Information on delta peak settings when charging in high ambient temperatures.

These 2 packs of GP3300s were peak detect charged to 0.08 with  Pro-Trak Temperature probes connected to monitor the ambient temperature and the pack temperature in 3 different locations.

The data shown is the end of charge only ( when any probe reached 45`C)

Pack 1 was charged in a gazebo with net sides, the ambient temperature was 25 - 26 `C 

The results would indicate that a delta cut-off of 0.04 would result in the pack reaching a safe 45`C. The results also indicate that a single temperature probe is not good enough for reliable temperature charging.  This is shown by the difference in temperature of the 3 probes monitoring the cells. It can be seen when probe 3 reached 45 `C probe 1 was only at 39`C.  If a single probe was used in the position of probe 1 then other cells in the pack could reach temperature in excess of 50 `C

These are the last 9 readings sent by Pro-Trak during charge of  Pack 1 (readings sent every 16 seconds)

 Peak 0.08V Ni-Mh Linear  5.00A GP3300 Pack 1
Row Pack 1 Ambient `C Probe 1 Probe 2 Probe 3 Pack F/B Time to charge Charge
in seconds capacity
1 8.93 25 39 42 45 0.04 2672 3711
2 8.94 25 39 43 45 0.03 2688 3733
3 8.94 26 40 43 46 0.03 2704 3756
4 8.93 26 40 44 47 0.04 2720 3778
5 8.92 26 41 44 48 0.05 2736 3800
6 8.92 26 42 45 48 0.05 2752 3822
7 8.91 26 42 46 49 0.06 2768 3844
8 8.90 26 43 47 50 0.07 2784 3867
9 8.89 26 44 48 51 0.08 2800 3889

 

Pack 2 was charged in a workshop where the ambient temperature was 28`C.

Here the pack had no delta fallback when probe 1 reached 45`C. When the delta was at 0.04 the temperature was at 50`C.

These are the last 15 readings sent by Pro-Trak during charge of Pack 2 (readings sent every 16 seconds)

Peak 0.08V Ni-Mh Linear  5.00A GP3300 Pack 2
Row Pack 2 Ambient `C Probe 1 Probe 2 Probe 3 Pack F/B Charge time Charge
in seconds capacity
1 8.91 28 45 43 44 0.00 2240 3111
2 8.92 28 45 43 44 0.00 2256 3133
3 8.93 28 45 43 44 0.00 2272 3156
4 8.93 28 46 44 45 0.00 2288 3178
5 8.94 28 46 44 46 0.00 2304 3200
6 8.94 28 46 45 46 0.00 2320 3222
7 8.94 28 47 45 46 0.00 2336 3244
8 8.94 28 47 46 47 0.01 2352 3267
9 8.94 28 48 46 48 0.01 2368 3289
10 8.93 28 48 47 48 0.02 2384 3311
11 8.93 28 49 48 49 0.02 2400 3333
12 8.92 28 50 49 50 0.03 2416 3356
13 8.91 28 50 49 50 0.04 2432 3378
14 8.90 28 51 50 51 0.05 2448 3400
15 8.88 28 52 51 51 0.08 2464 3422

Clearly some tests have to be done to see what charge detection is best to use in high ambient temperatures.

If using peak detect in high ambient temperature then a low delta cut-off must be set.  Temperature detect would appear to be the safest at this time.

We will endeavor to complete some tests on which detection method is suitable and what values should be used in high ambient temperate.