Outage: Car battery
- Thread starter hrdneglcry
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D.WhiteShark
Shoulder Deep in Saltwater.......Again
It woould depend on the size of your pump. If you can provide that, someone may have a better idea. I can tell you that I ran 2 NERO 5s off a battery for a couple days and it probably had a couple days left if I would have let them run.
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Should last a while however this is a loaded question. It’s going to depend on the load that is being drawn from the battery and the battery’s capacity
Not a physicists (so let's hope someone else can double check what I'm doing here), but maybe they didn't teach complete nonsense in school and I remember correctly:
So take the specs of your car battery (e.g. 12V, 70Ah) to calculate how much energy is stored in the battery:
The pump might have a different voltage (e.g. 24V) so you need a step-up converted which isn't 100% efficient. Assuming 85% efficiency should be fine, so the battery will only provide 85% of the 840Wh as actually usable energy:
The runtime is then
Car batteries don't like being drained below a certain percentage repeatedly, so this will probably shorten its lifetime significantly.
I also found some online calculator (but this doesn't consider the step-up converter you might need):
Energy (Wh) = Voltage (V) · Capacity (Ah)
So take the specs of your car battery (e.g. 12V, 70Ah) to calculate how much energy is stored in the battery:
Energy (Wh) = 12V · 70Ah = 840Wh
The pump might have a different voltage (e.g. 24V) so you need a step-up converted which isn't 100% efficient. Assuming 85% efficiency should be fine, so the battery will only provide 85% of the 840Wh as actually usable energy:
Usable Energy (Wh) = Energy (Wh) · Efficiency (%)
In this example:Usable Energy (Wh) ≈ 840Wh · 85% ≈ 714 Wh
The runtime is then
Runtime (h) = Usable Energy (Wh) / Device Power (W)
So for a 25W pump, you get:
714Wh / 25W ≈ 28.5h
Car batteries don't like being drained below a certain percentage repeatedly, so this will probably shorten its lifetime significantly.
I also found some online calculator (but this doesn't consider the step-up converter you might need):
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D.WhiteShark
Shoulder Deep in Saltwater.......Again
If your pump is 24V, you can wire 2-12v batteries in SERIES to get 24v. IMO, this is the most reliable way. If you are tight on space, a couple motorcycle batteries will work nicely and is smaller than a single "car sized" 12v
hrdneglcry
Well-Known Member
Ok. so its a Jebao 12,000 dc. Was wondering if it would be ok to keep a car battery charged for emergency. If it would run 6-8 hours that would be great. If it would do 12-24 awesome.
Jebao DC-12000 goes up to 85W (24V). With the same formula (or calculator) as posted above, you could get around 8.4h to 9.9h at full power, as long as the battery is as good as new.
Malum Argenteum
Well-Known Member
And you are willing to run the battery flat (which is what ah ratings are) -- which is really hard on an SLA battery. Usable capacity even on a good deep cycle battery is about 50% of rated capacity. Standard ah ratings are also made at a 20hr discharge rate; discharging at more than C10 as proposed is likely to noticeably impact the total ah capacity in a battery that's not designed for deep discharge (car batteries are not storage batteries -- they're starting batteries, designed to provide a lot of power for a very short period of time).
A much more sensible solution would be a lithium ion power station -- no need to trickle charge, built in charge controller and inverter, can be fully discharged without issue, and is usable for other purposes. I like the units from Jackery (we have two of them), but there are probably even cheaper options that are decent.
Dom
Theoretical Reef Keeper
I currently have (2) deep cycle marine batteries wired in parallel. I've connected an ATS and a 1000KW inverter along with a charger.
To this backup, I've connected only essential equipment; return pump and power heads. No heaters or lights.
I did a test over the summer. The setup kept the essential equipment running for 12 hours before I stopped the test.
To this backup, I've connected only essential equipment; return pump and power heads. No heaters or lights.
I did a test over the summer. The setup kept the essential equipment running for 12 hours before I stopped the test.
Small portable power devices like a jackery or bluetti are great backups. I use twin 100ah lifepo4 batteries with solar backup and grid charge. Last long time....can be viewed in my Tank thread
For battery backup go with a lifpo4 battery . Last along time a lot better then a yellow top .
True and you can run them down mostly to zero unlike over and over with no damage , while regular batteries will be damaged if used lower than 50%
I built a custom 140 ah that can do over a constant 1000amps draw . That and a good inverter you can power a lot of things on your tank .
I use mine for my tank my pc and small refrigerator and low voltage lights if a power outage. No need to be home it kicks in i milliseconds back and forth....
What transfer switch are you using . I am looking for one
Its a small solar setup. It's built into my solar all in one charge controller/invertor...its on my tank thread the photo. Doesnt handle more then 1000 watts if i remember correctly but i dont need it to. My bluettis do the same thing more compact. Leave plugged in to grid and auot switches fast as well. I use those for back up around the home. I have generator too but only use it if home and longer term or to run whole home. Its the last post at bottom. Solar MPP all in one with twin lifepo4 batteries
here a link https://www.reef2reef.com/threads/my-40-gallon-breeder-mixed-reef.1138537/
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BristleWormHater
5000 Club Member
Awhile
as long as you have dc to ac convertor or a low volt step down to 12 volt if your running low voltage things. Warning::::: But definitely do your research or ask a professional so you dont get hurt or worse.
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