HW: Leveller Evo (name pending approval by Dave Mac)

[JamesDavies]

Ok thanks. Where is the best place to get them?

[maddox10]

We buy our Burkert 5404 1/2bsp 24V DC coil 2/2 valves with RS components.

But there is a less expensive way, if you're willing to go Chinese. 2 disadvantages. No warranty whatsoever, and except the body, not compatible with the Burkerts (means you can use an original burkert body, but have to replace anything else if you want to mix and match). You can buy 5 "Churkerts" for the price of 3.5 originals. And that's including import tax. (why 5, because that's the minimum)

[JamesDavies]

Thanks for the info. Very helpful.

I'd like to understand before I buy- this valve (the 5404- I assume the same as the one you are referring to?) says it is good for pressures up to 50 bar. I thought the fire extinguishers produced about 60-70 bar? Am I being stupid here?

(link to valve: http://www.buerkert.com/COM/buerkert...e=5404&sk_id=2)

[maddox10]

The firm "Burkert" garanties that the valve will work constant and dependable @50 bar with a working voltage of 19-24V, what a standard PLC voltage is.

In the 13 years I use those valves, and a lot of roboteers with me, we learned that the pressure isn't a factor, and that the valve can withstand 200 bar(thanks to Mike Lambert, who spend the money to have them certified). The point is that it won't work always unless you feed it 24V+.
That is why we use a voltage booster in our feathers, meaning we don't have to lug around a 24V battery.
In the heavies we run 36V, so there it isn't an issue whatsoever.

The only disadvantage of 36V on the 24V coil is that it will run hot. But with a working time of 5 minutes max, the solenoid , ment for permanent powering, won't care.

Things that will ruin a 5404 are swarf and age.

[JamesDavies]

Getting this back on track again- I'm wondering what batteries people use? I dont think I'm ready to go full LiPo yet, but I think I need to finally upgrade from SLAs.

So-

What NiCads do/did people use? I'm hoping they will provide me a middle ground...

[daveimi]

Don't think you're allowed NiCad's anymore, would have to be Nimh.

[maddox10]

New NiCd isn't cheaper or safer than LiFePo4.

If you can find them. In theory it's old stock that's being sold.

[JamesDavies]

Oh right- good thing I checked! Any idea why they were banned?

Do NiCads come with a C rating like Lipos do?

[daveimi]

I think nicads are banned from sale under EU law because of the harmful chemicals (cadium I think). Nimh sprang up in their place and are pretty much identical. Think they even work with the same chargers etc.

[RogueTwoRobots]

If you can get old Nicad packs, then you can use them as far as I'm aware (haven't read the rules recently) but yes they are no longer allowed to be sold commercially. There are packs that come up for sale now and again on here but they're old packs that will have been used. Yes they might be fine but they'll have seen battle in most cases.

Nimhs are the next progression. Similar in size & stats but I don't think they are/were as good at providing as high a discharge current as Nicads. For the money, you'd be as well using Lipos. If you're unsure, just ask the right people lots of questions on them, read all the rules regarding them, and have a look at how other HW users have fitted them. If you follow the right procedures and treat them properly, they'll just be like any other battery.