lead battery charger

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Dr_Doggy

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for a small side project i have a 5v 1.5amp webcam which i would like to put in my truck, however my inverter shuts off when i turn off engine, so i have decided that i want to give it a basic battery backup, on 6v lead battery,

my thinking is that since it is 6v lead battery i can just attach battery in parallel to the 5v2amp charger

will this work, is there anything else i should consider, maybe find a charger that has more current, or adding a current limit resistor to battery?
 
it would not surprise me if you could run the webcam right from the 6 volt battery. chances are the webcam runs on 3.3 volts anyways, and the buck converter inside can probably handle 12 volts.
however, the USB side of the webcam runs on 5 volts, so you're going to have to break it open.
what i would do is find a 9-16 volt to 5 volt converter and run a separate line to your engine battery. it is unheard of for a webcam to draw that much current (is it wireless?) so you probably won't even need an extra charger for your truck.
 
Hi,

You have to be careful because the 6v lead acid battery can have a higher terminal voltage than 6v.

A simple idea is to just use a low dropout linear voltage regulator to power a USB device.
 
camera is wireless, 5v input from wall converter, and has nice 4wire databus for my pic.

here is my thought :

120v@wall-------ac-dc5v2A----------------------------------------Camera
add lead battery in parallel here------------/

is it that simple?
then when power goes out battery supplies and when power goes on pack powers cam and charges batteries(to5v)

maybe some diodes?
 
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I see problems right away.

Lead acid 6 volt batteries need around 7.2 volts to charge properly and don't survive long when being drawn down below 5.4 volts.
 
You can't simply slap a 6V battery in parallel with a 5V supply. The former would probably kill the latter. You'd need some sort of switch in there.
 
alec_t said:
You can't simply slap a 6V battery in parallel with a 5V supply. The former would probably kill the latter. You'd need some sort of switch in there.
Click to expand...

are you referring to the high current i noticed that i get charging my battery when its fully charged?



also i can get 7v plug no problem, then maybe some diodes to bring volts down to 5 for cam?
 
High, damaging current could indeed flow if you directly connect a 5V source and a 6V source
Use a low drop-out regulator as suggested by MrAl, plus some "ideal diodes" (google that) to OR the sources.
Your 5V source cannot charge a 6V battery.
 
i need to use inverter since it shuts off with engine, unlike old truck which had low voltage detector on 12v circuits.



so if i upgrade charger to 7v,
and add 3 series diodes to cam side (7v-(0.7v*3))=5 i can slap rite?

also i found LDR, pls confirm this is what i want,( i went for the broad voltage range for convenience of applying to other circuits

LM317AT
 
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The LM317A is not a LDR; it has a dropout voltage ~2.3V at 1.5A current.
 
If you just need a stable 5 volt output at 1.5 amps or less why not just use an off the shelf automotive USB power converter unit that plugs into the lighter socket or power port?

They cost around $5 - $10 for a good 2 amp rated one.
 
ciggy lighter drains/kills battery when truck is off, inverter is wired to ignition, so it fast charges on engine

(will eventually find adapter with more current aswell)
 
So you figure the small 6 volt battery will keep the camera going longer than the big 12 volt vehicle battery?

Given a at worst 7.5 watt camera load a typical 75 Ah 12 volt battery with a reasonably efficient buck converter based regulator should run for around 100+ hours at the combined load rate.
 
no but 6v is allowed to die, 12v cannot, i dont have booster kit

this one time in winter i left an interior light on,...
 
So why do you need a video camera running continuously in your vehicle any way and where are you sending the video feed to?

If the battery is going to be ran until dead on a regular basis a LA battery is a poor choice to use. I would go with a NiCad or NiMH battery pack setup and a dedicated charger that only comes on when the ignition is turned on.

As far as leaving the lights on until the battery is dead my wife does that so often I went the route of just leaving a large tractor battery and a set of jumper cables in the trunk of her car.
 
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well i use truck daily so charging is periodic and daily, more than commute, and battery says 4.5ah/20hr, so i do not intend to completely drain often, i just fear that potential, since truck may not run full day, for full charges.

feed is on home network, when we are parked since it would be better than mounting on side of house, since i am in area near universities.

however if this works ok, i may network truck as well since i am in public eye a lot and handle disgruntled customers and dense traffic volumes, it could come in handy to have around that additional protection.
 
That makes even less sense. You figure a 4.5 ah 6 volt battery will run this for extended periods but the far larger 12 volt multi tens of Ah battery in the truck won't last as long?
 
lol, again its not that,its more about protecting the 12v, my company is full of red tape, and i guess a few guys(other guys) left their 3or5watt lighter inverters on over night and killed the 12v, so now we have a policy that we are to only plug in to our newly installed inverters that are wired in to only run when engine is on, which i dont mind since they are alot higher wattage,
 
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