nigel99
Senior Heliman
Location: London
| To start with let me say that I have no connection with MEC other than as a customer.
This is a report on the performance of the Solderless Power Tube system from MEC used as 24 and 32 cell packs made up as 2 x 12 cells and 2 x 16 cells.
The background to this is that I had been flying my Logo 20 and Joker CX helis for about 9 months and from time to time I had to break the battery packs open to remove defective cells and replace them. I found this procedure to be both tricky and time consuming. I probably experience more problems than many people due to the amount of flying that I do; 2 sessions per day of about 90mins each 7 days a week (weather permitting).So when I read about the SPT I figured that I should give them a try. So I got enough kit from MEC to make 2 sets of SPT for my Logo and 2 for my Joker. For all these packs I was using sanyo RC 2400 NiCd from a very reputable source here in the UK. To cut a long story short I found that the 2x12 SPT packs for the Logo worked fine but the 2x16 packs for the Joker had severe problems after just half a dozen flights – cells venting, blackened end caps and generally rising internal impedance. To try and help matters I got hold of premium pushed and matched sanyo 2400 from the major German supplier; unfortunately this made no difference. As a matter of interest when I broke up the SPT packs and used those cells to make up soldered packs and after a good formatting session they recovered and went on to perform perfectly well (60 odd flights with little drop in performance).
At this point I think it is fair to say that I do seem to be almost alone in my problems with venting and the degree to which I suffered performance loss with my early SPT packs has not been experienced by others. Although I do believe that a few people did suffer a smaller performance loss than I did with their early packs. However read on and you will discover that none of this matters anymore because:---
I contacted Pete at MEC who was quick to respond and most concerned to try and sort the problem out. Initially he sent me (free of charge) the newest versions of the SPT parts and the special “shotgun barrel” shaped tubing to hold the cells. I made up new 2x16 packs again with the sanyo 2400 cells however the same problems occurred. After much discussion we agreed the best thing would be for him to make up the packs himself using their own supply of Panasonic 3000 NiMh cells. I have to say I was quite sceptical and wary of using NiMh in the Joker especially since I had very poor results with even the HV sanyo NiMh cells in my Logo.
The results speak for themselves – checkout the table of flight performances that I kept:-
Flight number time
5 10:15
6 10:20
7 9:57
8 10:27
9 10:31
10 9:23
11 10:56 fitted ceramic bearings throughout
12 10:54
13 10:49
14 11:41 very windy
15 11:14
16 11:11 air temp. -2
17 11:14 -2
18 11:21 -1
19 11:11 -3
20 11:17 -1
21 11:00 -2
22 11:48 FITTED U-BEC
23 12:20 very windy
24 11.24
25 11.18
26 13.03 25+mph winds
27 11.37
28 12.15 windy
29 11.57 windy
30 11.27
31 11.32
32 10.35 1500 rpm
33 10.45 “
34 9.50 “
35 10.00 “
36 11.00 1360 rpm
37 9.56 1500 and removed U-BEC fitted 4x3300NiMh Rx pack (U-BEC glitch problems)
38 9.58 “
39 9.58 “
40 10.58 1360 very still air
41 10.38 “
42 11.04 “
43 10.48 “
44 10.14 1500
45 9.23 “
46 11.15 1360
47 10.57 “
So there is the proof of the pudding.
I AM GOBSMACKED
I do make sure that the packs are well topped up before flying. My standard procedure is to charge them at 4.0 amps the night before, then I put them on charge on the way to fly which usually adds about 0.3 amps
And then whilst preparing at the field I hook them up again which usually puts in around 0.2 amps. This also means that the pack is nice and warm at the start. It must also be noted that the last 1:30 of the flight is close in precision hovering practice because a) the batteries are nearly out so you want to be close to home for landing and b) they wouldn’t provide the power for heavy manoeuvres and the motor really bogs down. However I do this with all my battery packs and whenever I have taken flight time readings in the past.
In conclusion I am extremely pleased with the SPT system and combined with the NiMh cells from MEC they really do provide a winning formula. The service that MEC has provided me with has been exemplary – wouldn’t it be cool if just half the people you buy things from behaved in such a customer friendly fashion.
Cheers Nigel |
