Hey guys i own a few of these:

12-Volt/7Ah Lead-Acid Alarm Battery - RadioShack.com

I want to know if someone can point me to some good info on how to charge it. Also any technical info would be awesome!!!


Thanks in advance.

Something like :
12 Volt 1 Amp Sealed Lead Acid Battery Charger: BatteryMart.com

I want to make. I found:

Charging the lead-acid battery

Would it be safe to say i can just plug the battery in and monitor the voltage and test it against that chart?

Originally Posted by AtomSoft

Hey guys i own a few of these:

12-Volt/7Ah Lead-Acid Alarm Battery - RadioShack.com

I want to know if someone can point me to some good info on how to charge it. Also any technical info would be awesome!!!


Thanks in advance.

You can float charge it continuously from a regulated DC voltage of about 13 - 13.2V.

wow lead acid seems really simple to charge.

I just mainly have to monitor voltage levels and keep a steady voltage until it reaches a certain level (voltage) then remove power or stop charge until it drops and when it does just turn charge back on.

This way i can leave it charging for a long time and not have to worry about the discharge issue.

Ok now for the technical part. Ill make a new topic in Micro section...


Thanks guys!!!!

You can float charge your battery @ 13.5 to 13.8V with the charger connected at room temperature and never overcharge the battery. Powersonic in their technical data book recomends that the charge current be limited to 0.2 times the capacity. For you 7AH battery that would be 1.4 amps.
I have been building chargers for 12 7AH gel-cel batteries for more years than I can remember. If you would like to build one I can post schematics for several different ones. One uses a LM317T, another one uses a PB137 IC that was designed for that purpose. This one requires no adjustment with a DVM.
The LM317T one has an added circuit that senses when the battery is charged and turns on an LED with the battey is charged. This one requires two adjustments, one for charge voltage and one for charge indication.

Originally Posted by k7elp60

You can float charge your battery @ 13.5 to 13.8V with the charger connected at room temperature .

I think 13.8V is good for a car battery's charging system where you want to replace lost charge quickly, but it's a bit too high for continuous float charging. Check the manufacturer's spec sheet, they always recommend a lower cell voltage for float charging. I use 13.2V for my motorcycle charger to keep it charged all year round and I get about 8 - 10 years life out of the batteries. Float charging to a higher voltage like 13.8V will boil the water out faster and require more topping off.

Float Charge: The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it's main purpose is to keep an already charged battery from discharging.

http://www.solarnavigator.net/battery_charging.htm

Originally Posted by bountyhunter

I think 13.8V is good for a car battery's charging system where you want to replace lost charge quickly, but it's a bit too high for continuous float charging. Check the manufacturer's spec sheet, they always recommend a lower cell voltage for float charging. I use 13.2V for my motorcycle charger to keep it charged all year round and I get about 8 - 10 years life out of the batteries. Float charging to a higher voltage like 13.8V will boil the water out faster and require more topping off.

LEAD ACID BATTERY CHARGING INFORMATION, BATTERY TYPES AND OPERATION - SOLAR NAVIGATOR WORLD ELECTRIC NAVIGATION CHALLENGE, NELSON KRUSCHANDL, BLUEBIRD ELECTRIC LAND SPEED RECORD CARS

I base my remarks on the attached PDF, page 10 to be specific.

I have a hunch that AdamSoft wants to charge dead lead-acid batteries that are suphated because they have been discharged (due to self-discharge) for years.

It ain't gonna happen. The batteries are ruined.

Originally Posted by k7elp60

I base my remarks on the attached PDF, page 10 to be specific.

Yeah, there is a divergence of recommendations for float charging. I have had best luck with keeping the voltage at the more conservative end (13.2). Float charging at 13.8V probably won't kill a battery, but it does increase gassing compared to 13.2V and I personally don't think you need to do it.

I suspect they went to a higher recommended voltage so that the chargers don't have to have built-in temp compensation. Lead acid 12V batteries have approximately -20mV/C tempco and the charger should track that. If it doesn't, the battery can be undercharged at cold temps where the battery voltage goes up but the charger doesn't follow. I use temp compensation on my charger so I can set it just a shade over the voltage it takes to keep the battery peak charged and I know it will always be right regardless of temp. Anyway, it's worked well for 25 years.

Originally Posted by jpanhalt

Here are the DOE documents I mentioned earlier. They are lengthy. DOE spends billions a year, so get your money's worth.

In this document, there is a nice table on page 20 (of the document, not pdf page) that tells about float charging.

If I read page 20 right:

Cell Float Voltage

(2.15-2.17) volts PbSb

A "12V" battery has six cells, so it would come out to 12.9V - 13.0V for float charging. That's probably what I was remembering when I recommended 13 - 13.2V initially.

It is slightly different for a different battery type:

(2.17-2.25) volts PbCa

Which would be 13.0V to 13.5V

heh these are brand new batteries. I own 2 and i had a few customers come into my job at radio shack asking me where to get a charger and why dont we sell them.

So i decided to buy a couple and try to make a charger on my own and see how much it cost compared to commercial chargers then if possible create them and sell them outside/apart my job. Will be sold with no warranty/guarantee and has nothing to do with my job. I will sell it as cheap as possible while trying to make the money back from parts and something for time spent reading and learning this myself.

13v was my main choice. The batteries i have like a IDIOT i threw away the boxes which had a ton of info on them heh

Ill go and make a photo copy of the box at work and show you all along with my idea of how to charge it and my method and schematic and source etc...

Originally Posted by bountyhunter

I think 13.8V is good for a car battery's charging system where you want to replace lost charge quickly, but it's a bit too high for continuous float charging. Check the manufacturer's spec sheet, they always recommend a lower cell voltage for float charging. I use 13.2V for my motorcycle charger to keep it charged all year round and I get about 8 - 10 years life out of the batteries. Float charging to a higher voltage like 13.8V will boil the water out faster and require more topping off.

LEAD ACID BATTERY CHARGING INFORMATION, BATTERY TYPES AND OPERATION - SOLAR NAVIGATOR WORLD ELECTRIC NAVIGATION CHALLENGE, NELSON KRUSCHANDL, BLUEBIRD ELECTRIC LAND SPEED RECORD CARS

NICE!!! thanks for link!