12v battery backup dilemma

[k p]

Hey guys, I need some help with a project I'm working on...

I have some electronics (low power draw) that I need to have running 24/7. I currently have the entire system hooked up to a 12v battery and the battery is being topped up with a trickle charger (a really cheap unit that is probably just wearing out the battery over time).

The battery is meant to act as a backup but unfortunately the way I have it hooked up now the battery is actually the primary power source.

I'm looking to have the power for the system supplied directly via the 110v outlet (through an ac adaptor of the correct voltage) and when/if the power goes out it automatically switches to the battery.

Is there a product that senses the power outage and "switches" over to battery power?

I've been looking at stuff like THIS But I'm not sure it can handle outdoor temperature fluctuations.

Any input or suggestions on this?

 

[MixManSC]

Cyberpower makes a few low cost DC UPS's. That is essentially what you want/need. A DC UPS. Look at their "CS" models.

http://www.cyberpowersystems.com/search.html?query=CS&x=0&y=0

Probably are better commercial/industrial brand ones out there as well like from Emerson/Liebert.... buy you are going to pay quite a bit more for anything higher end.

Just verify that the one you look at meets your temp requirements. The ones you will be looking for are intended for DMARC's and are often already in an outdoor waterproof housing.

 

[nehog]

... I currently have the entire system hooked up to a 12v battery and the battery is being topped up with a trickle charger (a really cheap unit that is probably just wearing out the battery over time).

The battery is meant to act as a backup but unfortunately the way I have it hooked up now the battery is actually the primary power source.
...

This is how you want it to be done. Battery on continuous charge with a smart charger, battery feeding either the devices directly or through an inverter. You need a smart charger so that it won't over or under charge depending on changing loads. The charger must be rated for more than the total load plus whatever charge rate you want to use.

 

[2ManyProjects]

Hey guys, I need some help with a project I'm working on...

I have some electronics (low power draw) that I need to have running 24/7. I currently have the entire system hooked up to a 12v battery and the battery is being topped up with a trickle charger (a really cheap unit that is probably just wearing out the battery over time).

The battery is meant to act as a backup but unfortunately the way I have it hooked up now the battery is actually the primary power source.

Actually, no, it isn't -- at least presuming everything is wired in parallel (which it near-certainly is) and the charger is of "adequate" capacity.

As long as the battery charger is powered-up, it is providing a higher voltage than the battery itself can. Therefore, the current flow is ALWAYS from the charger to BOTH the battery and the load. Hence it really is powering the load directly, as well as providing some degree of charging to the battery. The specifics of how much charge vs. how much to the load, and other details, will depend on the specific charger used vs. the characteristics of the load, vs. the size & type (flooded, AGM, Gel, etc.) of battery used.

I'm looking to have the power for the system supplied directly via the 110v outlet (through an ac adaptor of the correct voltage) and when/if the power goes out it automatically switches to the battery.

Is there a product that senses the power outage and "switches" over to battery power?

What you are talking about is, in principle at least, a "Standby UPS", such as the ubiquitous APC "SmartUPS" series. However, given that the load is (apparently) already 12VDC, you don't want that.

What you DO want is a high-quality three-stage "Smart" charger with a fully adjustable "charge profile", and an equally high-quality battery designed for deep-cycle applications. I would STRONGLY suggest an AGM type battery for this, especially if this rig is to be used indoors. I can't make a specific recommendation until I know more about the load. But just as a starting point, here is an example of a potentially good choice of charger:

http://promariner.com/products/dry-mount-marine-battery-chargers/pronauticp-series/

http://www.bluesea.com/products/category/Battery_Chargers/P12

And here are some excellent deep-cycle AGM batteries:

http://www.lifelinebatteries.com/marinedeepcycle.php
http://rollsbattery.com/products/19

I've been looking at stuff like {link deleted}. But I'm not sure it can handle outdoor temperature fluctuations.

First, stay away from Belkin ****. They will live forever on my sh*tlist, after the stunt they pulled a few years back by putting malware in their routers to hijack your internet connection and shove ads in your face.

Second, that particular device is intended for a specific application having to do with AT&T "U-verse" service (similar to Verizon FiOS, I think). It is simply not appropriate for your purposes. (And besides, with only a 7.2AH battery, it would not last long at all under any significant load.)

This is how you want it to be done. Battery on continuous charge with a smart charger, battery feeding either the devices directly or through an inverter. You need a smart charger so that it won't over or under charge depending on changing loads. The charger must be rated for more than the total load plus whatever charge rate you want to use.

A'yup.

 

[k p]

Cyberpower makes a few low cost DC UPS's. That is essentially what you want/need. A DC UPS. Look at their "CS" models.

http://www.cyberpowersystems.com/search.html?query=CS&x=0&y=0

Probably are better commercial/industrial brand ones out there as well like from Emerson/Liebert.... buy you are going to pay quite a bit more for anything higher end.

Just verify that the one you look at meets your temp requirements. The ones you will be looking for are intended for DMARC's and are often already in an outdoor waterproof housing.

This is how you want it to be done. Battery on continuous charge with a smart charger, battery feeding either the devices directly or through an inverter. You need a smart charger so that it won't over or under charge depending on changing loads. The charger must be rated for more than the total load plus whatever charge rate you want to use.

Thanks for the info!

 

[k p]

Actually, no, it isn't -- at least presuming everything is wired in parallel (which it near-certainly is) and the charger is of "adequate" capacity.

As long as the battery charger is powered-up, it is providing a higher voltage than the battery itself can. Therefore, the current flow is ALWAYS from the charger to BOTH the battery and the load. Hence it really is powering the load directly, as well as providing some degree of charging to the battery. The specifics of how much charge vs. how much to the load, and other details, will depend on the specific charger used vs. the characteristics of the load, vs. the size & type (flooded, AGM, Gel, etc.) of battery used.



What you are talking about is, in principle at least, a "Standby UPS", such as the ubiquitous APC "SmartUPS" series. However, given that the load is (apparently) already 12VDC, you don't want that.

What you DO want is a high-quality three-stage "Smart" charger with a fully adjustable "charge profile", and an equally high-quality battery designed for deep-cycle applications. I would STRONGLY suggest an AGM type battery for this, especially if this rig is to be used indoors. I can't make a specific recommendation until I know more about the load. But just as a starting point, here is an example of a potentially good choice of charger:

And here are some excellent deep-cycle AGM batteries:

http://www.lifelinebatteries.com/marinedeepcycle.php
http://rollsbattery.com/products/19


First, stay away from Belkin ****. They will live forever on my sh*tlist, after the stunt they pulled a few years back by putting malware in their routers to hijack your internet connection and shove ads in your face.

Second, that particular device is intended for a specific application having to do with AT&T "U-verse" service (similar to Verizon FiOS, I think). It is simply not appropriate for your purposes. (And besides, with only a 7.2AH battery, it would not last long at all under any significant load.)


A'yup.

Thanks for the detailed writeup, I appreciate it. I'll look into the links you provided, I have a feeling these solutions may be outside of my budget but I'll look into it.

 

[ForceFed70]

Not sure I fully understand your needs. Why not use a standard 120V UPS and then plug a 12V power supply into the back of the UPS?

If you want to keep it cheap and it's 12V power you need, just buy a "charge controller" used with solar panels. This is exactly what they are designed to do. Doesn't matter if it's a solar panel or a 12V battery charger that is providing the charge. Cheap and easy.

 

[ishiboo]

Hey guys, I need some help with a project I'm working on...

I have some electronics (low power draw) that I need to have running 24/7. I currently have the entire system hooked up to a 12v battery and the battery is being topped up with a trickle charger (a really cheap unit that is probably just wearing out the battery over time).

The battery is meant to act as a backup but unfortunately the way I have it hooked up now the battery is actually the primary power source.

I'm looking to have the power for the system supplied directly via the 110v outlet (through an ac adaptor of the correct voltage) and when/if the power goes out it automatically switches to the battery.

Is there a product that senses the power outage and "switches" over to battery power?

I've been looking at stuff like THIS But I'm not sure it can handle outdoor temperature fluctuations.

Any input or suggestions on this?

You are significantly over-thinking this. A large charger will act as a DC supply alone. It needs to be larger output than the draw you're taking.

If you want to really separate the two systems and isolate the battery/charger from your constant DC supply unless there is a power outage, it's quite simple. Use a relay.

 

[quatchi]

I think this will work for you?

http://www.aartech.ca/ps1520-dsc-12v-1.5a-power-supply.html
http://www.ebay.com/itm/ALTRONIX-PO..._Security_Fire_Protection&hash=item2a35c90876

These just need an external transformer (16VAC) on the input, a gel-cell for backup. These are primarily used for alarm/security applications. Should be low-cost and simply.