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Leaking Battery ?

L

Lorne

Veteran Member
Joined
Jul 27, 2008
Messages
1,164
Location
Chandler, AZ, USA
Is this the notorious leaking RTC battery that I keep reading about? (this one's on a Quadram by Quadboard)

Leaking Battery.JPG

If so, it would appear to me that I've caught this one early enough or before any real damage has occurred to the card. Does it look that way to others who've experienced this?
I suppose it can be cleaned off with isopropyl alcohol and a toothbrush, no?

I've read about repairs and options for replacing with lithium cells or AAA batteries, so I assume these are no longer available anywhere (Batteries Plus maybe?) :)

I've got two of these, and this one is the worst - I think the other one probably just started leaking.

I was much happier when I was just reading about someone else's battery having leaked. :(
 
Hi
That one is failing.
The board needs to be washed with some white vinegar then
rinsed.
Be careful not to get the vinegar into things like switches and
such that can't be easily rinsed.
Wear gloves and safety glasses. Even straight vinegar will damage hands with time.
Dwight
 
I've got a Quadboard here--the onboard battery gave out sometime around 1986. The circuit for the RTC is right out of the Oki databook, right down to the 8255. Replace the battery with a 3.6V alkaline, preferably not a coin cell.

Frist, take a damp rag and wipe any deposits that will come off easily, then use alcohol and a soft toothbrush to get the last little bit. The alcohol dries quickly.
 
Chuck(G) said:
I've got a Quadboard here--the onboard battery gave out sometime around 1986. The circuit for the RTC is right out of the Oki databook, right down to the 8255. Replace the battery with a 3.6V alkaline, preferably not a coin cell.

Frist, take a damp rag and wipe any deposits that will come off easily, then use alcohol and a soft toothbrush to get the last little bit. The alcohol dries quickly.
Click to expand...
Are you sure that's not a rechargeable NiCd? And assuming it isn't, I have to ask: why not a coin cell?
 
I went digging through old threads after making this post (I know, I'm as guilty as a newbie - ie: asking super simple questions before doing my own research through the forums, ebay, and google), and I came across this piece from a thread titled "Ah...battery day!":

(hopefully, I just made two points with that last paragraph - that "was" the intent)

"If you do open it up you'll probably find it's a standard shrink-wrapped 3-button-cell side-lug battery as found on many 386/486 era PC mobos, which you should be able to find in any computer shop (even down there :wink:. But you would have to remove the PCB to replace it (properly)."

Does it look familiar MikeS ?

This one looks like a shrink wrapped battery - is it a three cell thing?
I dug some more, and found that the manufacturer VARTA, is still in business making batteries.
I'd prefer to keep it original, so I've emailed them to see if they still have or make these (long shot, I know).

If not, do I need some sort of battery holder to hold the new battery? Surely, I don't just solder wires onto the ends of the battery. I'll do some more reseach - it's all in the forum somewhere (it'd be easier if we had all this stuff in one place).

Are we sure these things weren't rechargable (or is it a rechargeable alkaline)? How could they hold a charge for 10 years without being rechargable?
 
It sure looks like a flat version of the NiCd commonly used on 386/486 mobos, which is why I was questioning Chuck's advice to use an alkaline (I never learn, he's almost always right ;-)

I've got a manual for the Quadboard somewhere but as usual can't lay my hands on it.

What I do with batteries is put header pins into the holes left by removing the battery, mark the polarity, and use an old speaker cable (red & black wire with single header plugs) to connect to a battery mounted elsewhere with velcro tape.

Can't say I've ever seen a rechargeable Alkaline used as a backup battery; as to the ten years, depending on how much you're backing up it would be possible for a primary battery to last ten years (as in the also notorious Dallas clock and NVRAM chips which were rated for ten years battery life).

What do you get if you put a voltmeter across it with power off compared to power on? Unless it's shorted, if it's supposed to charge then the voltage obviously has to be greater than 3.6V with power on, and somewhat less with power off.
 
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MikeS said:
It sure looks like a flat version of the NiCd commonly used on 386/486 mobos, which is why I was questioning Chuck's advice to use an alkaline (I never learn, he's almost always right ;-)

What do you get if you put a voltmeter across it with power off compared to power on? Unless it's shorted, if it's supposed to charge then the voltage obviously has to be greater than 3.6V with power on, and somewhat less with power off.
Click to expand...


First: at least I know better than to ever question Chuck. You'll learn eventually.

Second: oh, here we go - these were two boards I've had laying around. Now you're going to make me have to pull out, and pull apart the XT. :)
I'll take measurements before (should be dead as a doorknob), and after to see if they're rechargeable.

Thanks.
 
I base my "it's alkaline" on the basis of my probing the board. Now, it's always possible that Quadram revised the board and there other other versions, but here's what I observe. The negative side of the battery (BAT1) is connected to the ground return, as expected. The positive side is connected to one side of a 100 ohm resistor, R6 and then through diode D1 to pin 1 of the MSM5832 (Vdd). +12 is taken from the bus and run through D2 then 220 ohm resistor R7 and thence to Vdd.

There's no return "charging" path for the battery.

That doesn't mean you couldn't modify the circuit to use a rechargeable (look at the data sheet where reference to "charging" is made), but it scarcely matters--the clock draws only 30 microamps on standby. An alkaline battery of sufficient size will last its shelf life. I'm not so sanguine about the capacity of a coin-cell alkaline, however.
 
Here's what I get between the positive and negative sides of the battery:

With the card out of the XT: 0.4V
With the card in the XT, and the XT powered up: 5.34V
Does that make sense? (I checked it twice)

I'm leaving the card in there while the XT is on, to see if it charges the battery (but based on Chuck's comment, I don't expect it will).
 
Yours is different from mine, apparently I get 0v with the battery out of the circuit. Use a rechargeable, then. My Quadboard is S/N 5748 and made in 1983 (yours was made in 1982).

It also explains, apparently, why my battery was toast by 1986.
 
Lorne said:
Here's what I get between the positive and negative sides of the battery:

With the card out of the XT: 0.4V
With the card in the XT, and the XT powered up: 5.34V
Does that make sense? (I checked it twice)

I'm leaving the card in there while the XT is on, to see if it charges the battery (but based on Chuck's comment, I don't expect it will).
Click to expand...

The battery is dead and leaking, remove it. You are seeing a voltage when it is in the computer and running because the system is trying to recharge it (making it leak some more). The 0V to 0.4V difference is probably from the meter you are using (accuracy and calibration).
 
Chuck(G) said:
Yours is different from mine, apparently I get 0v with the battery out of the circuit. Use a rechargeable, then. My Quadboard is S/N 5748 and made in 1983 (yours was made in 1982).

It also explains, apparently, why my battery was toast by 1986.
Click to expand...

Correct Chuck - mine says 1982 on the board.
I've got another one (exactly the same) and it's giving me (on my digital volt meter - reset to zero to compensate for the probes) 0.7 mV when out of the XT, and an OverFlow condition when it's in the XT and the XT is powered up. That must mean the battery in that one is toast.

I know that these batteries need to be replaced - I just want to know whether they're the rechargeable type or not.

I've also got another QuadBoard (1984) that doesn't even look like it has a battery (at least the normal type of battery anyway), but it's still a Quadboard by Quadram so I'm sure, or think, it must. What I think might be a battery is just to the left of the only switch block on the board (see below). Same as yours?

QBbyQR battery.JPG
 
It was a popular board and doubtless there were several revisions. No, I think your 1984 one had the battery removed and it's to the right of the switch block in the area marked "B1".

What's surprising about these boards is that they were all laid out by hand and they still managed to push out a design every few months.
 
Chuck(G) said:
It was a popular board and doubtless there were several revisions. No, I think your 1984 one had the battery removed and it's to the right of the switch block in the area marked "B1".

What's surprising about these boards is that they were all laid out by hand and they still managed to push out a design every few months.
Click to expand...

I think you may be right (as usual).
Look below:

Missing battery.JPG

Sure looks like someone removed a battery to me.
Do I want to put the same size battery in on this board, as on the others?
 
Chuck(G) said:
Frist, take a damp rag and wipe any deposits that will come off easily, then use alcohol and a soft toothbrush to get the last little bit. The alcohol dries quickly.
Click to expand...

Hi
I don't often disagree with Chuck but on this one I have to say something.
You need to neutralize the stuff coming out of the battery ( KOH as I recall ).
Alcohol won't do it. You need to use an acid. Vinegar is about the best
because it can be cleaned easily afterwards.
Dwight
 
I dunno Dwight. If it hasn't attacked anything by now, it's probably not going to if you simply clear it off. My quarrel with vinegar is that it can become trapped in vias, particularly under ICs and corrode the pc traces. It's sort of like the "Old lady who swallowed a fly":

I know an old lady who swallowed a fly,
I don't know why she swallowed the fly,
I guess she'll die.

I know an old lady who swallowed a spider,
That wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly,
I don't know why she swallowed the fly,
I guess she'll die.

I know an old lady who swallowed a bird,
How absurd to swallow a bird!
She swallowed the bird to catch the spider,
That wriggled and jiggled and tickled inside her,
She swallowed the spider to catch the fly,
I don't know why she swallowed the fly,
I guess she'll die.

...etc..
Click to expand...

I suppose if you wanted something to react with the base, I'd pick club soda (pretty much carbonic acid). That would react with any KOH and form K2CO3. Aside from that, a good inse in distilled water will do what you need.
 
Guys. You can definately catch Chuck out. Yes, it's rare, but it's worth the challenge because if you do manage to catch him out, it's something you can add to your CV/resume. Goes down very well at the interview for your next IT job.
 
So I emailed a photo of the battery to my local Batteries Plus and within a minute they had emailed back telling me the replacement battery model number, the price ($ 9.88 each) and that they had them in stock.

Get a load of this:

Replacement battery.JPG

Still made by Varta, same size, shape and with the pins, just green instead of blue because it's Ni-MH.

Varta part #: COMP-18-3NMHP
Batteries Plus part #: TC-3/V150HDP

Now that was easy - no fuss, no muss.
Just solder it in place, and it should be good for another 25 years.

When they first opened Batteries Plus a few years ago, I thought what a dumb idea - how can a store survive selling just batteries? I figured they'd be under in six months. I've been in the store four times, and every time there's at least two other customers in there at the same time as me. What do I know?

Edit: the replacement battery is about 1/4" longer than the original, but that was OK because it looks like Quadram designed the board for a larger battery. There are two holes on the + side, 1/4" away from the original holes, and they have traces running to the other holes. The replacement battery fit the other holes perfectly.
 
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Interesting. I had a similar looking battery on an old Apple II clock card. It was leaking and I removed it. I'n not sure if it was NiCad or otherwise...I've got a few other projects higher on the priority list but I probably will get around to replacing it one day. Good to know that such batteries may be around...albeit they may be thousands of miles from here! (everything else seems to be!).

I had to smile at Dwight's advice to Lorne about wearing gloves and safety glasses with vingar. It's good advice and he's quite right. However, Lorne is a man who plays with 30% H2O2 in his spare time :) . Vingar?? Ha!, I spit on thee...!

Tez
 
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