Help understanding how long a battery will last.

[USMA36]

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?

 

[Mperry622]

I took a 1500 APC smart-ups and wired for deep cycle marine batteries in parallel. I wired my Apex for power monitoring so it knows when the power goes out and will only power certain outlets the heaters are a no-go but everything else can run. Last time power went out I got at least 11 and a half hours. The default batteries that come in them are garbage and you might get 45 minutes.. looking to some deep cycle batteries and hook up a battery Bank. I also complimented mine with a solar array so it keeps it charged but make sure you get a good controler.

 

[Mperry622]

I took a 1500 APC smart-ups and wired for deep cycle marine batteries in parallel. I wired my Apex for power monitoring so it knows when the power goes out and will only power certain outlets the heaters are a no-go but everything else can run. Last time power went out I got at least 11 and a half hours. The default batteries that come in them are garbage and you might get 45 minutes.. looking to some deep cycle batteries and hook up a battery Bank. I also complimented mine with a solar array so it keeps it charged but make sure you get a good controler.

I don't believe the inverter can handle 24 volts so that is definitely out of the question.. increase the capacity by adding more batteries and putting them in parallel

 

[USMA36]

I don't believe the inverter can handle 24 volts so that is definitely out of the question.. increase the capacity by adding more batteries and putting them in paralle

They make 24 and 48 volt inverters. I was curious as to what I’d gain over 12v if anything. I want to run a heater as well off of the system not just the pumps. It only has to run 6 hours. I don’t need it more than that because I’ll have the generator up and running by then. My tank is in my basement and even in the summer it’s pretty cool in the house. The problem I’m having is figuring out run time. Each battery calculator I use gives me a different answer.

 

[Mperry622]

They make 24 and 48 volt inverters. I was curious as to what I’d gain over 12v if anything. I want to run a heater as well off of the system not just the pumps. It only has to run 6 hours. I don’t need it more than that because I’ll have the generator up and running by then. My tank is in my basement and even in the summer it’s pretty cool in the house. The problem I’m having is figuring out run time. Each battery calculator I use gives me a different answer.

My only comment was on using an old APC backup that is only built to handle 12 volts I know the bigger ones have different battery styles but I'm just dealing with what I DIY.

 

[Bret]

Best way to figure this out is to convert everything to watt hours. For your battery, take the nominal voltage (~12.6 for lead acid, 12.8 for LiFePo4) and multiply by the amp hours (100 in your case), giving you watt hours. So 1260 watt hours, cut in half for usable capacity of lead acid gives you 630 watt hours of usable energy. You could supply 630 watts for up to one hour, or 315 watts for 2 hours, etc. add up the wattage of all the equipment you need to run, and make sure you account for the inverter losses. Wiring at 24 volts will reduce the wire size required to hook things up, but will require a 24 volt inverter (which are also typically more efficient).

 

[Saltyreef]

My only comment was on using an old APC backup that is only built to handle 12 volts I know the bigger ones have different battery styles but I'm just dealing with what I DIY.

Don't APC 1500 smart UPS's come with 2 batteries and run in series @ 24v for the inverter?

 

[Mperry622]

Yeah they're all wrapped together with plastic but my marine batteries wouldn't fit in the case LOL

 

[Mperry622]

Yeah they're all wrapped together with plastic but my marine batteries wouldn't fit in the case LOL

That may be the case but when I tested it with my voltmeter I was only pulling a hair under 13 volts with a new battery. I'm pretty sure the batteries are wired in parallel not series. But this is an APC 1500 smart UPS

 

[Saltyreef]

That may be the case but when I tested it with my voltmeter I was only pulling a hair under 13 volts with a new battery. I'm pretty sure the batteries are wired in parallel not series. But this is an APC 1500 smart UPS

One 12v battery would show over 13v when fully charged and good.
APC backups that utilize 2 12v batteries are wired in series @24v and use a 24v to 120v inverter The charger won't like much of anything else besides SLAs rated for the unit.

 

[Mperry622]

One 12v battery would show over 13v when fully charged and good.
APC backups that utilize 2 12v batteries are wired in series. The charger won't like much of anything else besides SLAs rated for the unit.

Interesting and not sure what you're trying to say. I guess I don't have it hooked up... Appreciate your two cents but my MacGyver engineering worked just fine. I also never said the batteries and it were bad I was just giving my two cents on my DIY power generator for hours of power outage enjoyment...

 

[Saltyreef]

Interesting and not sure what you're trying to say. I guess I don't have it hooked up... Appreciate your two cents but my MacGyver engineering worked just fine. I also never said the batteries and it were bad I was just giving my two cents on my DIY power generator for hours of power outage enjoyment..

Im just wondering how you were able to get a 24v APC inverter to work on 12v marine batteries wired in parallel @ 12v.

 

[BeanAnimal]

Folks - you better know what you are doing when parallel and series combinations of high current/capacity batteries are built. A bad cell in part of the chain can be disastrous (fire or explosion). Fusing and circuit breakers in the chain are important. DC arcs do not self extinguish so fuses must have much larger gaps, etc.

And yes, there is a lot of difference between Wet, SLA and AGM and what the charging/maintenance circuit sees.

 

[Spicy Reef]

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?

You want something like this plug and play no brainer. Power goes out, backup kicks in no fancy wiring you do not have to be home or rely on some other system to switch the power for you...

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

watts247.com

pair it up with something like this...

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

The advantage of higher battery voltage as far as efficiency is minimal, it's there but minimal. The biggest advantage is being able to pair your bats with inverter.

 

[Saltyreef]

You want something like this plug and play no brainer. Power goes out, backup kicks in no fancy wiring you do not have to be home or rely on some other system to switch the power for you...

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

watts247.com

pair it up with something like this...

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

The advantage of higher battery voltage as far as efficiency is minimal, it's there but minimal. The biggest advantage is being able to pair your bats with inverter.

Thats some serious coin!

 

[Spicy Reef]

Oh, sorry, ur original question...
100Ah / 7 amps = 14.28 hours
If a battery is rated 100Ah That's what it should give you, not 50% of that.
SLAB's just don't last that long before they die, and they can die faster just sitting there not being used. the lead falls off the plate pooling at the bottom creating a short is the usual cause...

 

[Spicy Reef]

Thats some serious coin!

It is.
You can get less expensive lithium batteries that will still far outperform SLABs but this back up system would still be less than everything you intend to plug into it

 

[Saltyreef]

It is.
You can get less expensive lithium batteries that will still far outperform SLABs but this back up system would still be less than everything you intend to plug into it

I would be interested in backing up my aqariums this way but with solar installed on my home too lol.

 

[Spicy Reef]

Oh, sorry, ur original question...
100Ah / 7 amps = 14.28 hours
If a battery is rated 100Ah That's what it should give you, not 50% of that.
SLAB's just don't last that long before they die, and they can die faster just sitting there not being used. the lead falls off the plate pooling at the bottom creating a short is the usual cause...

My bad.....
you also have to add the draw of the inverter you end up using into the equation as well. Figure .85 amp draw...

All this is voodoo science until you plug it all in and do the test. I'm sure your heaters won't draw full power 100% of the time... and your pump could be drawing more or less depending on how clean it is and how high and how thick your pipes are...
there are cheap little $12 energy monitoring plugs you can use w/ a smart phone to get a graph of real usage...

https://a.co/d/8y9Urte

 

[BeanAnimal]

The advantage of higher battery voltage as far as efficiency is minimal, it's there but minimal. The biggest advantage is being able to pair your bats with inverter.

No - more voltage means less supply current and a safer stack. Of course to an extent…. Once you get over 96V fusing starts to become an issue. Then we see series parallel setups amd things get complicated with stack safety.

Losses at lower voltage stacks are significant actually due to step-up losses in many topologies…

However, the biggest losses are over sizing output capacity. If you have a 400 VA load you don’t need a 1500 VA inverter. You are losing efficiency in most cases.