Swallow Advance Charger: Not quite happy  
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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> Swallow Advance Charger: Not quite happy
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Swallow Advance Charger: Not quite happy - 11/25/2005 3:14:52 PM   
OldNick


 

Posts: 7
Joined: 11/25/2005
From: perth, AUSTRALIA
Status: offline 		Forgive me, those of you who have seen me on other forums with the same question....I only had one respondant, who had the same problem, but (as usual) was easier-going than I.

My problem in a nutshell. I am suffering from the urge to curse, flame, degrade, insult the Swallow charger <GG>

In Discharge mode, the Swallow Advance will cut off at the set cutoff voltage.

In Cycle mode (Discharge/Charge) it goes _waaay_ down...to the point where I panicked and stopped the process on a 6-pack of NiCds. I set 6.6 V (first try, just to see what happened) and when it got to 5.3 V I quit.

My electrics is pretty reasonable, but I am really working hard to catch up with battery rules and regulations. There were a lot of raves about the Swallow (and its rebadged fellows) and this caught me off guard.

If I disconnect the (dis)charger, the battery voltage is not 5.3, but is a lot higher, by check with an external VM. However I had the external VM in circuit while discharging and the battery V did drop to something like 5.3V.

On another Forum, someone said that if I stayed below c/10 this would be OK.

BUT
(a) I am not sure that is so
- if I do stay below c/10, will I avoid damage if I discharge to so low a Volts (and I am not sure how low it goes).
- do I have to stay <c/10, or do I trust the charger?
(b) If I cannot trust the charger, this seems to be a major design fault. Even if I am forced to cycle at <c/10, this is a bit silly.
(c) Is there a difference between discharging to 5.3V under load vs whatever V is actually in the pack with no load (again I have to trust the charger). When I am told I should not take NiCd below 1V/cell, is this under load or under no load?......if you see what I mean....

Any input from users of the Swallow, or those who know batteries/discharging etc?
       Post #: 1

RE: Swallow Advance Charger: Not quite happy - 11/25/2005 8:49:21 PM   
Red Scholefield



Posts: 4912
Joined: 12/8/2001
From: Newberry, FL, USA
Status: offline 		Your charger is working properly. The voltage cutoff setting only works on the discharge function, not on charge/dischare or discharge/charge. In these functions the discharge cutoff is 0.83/cell, this is not a problem as it is a loaded voltage. The unloaded voltage will be much higher, something between 1.15 and 1.2 volts/cell.

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Red S.
AMA 951 Leader Member

(in reply to OldNick)
       Post #: 2

RE: Swallow Advance Charger: Not quite happy - 11/26/2005 2:53:26 AM   
OldNick


 

Posts: 7
Joined: 11/25/2005
From: perth, AUSTRALIA
Status: offline
quote:

ORIGINAL: Red Scholefield

Your charger is working properly. The voltage cutoff setting only works on the discharge function, not on charge/dischare or discharge/charge. In these functions the discharge cutoff is 0.83/cell, this is not a problem as it is a loaded voltage. The unloaded voltage will be much higher, something between 1.15 and 1.2 volts/cell.


Thanks very much for that. I wondered if the loading was the reason it could go lower. I realise it's the reaon it _is_ lower, but I was not sure if loaded voltage could be as low as that.

So when doing a once-off discharge, should I apply the same principles, in order to ensure a complete discharge? And also, is there a "safe" discharge rate? I suppose even 1A s a LOT less than the 15+A so a motor can draw, but what is good practice?

Again, thanks for your help so far.

(in reply to Red Scholefield)
       Post #: 3

RE: Swallow Advance Charger: Not quite happy - 11/26/2005 2:55:51 AM   
OldNick


 

Posts: 7
Joined: 11/25/2005
From: perth, AUSTRALIA
Status: offline 		BTW. Your site rules! <G>

(in reply to Red Scholefield)
       Post #: 4

RE: Swallow Advance Charger: Not quite happy - 11/26/2005 10:48:00 PM   
aikon


 

Posts: 17
Joined: 10/1/2003
From: Alta,
Status: offline 		How can the charger know how many cells there is in the pack?

(in reply to OldNick)
       Post #: 5

RE: Swallow Advance Charger: Not quite happy - 11/27/2005 12:52:31 AM   
OldNick


 

Posts: 7
Joined: 11/25/2005
From: perth, AUSTRALIA
Status: offline
quote:

ORIGINAL: aikon

How can the charger know how many cells there is in the pack?


An intereeting question. You just beat me to it! <G> I was thinking dV/t as with charging. But all the graphs show that at on discharge, 1.1.V the cells will "knee" and drop from there like a stone. I could not find a graph that went far enoiugh to show if there's a re-flattening at some lower voltage. This would not make much sense, as it would mean the cell was "providing power" again. Although there is one other possibility, and that is that the internal resistance goes way up suddenly at .83V causing the current to simply stop.

I have seen one site where it was suggested that you discharge to "0V" under load, which bounces to .9-1.0V at no load. I confused.

Just showing I am looking and trying to think.

(in reply to aikon)
       Post #: 6

RE: Swallow Advance Charger: Not quite happy - 11/28/2005 12:33:56 AM   
OldNick


 

Posts: 7
Joined: 11/25/2005
From: perth, AUSTRALIA
Status: offline 		Well, I still do not understand _how_, but I used a cheapo little pack of 3 NiCds from a phone, and the charger did as predicted. I set it up to charge at 1C, and the discharge at .5C. It cycled as predicted.

(in reply to OldNick)
       Post #: 7

RE: Swallow Advance Charger: Not quite happy - 11/29/2005 12:14:21 AM   
OldNick


 

Posts: 7
Joined: 11/25/2005
From: perth, AUSTRALIA
Status: offline 		This would appear to have to remain among the many unknowns of the battery world..sigh. I have asked everywhere.

(in reply to OldNick)
       Post #: 8

RE: Swallow Advance Charger: Not quite happy - 9/22/2007 12:45:38 AM   
tuxedo


 

Posts: 11
Joined: 9/12/2006
From: fennell bayNSW, AUSTRALIA
Status: offline 		if i was charging a 7.2v 1200mah nimh, what settings would i set to discharge it, ive sorta lost my manual for the swallow advance charger

(in reply to OldNick)
       Post #: 9

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