Sealed Lead Acid, What's the story?

[Rebus]

Sealed Lead Acid, What\'s the story?

I got a cheap 1,200,000 CP spotlight for
Christmas from my son. (Here Dad,
what are you doing messing around with thos
little expensive flashlights, I only paid
$16 bucks for this...) It is bright, with a
nice beam and has a 40 min run time.

It uses a rechargeable sealed lead acid
battery. I have no experience with this
kind of battery and am wondering how they
compare to NiCads and Nimh rechargeables
regarding power delivery and how long
it will last?

-Rebus

 

[drs2000]

Re: Sealed Lead Acid, What\'s the story?

I use a lot of SLAs in my emergency lights and systems. They have the advantages of:
Cheap.
Reasonable power levels.
Easy to charge maintain if you're careful.
Longish charge retention.
Good life if handled well.

Disadvatages:
heavy.
bad to toss. Lead's nasty.
Easy to kill if left flat or overcharged.
Will self-discharge fast if hot.
May gas if overcharged or overheated.
Can freeze especially if discharged.

I've got some here that're 5 years old in float
service that're doing great. Have had more than a few last 10+ years..
Also just replaced 1700lbs worth of battery pack that should have lasted 6-8 years after 2 years due to highish charge voltage and excessive heat in the room. "Put some fans in the wall to steal air from the 64degree room next door!" "It'll take electrician time and money" "Well, it just took 3 guys and $5,000 worth of batteries. That's time and money!" Some daaaaayyyy... They'll get the hint..

Modified M*glites (3 D cell) using SLA Gates cells managed to stay good for over a year on a charge in the car cab in California coastal/Bay Area. Got about 6 years more out of 5 year old cells.. Then they went FLAT.... /ubbthreads/images/graemlins/grin.gif

The catch is that charger. The cheaper products out there that use SLAs tend to come with a wall wart that's unregulated. If left plugged in after the battery's topped off, they'll overcharge, overheating and/or at least gassing and reducing the life/output of your battery.

A regulated charger is much better, especially if left powered.

Best bet's to only charge it as per instructions, and maybe even a bit shorter. Definitely unplug if the battery's getting warm. It's full.

Or charge off the car cord. The car system's better controlled than the cheap wall warts..

As will all batteries, careful charging at high battery temps. SLA charge voltage should be reduced at higher temps, if this is something you have to have.

I'm a self-proclaimed, (Actually, I've been accused of it for decades!), battery junkie..
I've used pretty much every common type in gadgets and equipment, changed types in equipment that really needed help, and feel that almost all still have merit.
I use SLA, Nimh, Nicad and Li-ion in various items.
Each has it's issues. Nicad's pretty much been supplanted by Nimh.
SLA's still slugging along, tho. Especially if you don't have to lug it around all day.. Lithium's muuuch nicer for that.

Hope this didn't bore ya to tears..

Yours, DRS the crazed..

 

[Rebus]

Re: Sealed Lead Acid, What\'s the story?

Thanks a lot drs2000, great info.
It does just have a wallwart, I
will just have to be carefull with
it.

-Rebus

 

[Gene]

Re: Sealed Lead Acid, What\'s the story?

I agree with most of what DRS said. I have one in a LSI hand held that is still going after about 8 years. I also have one in a wireless satellite speaker that I just replaced after about 11 years. It went out because I would sometimes inadvertently leave it on the walwart for days and even weeks at a time. Still, 11 years wasn't bad! As DRS said, overcharging or not giving them a charge every so often, is what really kills them. They are cheap to replace as DRS also said and I replaced the one in my wireless, (which is huge!), with one with about double the capacity for $20.00. Though with spotlights now, they are so inexpensive, (as you found out), that when the SLA goes, it's sometimes cheaper just to buy a new light.

 

[drs2000]

Re: Sealed Lead Acid, What\'s the story?

Gene had a couple of really good points there, as well as some good run life on his units.. Thanks!!

One of the stinky things about batteries, primary and secondary, is that what the manufacturer pays for the battery, compared to what the end user may have to pay, makes it pointless to 'repair' many units, unless you have a good source. Those $1.00 lights from CountryComm have 2 CR2016s in them, that Joe Public pays $2.00 each for.
On Ebay, or direct, I pay a tenth or less. Same with SLA batteries. Good tip, tho, is to see if you have a local alarm contractor supply house near you that will sell to you. (Or hit up a contractor buddy.) 1/3 to 1/5th the price, and much fresher than most 'retail' joints. My supplier gets them by the full-sized container load.

I'm known as "The Battery Santa" to most of my family and in-laws with children. Hate to see someone pay retail for dreck. Good to see that the CPF sponsors include a battery outfit, especially with the way some of these lights eat batteries!! (And he's a nice guy, too! /ubbthreads/images/graemlins/grin.gif)

And something that I forgot to mention on these comments. The 'information' I present is based on my opinions, readings, experiments and experience. Your Mileage May Vary. Other people may and probably have had different results.

Glad to see that folks found the info useful and reasonable.
In my opinion, the SLA battery still has 'legs'. Cheap powerful and pretty dependable. Tho heavy.. /ubbthreads/images/graemlins/grin.gif

Yours, drs the crazed..

(Working on a pocket Li-ion setup to run an interactive gas fluorescent display based 'name' badge. My old one was LEDs and LCD, but too hard to see in the stuff that hotels laughingly refer to as 'lighting'. New one's bright, but won't run off a 9V alkaline for a week... Won't use SLA for this one.. /ubbthreads/images/graemlins/grin.gif)

 

[Gene]

Re: Sealed Lead Acid, What\'s the story?

Thank YOU for some more excellent tips drs! Your point about retail stores having old batteries on shelves is well taken especially when they have to stock so many different sizes. Thanks for all your excellent thoughts "Battery Santa"!

 

[milkyspit]

Re: Sealed Lead Acid, What\'s the story?

Drs2000, great info! Nice to have some background on SLA batteries. I'm planning an LED hanging worklight project, and SLA was one of the candidate power sources. It's nice to get better acquainted with them. /ubbthreads/images/graemlins/grin.gif

 

[cheesehead]

Re: Sealed Lead Acid, What\'s the story?

Is there a voltage difference with SLAs and standard lead acid batteries (I thought there was some "regulation" with SLAs? Also, it seems the standard batteries are more resistant to overcharging since they can be re-filled with more water, while the gel cells typically can't (although some have a "reservior" that stores some water from overcharging).

Although, I guess with standard lead acids, I'd have a tougher time pointing up to the sky without acid flowing down my arm-so maybe that one advantage out-weighs the others.

 

[drs2000]

Re: Sealed Lead Acid, What\'s the story?

Thanks, folks for the nice comments! I spend a lot of time working with batteries and love to share and learn. There're some really great and knowledgable (and talented!) folks on these boards, and I'm happy to be able to contribute and absorb knowledge. There's always more to learn.

Cheesehead:

The voltages are pretty much the same accross the lead/acid types. The per cell voltage is what's critical, and does vary by temperature. (Warmer battery, use a lower voltage float charge.)
The good thing about it is that you don't have to be real precise. I always try to aim a bit low, just in case, as I'd rather not get the total capacity of the battery, then lose it totally or really wack the capacity by drying it out..

It's very true that moderate overcharging on a 'flooded' or wet cell is far less of an issue, 'cause you can refill it. As long as the plates don't warp or dry out, it'll usually be fine. Overcharging a gel or starved cell, tho, can dry it out, along with venting corrosive gasses in your equipment. And they may swell and crack.

Fortunately, for most electronic equipment and temperatures, a rather simple regulator circuit can handle it well.Some of my home-built emergency CCFT lanterns have been on-charge for 4 years+, most with used batteries, and the only one to fail was after 5 years running on a originally 7 year old battery. With a stated 6-10 year life. The charge controller's extra parts from a standard 'Wall-wart' or cheap car charger add up to about 80 cents, and are only, with charge limiter, about 5 parts.

As for using a wet cell, they're nasty. Not only would it ruin your clothes and make you itch like crazy, it can ruin your light, too.. /ubbthreads/images/graemlins/grin.gif Or tip over in the trunk and eat thru the car..

(I semi-collect early transistor or hybrid radios, and some battery tube sets. GE made a series of 'portable' radios in the 40's and 50's with a single 2V Willard wet cell, designed to be plugged in at night and charged, then taken to a job site and played for 8hours daily. Built like a tank. The battry is clear, with three little balls to indicate charge level, a fill plug, and a vent hose. Not real spillable, but very wet. I'm restoring a couple of these using modern conversion technology, but still a sealed 2V battery.. What can I say? I'm wierd..)

I'd rather just regulate the charger and use my SLAs.. Some of the best-lived ones I've encountered for general use, with rather good standby retention as well as good float life, are the Panasonic units. I've also had good luck with the round 'D' sized and up Gates-GE types, tho they do tend to end-of-life suddenly. Tho, if treated right, that's been 10yrs+. 2 Gates 2.5AH 'D' size in a 3D m*g with a halogen bulb and the charge reg built into the tailpiece, hold up for over a year uncharged, and still lasted years on used cells.

Anyway, I'm getting glared at. Time to go to bed..

Hope this info has been useful..

Keep on glowing!!

Yours, drs the crazed..

 

[JSWrightOC]

Re: Sealed Lead Acid, What\'s the story?

I have several Panasonic SLAs in service, and a couple Yuasa batteries as well. I have not had any problems with any of them, and they have all replaced other cheaper brands of batteries.

For charging (the bare batteries, most of my SLA-using equpment are computer UPSes) I use a 1.5A battery tender. Hook it up, plug it in, and forget it. Such devices can be found at auto parts stores, RV/marine stores, and even from electronics suppliers as complete units or kits. They start out with a constant-current charge that terminates once a certain mild overcharge voltage is reached (~14V for a 6-cell design, this ensures the battery is "topped off" and does not harm it in any way), then the charger switches to a temperature-compensated float charge mode. The charger's output voltage will vary according to ambient temperature. This is perhaps the best thing you can do to an SLA or any other lead-acid battery for that matter. A charger like this will NOT cook or dry out any lead-based battery! 6V and 12V battery tenders are readily available, and the kit (Ramsey Electronics makes one) I believe can be configured for just about any voltage and a range of output currents. The chip is a standard part made by Unitrode (now owned by Texas Instruments semiconductors), but the number escapes me. A search for lead acid charge controller should reveal something.

 

[cheesehead]

Re: Sealed Lead Acid, What\'s the story?

Thanks for the updates. SLAs are good durable high current batteries, just need a little TLC.

Sounds like the sealed cell would be better, but the standard LA batteries that they sell at Walmart, etc come with a separate acid bottle, so you can mix the battery yourself and be guaranteed of freshness. Eh, freshness isn't worth spilling acid all over the place.

I was worried that with high current the standard LA would be better, but from a few sites I looked at, it seemed SLAs are as good, if not better. That doesn't make sense to me, but hey, I'm not a battery engineer.

 

[RussH]

Re: Sealed Lead Acid, What\'s the story?

I use a cheap slightly modified 4a 13.8v bench power supply. It drops down to a more acceptable current as the battery charges. It's a little slow (not as slow as wallwart) on 17ah batteries but won't overcharge a 4ah battery. I think these were from MPJA @ around $20 each on sale. I added a heat sink to the transistor (mounted on outside of rear) and a small muffin fan internally. This one works fine up to 8 amps. I'm also modding one to use a larger fan & 2 transistors on a large heat sink on top of the unit (fan is inside of the back) for a 10amp supply. The two transistors will be regulated by an LM317 adjustable from around 4.5v-18v, or as high as it will go with the existing transformer. Unless/untill the xformr burns up............... -RussH

 

[AilSnail]

Re: Sealed Lead Acid, What\'s the story?

I have a dumb charger that does 2A on low - would it be stupid to hook it up permanently to a 200Ah LA bank?

 

[RussH]

Re: Sealed Lead Acid, What\'s the story?

It shouldn't hurt anything at all. That would be 1% of capacity. Most battery manfs. recommend C/20 or less trickle charge...although I've seen C/40 or C/50 recommended for long term...You could also check current into a fully charged battery - it will likely be well under 2a, depending on actual voltage. If the batteries aren't fully charged, then you will just be giving it a very slow charge. 2a would probably be close to the self discharge rate in hot weather, a little higher than self discharge rate in cold weather. HTH, -RussH