Nate Duehr wrote: > Careful.. > > 1) You should never let a lead-acid battery go "completely down", not even a > so-called "deep-cycle" one, if you want it to last a long time. Look at the > manufacturer's specs and build a voltage-based cut-off switch that will shut > down the output before they go below the manufacturer's recommended > discharge voltage. You could get fancy and include some kind of over-ride > for a "real" emergency, but at that point you really should have a generator > and someone to fuel it. > That's what I am trying to avoid. I am once again violating my personal rule to not get involved with a club owned repeater. There are always way too many "experts" and it usually gets to me when they are at the frustration point. > 2) Direct charging of even that big of a bank with a 50A charger could be > above the manufacturer's upper limits on charge rate, and you'll likely boil > off water, reducing the life of the batteries, venting gas, and generally > wearing out the system. You need to limit the charge rate to their > recommendations, if you want the batteries to survive a long time. (Number > 1 should help with this. Maybe the 5A charger will be fine, if you do #1. > It won't take 80 hours then...) > You're right.
> Most of the time, the better option is a generator. Yes, the repeater > system goes down while it takes over, but you can run for a very long time > for a lot less headache than a battery system. You could design the battery > system just to hold-over the system during generator cut-in, but even that's > overly complex. Most generators take less than a minute to start and decide > that their output is sane enough to switch in the load... > You're looking at the same thing that I have already considered. At this point, they don't know what they want to do. I'm just looking for possible solutions to present to their committee.. > Are they designing for long-term outages or smoothing out short-term ones? > That's the main design question to ask... Well, they just went about 10 days with intermittent power because of the huge ice/snow storm that blew through the mid eastern US. So they're fresh from the "gotta last forever" mentality.. Doesn't matter that it sits 90% of the time unused, they want it to be there whenever... Current plans are for a Saturday morning breakfast and subsequent trip to the repeater site. I've never been there, so it will be interesting to see what they've done up to this point. thanks for the input. Mike KA4MKG
