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 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.
