How hard can they be driven?

[George Simmons]

Hi,

This is probably a question best answered by Dan, but if someone else has specific experience, I'm open to all answers. Can a channel continuously drive 8 amps?

I've got HD heatsinks on all 9 of my controllers. Owing largely to LED's and also the way I've set up the yard, eight of the controllers won't even be breaking a sweat. The ninth one will be driving 14 LED channels (which amount to less than one amp total) and two incandescent channels. The incandescents will be pulling 7.9 and 8.0 amps respectively and will be on a lot (or maybe most) of the time. Will that be a problem?

Thanks.

George Simmons

[LightORamaJohn]

It is not a problem to draw 8 amps through a channel continuously. You should probably put one of the high current channels in the 1-8 group and the other in the 9-16 group to guaranty enough heat sink capacity.

[George Simmons]

Thanks John,

Your response prompts the question: I know the book says 8 amps, but realistically, how much can I push through a channel without a major meltdow of some kind? It would simplify my life considerably if I could squeeze 9 amps through the aforementioned channels.

George

[John Hertig]

I doubt it would ever be recommended that you exceed 8 amps per channel. Why not use 2 channels with 4.5 amps each. Program them the same and it should be pretty much like 1 channel, but with more current capacity (total). Or you could use the channel to switch a relay on/off which would then power your load up to the capacity of the relay, which can be quite large.

There are 2 possible reasons for the '8 A' limit per channel. Either the SCRs would get too hot and fry with more current, or there is some other component in each circuit which would melt if you attempted to get more current out.

In the first case, it is possible that you could add cooling capacity (bigger heat sinks, fans, active cooling systems) but this would not be trivial, and the cost of not doing it right is likely a fried board. In the latter case, it would be even more of an annoyance; you'd have to find all limited components and replace them with higher capacity ones.

[LightORamaDan]

George Simmons wrote:

Thanks John,

Your response prompts the question: I know the book says 8 amps, but realistically, how much can I push through a channel without a major meltdow of some kind? It would simplify my life considerably if I could squeeze 9 amps through the aforementioned channels.

George

As John H. said you should not push the 8A limit. There is a safety margin there and we need to keep that margin to help keep the controller alive. For example there can be as much as a 30% increase in power usage (extream case) when things get real wet or you have loose connections, etc....