24v DC pump battery back up

[Stonec4435]

So if you run DC pumps that are 24v why can’t you just use 12v battery’s hooked in series Parallel with a battery charger charging the batteries. In theory the pumps would run until the batteries were dead. You could even put some kind of cut out if the battery voltage dropped below 24v. What are the problems with this.

 

[Reefing Madness]

 

[BZOFIQ]

So if you run DC pumps that are 24v why can’t you just use 12v battery’s hooked in series Parallel with a battery charger charging the batteries. In theory the pumps would run until the batteries were dead. You could even put some kind of cut out if the battery voltage dropped below 24v. What are the problems with this.

With a proper relay one can build what you're describing - it's a actually so simple I'm surprised every manufacturer isnt offering their flavor.

 

[DancingWind]

So if you run DC pumps that are 24v why can’t you just use 12v battery’s hooked in series Parallel with a battery charger charging the batteries. In theory the pumps would run until the batteries were dead. You could even put some kind of cut out if the battery voltage dropped below 24v. What are the problems with this.

I build one for myself.
2 12V deep discharge ups batteries in series.
1 Meanwell AD-155B - 24V 155W psu with battery backup functionality (there are lower power options)
1 Voltage regulator: Meanwell does not have a proper charger integrated. It outputs to battery the same V as the primary output - so I set psu output to 24V and use voltage regulator to boost it to 26.6V - works like a charm.

Problems: if psu is off - simply connecting a battery to it will not turn it on.
I would recommend a completely DIY solution with a relay and maybe a proper battery charger and discharge protector

 

[Gareth elliott]

Simplest solution pick one of the three pump brands that have backup solution.

Ecotech
Tunze
Icecap

Current told me they were eventually making one. But that was 1.5 years ago, and nothing else they said was in the pipeline came out yet either lol.

Short of that the inverter above or some sort of generator are your only options sadly.

 

[DancingWind]

Simplest solution pick one of the three pump brands that have backup solution.

Ecotech
Tunze
Icecap

Current told me they were eventually making one. But that was 1.5 years ago, and nothing else they said was in the pipeline came out yet either lol.

Short of that the inverter above or some sort of generator are your only options sadly.

DC pumps have no need for inverter. It's a moderate waste of money and space, and huge waste of power.
A DC relay can very easily done by yourself.
And Tunze is selling not a battery but a 59.99eur relay with a nice jack ... parts are like 5eurs

 

[DancingWind]

So if you run DC pumps that are 24v why can’t you just use 12v battery’s hooked in series Parallel with a battery charger charging the batteries. In theory the pumps would run until the batteries were dead. You could even put some kind of cut out if the battery voltage dropped below 24v. What are the problems with this.

Here is a schematic/demo: link

 

[DancingWind]

Oh and another thing: there is no reason for the battery/relay/psu setup to be next to the tank - if you use fatter wires you can place it in the next room

 

[BZOFIQ]

I'm going one step further

Here is a schematic/demo: link

I'm going one step further with DPDT relay which would also provide 3.7V (18650) control voltage slowing the pump to 37% or even use AA with 1.5V, running the pump at 15% basically "forever" on a set of automotive sized batteries.

 

[BZOFIQ]

Oh and another thing: there is no reason for the battery/relay/psu setup to be next to the tank - if you use fatter wires you can place it in the next room

doing that too.

 

[DancingWind]

American Wire Gauge Chart and AWG Electrical Current Load Limits table with ampacities, wire sizes, skin depth frequencies and wire breaking strength

AWG Wire size chart and ampacity table for design engineers including skin depth frequencies and tensile strength data; electrical cable size

www.powerstream.com

doing that too.

Scratch that - here is better source for wires and power: https://www.powerstream.com/Wire_Size.htm
Check the voltage drop at then end wire. PSUs like meanwell have dc V output adjustment pots - use that to compensate for the drop or get fatter wire.

 

[Stonec4435]

So upon further research my idea of a battery cut out is not necessary. The only problem I have now is finding an affordable battery charger option. 24v battery tenders apparently are not cheap. Also looking into it the manufacturers that have battery backups on the market don’t have that big of batteries in them. On average I think they are about 7-12 Ah batteries in the units. I have some 100Ah batteries laying around and planning on using those. It’s probably a little over kill but hey why not. Another thing I don’t think eco tech when on battery runs the full 24v I think the pumps only run 12v which is why they go down to something like 30% power. Someone with those battery backups could chime in and give a little insight. If that is the case then is there anyone out there with a Jeabo that runs a battery back? If so do they run at 50% or less on 12v?

 

[DancingWind]

So upon further research my idea of a battery cut out is not necessary. The only problem I have now is finding an affordable battery charger option. 24v battery tenders apparently are not cheap. Also looking into it the manufacturers that have battery backups on the market don’t have that big of batteries in them. On average I think they are about 7-12 Ah batteries in the units. I have some 100Ah batteries laying around and planning on using those. It’s probably a little over kill but hey why not. Another thing I don’t think eco tech when on battery runs the full 24v I think the pumps only run 12v which is why they go down to something like 30% power. Someone with those battery backups could chime in and give a little insight. If that is the case then is there anyone out there with a Jeabo that runs a battery back? If so do they run at 50% or less on 12v?

Ecotech since it takes 12V on battery input naturally max out on 50% - but also in battery mode they also reduce power further (i'm not sure but I think its adjustable)
I run a jebao SCP-120 (gyre 45V on meanwell battery protected psu) on 2 10Ah 12V battries - works great.
I'm pretty sure you can connect a battery tender to each battery individually if 24V is expensive

 

[Stonec4435]

Ecotech since it takes 12V on battery input naturally max out on 50% - but also in battery mode they also reduce power further (i'm not sure but I think its adjustable)
I run a jebao SCP-120 (gyre 45V on meanwell battery protected psu) on 2 10Ah 12V battries - works great.
I'm pretty sure you can connect a battery tender to each battery individually if 24V is expensive

So do you run the batteries in series or parallel.

 

[DancingWind]

So do you run the batteries in series or parallel.

In - series almost all but the smallest pums these days are 24V or more. high V keeps the Amperage and thus power loss low