Unable to charge Laptop with UPS....

[rocky_upadhaya]

UPS unable to charge a Laptop...

Hello,

I have changed the configuration of my old UPS where a car battery is used. All thanks to Mneary, Reloadron who helped me in this idea in this same forum.

It was working well. I could connect my internet router and light a florecent lamp for very long Hours. But now I have my new laptop but This UPS can hardly hold the charging of my laptop with this UPS. It cannot keep my laptop charged for more than 15-20 minutes even if the UPS battery is fully charged. Why is this happening?? Can't a UPS charge a Laptop because it have a decent 35Amp car battery.
Please reply if you know something or if my question is unclear to you.

Here is a UPS
**broken link removed**

It uses 35Amp car battery and 7amp external charger to charge the battery.


My Laptop Model is Lenovo y560 with 6cell 57watt battery.

Charger Details:
Charger Model: 41A9734
Input: 100-240V≈1.8A 50-60Hz
Output: 19VΞΞ6.15A

 

[Diver300]

Do you mean a 35 Ah car battery? That seems quite small for a car battery.

What happens after 15 - 20 mins? What is the voltage on the car battery after that?

It's a laptop. It carries on working when the power is removed because it has its own battery. Why do you need a UPS for it?

July 2002

 

[rocky_upadhaya]

Hey Diver300,
Yes it is a 12Volt - 35Ah battery. It is a battery of a small economic class 800CC Maruti car. It is connected to a Computer UPS to be used as AC current.

It used to power a router and a florecent light. It even backed a 14" CRT television durring the FIFA world cup for nearly an hour. But strangely I cannot charge my Laptop mero than 15-20 if it is fully charged. The UPS stops working, cutting off the electricity.

Hey I would like to say that we have regular and long hours of Power shedding(Load shedding) in here. I am from NEPAL and being in the capital Kathmandu doesn't help either. It is really a shame that we have upto 18 hours of Power shedding per day in winters and upto 3-4 hours per day of Power shedding in summers. So I heard that It is not good to run Laptop for long hours without plugging in it to the charger. Plus My laptop has only the 6cell battery which gives me backup of max 3hours which is not good enough for me.

Greetings,
Rocky

 

[Diver300]

It certainly seems that the laptop wouldn't be taking enough power to flatten the battery that quickly, but it might do. You need to measure the voltage on the battery when the UPS stops working.

If the laptop has a 57 Wh battery, and the 12 V battery is 35 Ah, that is about 420 Wh, or about 8 times the laptop battery. Even if you have to charge the laptop, that should be OK.

I think that either the 12 V battery is poor, or that the laptop power supply is upsetting the UPS and causing it to overheat.

How long does the laptop last when connected to the UPS, but with the laptop battery removed?
If you wait the 15 - 20 minutes until the UPS stops working, can you still run the router and the light for a long time?
After the UPS stops working, will it work again if you leave it an hour to cool down, or do you have to recharge the battery?
What is the charger that you are using for the battery? Some are better than others.

 

[rocky_upadhaya]

Hi Diver300,

Thank you for showing so much interest. I have now noticed that at discharged condition multimeter shows the voltage reading of 12.6 V. As it is at discharged state I could't provide you exact voltage reading at fully charged state in this reply. My Laptop last for about 3hours unpluged and continues working on its own battery backup if the charger is not working. Sir, I would also make you clear that the It wont power even 0.8A router after cooling for about 3 hours. Strangely I have connected the charger and the router in the same ups but the router power goes down before the Laptop and its charger. After the ups stops working If I get rid of the laptop charger and connect only the router from the UPS it still wont work.

P.S Sir, it seems like the charge in the battery is only the question remaining so I will measure the charge at fully charged and discharged state of the battery as soon I borrow a new multimeter because my multimeter is too small to measure the car-battery's current. Please subscribe to this forum and reply if you have any other idea.

 

[Diver300]

You cannot measure the car battery's level of charge with any multimeter.

I think that the car battery is not in a good state, or it is not being fully charged by the charger.

What charger are you using?
Why are you not using the charger in the UPS?

 

[rocky_upadhaya]

hello,

I used external charger because I had no clue what is the ampere of the charger in the UPS because nothing is written there. Can you figure out what is the ampere of the UPS's charger by looking at the link above?? I used external charger because the UPS's charging capacity is a bit smaller for the 35amp battery because originally it used 8amp battery.

Other question is how do we know weather the battery is fully charged or not or if the battery itself is in the good condition or not.......

Take Care
Rocky

 

[crutschow]

**broken link removed**an article the shows the state-of-charge of a lead-acid battery versus it's open circuit voltage (about 3/4 down the page). As noted, if it's a maintenance-free battery with calcium added to the plates, the voltages will be about 5-8% higher.

 

[rocky_upadhaya]

Hi crutschow,

My multimeter shows 12.58-12.6V even at the discharged state. Do you guys think that the battery is not in the good condition or is short circuited. I have now checked the acid level also and it is really near the Max marker. And plus Can anyone tell me the charging capacity of that UPS above (Link given above s600b) in Ampere? like my other external charger is 7A 12 V charger.

Regards,
Rocky

 

[ronv]

Seems like the battery voltage is ok. Maybe you could pick a time when you could leave the car battery on the charger just to make sure that the inverter stays on.

 

[rocky_upadhaya]

Sir how can know the charging capacity of the UPS in terms of Ampere?? can we figure out by looking at the specification linked above??

 

[ronv]

You could "back into it" using this.

Most chargers use C/10 for the bulk charge. Or .8 amps in your case.

Battery Charging Voltages and Currents:



Most flooded batteries should be charged at no more than the "C/8" rate for any sustained period. "C/8" is the battery capacity at the 20-hour rate divided by 8. For a 220 AH battery, this would equal 26 Amps. Gelled cells should be charged at no more than the C/20 rate, or 5% of their amp-hour capacity. The Concorde AGM batteries are a special case - the can be charged at up the the Cx4 rate, or 400% of the capacity for the bulk charge cycle. However, since very few battery cables can take that much current, we don't recommend you try this at home. To avoid cable overheating, you should stick to C/4 or less.