So...
Charge to peak voltage (charger detects and shuts off)
wait 12 hours
Discharge to 5.4@0.8A

using the above, your charger(s) reported 7100-7500mAh capacity?

30 seconds for the high load discharge was arbitrary. I know a 100A load test for 10 seconds is very taxing on a stick. The tester is resistance based, so the load on 6V is not 100A but 50A.

I'm not sure how you calculated capacity based on the "100A" (really approximately 50A) discharge. It was intended as a cheap way to verify they can stand up to high loads. The fact that you never got close to 5.4V is very positive. Can you tell me what the end voltages were for the 5 sticks and how you extrapolated capacity?

There are 3600 seconds/hour.

50A for 30 seconds = 50*30/3600 = 417mAh.

Assuming 6.5Ah capacity, 50A would take 7.8 minutes to hit 6V, which is the official cut-off. It's unlikely the battery can deliver that current for that long.

 

I didn't extrapolate the capacity for the 100A load tester. I just got 6.2V to 6.5V readings after 30 seconds. I incorrectly stated that it was a mAh reading. I was thinking performance and said capacity. I got the capacities from the chargers of between 7100mAh and 7500mAh because I was reporting the wrong line of my notes. I should have reported that I got between 5900mAh and 6400mAh. I really botched up my report back. Thanks for the corrections. Are these acceptable/good sticks? The vehicle had 94,000 miles on it. - Jen

 

Ah! That makes more sense... the 7100-7500 was the input where the 5900-6400 was the output.

Those sticks are likely good. Is there a correlation between capacity and voltage, i.e., the 6.5V stick was also the 6400mAh where the 6.2V sticks was 5900mAh?

It's very helpful to have these in a table for comparison. Google sheets is very useful for this.

My initial reaction is that these sticks are good. The primary reason is because you didn't have an IMA light when you pulled the pack. Everything else is just data supporting that fact.

When you terminated the 30 second load test, were the voltages pretty stable, i.e., they were slowly dropping? This is important. If they were falling quickly through that voltage at 30 seconds, then they may not be very healthy.

This would be interesting, and we could approximate capacity:

Take the 6.2V stick. Continue testing it 30 seconds on/30 seconds off until you hit 6V, record total time. The 30 on/30 off is to prevent overheating the tester, and you may want to cool it in the 30 second off period. Once you have the total time, you can approximate its 50A capacity via (50A * # of seconds*.278) = mAh.

Have you done any testing on the light bulbs tester?

Steve

 

There wasn't as much correlation between the capacity on the chargers and the test at 50 amps as you would think there should be. I will chart the data and post it. I have another pack coming tomorrow that I want to refurbish too. I'm getting hooked on this.

The voltages quickly dropped to about 7 volts then smoothly to their final voltage where they pretty much stayed for the last 10 seconds perhaps losing 0.2 volts. They rebound back to their original voltage minus 0.2 volts immediately upon removing the load.

I will do your 30 second on/ 30 off test tomorrow. My work table is full at the moment.

I have not yet tested the bulb discharger. I'll mess with that tomorrow too. At the risk of sounding ignorant where does .278 come from in your equation? - Jen

 

Given the capacity is based on 800mA discharge, I wouldn't expect any correlation, but one can always hope.

In order to save yourself a LOT of work, I recommend you go the grid charger route on the pack:
Grid charge for 36 hours.
Discharge to 12V with 2X 25W bulbs in series (~2 days)
Charge the whole pack for 2 hours
Break pack down and do a 5-6A charge to deltaV cut-off on each stick.
Do the 30 second load test.
Do the light bulb discharger test

From the two tests, you can compute a capacity number OR you could use one of these:


To actually measure each capacity.

That's it. no waiting for cycling, and you'll have a LOT less bench time with much less calendar time.

Let me caution you that old HCH1 packs from salvage yards are usually ragged out. If half the sticks are good, you've gotten lucky.

The voltage response you describe sounds very favorable.

In order to kick out the right number, you have to divide by 3600 sec/hr and multiple by 1000 mA/A

1000/3600 = .278

Steve

 

Here is a link to my data so far:

https://docs.google.com/spreadsheets...it?usp=sharing

I haven't had time to make tables to make the data easier to assimilate. I hope it is understandable. I will add columns for the "bulbs" test once I do them. - Jen

 

Be sure to scroll down on the spreadsheet to see the tables I've created. The sheet is a work in progress and data and tables will be added as I have them. I've created a capacities table which is limited by the late standardization of technique and measurement in the first five sticks but will become more useful with the rest of the sticks as they complete. The voltage measurement table is less limited in its interpretation. - Jen

 

Ok, I just finished testing stick #1 on the 20A light bulbs (which didn't shut off automatically, BTW). The stick took 17 minutes and 55 seconds to get to 6 volts from a resting voltage of 8.2V. So 20A * 1075 seconds * .278 = 5977. Correct? How much of a load does the 20A bulb thingy actually draw in your opinion? Have you taken a look at my spreadsheet that's linked above? Thanks - Jen

 

Your calculation is correct. If the auto shut-off actually works, it may be in the vicinity of 5.4V.

Can you see a part number on the bulb?

 

BTW... again... one of these for $17 would remove all doubt...