12V 3Amp monitor - can I use a 12V 4.5 Amp battery? Help please

I don't want to fry my security monitor, but I want to hook up a 12V

4.5A rechargeable battery to it. Since the monitor on the back says "12V 3amp", would the monitor fry or would it just take what it needs and be ok with this amperage?

Thanks

Reply to
David D
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It will just use what it needs.

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Reply to
Meat Plow

In this case the question should be: "how long can I use the monitor before I have to recharge the battery?"

Reply to
Ryan Weihl

"Ryan Weihl" wrote in news:f0r10i$3va$ snipped-for-privacy@aioe.org:

A little over an hour.Maybe more if you are lucky.

Reply to
Gary Tait

Make sure the polarity (+ and -) are correct and you'll be fine.

Reply to
Jumpster Jiver

beware, as the battery discharges, the voltage will drop. as that happens the monitor will attempt to compensate for the loss of voltage and may ( may) cause internal power regulating components to overheat or fail.

these things require a steady 12v level to attain good design performance (give or take a volt or two). if you are lucky it will just slowly dimm and become uselesss, then u know its time to recharge the batt, or it may just turn itself off due to voltages it will not accept,

it depends on the manufacturer and just how much design thought they have invested in the monitor

some may be very forgiving, some may give u poor performance as the battery volts drops.

if it starts to smoke, you know what to expect.

be very attentive during the first time you use the battery setup, smell, feel and even use a voltage meter DVM to track the voltage value of the battery power.

Reply to
<hapticz

=CF/=C7 David D =DD=E3=F1=E1=F8=E5:

I 'm from greece and i don't know so much english. Yes you can use this battery the problem is in Volts. If you have a batterry with up of 12V don't try to use it with this monitor because you burn this monitor. The 4.5 Amperes of battery say how much current you can use from battery and if you have a monitor with up of 4.5A and conected with this battery you burn the battery and maybe this can make the battery to BOOOOOOOOM. You Understand?

Reply to
mousatos_5

'thanks for the replies. Right now, I am interested in getting 12V battery with a 4.5 amperage. The only problem is I am doing it DIY and trying to make it on the cheap - therefore I am stuck with finding a way to RECHARGE the battery. Of course without LED lights and levels, I won't know know if it is charged or not. And yes, I don't want to blow a $100.00 monitor either. My main purpose for this is to create a portable monitor system. I went to Canadian Tire to find the 12V cordless drill batteries, but they only pump out 1.5 Amp, so it is getting harder then I thought...

Reply to
David D

'thanks for the replies. Right now, I am interested in getting 12V battery with a 4.5 amperage. The only problem is I am doing it DIY and trying to make it on the cheap - therefore I am stuck with finding a way to RECHARGE the battery. Of course without LED lights and levels, I won't know know if it is charged or not. And yes, I don't want to blow a $100.00 monitor either. My main purpose for this is to create a portable monitor system. I went to Canadian Tire to find the 12V cordless drill batteries, but they only pump out 1.5 Amp, so it is getting harder then I thought...

Well, now we're getting to the root of the problem. The answers that other posters have given are correct, for the most part. The issue now is.. how long do you need to operate the monitor on battery? The ampere-hour (AH) rating of a battery is useful in determining how long the battery can supply power. The load current is a major factor in determining this time. The chemistry of the battery is also a major factor in this calculation.

A fairly good tutorial on batteries, AH ratings, Loads and recharging is at

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I suggest that you read that with great attention and you will get a better understanding of your situation.

For your portable application, I suggest that you look primarily at sealed lead-acid (SLA) batteries to start. Newer chemistries such as Lithium-Ion and others typically used in laptop computers have a higher energy/weight ratio, but are significantly more expensive.

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DaveM

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Reply to
David D

There's problem one. Don't go to Canadian Slime.

Reply to
Homer J Simpson

Ha, I do like their return policy though.

Ok, I found a battery - $24.00 - 12V 4.5amp so therefore I am going to only get 1.5 hours out of the monitor, right? Ok, I also picked up a female sleeve for a 12V lighter - but it is called "VDC 12V", is that the same? I guess I am going to have to spend more money to get a larger battery with more Amps, right?

Reply to
David D

Yep... that's what I'd suggest as a starter. You still need to do the math and figure just how long you need to operate the monitor from battery. It's the single most important piece of information you need to have. Next, use the charts on that web site that I posted for you to calculate the approximate run time for a given AH rating. Generally speaking, the higher the AH rating, the longer your monitor will run. Charging the battery is another question altogether. If you don't feel comfortable constructing your own charger (and from your previous questions, I gather that you don't), I suggest that you look for a charger that has normal charging with automatic switchover to float charging. Use Google.. search for SLA battery charger.

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Dave M
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DaveM

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There seem to be some misunderstandings here.

Firstly there is no such a thing as a 4.5A battery, what you have is a

4=2E5Ah battery. This tells nothing about what current it will supply, but rather its capacity. 2nd, you wont get 1.5hrs from a 4.5Ah battery on 3A, for 2 reasons: a) Ah capacities are only correct for 20 hour discharge. High discharge rates will reduce capacity considerably. b) If you discharge a lead acid battery until flat it wont last long. You need to stay above 20% charge at least.

For 4 hours of run time, if we momentarily ignore the 2 above issues:

4x3 =3D 12Ah Add 50% (guessed) for a short run time -> 18Ah Add 25% to permit discharge down to 20%: 22.5Ah

So really you want a 25Ah or more battery to do what you want.

There is one last issue. Is the monitor 12 real volts or 12 battery volts? What are known as 12v batteries arent really 12v. This is fine if the monitor is designed to run off car supplies, but if it needs a

12v regulated supply it might be unfine - or it might be ok. Would be wisest to check first.

NT

Reply to
meow2222

You are probably right, I don;t have the battery in front of me to check.

that is probably a good start.

How do I check? The monitor did not come with instructions and the specs I am detailing are from the back of the monitor, so I cannot really tell the voltage it needs. IS there a way to check this reliably?

Thank you for the interest.

Reply to
David D

I wish you people would get your terminology right. Nowhere do I see anybody talking about Ah (amphours/Battery capacity) A battery does not produce Amps, what you mean the battery produces 12V(DC) at 4.5Ah for 1 hour (amp hours). Thats 12V for 4.5 hours at 1Amp load. If the monitor needs 1.5A, the you take the 4.5 Ah from the battery and divide this by 1.5A load from the monitor and it will tell you how long the monitor will run. rw

Reply to
Ryan Weihl

Simple way is to determine what it expects to run off, large wall wart, stabilised psu or battery. One giveaway would be a dotted equals sign, meaning rectified ac, which would mean it expects to see unregulated supply, hence a battery would be fine.

____ .... (works in non-proportional font)

However there's no guarantee that there will be anything on it to tell you one way or the other.

NT

Reply to
meow2222

No, this is a common mistake. My post explains why.

NT

Reply to
meow2222

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