Author Topic: SLAs and soldering... heat issues. (Read 6101 times)

aberg · « **on:** July 30, 2004, 12:06:56 PM »

I was wondering if it's a bad idea to solder leads directly to the tabs. I have an SLA that worked fine when I first got it but since I've done some work with it... soldered RC clips to it, and ran it totally empty once by mistake, it doesn't seem to want to charge anymore. What can I do? Thanks.

jk labs · « **Reply #1 on:** July 30, 2004, 12:44:05 PM »

Quote from: aberg83 on July 30, 2004, 12:06:56 PM

I was wondering if it's a bad idea to solder leads directly to the tabs. I have an SLA that worked fine when I first got it but since I've done some work with it... soldered RC clips to it, and ran it totally empty once by mistake, it doesn't seem to want to charge anymore. What can I do? Thanks.

It could so be that you have managed to damage the internals of the battery with heat. I imagine that you had to apply huge amounts of heat to the terminals to make the solder melt. Did this melt any internal connections, destroy plastic separators or damage other components?
Don't give up before you are positive the battery is dead.

When it comes to "deep discharge survival" this depends strongly on how the battery was made and the materials used.

To recover a deeply discharged SLA let it sit on 3 Volts or so per cell for a few days. If you are lucky
it will start to accept charge.

Jon

aberg · « **Reply #2 on:** July 30, 2004, 02:12:52 PM »

I don't know how to let it sit on 3 volts per cell....

jk labs · « **Reply #3 on:** July 30, 2004, 03:18:24 PM »

Quote from: aberg83 on July 30, 2004, 02:12:52 PM

I don't know how to let it sit on 3 volts per cell....

Well, let the SLA sit on the charger for a few days but make sure the charger puts a voltage across the terminals of the dead SLA.

See, some LA chargers will not output a voltage (or current) if the battery is dead. If you have this type of charger it will be of no use in bringing the dead SLA back to life.

The net is full of constant current & constant voltage circuits.

Personally I'd use the charger, the second SLA and a 12 V/6W light bulb to make a charger circuit for the dead SLA:
Charger on second SLA. Wire from ok SLA to dead SLA. Put a 12V 6W lightbulb in the charge-feed to prevent exessive
currents from flowing should the "dead" battery come back to life or present a short to the charger contraption.

Best of luck

Jon

aberg · « **Reply #4 on:** August 02, 2004, 02:34:04 PM »

Whoa.... this might be a little out of my league... Where can I read up on this more?

aberg · « **Reply #5 on:** August 02, 2004, 06:21:02 PM »

Ok, I think I get what you're saying... unfortunately, I don't have a multimeter right now to see if my charger is even supplying a voltage to the dead SLA.. I will pick that up and then chances are it's the type of charger in question, which doesn't supply voltage to a dead battery. What you're saying to do then is to use the new SLA as a charger itself and then put a light bulb in series to act as a sort of current regulator/fuse type of thing... why would the charger need to be connected to the good SLA though?

BCostigan · « **Reply #6 on:** August 02, 2004, 06:46:46 PM »

If I remember right most chargers have indicators for faults and automatically won't send a charge if there's a short. A dead battery may seem like a short to the charger so....it won't charge. The extra load kinda tricks the charger into continuing outputting voltage in hope that your battery will eventually accept the voltage/charge.

As for soldering/heat....I think a few of us have soldered wire to sla's with no trouble. The trouble seems to be too deep of a discharge.

My advice.....your battery is junk. Even if you can revive it it won't have the capicity or reliabilty you want. Find your local electrical supply house and buy a new one....usually less than $20.

keepongoin · « **Reply #7 on:** August 02, 2004, 06:55:33 PM »

i have soldered onto SLAs without a problem, but I prefer to use solderless connections and then put epoxy over them to hold them in place (if you are sure you don't want to remove the cables). it would take a good amount of heat to mess up the cells in an SLA (or more sustained heat for a period of time).

F.O.Bean · « **Reply #8 on:** August 02, 2004, 07:18:12 PM »

i have a 'dead' sla 12v 7amp that i got in great shape, and when i ran it down doing jb3 tests, it just wont charge up anymore, and its a damn ecocharge

i got a powersonic 12v 12 amp that i have now atht has worked beautifully so far, i think the key w/ some batts is dontlet them deep discharge

ive done that MANY times w/ my eco 6v's, but its not good practice, and because of the deep discharge thing, i beliefve i have a dead battery that i MAY get going w/ a bulk, ie~not smart charger

so if ya dont need to run your batts all the way down, dont

YMMV tho

Lil Kim Jong-Il · « **Reply #9 on:** August 02, 2004, 07:40:19 PM »

Quote from: BCostigan on August 02, 2004, 06:46:46 PM

Find your local electrical supply house and buy a new one....usually less than $20.

And buy some connectors...usually less than $1.50 for a pack of 10.

aberg · « **Reply #10 on:** August 02, 2004, 08:10:39 PM »

Yeah, it's hard to avoid doing a deep discharge though when you're trying to test how long the battery will last.

Lil Kim Jong-Il · « **Reply #11 on:** August 04, 2004, 09:49:58 AM »

Quote from: aberg83 on August 02, 2004, 08:10:39 PM

Yeah, it's hard to avoid doing a deep discharge though when you're trying to test how long the battery will last.

It's easy.

The manufacturer web site has a spec sheet that will recommend the lowest discharge voltage for the battery. Put a DVM across the terminals of a fully charged battery and then run your rig until it hits .1V below the recommended lowest voltage. Thats how long you can run within the battery's intended discharge curve.

If you want to run to deep discharge just to see how far you can push it, be prepared to replace the battery. Some gear (a properly calibrated V3 for example) will not allow you to run past the recommended discharge point so if you run until it shuts down, you won't damage the battery.

(Edited for spelling)

F.O.Bean · « **Reply #12 on:** August 04, 2004, 01:09:59 PM »

hence why my 6v's are ok, ive only used em w/ a v3 lately

aberg · « **Reply #13 on:** August 04, 2004, 06:19:23 PM »

Thanks, that's a great piece of information! Now I'm off to grab a multimeter.... cheers!

aberg · « **Reply #14 on:** August 04, 2004, 06:22:50 PM »

Ok, my SLA is made by a company called Exaltor. I can't find anything on the net but on the battery it has a chart which lists a few 'rules':

- Do not short circuit
- Avoid total discharging (deep discharge)
- Do not charge in sealed container
- Replace every 3-5 years

And there is info about voltage regulation for standby use and cyclic use

Standby: 13.5-13.8V
Cyclic: 14.0-15.0V

What can I make of those voltage quantities?

F.O.Bean · « **Reply #15 on:** August 04, 2004, 06:41:31 PM »

its just saying, when your batts are disconnected from the charger, ie: standby, they should show a voltage NO lower than 13.5 volts, and when charging, they should NOT show a voltage no lower than 14 volts

tahts a pretty high standby voltage IMO, especially considering its a 12v

i think mines like 10.5 or something

Lil Kim Jong-Il · « **Reply #16 on:** August 04, 2004, 07:20:12 PM »

Quote from: aberg83 on August 04, 2004, 06:22:50 PM

And there is info about voltage regulation for standby use and cyclic use

Standby: 13.5-13.8V
Cyclic: 14.0-15.0V

What can I make of those voltage quantities?

Bean, that "standby" voltage is not the voltage on the battery terminals when it is disconnected from the charger. It is the voltage that the charger puts across the terminals when it is not in the charging state but is maintaining the battery.

Smart chargers typically have two modes: charging and standby. The higher voltage drives charge into the battery and the lower voltage (standby) just maintains the battery in the charged condition. The shelf voltage (disconnected from charger and load) is usually higher than 12V when fully charged and then when loaded it works it's way down.

Those voltage ranges are standard for a 12V SLA battery charging and maintenance.

If you can't find the sheet for your battery, go to Yusa or Powersonic and look at the specifications for their 12V SLA batteries. The discharge curves will be similar and you can use the numbers safely for your test.

aberg · « **Reply #17 on:** August 04, 2004, 09:11:38 PM »

Thanks teabag, and +T to you and bean... and anyone else I can see that gave me a good hand here... I'm going to pick up a new SLA and using a circuit propsed in a different thread, attempt to revive my old one.. if it doesn't work, well... I've got a new SLA anyways... I'll be a little smarter about charging and discharging now. hehe. Thanks guys!

jk labs · « **Reply #18 on:** August 05, 2004, 08:05:49 AM »

Quote from: aberg83 on August 02, 2004, 06:21:02 PM

Ok, I think I get what you're saying... unfortunately, I don't have a multimeter right now to see if my charger is even supplying a voltage to the dead SLA.. I will pick that up and then chances are it's the type of charger in question, which doesn't supply voltage to a dead battery. What you're saying to do then is to use the new SLA as a charger itself and then put a light bulb in series to act as a sort of current regulator/fuse type of thing... why would the charger need to be connected to the good SLA though?

"What you're saying to do then is to use the new SLA as a charger itself and then put a light bulb in series to act as a sort of current regulator/fuse type of thing"

YES. And the bulb is a visual "current is flowing" indicator. Very useful when working with batteries.

The charger is there to make sure the battery delivering charge is not at risk of being abused.

Jon

jk labs · « **Reply #19 on:** August 05, 2004, 08:24:54 AM »

Quote from: BCostigan on August 02, 2004, 06:46:46 PM

If I remember right most chargers have indicators for faults and automatically won't send a charge if there's a short. A dead battery may seem like a short to the charger so....it won't charge. The extra load kinda tricks the charger into continuing outputting voltage in hope that your battery will eventually accept the voltage/charge.

... snip

My advice.....your battery is junk. Even if you can revive it it won't have the capicity or reliabilty you want. Find your local electrical supply house and buy a new one....usually less than $20.

But the battery was new if memory serves. Even the crappiest of SLA chemistries should survive ten deep discharges. If one assumes a linear loss of capacity that translates into 10% loss in capacity per complete
discharge (which I think is about right for flooded car batteries).

Jon

aberg · « **Reply #20 on:** August 05, 2004, 12:33:08 PM »

Yeah, my plan was to try your method of reviving it tonight... how long should I keep it attached to the charging circuit? Until the voltage across the terminals is higher than the cut-off voltage, which I'm assuming to be about 8.10V, on par with power sonic SLAs...? Does that sould right? Then once it's above that voltage, it should be able to accept charge from the charger as per normal?

F.O.Bean · « **Reply #21 on:** August 05, 2004, 01:51:50 PM »

id like to do this too to save a 12v 7 amp battery i have

so exactly ghow does one run parallel w/ the good sla

would/could you just hook up an xlr in one to an xlr in the other

aberg · « **Reply #22 on:** August 05, 2004, 09:53:58 PM »

Excellent!!! I got a new SLA, and a multimeter and a 12v bulb.. and rigged up that propsed charging circuit... before doing so, I checked the voltage on the dead SLA and it was under 6 volts... well below the 8.1v final voltage listed for SLAs by powersonic so right away that's obviously the problem.. anyways, I rigged up the circuit and it took about 20 mins or so before it would accept a charge with the charger and now it's charging fine... it's up at like 11.9v... the only weird thing that happens is that when I take it off the charger, and then check the voltage, it slowly decreases.. like it drops by 0.1v every couple of seconds... is this normal?

leegeddy · « **Reply #23 on:** August 05, 2004, 10:02:40 PM »

Quote from: aberg83 on August 05, 2004, 09:53:58 PM

Excellent!!! I got a new SLA, and a multimeter and a 12v bulb.. and rigged up that propsed charging circuit... before doing so, I checked the voltage on the dead SLA and it was under 6 volts... well below the 8.1v final voltage listed for SLAs by powersonic so right away that's obviously the problem.. anyways, I rigged up the circuit and it took about 20 mins or so before it would accept a charge with the charger and now it's charging fine... it's up at like 11.9v... the only weird thing that happens is that when I take it off the charger, and then check the voltage, it slowly decreases.. like it drops by 0.1v every couple of seconds... is this normal?

you should charge your SLA overnight and see what the voltage is. it should be over 12v since many 12v-rated chargers output over 14v.

marc

aberg · « **Reply #24 on:** August 05, 2004, 10:56:39 PM »

yeah, that's what I'm doing now... we'll see what happens in the morning.

jk labs · « **Reply #25 on:** August 06, 2004, 10:19:47 PM »

Quote from: aberg83 on August 05, 2004, 09:53:58 PM

Excellent!!! I got a new SLA, and a multimeter and a 12v bulb.. and rigged up that propsed charging circuit... before doing so, I checked the voltage on the dead SLA and it was under 6 volts... well below the 8.1v final voltage listed for SLAs by powersonic so right away that's obviously the problem.. anyways, I rigged up the circuit and it took about 20 mins or so before it would accept a charge with the charger and now it's charging fine... it's up at like 11.9v... the only weird thing that happens is that when I take it off the charger, and then check the voltage, it slowly decreases.. like it drops by 0.1v every couple of seconds... is this normal?

Such a drop in the measured battery voltage is to be expected. Your are literally stuffing huge amounts of charge into the battery every second and the battery accumulates this charge by sending charged ions into the aquatic solution. It's a diffusive process and it just takes time.

I.e. if you remove the charger, the voltage will drop as a function of time.

You see this at the end of the charge cycle also where ballpark numbers for this drop is 0.8 Volts on float charge and about 2 Volts when terminating cyclic charge (assuming the fully charged SLA has a no-load voltage of 12.80 Volts). A less than full battery will drop more.

Regards
Jon

aberg · « **Reply #26 on:** August 07, 2004, 09:22:14 AM »

Ok, that makes sense.. thanks! I think they're both working fine now... got the dead one workin' like a charm now.. it's still maintained the same capacity as the brand new one so we're definitely in business. Thanks!

dklein · « **Reply #27 on:** August 07, 2004, 01:40:12 PM »

Nice save JK! +t