voltage and ampere-hour rating of the battery

[prashanth]

Hello everyone!

I have emergency lamp based on white led's. It is operating at between 5 to 7V and consuming 1 ampere of current. I want to use the lamp for 2 hour continuously.

i am planning to use sealed lead acid rechargeable battery for the emergency lamp

so what should be the voltage and ampere-hour rating of the battery to meet the requirement.

 

[wptski]

If it draws 1A, you'd need a 2Ah batttery to give you two hours of use. You need a 6V battery but a fully charged battery maybe over 7V a bit though!

EDIT: A 6V lead acid is 6.36V fully charged, so that should be fine.

 

[Flash_Gordon]

A 6V battery should be fine. You will want to confirm the current at 6V. As with most cells, but especially with an SLA, you do not want to regularly deep discharge the battery.

An SLA 6V 4Ah should give you enough headroom to safely operate your light for 2 hours. Depending on your size and space limitations, bigger (higher Ah) will never hurt.

Mark

 

[viorel00]

A 6V battery should be fine. You will want to confirm the current at 6V. As with most cells, but especially with an SLA, you do not want to regularly deep discharge the battery.

...
Mark

Hi Mark, could you please educate me a little bit on this matter? a link or very very brief explanation would suffice. Thanks

 

[Flash_Gordon]

Hi Mark, could you please educate me a little bit on this matter? a link or very very brief explanation would suffice. Thanks

Unlike some other chemistries, Nicad for example, lead acid batteries whether flooded or sealed do not do well with deep cycling. Each full or deep discharge cycle causes a lead acid battery to lose some capacity which cannot be restored. To prevent this, a larger capacity battery is used which is not fully discharged in its normal use. Also deep discharging a lead acid battery can greatly reduce the number of charge/discharge cycles in its life. Again non- reversible damage occurs.

In the example of this thread, if a 2Ah SLA battery was used and run for two hours, it would be fully discharged. By using a larger capacity battery, this situation is eliminated.

Mark

 

[prashanth]

thank you for the information about the battery requirement.Now i am using 6V 4.5Ah SLA battery.In that battery it is written as

cycle use :7.20-7.50v
standby use:6.75-6.90v
initial current :less than 1.35A

what does it mean?.and what is the voltage and the current required to charge the battery?
.how many hours it needs to be charged?

 

[Flash_Gordon]

Lead acid batteries do not like to be fast charged. Unless it is an emergency I would avoid doing this. You need to use a smart charger such as a small Battery Tender, or other, and use a charge current of .75A to 1A max.

This type of charger is more sophisticated than a basic trickle charger and will keep your batteries topped up without overcharging.

Also remember, lead acid batteries do not like siting around in a discharged state. They must be kept charged even when not being actively used.

Mark