SLA Battery Help Needed...

[christian.ckr]

Hello everyone,

I am inexperienced with using SLA batteries or any large battery of the kind but I am having some issues with my 12v 18amp SLA battery purchased from bintel 2 months ago (http://www.bintel.com.au/Accessories/Power-Supplies/18-amp-12vDC--br-SLA-Battery/940/productview.aspx ). I had it powering the astrotrac over a few nights for a few hours each session and it has been on the charger as well (not over charged, was only on for a few hours at a time since I really have not used it much at all) and I noticed it stopped powering the astrotrac. I bought a multimeter and tested the output, it is running well under the 12-13v that a fully charged 12v battery should be showing (11.8v) and when I connect red to positive and black to negative the astrotrac would not power up.

This is the strange thing, I tried reversing the connections (red to negative, black to positive) and the light on the 12v cable lit up, I did not plug the astrotrac in for fear of damage to the electrical system.

When applying red to positive and black to negative, the multimeter gives me a negative reading but when reversed gives me the exact opposite as per the pictures attached below.

I may need to head into battery world to see what is going on, I am new to this so I may just be missing something?:confused2::shrug:

Any input would be greatly appreciated.

Thankyou!

[OffGrid]

G'day Christian,
We need a bit more info.
What brand and type of battery charger do you have, if it is the 2x voltage type, that is, 6 and 12 volt, make sure it is set at 12 volt.

Now take a voltage reading of your battery with nothing connected and note.
Connect battery charger and you should see battery voltage rise to at least 13 plus volts within first few minutes.

Keep recording voltage at 15 minute or so intervals for a couple of hours.
Let us know the results.

Steve

[christian.ckr]

Thanks for your reply Steve, the charger I am using is this purchased from bintel but the jaycar description is a little more detailed http://www.jaycar.com.au/productView.asp?ID=MB3523 and it has always been sent to 12v.

I have had it charging for the last few minutes but there has not been a change in voltage, it is still at 11.8v

I am at a loss as to what to do, is it odd that it seems to power up the mount when I attach the red to negative and black to positive? I know was a little idiotic but it was more of a test and it seemed to work...

[christian.ckr]

And when I say mount I mean the astrotrac's 12v cigarette adapter had a little red light that turns on when there is sufficient current, I did not plug it into the mount itself.

[GrampianStars]

You have reverse connected the charger and shorted it out !!!! :eyepop:
the charger you have is pretty much a float charger and will not charge a flat battery.
There's not enough Amps to reactivate the SLA

Get one of these for a great result : :thumbsup:
http://www.radioparts.com.au/product/03617100/sbc2105-12v-5a-sla-battery-charger-3-stage-switching-mode

Note: You have only 9Ah of recomended use (50% discharge)
Charge the battery after every use (Minimun 6 hours)
The charger will go into a float mode when the battery is full

[OffGrid]

Christian,
As I suspected, you have the same charger and battery that I have.
Disconnect the charger from the battery and 240v supply.
Connect your DMM ( digital multimeter ) across the positive and negative alligator clips of the charger.
Make sure that the leads are not or will not short.
Switch the charger back on.
You aught to be getting at least 16 volts.
I suspect you will be getting zero or at least minimal voltage.
Do this only for testing.
If very low or zero volts, take it back to Bintel.
I do not use my similar Bintel charger for any more than a few hours as there is no documentation to suggest that it is a 3 stage charger, ( bulk, absorbption and float).
If I need to ensure that my battery is fully charged before an event, then I use my trusty 3.6 amp CTek that can be left on permanently if needed.

Steve

[killswitch]

The battery has been charged in reverse polarity, thats why its showing a negative readout .. yikes!

[GrampianStars]

Can be fixed
First drain the battery FLAT (I have used a 12V auto light globe)
Then wire in paralel with another charged battery
and recharge should revert back to correct polarity
in about 4-6 hours ;)

[christian.ckr]

I have always connected red to positive and black to negative, unless I have recently gone colourblind :/

Any tips on how to reverse this? A 3 stage charger is definitely on the list now...

[christian.ckr]

Is there any way of doing this without buying a second battery?

[killswitch]

In case its just your multimeter, test it on a AA battery and see if you get a positive readout.

It can be revived as Rob said, i use a similar method to revive AA rechargables. Though i fear the batterys capacity wont be as good before. The positive and negative electrodes have different chemistry's and should be charged accordingly.

[OffGrid]

Christian,
When you get your battery and charging sorted, I would strongly recommend that you get a 'WattMeter' so that you can accurately determine the amount of Amp Hour discharge from the battery during a session.
Determining SOC ( state of charge ) by taking voltage readings is not very reliable.
Rob was on the money when he said your should not exceed 9 amp hours from you 18 Amp Hr battery.
This equates to an approximate maximum 50 percent discharge of the battery.
This seems to be an industry standard in order to get a reasonable life from a battery between cycles( discharge/charge).
A WattMeter will give you live voltage and discharge in either watts, watt hours, amps ( also milli amps), amp hours ( also milli amp hours ) accumulative.
They are very cheap, run from the source battery inline to the load (scope etc).
Here is an example..
http://www.ebay.com.au/itm/Digital-LCD-Watt-Meter-Battery-Balance-60V100A-DC-RC-Volt-Ammeter-Amp-Analyzer-/321507941717?pt=AU_B_I_Electrical_T est_Equipment&hash=item4adb5ddd55

I do not run my gear without it being inline and at the end of a session I know exactly how many amp hours I have consumed. If I am likely to exceed 50 percent discharge during a sessions, then i know my battery is not big enough.



Steve

[raymo]

You could use the battery out of your car, remembering that you will have to recode your car radio if you disconnect the battery from the car. [only
takes a couple of minutes, provided that you know the code number].
raymo

[christian.ckr]

Thankyou for your advice everyone, if I run the battery at reverse polarity for now, after checking some forums this will affect the longevity of the battery and the capacity as well, I have a HEQ5 as well but would only run this for a few hours at a time so the reduced capacity may not be an issue but will this damage the electronics? I just see this as a lot of effort since it will take so much to reverse the polarity to its original state and there has already been so much damage done...

[BPO]

There's good reason for the old saying, "Batteries never die, they're always murdered."

Deeply discharging a battery will drastically shorten its lifespan, and reverse-polarity "charging" it is akin to driving a stake through its heart.

You may be able to force some small amount of zombie life back into that battery, but it won't be much and it won't be for long.

This is the bad news. The good news is that you'll get a lot of use from any new cell you buy that is properly maintained with a quality charger.

[christian.ckr]

So essentially avoid using a bargain basement charger for the future, in regards to what I can do now, is it even worth attempting to restore the battery to its original state?

[The_bluester]

Before doing anything else, check your meter on your car battery to make sure that it is not a meter issue rather than a reverse polarity charge issue.

[christian.ckr]

I am pretty certain this all stems from a reverse polarity issue... :sadeyes:

[christian.ckr]

After doing a search on reversed polarity in SLA batteries I found the battery needs to be dead flat before it can reverse, but I used it once every week or 2 for a month so this does not make any sense to me..

[OffGrid]

Christian,

Your pic of the meter connected to the open cct output of the charger tells me it is producing the same output as mine and mine is charging ok.
It also indicates that the charger has the correct polarity with respect to the alligator clips.
As previously suggested by another member, try testing your car battery to confirm polarity with your DMM.
So, I have reached the limit of my knowledge as I have never experienced a reverse polarity battery.

I trust the IIS community can assist in resolving your case.

Steve

[BPO]

They're fine so long as you understand the severe limitations of any low end unregulated supply such as these cheapo chargers.



You'll never get it to its original state. Not even close. You may be able to restore some capacity which will let you run very light loads of short duration, but you shouldn't hold out any hope of making it like it was.

[The_bluester]

I will be honest and say that I never even knew you could reverse polarity charge an SLA. I did not think the chemical reaction allowed for it.