DIY battery backup

[Ratherbeflyen]

clarification. Because we use the DC power Supply when electricity is working, what’s the use of the 110V? Is there a relay that I can use for switching between battery operation and DC power outlet operation?

When the 110v line is plugged in and energized, it moves the relay switch to use the electricity from the grid. When the grid goes down or break trips etc, the 110v line will be de-energized and automatically switch the relay to using the batteries.

They do make DC only relays and you certainly can use one. You would just have to splice the wires running from a DC power source that you want to automatically switch to the battery backup. I just used the 110v version because it was easier for me to wire it into my 110v power strip than a DC source.

 

[Nurse.Reef.Reapeat]

When the 110v line is plugged in and energized, it moves the relay switch to use the electricity from the grid. When the grid goes down or break trips etc, the 110v line will be de-energized and automatically switch the relay to using the batteries.

They do make DC only relays and you certainly can use one. You would just have to splice the wires running from a DC power source that you want to automatically switch to the battery backup. I just used the 110v version because it was easier for me to wire it into my 110v power strip than a DC source.

Have you thought about using this?


so we only need the battery wire, DC wire from power supply and DC wire to the pumps?

 

[DaddyFish]

Have you thought about using this?


so we only need the battery wire, DC wire from power supply and DC wire to the pumps?

That is a most excellent find. Stay away from the 110 VAC wiring and stick to the 24 DC side.

 

[Ratherbeflyen]

I don't see the link, it just says amazon.

 

[DaddyFish]

This is a complex electrical problem to explain via web posts.
What I'm proposing is forget about monitoring the 120 VAC power coming in from your household receptacles. Instead, setup the two batteries, two chargers and some wiring so that THEY are your constant source for 24 VDC power. When the household 120 VAC power dies the chargers will cease to function and the batteries will begin to discharge. If your power remains off for more than the 24-hours capacity of the batteries, your pumps go dead. If the household 120 VAC power is restored before the batteries totally discharge, then the two 12v chargers will immediately begin recharging the batteries and automatically shutdown to a trickle charge once complete.
No relays, no potentially lethal and exposed 120 VAC wiring, nothing gets disturbed but 24 VDC circuitry.

 

[wcharon]

This is a complex electrical problem to explain via web posts.
What I'm proposing is forget about monitoring the 120 VAC power coming in from your household receptacles. Instead, setup the two batteries, two chargers and some wiring so that THEY are your constant source for 24 VDC power. When the household 120 VAC power dies the chargers will cease to function and the batteries will begin to discharge. If your power remains off for more than the 24-hours capacity of the batteries, your pumps go dead. If the household 120 VAC power is restored before the batteries totally discharge, then the two 12v chargers will immediately being recharging the batteries and automatically shutdown to a trickle charge once complete.
No relays, no potentially lethal and exposed 120 VAC wiring, nothing gets disturbed but 24 VDC circuitry.

Waooo this looks interesting.

@DaddyFish can i PM you later to see if ypou can help me out?

Thanks in advance...

 

[Ratherbeflyen]

This is a complex electrical problem to explain via web posts.
What I'm proposing is forget about monitoring the 120 VAC power coming in from your household receptacles. Instead, setup the two batteries, two chargers and some wiring so that THEY are your constant source for 24 VDC power. When the household 120 VAC power dies the chargers will cease to function and the batteries will begin to discharge. If your power remains off for more than the 24-hours capacity of the batteries, your pumps go dead. If the household 120 VAC power is restored before the batteries totally discharge, then the two 12v chargers will immediately being recharging the batteries and automatically shutdown to a trickle charge once complete.
No relays, no potentially lethal and exposed 120 VAC wiring, nothing gets disturbed but 24 VDC circuitry.

I think that could work. You would have to use a battery charger/tender that produced more amps than your pumps used. The battery tender I bought for ~$5 is around 10 watts and would not keep up with pumps much less charge the batteries. Harbor freight does sell a 4 amp (48 watt) smart charger, but it's cheaper to buy the relay and $5 battery tender. It may be worth doing if you didn't have the outlet space or something similar. I doubt it would be cheaper though.

 

[Clownfishy]

Ratherbeflyen,
What would your advice be for those of us that want to run a heater for long periods of time? Is it just too energy intensive to consider? I live in the UK and in the winter, I need to run a heater if I lose mains power. I already have my Tunze pumps linked to a battery that will run for days. I have a 100w heater attached to this UPS -

No idea how long it would run the heater for but is there a better way of keeping a heater on battery backup?

Many thanks for any help

 

[Clownfishy]

Cool! I built one to power mt 500watt heater and return pump for 10hours i thought i was the only one doing this type thing.
I also live in the mountains and am prone to loose power for a few days in the winter. Heres my battery wall

Can you explain your battery setup

 

[Ratherbeflyen]

Ratherbeflyen,
What would your advice be for those of us that want to run a heater for long periods of time? Is it just too energy intensive to consider? I live in the UK and in the winter, I need to run a heater if I lose mains power. I already have my Tunze pumps linked to a battery that will run for days. I have a 100w heater attached to this UPS -

No idea how long it would run the heater for but is there a better way of keeping a heater on battery backup?

Many thanks for any help

You need a really large battery or group of batteries to be able to run a heater for any meaningful period of time. It can be done, it's just usually a lot more cost effective to have a generator.

If you do the math on a 100 watt heater, running on 12 volts, it uses 100w/12v = 8.33 amps per hour. My 14 amp hour battery backup would only run the heater for a little over an hour if there was nothing else running on the batteries. If you take into account the power loss by a DC to AC inverter, and you can only deplete lead acid batteries to ~50% of its charge state before the batteries are damaged, you really only have ~30-45 minutes of run time for a 100 watt heater.

Even if you step up to a 80 Amp hour battery, you would get 8 to 10 hours of heater run time. Even less if you don't deplete the battery below 50% charge. Then what do you do if your power is still out? Usually for the cost of a battery that size, or larger, you can get a small generator that will run your heater for as long as you need or have the gas to put in the generator.

I went ~24 hours without power in the Texas freeze back in February. I ran 2 x 300 watt heaters and the return pump for the duration of power outage on a 1200 watt generator. My tank survived with no losses even though my house got below 50f inside, the tank stayed within a couple degrees of normal. If I was to try and make a battery backup for the heaters instead of the generator, 600 watts x 24 hours / 12 volts = 1200 amp hours, or 1.2 Kilowatts. Go price a 1.2 kilowatt battery system, and you'll probably conclude a small portable generator is a better investment. A generator also gives you the option to run a few other appliances in a power loss, like your refrigerator or freezer.

How big of a generator do you need for your tank?

I live in Houston where the overnight low was 13 degrees fahrenheit. This city is unprepared for weather that cold and is having rolling blackouts. We lost power about 15 hours ago and I have been running my generator ever since. My tank is a 220 gallon display tank with a 75 gallon sump. A few...

www.reef2reef.com

 

[DavidLu]

Get involved.
Now there is a relay, solid-state (ssr)
The contact of this relay has no spark, no sound and can be contacted for a long time.
(Because of the traditional contact relay. It has been used for a long time. The contact point will be dirty. It is dangerous)

 

[AdamD76]

Get involved.
Now there is a relay, solid-state (ssr)
The contact of this relay has no spark, no sound and can be contacted for a long time.
(Because of the traditional contact relay. It has been used for a long time. The contact point will be dirty. It is dangerous)

Do you have a link to one that would work?

 

[DavidLu]

 

[dmsc2fs]

I use an old computer battery back up unit. I just open it up throw away the battery and add wire and clips and use a deep cycle boat battery hooked up to the backup unit I can keep my dc return punp and skimmer going for about 8-10 hours. When the power goes out it automatically comes on. Also you can get the unit really cheap at like good will or something as people get rid of them when the batteries go bad...

I think that could work. You would have to use a battery charger/tender that produced more amps than your pumps used. The battery tender I bought for ~$5 is around 10 watts and would not keep up with pumps much less charge the batteries. Harbor freight does sell a 4 amp (48 watt) smart charger, but it's cheaper to buy the relay and $5 battery tender. It may be worth doing if you didn't have the outlet space or something similar. I doubt it would be cheaper though.

I have thought about going this route. If I do figure out where I can stash some batteries I will set this up the same way I did my camper. In my camper I did all the electrical (Except the trailer towing) on 12v. The trick is you need to have a smart battery charger that is designed to perform as we are discussing here. It will take in 110V and when it does it will power the 12v devices and condition and charge the batteries. When it is not on 110v it will power the devices from the batteries. It will switch between both states of operation without any hassle.

When I did my research this is the best option I found and I used it for a number of years without fail. You would simply need to size your battery bank and device for the amount of amps you wish to use. Or, do the same thing on 24v instead of 12v if that is the goal.

You can make a DIY option with relay's or even a UPS. Both options discussed are good successful ideas. The proper tool for this job will prolong the batteries for the longest life possible. Batteries aren't cheap. Think of it as the difference between building a sump with a glass tank and gluing in all the dividers yourself or buying a pre made sump. Both get you to your goal. One is easier on the pocketbook, one is easier on the back, toolbox and man hours.

Good luck!

https://www.batterystuff.com/battery-chargers/brands/iota/

Here is a 24v example
https://www.batterystuff.com/power-...ger-converter-power-supply-dls-27-15-iq4.html