from the Hawker nursing home

[Gary Graunke <graunke@teleport.com>]

Continuing the saga of newbie meets aging battery pack of 42AH
Hawkers...

Lee Hart wrote:
> First, I assume these were the voltages after the batteries had been
> fully charged, and allowed to rest for at least a few hours, and were at
> room temperature (70-80 deg.F)? If so then the ones around 12.8-13.0v
> are fully charged and sound OK (based on this tiny bit of data). The
> voltage variations between them are a sign of imbalance in their
> relative states of charge.

The batteries had an overnight rest after being charged as a pack. The
temperature was probably 55F (my semi-heated garage is usually in the
50-60F range). 

> #3, #19, and #27 are probably ruined, as they have been asked to deliver
> high currents with a dead cell. It won't hurt to put them on a
> low-current high-voltage charge until the voltage stops rising. This
> would be something like 1 amp maximum and 16v maximum.
> Then do a load test. You will probably find that their amp-hour capacity
> is seriously reduced, so they should not be put back in service.

They don't seem to get back to 12 at all, so I assume they have one dead
cell each. I didn't load test them yet.

Yesterday, using the ".3G on a nylon rope and thumping on the bottom of
the battery box to overcome friction" technique, I removed the remaining
16 batteries from under the cab on the 94 US Electricar S10. The bad
news is that there are three more batteries with apparent dead cells.
(The good news is that the truck should run sooooo much better without 6
dead cells.) 

John Wayland managed to find a new 42AH Hawker that had been sitting in
his garage for 2 years. That one is #53. It doubtless needs a few cycles
to get up to speed (hmmm, I should also be careful to not exceed 50% DOD
on it until it is broken in, right?). 

There is probably experimental error here, since I tested them (using a
NiChrome tester for about 10 seconds--the tester switch is manually
operated) all in a short time, starting with a cold tester on #1, and
proceeding to #53 in order. I paused every 5 batteries to let the tester
cool down for 3-4 minutes. So the first few batteries probably underwent
a heavier load due to the relatively cool tester.

The load test results (sorted by descending order of load test terminal
voltage) at 55F:
battery	load V	original no-load voltage
51	11.8	12.95
52	11.7	12.92
29	11.6	12.93
31	11.6	13.02
35	11.6	12.91
40	11.6	12.84
41	11.6	12.83
42	11.6	12.85
44	11.6	12.93
47	11.6	12.87
48	11.6	12.74
49	11.6	12.85
25	11.5	12.89
30	11.5	12.91
37	11.5	12.84
28	11.4	12.82
34	11.4	13.02
38	11.4	12.91
39	11.4	12.86
46	11.4	12.92
26	11.3	12.91
36	11.3	12.91
9	11.2	12.97
22	11.2	12.84
24	11.2	12.85
32	11.2	12.89
33	11.2	12.94
53	11.2	new
16	11.1	12.81
6	11	12.9
8	11	12.76
10	11	12.81
17	11	12.96
20	11	12.78
21	11	12.9
2	10.8	13.02
7	10.8	12.9
14	10.8	12.83
18	10.8	12.91
23	10.8	13.02
4	10.7	12.91
12	10.7	12.91
15	10.6	12.78
1	10.5	12.95
5	10.5	12.92
11	10.5	12.89
13	10.2	12.66
3	0	10.86
19	0	10.64
27	0	10.56
43	0	10.79
45	0	10.53
50	0	10.88

Looks like I have a few that are marginal. Some of the first five tested
might be lower due to the cold tester and resulting higher current
drain. I guess I should put them on top, where they are easy to reach
without disassembling the entire pack. (The US Electricar has completely
enclosed, two level battery box with separated left and right strings of
26 batteries that straddles the drive shaft).
Any comments? advice? (Anyone have a few oldie but goodie 42AH Hawkers?)