SSR: Finding a good Solid State Relay

[THDLink]

I used a 25 amp Solid State Relay for an 8 amp max solar application and it failed within a day. The product was $12 shipped. I have heard everywhere that some of these products fail in this time-frame. My question is will a $90 relay fail... it is worth it? I'm looking at possibly purchasing this one: http://www.mouser.com/ProductDetail/Crydom/DC100D20/?qs=sGAEpiMZZMtq49AUx5G37wsxuQiiAVkEAxnGuO0fk0g%3d

[dnix71]

SSR's need heat sinking. Mechanical relays don't. I salvaged a microwave oven once with a triac that shorted hot to gate and would have burned a house to the ground with it. I was paying attention and shut the door and noticed magic smoke coming from the circuit board. I was able to ID the burned resistors and replace them, along with the triac. But I have distrusted SSR's since that day.

[OperaHouse]

It might be an issue of how fast you were turning it off and on. If turning them on and off faster than every half second, they will not turn fully on or off, likely even a bigger issue with cheap ones. These have a very low gate drive since they are self powered.

[DamonHD]

Also make sure that you have a good snubber on an SSR (or built in) if there is any hint of inductivity (?) in your load.

I've had SSRs fail though failing to get that right.

Rgds

Damon

[THDLink]

looks like I'll have to find another way to equalize my battery because I don't understand SSRs yet. Thinking just using mechanical relay then using grid power to equalize

[kitestrings]

Hi,

I'm not real sure what your application is.  On the original question, I've used two of these in the past:
http://www.futurlec.com/Relays/SSRB40Apr.shtml

They are relatively inexpensive (and probably lesser quality than the Crydom), but so far haven't had one fail.  As dnix says they have top be mounted on a chunk of aluminum fin-tube to keep them cool, but otherwise they are silent and well suited if it is turning on and off rapidly (as with a diversion controller).

Equalization is a periodic, controlled over charging to get all the cells of a battery to "equalize".  I'm not sure how this fits.  Most charge controllers have the ability to set a equalization charge.  If you have grid power you can certainly do it with a charger of any quality.

[kitestrings]

Oops, wrong link.  I think it is this one (DC version) that I've used:

http://www.futurlec.com/Relays/SSRDC100V40Apr.shtml

[madlabs]

SSR's are much better for this kind of thing. You just need to get the right one for your application. Tell us more about exactly what you are doing.

Jonathan