Use Car Battery with small UPS.....

[rocky_upadhaya]

Hello there,

I have a small Computer UPS and its battery is useless since it gives 3-4 min backup. I also have a 35 amp Car battery. So Can I Use the Battery with the UPS that I already own? I think the UPS cannot charge such big battery nicely so I can buy a charger for it. Does the UPS that I own will be of any use to convert Battery's DC current to AC current safely? Will it be use safe to use such connections?
If yes please suggest me how much ampere charger do I need to buy to charge that battery?

here is the exact model of my UPS and its specification.
**broken link removed**

Greetings,

 

[mneary]

A few issues that you'll want to manage:

Charge voltages are slightly different. With the float voltage set for the original UPS battery (probably AGM), the car battery might not retain a full charge.
The car battery will require watching the fluid level.
The car battery will run a lot longer, and the UPS does not appear to have a fan to keep it cool in long term use.

 

[rocky_upadhaya]

Thank You Very Much.

Charge voltages are slightly different. With the float voltage set for the original UPS battery (probably AGM), the car battery might not retain a full charge.

I have little problem understanding this line. I also want to say that I can buy the external charger for the Charging Purpose so how much ampere's Charger will you recommend me to buy.

2. I will have no problem filling the fluid.
3. I can mannage the 3rd problem also.

Does that mean it is safe for me to use my old UPS?

 

[mneary]

Your external charger should have enough 'amps' to charge your battery in the time that you want to spend waiting for it. If you have a 35Ah battery and you can wait 5 hours until it is full, then a 7A charger is needed. Charging a battery too rapidly is wasteful and dangerous, so don't stretch this too far (Don't try to charge it in two hours with 18A). The battery should not ever be in a living space because of the acid and danger of hydrogen explosion. A flooded battery seeps acid from its caps, so it must be kept away from children and animals. Make sure you don't let anything get too hot.

I use an old UPS with a car battery the same way that you plan to. It is safe for me, but I can't see if there is anything you might have missed.

 

[rocky_upadhaya]

Thank You very much. That really helped. And oh Have you used the extra external charger of had some tweeks with your UPS?

 

[Reloadron]

I have done this in the past. Rather than a car battery I used a battery used in marine and recreational vehicle applications for its deep discharge ability. I happen to live in the US in an area where power outages are seldom so much of how you do this depends on how often your battery will charge and discharge. There is a big difference between running once a month or less for an hour or so and running daily in countries where power loss (power shedding) is common place.

Next as pointed out, you don't want the battery in your living quarters. This presents a small problem. Note the size (gauge) of the wires to the battery in your UPS. They are likely large and purposely kept short. Since the battery should be away from the UPS you should use a larger gauge than used. Meaning if the UPS uses AWG 12 you want to use AWG 10 or even larger depending on the length of the wires used. The battery should be in a well ventilated area! Mneary covered all that.

Also, remember a larger battery will buy you more time, it will not buy you more power output from the UPS. What you have is what you get from the UPS so never overload it! Also as was well covered, cooling is important. My UPS units had fans. Your small UPS likely does not. Prolonged use will require some good cooling so make sure you have good airflow and cooling added.

I didn't use an external charger for my application. The trickle charger in my UPS did just fine but again mine was infrequent use.

Ron

 

[rocky_upadhaya]

Hello ,

Thank you for your answer. I am from Nepal. It is shame to say that Nepal is the second richest country in the World in Terms of fresh waters behind Brazil, but also we have very regular power shedding or load shedding over here over the years. Power shedding is normally 7-8 hours a week in summers and upto 18 hours a day. Yeah upto 18 hours a day. I am not proud to say that we are somewhat used to live without electricity for long hours.
But also as a student I decided to make a use of 2 old and unused things, my computer's UPS and my uncle car's battery just for Curiosity and knowledge. So really thank you guys. Hope to see further guidance if I am stuck.

Thank You