulers and calipersImage
So the short answer is NO but the long answer is YES.
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Can discharged Headways be saved?

Post by Johny » Thu, 20 Mar 2014, 21:28

So far I have had only 2 failures out of 384 cells running the car - and those two were while in storage for a year or so with BMS connected - my fault (those are the two I mentioned ealier in this thread). Pretty reliable cells if treated correctly.

I'm just over 150 cycles now with about 70% of cycles being around 30%-40% DOD and the rest averaging around 60% DOD. Never been below 71% DOD yet.
No detectable change in behaviour (other than temperature related - see blog).

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Can discharged Headways be saved?

Post by jumpjack » Fri, 21 Mar 2014, 02:15

Richo wrote: Yeah I was under the impression when under extreme load causing the internals to gas out and pop the valve.
continuously discharging to 0V is different and wont pop the valve.

I have had poorly treated headways still recover from over discharging.
I have had only 1 pop the valve and go open circuit.
I use it now for measurements with metal rulers and calipersImage

Then maybe mine got shortcircuited, so they had both extreme load and overdischarge. Image
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Can discharged Headways be saved?

Post by Richo » Fri, 21 Mar 2014, 20:25

Mine was due to:
1. In parallel with other cells not matched.
2. At the top of a string with the main + directly connected to it.
3. A crappy wire link rather than a busbar joining to parallel cells.
4. No BMS (discharge protection/warning)
5. Left in a discharged state for extended periods.

So moral of the story - build the pack properly.
Last edited by Richo on Fri, 21 Mar 2014, 09:27, edited 1 time in total.
So the short answer is NO but the long answer is YES.
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Can discharged Headways be saved?

Post by jumpjack » Sun, 23 Mar 2014, 07:39

Mine were connected to a broken-then-repaired BMS.
Tne full story (for the records):
built a 20-cells "quick-and-dirty" battery just to do some tests;
tested on e-scooter; worked fine... for just three days; then, road-induced vibration caused a BMS wire to loose the insulation because it passed between two cells; it got in touch with metal and burned up, also burning up first stage of BMS (cell 1).

Cell replaced, BMS repaired, wiring improved... but BMS was maybe not so "fixed", so replacement cell died too.
Electrolyte also leaked from both cells.

So I agree with your moral: don't do "quick-and-dirt" batteries, just do perfect batteries! Because, if your quick-and-dirt-battery-for-testing-purposes works... it will become your "ultimate" battery, and soon or later it will fail...
Jumpjack

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