My UPS has external battery connectors - Can I just connect a car battery to it? | (Apologies if wrong thread, couldn't find a good place for UPS Qs)

[Euphoria]

I bought a reasonably good quality UPS (APC Smart-UPS C 1500VA 2x IEC Jumpers outlets | SMC1500IC) for my home workstation and it has external battery connectors, but I have a few questions as I'm nervous, my knowledge of electrics is... basic at best.

• Can I just connect a car/truck battery to it to extend the UPS load time?
• If yes, does it need to be a *certain type of car battery? Sealed, lead-acid, SLI, wet (refillable) battery...?
• Would they be a max capacity or could I use 2x large SUV batteries or one from a truck?
• Would having external batteries connected be affected or cause issues if they were powered by a gasoline generator? (we have constant blackouts during winter)
  I know most UPS don't like being on dirty generator power but would external batteries add more issues?
• Is there anything I need to be aware of or cautious about? A guy I work with said car batteries give off toxic fumes! << This made me 5hit my pants, thanks Steve.

[OhioYJ]

• Most UPS use two 12V batteries series to get 24 volts. You'll likely find the external battery sold for that model is 24 volts. So you would need two batteries to rig something up.
• A "normal" car battery will not handle being run down (discharged) very many times. This is not good for them. Batteries for this purpose are called deep cycle / marine / RV. These batteries still generally don't have long lives, but will have a much longer life than a standard battery if you need to deeply discharge it, like in a UPS function.
• Capacity could be calculated based on load. 
• The UPS will either run on the generator or not, I don't think the batteries will change that. However that's just speculation.
• Regular batteries can release fumes. This is why they use "sealed" or AGM batteries when the battery will be mounted in a passenger compartment of a vehicle. 

There are actually several YouTube videos of people doing things like this. Many are actually just replacing the internal batteries rather than using the external connector. However similar concept. I've seen one guy replace the two internals with two full size RV batteries. 

 

I would say if you have a generator, run off that, rather than trying to run off battery power for so long. Let it power your UPS. This sounds unnecessary to me.

[IPD]

I'm not sure on APC (or this model) specifically, but I'd hazard a guess that expandable battery choice is probably proprietary and you'd need APC's own offerings to "Expand" what you have.  These are all listed as lead-acid on their website from what I can tell. 

 

https://www.apc.com/shop/us/en/products/APC-Back-UPS-Pro-External-Battery-Pack-for-1500VA-Back-UPS-Pro-models-formerly-Back-UPS-RS-1500-/P-BR24BPG

 

Not sure if this is the right one (also, Croatia is throwing off my ability to navigate their site, so I'm using USA).  Every UPC I've encountered that has expansion uses some kind of proprietary connector and they usually sell packs similar to this...for this purpose.

 

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As to compatibility with emergency power generator compatibility...you'd have to ask directly.  I don't know that I've ever heard of it being a problem, but the MFG will be the authoritative source of info on this.  Generators (from what I can tell) can vary WIDELY on the quality of sine wave they dish out.  So there's no 1 answer that will fit.  You'd need to know what your generator is putting out and you'd need to know what your UPS can tolerate.

[IPD]

4 minutes ago, OhioYJ said:

• Most UPS use two 12V batteries series to get 24 volts. You'll likely find the external battery sold for that model is 24 volts. So you would need two batteries to rig something up.
• A "normal" car battery will not handle being run down (discharged) very many times. This is not good for them. Batteries for this purpose are called deep cycle / marine / RV. These batteries still generally don't have long lives, but will have a much longer life than a standard battery if you need to deeply discharge it, like in a UPS function.
• Capacity could be calculated based on load. 
• The UPS will either run on the generator or not, I don't think the batteries will change that. However that's just speculation.
• Regular batteries can release fumes. This is why they use "sealed" or AGM batteries when the battery will be mounted in a passenger compartment of a vehicle. 

There are actually several YouTube videos of people doing things like this. Many are actually just replacing the internal batteries rather than using the external connector. However similar concept. I've seen one guy replace the two internals with two full size RV batteries. 

 

I would say if you have a generator, run off that, rather than trying to run off battery power for so long. Let it power your UPS. This sounds unnecessary to me.

He'd still need to use the UPS, otherwise he'll get unexpected shutdowns every time power switches from utility to generator and back.  You also want the UPS to be charged for this purpose--hence keeping it in the loop.

[OhioYJ]

20 minutes ago, IPD said:

He'd still need to use the UPS, otherwise he'll get unexpected shutdowns every time power switches from utility to generator and back.  You also want the UPS to be charged for this purpose--hence keeping it in the loop.

Yes. I meant leave the UPS in the loop, but plug the UPS into the generator so the PC or whatever gets "clean" power. There is no reason to run for extended periods on battery if there is a generator. Especially if running for extended periods means rigging something up. The costs of the batteries alone will likely make this modification very expensive, meaning it is rather unecessary in my opinion with a generator already available. However just my thoughts.

[Euphoria]

Oh my goodness the irony. I couldn't reply due to... No power for 32 frickin' hours!!

 

Thank you, I hugely appreciate the info and advice, that gave me a lot of new insight and info to read up about.