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E-Bike Battery Surgery

battery deadOne of our long term visitors is an e-biker. One of his batteries was on the blink. There was no output on the normal output connectors, but there appeared to be an output via the charge port. We suspected that the balance circuit was shot, but when we opened the battery case, it looked like one of the cells was physically damaged. Lots of pics here.

We ordered a replacement cell. When we removed the bad cell, we noticed some others damaged. It looks like we need 4 replacement cells in all. We plan to cannibalise these from an old spare battery. We tested the remaining cells and they seem able to take a charge and deliver reasonable current. A 2 Ohm power resistor came in handy. Check back with us to see how the rest of the repair went.

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Blackpitts Makeover

spruce upThe front of our building is getting a bit of a makeover. Pics here. New cement render on the outside, painting, new bike racks, steps and ramp cleaned up. Inside we’re getting a spruced up entrance lobby, a new entrance door and other works. Drop in and have a look.

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TOG April Open Social

blower2

Our April Open Social takes place on Sat 16th April at 7pm. If you fancy a great alternative Saturday evening in town, why not drop in and see us. We’ll show you around the space and update you on the progress. Things are moving along nicely. Our workshop walls are going up and we’ve now had our first brewday. We might even have some beer samples for you to try 🙂

The Open Social is a great informal way to visit us. You can talk to members and visitors, see what’s going on, or just hang out for the evening. The space stays open until the last member is left……usually the small hours of Sunday morning. The evening is free to attend for members and visitors alike. Drop in for 10 minutes, or stay the whole evening. We have parking available. Bring beer, food, gadgets! Hope to see you there.

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Fixing the Variac

variac

Actually there was nothing wrong with it. It didn’t really need “fixing”. A variac is a kind of variable AC transformer. They are very useful for testing AC loads because they can give a variable output voltage usually from 0 up to some value. This particular one can output from 0 to 250V and supply about 12A of current.

It is rated at 3kVA which is quite a bit. A big horse of a transformer like this has a big inrush current when it is plugged in. The surge is so great, that it was tripping the circuit breaker on our distribution board. The breakers on TOG’s board have C-curve trip characteristic, so they’re really not suited to this kind of load.

So something had to be done to limit the inrush current. We thought about a power resistor and a shorting relay, but in the end opted to try an NTC type surge limiter. This is a type of resistor where the resistance falls with temperature. At room temperature the resistance measured was about 12 ohms. The resistance falls rapidly as the temperature rises. Even so, the thing gets hot at heavy load. We used the 2kw heatgun as a heavy test load. We mounted the limiter high up inside the enclosure, in free air. Plenty of insulation and some cable ties to secure it. Tested it and no tripping now. A bit more testing is required however. particularly at higher currents. Need to do some I²R calculations and temperature measurements. Pics here.

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OSM MapJam Saturday 23rd of April

OpenStreetMap (OSM) Ireland members will meet Saturday 23rd of April in Dublin and do OSM mappy stuff on laptops in TOG. Like an indoor mapping party / hack day / social meet up / barcamp.

What is OpenStreetMap?
OpenStreetMap is a world wide, open content map. It’s often referred to as the Wikipedia of maps in reference to the fact that it is open to be edited by anyone.

If you’d like to learn more about OpenStreetMap, come along! Want to start mapping your local area, and want help? Come along! Want to find out how to use the low level OpenStreetMap data? Come along! This event is open to all.
If you’re already an OSM mapper and would like come, but not sure what to do, don’t worry we have loads of townlands to map and plenty of people who will give you a hand learning the details.

In addition there will also be a meeting of the Irish Open Source Geospatial Foundation, their first in person meeting. OSGeo was created to support the collaborative development of open source geospatial software, and promote its widespread use.
Where and When?
Tog Dublin Hackerspace
Saturday 23rd of April 2-5pm
Open Street Map Ireland Website

Worldwide editable map

OSM Ireland email list

Open Source Geospatial Foundation

OS Geo Ireland email list