Nickel Metal Halide Vs Lead acid battery

[ep.hobbyiest]

Which battery is good to use and reliable to use and charge.
I was decided to use lead acid battery first but after internet search i get to know NiMH battery is good.
so which is reliable ?

 

[Tanmay Dash]

The significant disadvantage of NiMH batteries is the high rate of self-discharge; NiMH batteries typically lose 4% of their charge per day of storage.that is thereason why lead acid is more reliable than niMH.my point is taht in consumer point of view power management come into play ..whatever may it be if a technology is enough to conserve or save power than it is the best of all no matter is it hazardeous to environment or not

 

[Audioguru]

The significant disadvantage of NiMH batteries is the high rate of self-discharge; NiMH batteries typically lose 4% of their charge per day of storage.that is thereason why lead acid is more reliable than niMH.my point is taht in consumer point of view power management come into play ..whatever may it be if a technology is enough to conserve or save power than it is the best of all no matter is it hazardeous to environment or not

No.
New Ni-MH batteries hold their charge for 1 year, old ones had a fast self-discharge. Lead-acid batteries lose their charge much faster. Old Ni-Cad batteries are toxic and are a hazard to the environment.
I use rechargeable Lithium batteries for almost everything now.

 

[ep.hobbyiest]

So i am thinking to use NiMH battery 7.2 volt pack.
But after surfing i got different packages of this battery.?
Then how to choose this batteries?

 

[BradtheRad]

After you have chosen voltage, another important factor is ampere-hour capacity.

Determine how much current you must draw, and for how long, between charge sessions. You can calculate roughly the length of time the pack will power your load. Then it will take a certain length of time to recharge.

If you need high energy and light weight, look for 'pushed' batteries. These are selected as providing the most power for their size. They are usually more expensive.

 

[ep.hobbyiest]

Here is my load on that battery.
DC motor need 6v, 0.46 Amp.
LCD 16x2. And controller circuit.

 

[BradtheRad]

Did you consider a simple AC adapter?

How long will the device need to be powered?

How often do you intend to recharge the batteries?

How much time do you have to charge batteries?

Does your controller circuit need a regulated supply?

 

[ep.hobbyiest]

yes sir i have i am going to use ac adapter for charging the batteries.
Device should get powered through battery for 7-8 hours.
after that battery should get charge in 2-4 hours.
Yes controller circuit will need regulated power supply.

 

[BradtheRad]

Device should get powered through battery for 7-8 hours.
after that battery should get charge in 2-4 hours.
Yes controller circuit will need regulated power supply.

To provide .46 A for 8 hours, you'll need a 4 AH battery pack minimum.

7.2 V is sufficient, if your regulating device does not cause too much voltage drop.

To charge a 4 AH pack in 2 hours, you must feed it 2 A continuously. This is a severe charge rate (C/2). It is not normally recommended that you charge a battery so quickly. The batteries will get hot during charging. This shortens their useful life.

Or...
To charge a 4 AH pack in 4 hours, you will feed it 1 A continuously. This is a charge rate of C/4. The batteries will heat up, but not so much.

It's a good idea to use 5 or 6 AH batteries, since they will start to drop in performance as soon as you put them into service.

Expect to need about 'D' cell size.

 

[D.A.(Tony)Stewart]

Total life cost is an important factor , where depth of discharge , temp, discharge % rate C rated at 20hrs for chemistry and construction are all factors.

That being said you can get more Ah x charge cycles by only using 50% of capacity, so double up expected consumption.

Cordless phones use lower current than cell phones, so cordless tend to use NiMh and cell phones use LiPo.

Lead acid being much cheaper also perform much worse so often used for brief power outages when AC is not used, rather than brief charge cycles with less than 20h drain. Or used when drain is >> 20 hrs or for cheap standby power.

Always keep cool for long life during charge and discharge.

Beyond these "hand-waving" generalizations, we need your budget for battery, expected power drain (V,I, AH, desired lifespan, size, complexity of charger)

These are all concerns as well as temperature Compensation of charger for SLA and 3 level mode control. (CC, CV, float or off)

 

[ep.hobbyiest]

My DC motor is of 6 Volt and 2.8 Watt. so battery must be greater then 6 volt.
and current is 0.467 amp required.
Size is should be small.
And charger i am using is AC adapter which convert AC to DC.
Battery charging is 5 hour can be ok.

 

[BradtheRad]

It will be easiest if you purchase a ready-made battery pack. You will need to shop around at hobby outlets and see what is available. Ebay is another option.

Battery packs contain various amounts of NIMH or NICAD cells. The sizes might be AAA, AA, sub-C, C, etc.

It is difficult to construct your own pack from individual cells.

Your connectors are a factor. If you draw under 1/2 A, then they do not need to be heavy duty.

A freshly charged pack might start out at 1.4 or 1.5 V per cell. As it powers a load, this will decline. The customary figure quoted for operating voltage is 1.2V (for rechargeable type). So if you want 7.2V for 8 hours at .5A, then expect to need 6 cells.

Sub-C size will not be adequate. You may get by with C size, but only if they are high-performance, and you may not get 8 hrs of operation. That is why I recommend you look at D size.

 

[ep.hobbyiest]

Thank you sir. I saw some batteries on ebay https://www.ebay.com.au/bhp/7-2v-rc-battery-nimh
but which current rating i should select.

 

[Audioguru]

You need to look at the specs for a battery.
I bought some Name Brand Ni-MH battery cells on sale for half price. Then they turned out to have half the capacity of normal ones.

Energizer sells a low cost D size Ni-MH cell. It has a little AA cell inside.

 

[schmitt trigger]

My two yen on the subject:

If you are planning to make your own series connected pack, it pays to ensure that all the individual cells have very similar capacities, as the available mAHr from any string is equal to its weakest cell.

This means either:

-purchase brand name cells from reputable vendors (which will be individually more expensive)
-or purchase a larger amount than actually required from ebay or alibaba, and individually measure and select them.

 

[Audioguru]

Why would anybody pay a cheap price for a Japanese battery on ebay from nobody you know that is shipped from China?? FAKE, FAKE, FAKE??
Please buy a real genuine Japanese battery from a well known local hobby store who is a dealer for the battery company. Then you will get a real battery.

 

[ep.hobbyiest]

No sir i am not going to connect the single battery i want pack battery.
D size is good choice?
which battery specification can suite my application.
will the charger of 12 volt work?

 

[Audioguru]

No sir i am not going to connect the single battery i want pack battery.

A battery is a group of battery cells connected together. A 12V car battery is six 2V cells in series.

D size is good choice?

You must look at the specs then decide if it will do what you want.

which battery specification can suite my application.

You have not said how long you want the motor to run from one charge so we cannot spec the capacity and size of a battery.

will the charger of 12 volt work?

An AC-DC adapter powers a charger circuit that charges the battery, just like a cell phone. Without a charger circuit a dead battery will overload and maybe destroy the charger. Without a charger circuit an over charged battery might blow up.

 

[ep.hobbyiest]

I have DC motor of 6volt and 0.5 Amp current rating. and also controller is there with 16x2 lcd. controller +lcd consume 30mAmp . So those things will run for 7-8 hours.
battery charging can take 4-5 hours.
Yes sir there should be charging controlling circuit. So i will check IC and circuit for that.

 

[Audioguru]

530mA for 8 hours needs a battery rated at 4.24Ah for the battery to be dead or use 6.4AH for the battery to still power the motor fairly well for 8 hours.
Then you need high capacity and high price Ni-MH D cells.