Advanced Notification of Interruption to Shipping
We are now expecting to move to our new premises in Rugby during the last week in November. During the move, we will not be shipping any orders out for the period Tuesday 25th November to Tuesday 2nd December. Last shipping day will be Monday 24th November and re-commence Wednesday 3rd December. Orders placed after 12 noon GMT on the 24th will be processed from the 3rd December
Whilst our machine shop is re-located, we are unable to carry out machining modifications on gears, sprockets, pulleys etc. Any order placed which includes machining options is unlikely to be processed until mid December.
How long will a 17Ah battery last in a heavyweight robot?
Post Number: 12
This naturally depends on how quickly it is discharged but is also a bit more complicated than that. Firstly it depends on the robot, its motors, the amount of torque needed to drive it and how you drive it. A common set up in heavyweights is to use a pair of Bosch 750W motors at 24V. These motors have a current consumption of 40A at their nominal 750W output power. Let's assume an average consumption of 30A per motor for a 5 minute fight which adds up to 60A for 5 minutes or 60/12 = 5Ah.
You would naturally assume that a pair of 17Ah batteries would be far too big but no. The 17Ah is based on a 20hr discharge, as you discharge the battery more quickly, the effective Ah capacity falls. Our tests on Yuasa batteries give an effective capacity of 33% of their 20hr rating on a 5 minute discharge. Europa give 38% and Hawker Odyssey 43%. Thus, for the worse case Yuasa a 17Ah battery would only give 5.6Ah which happens to be enough for our example above.
In practice, most teams do use 17Ah packs although some do use smaller but largely depends on gearbox ratio, 2 or 4 wheel drive etc. It is worth mentioning that the NiCD Bot-Packs have an effective capacity of 82% on a 5 minute discharge which is why 3 x 3Ah packs in parallel (9Ah) replaces 17Ah of SLA. In fact many users report a longer running time than with SLA's.
Archive of the technobots.co.uk support forum
This copy of our old forum that closed to new posts in 2010. It is a 'work in progress' as we copy the pages across. The posts still provide a valuable source of information for both our customers and general info to the casual reader arriving here from search engines.
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