The Lamp Room

Anyone had any issues with Tridonic PC combo ballasts?
I recently got a couple of 2x28W T5 EM weatherpacks fitted with Tridonic PC 1x21/28-5 T5 combo ballasts for 5 cell battery packs.
Both are faulty, one is completely dead on the mains side while the other randomly lights between a few seconds and 20 minutes after being powered on the switched line side.
The emergency sides of both appear to still work though both have dead batteries that only manage a few seconds-minutes of operation.

Will likely convert them to just mains only fittings with normal ballasts but was interested to see if the combo's could be repaired.

Disconnect the batteries and see what happens or just chance them. Those ballasts are designed to shut down the switches side of the ballast if the batteries fail. That being said I have some 1X49W here that will light with the batteries disconnected but as soon as you connect them even new batteries they will stay on but as soon as you switch them they won’t come back on. Basically they are only as good as a normal ballast now.

I'll give that a go, worth a try. The batteries are completely dead going out after less than 30 seconds most of the time.
The fittings are only 2015, not even yellowed yet and still on their original not hugely worn Osram 28W/840's. I may end up sticking a HF-performer in them or whatever decent T5 HF I can get. Could even make them 2x36W T8 as they are Dextra Hydra's with all the T8 cut outs in the tray.

Well it seemed to work on the first one I tried, unplugged the battery and they immediately came on, plugged it back in and they went out! Though having left it for a few minutes with them plugged in and the tubes were unlit they've just struck up again.

Some further investigation reveals dead batteries are indeed the cause of issues for both of them, they both light immediately when the batteries are unplugged.
The batteries are totally dead and have no voltage in them when disconnected for a few minutes and appear to measure as a short or as good as across the pack.

The OCV of the battery charger of the ballast is about 10V, when the battery is connected this falls to around 1V or so and the tubes which are lit then go out, though the green charging LED is lit up.
Gradually the voltage across the battery rises and when it hits about 4.5V the tubes then light and the ballast works normally. After a while they only seem to get up to around the 4.8V mark, so rather short of the 6V design voltage, when the permanent supply is removed the tube briefly light for literally two seconds and then goes out which is exactly what they did when they were still installed.

When intentionally shorting the ballast's battery output with a piece of wire the same thing happens and it essentially goes into stand by as Kev described.

When connecting a brand new set of batteries up it just works as normal like you'd expect, so it would appear a battery is all is wrong with them and they were basically scrapped for nothing! It's a shame nobody can be bothered to replace the batteries in any of them as I expect there are others not far behind these that may well be going out soon and will then be scrapped for nothing but poor maintenance.

That’s a shame they have already been removed probably for some tat, you should just replace the batteries and re install them or make the site team aware that all that is needed is the em batteries.

Indeed, replaced for Ansell tornado crap, no chance of them getting reinstalled sadly, though they are home with me now so are safe for good!
I have told them multiple times about he batteries but unfortunately it seems they are not bothered, they've been dead for at least 3 or 4 years now, for the last couple of years they have been tested every year and are of course still dead (not sure if they think they are going to heal up or something! ), must just now be reaching the point where they are too far gone for even the combos to work.

Might see if I can get permission to order and replace the EM batteries in the others myself though to prevent them going. There has been Aquaproofs (the old decent version) from the other building thrown away for nothing more than EOL tubes in recent times so batteries don't stand much chance of being changed otherwise!