The ePMP sync APs die right at 20 volts FYI. In my case I use the regulator as a LVD - it will continue doing 24v until something like 19 or 20v from the batteries. I'd rather lose some batteries than have the site go down.
Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373 On Wed, Dec 2, 2015 at 3:53 PM, Mathew Howard <[email protected]> wrote: > I don't see that there's really a lot of value in running batteries below > 10.5 volts or so, at that point the voltage is going to be low enough that > a lot of radios aren't going to run anyway (for example, ePMPs will die > just a little under 22v), which means your going to just be wearing out the > batteries for nothing. > > One time I had a Mikrotik router lock up after a power outage - > apparently, when the voltage dropped to low (and all the radios had long > since died), the Mikrotik locked up, but it never actually got low enough > for it to completely shut down, so when the power came back on, it stayed > in it's locked up state until I went out there and unplugged it. it > would've saved me a trip out there if there had been an LVD on the > batteries. > > On Wed, Dec 2, 2015 at 2:12 PM, Ken Hohhof <[email protected]> wrote: > >> I have anywhere from 2 to 8 x 100Ah AGM batteries at a bunch of sites. >> That’s a lot of money. They are not throwaways. It does help somewhat >> that more expensive batteries tend to survive more discharge cycles. >> >> But it seems to me from graphs that once you get down to 11 volts, it >> declines pretty rapidly from there. I could be wrong, but I don’t think >> you’re getting that much extra runtime continuing to drain the batteries >> below let’s say 10.5 volts. >> >> I try to have at least 8 hours of runtime, some sites that are hard to >> get to in winter more like 2-4 days of runtime. The idea is to bring out a >> portable generator before the batteries are dead. If you have mountaintop >> sites, maybe that’s different. >> >> Smaller sites we often see zero customers registered while running on >> batteries because none of them have power or generators. It might make >> sense to have remote per-radio power control, to shut off the APs but keep >> the backhauls running for downstream towers. But if they are licensed >> backhauls, they may consume most of the power anyway. >> >> >> *From:* That One Guy /sarcasm <[email protected]> >> *Sent:* Wednesday, December 02, 2015 1:56 PM >> *To:* [email protected] >> *Subject:* Re: [AFMUG] Calculating battery bank size >> >> so how dead does it make the battery for fully discharge, the rhetoric, >> is run em down, throw them away, is there a rule of thumb for damage? >> >> On Wed, Dec 2, 2015 at 12:49 PM, Bill Prince <[email protected]> wrote: >> >>> He didn't indicate how the 400 ah were configured. Is it one 12V 400 ah >>> battery, or one 24v 400 ah battery, etc. But as you noted, once you convert >>> the battery voltage and amp-hours to watts, it eliminates any confusion. >>> >>> If I had 4800 watt-hours of battery (assuming 12V X 4 at 100 amp-hours), >>> I would estimate 9 hours of run time until the batteries are dead as a >>> doornail. If you want to use them again (and most people do), then cut that >>> time in half. >>> >>> On the other hand, if you have a 48 volt battery with a 400 amp-hour >>> rating, then you actually have 19,200 watt-hours of capacity, and you could >>> multiply the above by 4. >>> >>> If you configure the four 12V/100 ah batteries in series, then you don't >>> have 400 ah, you have 48V/100 ah. The watt-hours are the same. >>> >>> bp >>> <part15sbs{at}gmail{dot}com> >>> >>> >>> On 12/2/2015 10:23 AM, Mathew Howard wrote: >>> >>> watt-hours stay the same - 200x24 and 100x48 both equal 4800 watt hours. >>> In other words, unless you have some horribly inefficient voltage >>> converters in the mix, it makes little difference. >>> >>> On Wed, Dec 2, 2015 at 12:05 PM, Bill Prince <[email protected]> >>> wrote: >>> >>>> wrong. >>>> >>>> bp >>>> <part15sbs{at}gmail{dot}com> >>>> >>>> >>>> On 12/2/2015 10:04 AM, Josh Luthman wrote: >>>> >>>> If you do 4x 12v 100ah batteries and do 24v it's twice the time as 48v >>>> >>>> Josh Luthman >>>> Office: 937-552-2340 >>>> Direct: 937-552-2343 >>>> 1100 Wayne St >>>> Suite 1337 >>>> Troy, OH 45373 >>>> On Dec 2, 2015 1:01 PM, "Bill Prince" <[email protected]> wrote: >>>> >>>>> What voltage? >>>>> >>>>> bp >>>>> <part15sbs{at}gmail{dot}com> >>>>> >>>>> On 12/2/2015 10:00 AM, TJ Trout wrote: >>>>> >>>>>> >>>>>> How long will 500w load last on 400ah? >>>>>> >>>>>> >>>>> >>>> >>> >>> >>> >> >> >> -- >> If you only see yourself as part of the team but you don't see your team >> as part of yourself you have already failed as part of the team. >> > >
