Team Death - New Heavyweight

[emisnug]

Today was another day of misses, with a recovery towards the end.
As soon as I met up with Colin, we took a trip to Maplin, and got some ceramic 1 ohm resistors of varying wattages. These were to be used to try nulling an issue with getting things up and running, when the battery was connected there was a huge spark. The plan is to have a resistor make the first connection, and ease the flow of energy in before the main connection is made, similar to how a British style plug works, the earth pin is slightly longer so it always makes contact first, where the longer pin would be the resistor pin here.

We use a 270 ohm resistor for our anti-spark link! Have you reached out to E0D/Charles to see what might be up with it?

[typhoon_driver]

What voltage are you running the Ragebridge at?

[Redirect Left]

What voltage are you running the Ragebridge at?

The battery we were using yesterday was around 12V (of indeterminate A). But the main battery packs are 2x 14.4v nominal LiPo. The spark is certainly down to the capacitors of the ESC instantly charging, and the LiPos can give out up to 250A (200A continuous), but exactly how much of that was very briefly used for the cap charge is unknown (the 200A in line fuse didn't blow though), each motor side is further fused for 70A (in line with the RageBridge max A per channel), but the motors weren't in the equation for the sparking issue last week.

We use a 270 ohm resistor for our anti-spark link! Have you reached out to E0D/Charles to see what might be up with it?

Some research online suggested just 1 ohm would do it, although we never got to find out exactly if that was true to any degree or not, as the ESC wasn't taking any power, so there was never a completed circuit for it to spark to begin with this week.

We had further issue, as Colins multimeter had battery issues, and then display issues. So i'll bring along my AMECaL meter next week and see if we can diagnose anything and get some readings with that. The three resistors we got cost less than £1 all together, so we can easily get others if needed, no big loss.

[typhoon_driver]

"2x 14.4v nominal LiPo"

What's the actual measured voltage of the packs together? I fear you may have flown too close to the sun.

[Redirect Left]

Even at maximum charge, 2 14.4v nominal LiPos won't exceed (or approach) the maximum 40v of a Ragebridge 2. I'm not with the batteries to measure them. However, assuming Colin hadn't fully charged any, and they were at the last measured voltage I did, they'd be around 26 to 31v together.

Exact voltage limits is 8 - 40v absolute, 12 to 30v nominal for the Ragebridge 2.

[Anttazz]

I think Garys issue he's bringing up is that LiPo voltages are multiples of 3.7v. 14.4v was an old NiCad/NiMH voltage. So running if those batteries you're running are connected in series they're be more than 30v, as LiPo's they will be either 11.1 or 14.8v nominal (3s or 4s) and really pushing the limits

[Redirect Left]

as LiPo's they will be either 11.1 or 14.8v nominal (3s or 4s) and really pushing the limits

Checked the bills, and yes. They're 14.8 nominal at 4s. Still at full charge, should not approach the absolute max, and should be within the comfortable, but slightly absolute max of around 35v

[typhoon_driver]

Bingo. I remember discussing the limits with Charles before originally buying them for PP3D. I asked whether I could get away with running 2 x T64s on 8s on a single controller. He said I'd really be pushing the limits of things. Especially when a fully charged lipo cell will pump out 4.25v or thereabouts. I dropped down to 6s for safety sake and have never had an issue with them.

From memory if the LEDs light up when you hook up a battery then it should be fine. If they don't then it's nackered.

[Redirect Left]

If it died from (less than, as not fully charged) 35v, i'd be very disappointed, as the website for the Ragebridge 2, in the first paragraph, advertises its ultra-wide 8-40v input very proudly. Which you're apparently now telling me is far from the case.

Even assuming that the LiPo was fully charged (both of them), 4.25 x 4, then doubled to account for both, 34v. Except they weren't fully charged anyway, so would probably be at least 2-3 volts shy of the above math.

[typhoon_driver]

I can only speculate Adam as I don't have the setup in front of me. First of all I would bench test the rage and get in touch with Charles. In my experience he's happy to help out with his speedos.

[Redirect Left]

The Rage is certainly not happy about the situation. Using both the LiPo and the SLA battery, it didn't respond, even after removing everything else from the circuit. I'll see if I can find out who Charles is and where to find him, we got the ESC from Ranglebox, but might still be worth contacting Charles.

[emisnug]

Hi Adam

Here's the link for Charles: http://e0designs.com/contact/

[team death]

Reliant Robin or Renault 5? ......my mind often wanders when building Robots
but its fine as long as you can keep one eye on the task in hand and your thoughts
are relative.
When building a robot it's important for me to make it as easy as possible
to work on when it's built so that's the aim with this latest creation and that's when
recalled cars I worked on where easy maintainance was not considered in the design.
One of my first cars was a 1972 renault 5 and the only way to do the clutch was
to take the entire engine out.
Secondly I recall my uncle asking me to take a look at his Reliant Robin 3 wheeler
-the spark plug would shoot out of the cylinder head when he tried to start it,
his son had told him it needed helicoiling, I remember taking a look through the
letterbox size bonnet and thinking a keyhole surgeon is required here).


I contacted Charles regarding the speed controller by e mail and he
said it sounds like a classic reversed polarity spark.
Needless to say Niall and myself are not happy with that explanation.

Todays build diary.
Unfortunatley Adam was unavailable this weekend and Niall was still in
Scotland so I did a double shift on ny own.
With the electrics on the back burner for now I turned my attention to
fabrication.
Although our Robot should easily drive with its scoop running along an arena
floor I thought shock absorbing castors would make for a smoother drive so
on Saturday I continued to make and fit said castors to the top of the body.
On Sunday I needed to duplicate the process so it was a case of flipping
the robot over and I thought while I'm doing that I would weigh it 87 kg-
before todays add ons.
The underbody of the Robot provides access to all the inner workings and
needed covering, so that and the castors was todays task.
I decided that some angle iron that we had used in other areas was best
suited -Adam had complained about the noxious fumes it gives off when
worked but needs mustoops:.
I was going to make a rounded shape to match the existing body shape but
found a angled shape worked just as well.
Adam and myself had picked up some polycarbonate when we visited the bus
dismantlers early in the year and I cut out a piece to fit the frame I made and
bolted it on.
I made the castors for the underbody but didn't have time to fasten to the frame.
Heres todays pics
DSCN1881.jpgDSCN1886 (3).jpgDSCN1890.jpgDSCN1891.jpgDSCN1898 (2).jpgDSCN1904.jpg

[team death]

Costings and build time
After seeing last nights Robot Wars and some teams stating thier
build times and costings-3,000 hours and 25,000 pounds.
I thought I would try to do my own retrospective costings and
build time in hours.
speed controller £200
wheels £40
bearings £20
winch £15
car jack £35
motors £250
link £30
rc gear £90
batteries/chargers £120
bolts + welding rods £60
Sprockets large/small and chains £90
elecrical sundries £30
steel for fabrication £80
use of electric for welding
and cutting ect est £200


Still to buy hydraulic trolley table est £200
Total inc trolley £1460

hours spent building 2x4 hours x 8 months +40 hours overtime
320 hours.
Or if you were charging for your time at say £20 an hour-£6400

[Deathly Hallows]

I think most of us are working on a budget and I like your figures. I guess if they counted in man hours of the whole team and had high bill rates you could get big numbers pretty quickly. I also see no issue in buying certain parts second hand or re-purposing items. Custom parts is where the money starts piling up would I guess, outsourced work is going to cost a bomb unless you know someone in the trade. Custom drop forged or single crystal weapons only for the millionaires out there.

Thinking about it - I would be happier to lose to a £25k bot after putting up a good fight with a machine costing £500, than just managing to beat a £500 machine with a £25k machine. Like a track day warrior turning up in a super car beating a kit car, just hanging on their tale would give you a buzz.