A good way to avoid confusion is to convert to convert to watt-hours. I’m assuming when you say 400Ah, you probably have 12V batteries and are adding up the Ah ratings of all the batteries. Like maybe 4 batteries, each 12V and 100Ah. Although there are certainly other common battery voltages like 2V and 6V.
So I look at a typical 12V battery rated 100Ah, multiply them and get 1200 watt-hours. If you have 4 of them, it’s 4800 watt-hours no matter how you hook them up parallel, series, or some combination. That’s how much energy is stored in those batteries when fully charged. So in rough numbers, a 500 watt load will drain a ~5000 watt-hour battery bank in ~10 hours, assuming you are running the loads directly off the batteries, with no conversion loss due to an inverter or DC-DC converter. And as someone pointed out, you need to check what depth of discharge the 100Ah is rated at. If that’s 100% discharged, the battery life is going to be severely degraded. Also likely you may have a low voltage disconnect (LVD) that will disconnect the loads before you get to that point, in order to protect the batteries. From: Bill Prince Sent: Wednesday, December 02, 2015 12:05 PM To: [email protected] Subject: Re: [AFMUG] Calculating battery bank size 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?
