I have a 6V device to power and Li-ion batteries only come in 3.7V multiples, 7.4V a problem?

Question

I found a battery that says it discharges at 6-8V, but I don't have the knowledge of electronics to know if this is a problem I should consider. What are the details involved here, can you provide me with sources?

Answer 1

nominal is 3.6 volts. x 2 that is 7.2 volts, and could be as high as 7.4v

What is the 6 v device? odds are good that 7.4 volts would be ok. You hint that it is a 6 volt battery? you are running one battery off another, that doesn't seem to make sense.

If not you have several alternatives. Simplest is to put two diodes in series between the battery and the device. That will drop the voltage by about 1.2-1.4 volts to get you to close to 6 volts.

You could also use a 3 terminal regulator, but they tend to drop out with less than 2 volts across them.

There is also a switching regulator like the LM2698 that could be used with some work.

edit

" I'm looking to replace 4 D-Cells with 1 Li-Ion pack that is similar in size to the D-Cells because I don't want mod the casing. I want to make sure voltage won't be an issue in the changeover."

Actually standard alkaline batteries are closer to 1.55 volts each, so that adds up to 6.2v

it depends, again on what you are using the batteries for. You could add the 2 diodes I suggested. Use 1N4002 or any 1 amp diode.

Answer 2

you should also check the current rating of the device. is the device current rating more than that of your li-ion batts? then, it probably wont work. if its less, its k.

in general, though devices work with non prescribed sources, in the longer run, they may get damaged. so, if its a costly/ sensitive device, i suggest you use the prescribed voltage source.

Answer 3

My feeling is that it will be a problem. Without knowing exactly what electronics is being used, I can only go on instinct (and the fact I just had a torch fail that turned out the electronics could not take the 7.2v from rechargeables).

Alkalines will give you a substantial increase in life compared to carbon zinc. The electrochemical inputs of cylindrical Alkaline batteries are greater than that of similar sized Carbon Zinc batteries. This additional energy, in conjunction with high efficiency, gives cylindrical Alkaline batteries a service advantage on simulated application tests of 4 to 9 times that of Carbon Zinc.