Discharging batteries to 0.90? Under load?

[JeffEmbracedDC]

Hey, guys.

So I when I place my batteries on a discharge tray and watch its voltage with a meter.. I let a cell go all the way down to 0.0v. Then once I remove it from the tray I will climb back up to some other voltage and stay there. So basically, how do I know when to take my batteries off of my conditioning tray? Monitoring voltage on a meter doesn't help much seeing as how voltage changes under load anyway. I'd have to disconnect a cell and let it sit for about 30-40 seconds before I get an accurate voltage.

Any thoughts? Thanks.

-J

[JeffEmbracedDC]

Anyone wish to comment? Thanks.

[terrible-t]

After discharging them, I feel that if they do climb up to a certain voltage, battery is good. Storing the battery, should have at least 1.5v to store. NiCd carrys a memory for thesehold. NiMh doesn't hold a thesehold memory.
But they do get lazy. Never store with a completely charge battery.
Voltage on the battery you're not concerned about. How many amps it takes. NiMh batteries never charge up to it mah, usually your charger shut off @ 2% its mah, and trickle charge the rest. Mh cells you can charge them 2% higher,i.e. 3300mah @3.366 amps, if charger is adjustable in amps.
Just monitor the temp of the battery pack when charging.
Reconditioning battaries Is a way to try to match a set of cell for peak performance, or charging a set before racing. You want to start a race with freshly charge battery.

[JeffEmbracedDC]

What I do is drain my battery most of the way with my run (let's say a 5 minute race) and the battery has about a 35% charge. I then use my bulb discharger and discharge till they start to get a little dim. I them switch it over to my conditioning tray which discharges at "2A". I put a meter across each cell and watch the voltage drop as the conditioning tray discharges. I let my meter go down to 0v. Once I remove the batteries from the tray I will let it sit for about 5 minutes and the voltage climbs back up to around 1.10v. If any cells are over 1.10vish I'll discharge that particular cell some more with the tray until they all read about the same voltage (about 1.10v).

Am I discharging them enough? Everyone says "discharge to 0.90 or 0.85v" but what the heck does that even mean? under a load? and if so, what load? Under no load after the voltage climbs back up? That would take forever. Do people leave their batteries on the novak smart trays for like hours or days at a time to discharge to 0.85v? I have left my cells on the conditioner for about a half hour and they still climb back up to over 1v easily.

Anyway, thanks!

-J

[terrible-t]

1.10 is enough. The residual charge it recover from still Battery. I would question the cells that dont recover over 1.10 volts. Thet are concidered as dis charged at 1.10v. Discharge doesn'y mean 0v. Batteries that recover well are good. Cells that dont are questionable, but can be used for prelim races. Final you want your best battery cells.

[SS Pede]

Normally, a discharge to .9 volts is under load. A high discharge rate down to .9 volts (like 10 or 20 amps) won't be that accurate. A low-ish rate should get you down to below .9, then you can stop discharging if you want. You are discharging them plenty low enough, unless you're truly trying to "dead short" the cells.

[guver]

It won't matter much, as the cells are "empty"

In any case no matter how long/deep you discharge a cell (even if you dead short it for a week or so) it will tend to spring back up to over a volt after setting a bit.

Some old/worn out cells may tend to "rest" closer to zero, but they are probably shorted internally and is still an ok cell to use, but may appear to have a high self discharge rate.