Help understanding how long a battery will last.

[BeanAnimal]

The first part was incorrect also. (2) 12v 100ah in parallel would be 12v@ 200ah. You had the concept perfectly backwards, a obvious accident.

Correct also.

I often build posts like that in blocks... sometimes changing the math example as I go, lots of cut and pasting because I despise typing on an iPad. I go back and delete what I don't need or like for the final post.

I did all the of the math and didn't like the layout or wording so swapped stuff around and cut and pasted a few times. I think I started with 200Ah batteries... who knows. Somewhere in there got the two lines intermingled as well as what I started with and ended with. The math was done, the examples to use for the math mangled.

I tried to go back and edit a few mins ago and fixed the second line, clicked save and then tried to edit first line as well and it was too late.

Ohh will - typos memorialized forever
Embarrassing given that I was attempting to offer an illustrative solution.

(2) 12V 50Ah batteries in parallel provide 100Ah at 12 volts.
(2) 12V 50Ah batteries in series provide 50Ah at 24 volts.

 

[Reefering1]

Correct also.

I often build posts like that in blocks... sometimes changing the math example as I go, lots of cut and pasting because I despise typing on an iPad. I go back and delete what I don't need or like for the final post.

I did all the of the math and didn't like the layout or wording so swapped stuff around and cut and pasted a few times. I think I started with 200Ah batteries... who knows. Somewhere in there got the two lines intermingled as well as what I started with and ended with. The math was done, the examples to use for the math mangled.

I tried to go back and edit a few mins ago and fixed the second line, clicked save and then tried to edit first line as well and it was too late.

Ohh will - typos memorialized forever
Embarrassing given that I was attempting to offer an illustrative solution.

(2) 12V 50Ah batteries in parallel provide 100Ah at 12 volts.
(2) 12V 50Ah batteries in series provide 50Ah at 24 volts.

Sorry, it wasn't until I posted then re read yours that I realized your math was correct, just mixed up those 2 lines. Point is, op will get more then 6 hours with (2) 12v 100ah batteries, @700w, regardless of how its wired

 

[Sleepydoc]

Because I during outages I lose about 2° per hour.

In general, fish and corals handle drops in temperature far better than increases in temps. I had a thermometer failure that caused my tank to drop to 68º for a week before I recognized it. It didn’t seem to affect the inhabitants at all.

Heaters are large consumers of power; one strategy would be to only use half of the heaters. That would slow the temperature drop but reduce the power draw.

 

[SteveMM62Reef]

Little note on Running Batteries Series/Parallel, this is from Serving Computer Room Generator Start Batteries. 24 Vdc Parallel Batteries had a decoupler for charging, and maintaining a charge. If the Batteries are not the same age, temperature and same electrolyte levels, one could “eat” the other one. On series batteries, 24 Vdc gets hazardous, 36 Vdc is dangerous, 48 Vdc can burn you all the way through your hand. BTW, I’ve also worked on UPS, 480 Vdc Battery systems, one wrong move and you are toast. Decoupling, Ground Busses and PPT/Arc Flash protection were a must.

 

[USMA36]

In general, fish and corals handle drops in temperature far better than increases in temps. I had a thermometer failure that caused my tank to drop to 68º for a week before I recognized it. It didn’t seem to affect the inhabitants at all.

Heaters are large consumers of power; one strategy would be to only use half of the heaters. That would slow the temperature drop but reduce the power draw.

I understand that heaters use a lot of energy, but if its possible to build a battery backup system that gives me 4-6 hours and is cheaper than a whole home standby generator, that's what I am going to do. People spend thousands and thousands of dollars on livestock and reef equipment, but skimp on backup solutions. Not worth the risk to me. Running a smaller heater may work, Ill have to see how much a difference it makes over the full power heater. I run a 600 watt main heater and a 300 backup. It would save me 300 watts which may not be that much considering it would always be on as opposed to the full 600 watt heater only coming on as needed and not always at full power.

 

[USMA36]

Little note on Running Batteries Series/Parallel, this is from Serving Computer Room Generator Start Batteries. 24 Vdc Parallel Batteries had a decoupler for charging, and maintaining a charge. If the Batteries are not the same age, temperature and same electrolyte levels, one could “eat” the other one. On series batteries, 24 Vdc gets hazardous, 36 Vdc is dangerous, 48 Vdc can burn you all the way through your hand. BTW, I’ve also worked on UPS, 480 Vdc Battery systems, one wrong move and you are toast. Decoupling, Ground Busses and PPT/Arc Flash protection were a must.

If I can avoid running series and parallel, I will. The battery linked back on page 1 (linked again below) is a 24 volt 200ah battery in a sealed case. Again, I am no electrician, but that seems like a safer/easier bet. The total cost with the inverter and battery is 2k, not terrible considering how much of an investment it's going to protect.

EG4 LifePower4 Lithium Battery | 24V 200AH | Server Rack Battery

EG4 Lithium battery 25.6V (24V) 5.12kWh with 200AH internal BMS. Made of UL Listed Battery Cells. Off Grid Solar Batteries - Off Grid System - Solar Batteries for Home - Lithium Solar Batteries - Deep Cycle Solar Batteries - Power Reserve - Solar Panels Plus Battery - LifePo4 - LifePower4 - Life...

signaturesolar.com

PIP 2724LV-MR 24V 2.7kW 120V Inverter, 750W Solar Input, Easy DIY, No 120V Wiring! – Watts247 Wholesale

watts247.com

 

[SteveMM62Reef]

From Memory, it seems like Bass Pro Shops had a 24 volt Deep Cycle Battery, and I imagine the Charge/ Maintainer. It would have been for a Trolling Motor.

 

[Sleepydoc]

I understand that heaters use a lot of energy, but if its possible to build a battery backup system that gives me 4-6 hours and is cheaper than a whole home standby generator, that's what I am going to do. People spend thousands and thousands of dollars on livestock and reef equipment, but skimp on backup solutions. Not worth the risk to me. Running a smaller heater may work, Ill have to see how much a difference it makes over the full power heater. I run a 600 watt main heater and a 300 backup. It would save me 300 watts which may not be that much considering it would always be on as opposed to the full 600 watt heater only coming on as needed and not always at full power.

If you're using that logic you should just get a whole house generator with a transfer switch. It's all a matter of degrees (pun intended.)

How often do you lose power and for how long? What's the weather like when you do and how fast does your tank drop? Is it a concern for other inhabitants of your house? Are you home when it happens? There are a lot of variables but for areas that experience frequent or prolonged outages either a whole house or a stand alone generator may make more sense.

 

[The Rasta Reefer]

I’m considering building a stronger battery backup system. My plan is to hook an Apex EB832 up to a 1500 watt pure sine wave inverter along with a transfer switch and a 100ah battery. The EB832 currently runs my Vectra L2 at 65%, 3 MP40s at 80% reefcrest, 1 600 watt heater, 2 Radion G4 pros and my ato. Max power consumption is never more than 785 watts and 7 amps. When the power goes out I would have apex shut down the lights but keep everything else running including the heater. How long will that 100ah sealed lead acid battery last? I understand the useable load of that battery is only 50%. If need be I would build the system with 2 batteries to get a full 100ah of power. I’d like to get 4-6 hours which is enough time for me to get a generator hooked up. What advantages if any would wiring the two batteries as 24v offer over 12v?

My general approach to sizing battery backups is to ensure that the unit covers 150% of the average power outage down time in the city which for me is 90 minutes. However the main purpose of a pure sine wave UPS to me is to provide constant protection for the sensitive electronics that can be seriously and suddenly damaged due to brown outs and surges which we often don't see.... Here is my emergency setup an a nano reef tank: