Ni cads

[kodster]

Ive heard some NiCads are rechargeable, but I could be wrong. Theyre definitely more powerful than NiMh batteries, and I think as powerful as SLA batteries, depending on the robot. :wink:

Team Gore

[knightrous]

Kody, NiCads have always been and always will be rechargeable. I dont think anyone would be using NiCads or NiMHs if they were use once and throw away job.

NiCads are lighter then SLAs, but the SLAs can source a lot more current on peak then a NiCad and they can also take more physical abuse. The Nicads have a much better effeciency rate then SLAs and also are much lighter.

[big_nipper]

james,

We use 2400mAh Sanyo C cells and yes they are NiCads. NiMH just couldnt provide the current.

Weve simply got 3x 9.6V & 1x 7.2V RC Racing packs to make up 36V with 3 of these in parrallel (Yes weve changed it again). We did not take theses packs apart all we did is cut the connectors off and joined them together. Each cell is spot welded to each other at 5 points unlike standard packs with just one weld. They are designed for model cars to be fully discharged in 5 minutes.

We have however burnt the plastic of a few cells when just running one set on the weapon and stalling the motor for a while (with 120A current limit) so you do need to be careful if using these size cells. A test we did a few weeks ago showed a 2V drop with 84A with one 36V pack (better than most Lead acid).

The 2400mAH cells are far better that the 3000mAH for weight/capacity but have a far lower current rating. We simply used them to get the robot down to weight from Lead Acid as the 3000mAH ones would not provide much weight saving. From memory our cyclon Lead Acid battery weight was 9kg, the 2400mAh (at 28.8V) was 4.5kg and the 3000mAh was 8kg.

If you can use the 3000mAH ones then those are the ones Id recommend.

[big_nipper]

Err.. Meant sub C Cells

[m2xt]

I have approached many manufacturers for their recommendation for Ni-Cad or Ni-MH cells in heavyweights and not one had a product in their range that would suit (including Sanyo). However, there is considerable experience of using the Sanyo N-3000CR both in the US and the UK in heavyweights and that experience is worth far more that any spec sheet. Technobots alone has sold over 4,000 N-3000CR cells (either singularly or assembled into packs) to European robot builders over the last 2 years and failures have been rare. The failures I know of have been more often than not been due to incorrect usage. As far as I am concerned, there is no real choice, its the Sanyo N-3000CR but I keep looking.

Paul

[kodster]

And what about Bosch motors? Im considering them, but I dont think theyre as powerful as some MagMotors

Team Gore

[typhoon_driver]

we use saft ni-mh cells in typhoon 1 + 2, they do what we need them to do and havent given us any trouble

It just depends on the needs of your machine

[kodster]

Too true Gary. Hell you won RW7 with them!

Team Gore