Recent content by zaps

I think you're saying you have two of these 6V batteries in series: http://nppbatteries.com/static/NPD6-180Ah.pdf But, you haven't told us much about the charger or your testing capabilities. Could you tell us the make and model of the charger, or measure its open circuit voltage, or provide...

@tictag The way that ideal wires have always been getting around the problem of having inductance is that they don't actually exist, except perhaps as lines on schematics. The infinite capacitor current was first explained to me via an old Jedi math trick. Here's how it goes: For any capacitor...

You aren't by any chance talking about the Somnetics Transcend Auto CPAP?

@smoothJoey The DC Bus to Battery Interface (DBBI) was just conceived; it hasn't been implemented for LiFePO4 yet. Maybe there's something that does the job of the DBBI for LiFePO4 that someone reading this thread can make us aware of. Otherwise, it may become a DIY project. For the DIY...

The theory behind the high current is that if you hooked up an ideal capacitor, an ideal switch, and an ideal battery in series using ideal wires, and then flipped the switch to charge the capacitor, the capacitor would become fully charged to the battery voltage in an instant, using infinite...

@sremick: For the bypass switch, I haven't decided on a particular product, but I was thinking along the lines of a manual toggle switch. @gnubie, @smoothJoey: Thanks for your comments. While pondering the problem I had a "Eureka!" moment. Here's a new block diagram that shows an improved...

I've been thinking about making an online UPS with a LiFePo4 battery. "Online" means the load is running on the inverter even when mains power is available. To show the general idea, there's a diagram of one below based on a lead-acid battery. The 120VAC mains power on the left drives the...

Gnubie, you touched on something I couldn't quite figure out -- how to make an online UPS using a LiFePo4 battery. To avoid hijacking this thread, I'll open another for that.

My understanding of the collective wisdom of the net is that LiFePo4 batteries don't need or want a float voltage, and that a float voltage of 13.8 V is high enough to be detrimental. The instruction manual for the charger says on the second page, in all caps: "FOR CHARGING 12 VOLT LEAD ACID...

Congratulations, that's a great story. (y) I couldn't tell you what caused the problem, but my guess is that there's a reason those cells were so cheap, and they appear to have no markings on them. Anyway, I think the "current" problem is due to your cells having mismatched capacities in amp...

From https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/, about premature LiFePo4 battery aging:

I'm not familiar with LFO (Lithium Iron Oxide) batteries. Did you perhaps mean Lithium Iron Phosphate (LiFePo4 / LFP)?

I was thinking of a third way to go off grid... with a hurricane!

About that peak AC load, if everything listed in the table were on at once and only drew the watts shown, that totals only 2491 watts. At 120 VAC in the Bahamas, that's 20.76 amps.

If you wanted your battery bank to use 48V, I think using 8 of the 1000 Ah batteries in a 4S2P configuration, or 40 of the 200 Ah batteries in a 4S10P configuration, might work. But, I'm new at this, and as nosys70 implied, such a battery bank would need hundreds of amps from a solar charger to...