DIY question on a battery backup.

[Taxus812]

I have been looking at the icecap battery backup and have seriously been thinking of making my own with a little larger battery (I probably don't need more than 12hrs since I have generator but you never know).

One question I have is how do they keep the pumps normal power supply from back feeding the battery backup unit and overcharging the battery? Do they have a diode between connection to the pumps power supply (A) and the battery backup unit (B1) ?

 

[Kristophf]

Im currently looking into making my own with a 12v deep cycle battery. I have a maxspect turbine and i assume i just need to connect it to the 2 way adapter

 

[laverda]

I have been looking at the icecap battery backup and have seriously been thinking of making my own with a little larger battery (I probably don't need more than 12hrs since I have generator but you never know).

One question I have is how do they keep the pumps normal power supply from back feeding the battery backup unit and overcharging the battery? Do they have a diode between connection to the pumps power supply (A) and the battery backup unit (B1) ?

I don't know how IceCap does it but a relay would be better, although a diode would work.

 

[laverda]

You need to charge the battery somehow. I just modified an inexpensive UPS to power 12 volt items directly. It was free, I just had to buy a new battery for it and less than $15 in parts. I plan to also modify a larger 1500 UPS to run some 24 volt items directly. I use the Tunze Safety switch to do the actual switching.

 

[Taxus812]

I don't know how IceCap does it but a relay would be better, although a diode would work.

I just found out they use nothing but a fuse. No lie I opened a ticket with coralvue. I also found a few pictures of it open. There is a board for the plugs but I can’t see any diodes or other components. The EcoTech one is the same way (not even a board). I would love to find out if the y-harness on either have one imbedded. So for now apparently they let the pumps normal power supply back feed?

I suppose the pumps supply would be at sitting at 12v while the battery would be at 13ish volts. The battery would always be trying to power the system. If you put my 24v power supply on (states 12-24v) it absolutely would cook the battery.

Think I’m going to use a relay and a 12 to 24v step-up (relay after the step-up) or a mosfet. Then a simple charger to tend the battery.

I just hate making electrical stuff that connects to AC power. I always feel like it’s one hiccup away from a fire.

 

[DancingWind]

I made a "battery buffered PSU" for my 24V dc pump(s) this weekend - it's ugly but it works :)

Key component: https://www.meanwell-web.com/en-gb/ac-dc-enclosed-power-supply-with-ups-function-ad--155b
You will also need a DC-DC regulator board - something like this expensive beauty: https://www.aliexpress.com/item/32953266992.html?spm=2114.search0204.3.57.781825c71v9WLj&s=p&ws_ab_test=searchweb0_0,searchweb201602_9_10065_10068_319_10059_10884_317_10887_10696_321_322_10084_453_10083_454_10103_10618_10307_10820_10821_10303_537_10302_536,searchweb201603_52,ppcSwitch_0&algo_expid=eea63125-2381-47ad-92e0-7fdd3fe5df9c-11&algo_pvid=eea63125-2381-47ad-92e0-7fdd3fe5df9c&transAbTest=ae803_3 (I used a 5A I got laying around so its good up to 75W but I will be powering only 1 backup pomp for now)
It's needed because Meanwell output voltage is the same for load and for battery circuit :/ 27.6V is probably not good for your 24V pump.

Box, dc jacks, cables is up to you. I put dc-dc regulator inside the black box. Green illuminated button glows when AC power is on. Black button is for shutting off DC sockets. DC sockets are output for your pump (only DC pump controller's side connector needs to match - Box side jacks I recommend you use the biggest dc jack/socket combo you can find, safer and easier to install)
XT60 connector is for connecting to batteries (two 12V AGM batteries in series for now). You can chain them however you want.
Total cost: ~110 euros (psu +box +2*batteries +bits and ends -xt60 connector) + a couple of burnt fingers from soldering iron :)

Caveats: Meanwell AD-155B is not a fully fledged battery charger. It will only float your battery. Recommend you use a good charger to cycle your batteries (discharge and then fully charge) every few months. They will last longer + you will know if they are still good.

 

[Taxus812]

I’m testing now but I used a $16 negative ground solar controller and a boost converter (steps 12 to 24v). The controller does all the switching (from wall too battery)and tends the battery to boot. It also gives me readouts with voltage and amperage etc. to put it over the top it isolates the battery and has reverse, surge and over voltage protections.

I’m pretty excited about it. I’m going to run both my eflux pumps overnight tonight with it. Tomorrow I get the 15v 6a power brick and can connect the system up fully. After that just have to make a case for the boost converter and mount.

Later I may pick up a 100w solar panel. The manufacturer states that as long as you don’t exceed 80watts it can both charge the battery and power the pumps

 

[Swaysreef]

Go check YouTube Eat Sleep Reef did a two part on a battery backup. Awesome build

 

[Taxus812]

Go check YouTube Eat Sleep Reef did a two part on a battery backup. Awesome build

Thanks I watched that video and a many others. He built a great simple battery bank that sits and is ready to be plugged in when power is lost (the pelican case was a nice touch). The only negative is you need to be there to plug it in. If you trip a gfci while you are gone for the day it doesn’t help you. A standby system remains plugged into the pump and automatically switch over to battery.