DC solar trailer - forklift BATTERY CELL EXPLODED!

[Dude77]

As the title says, I had a forklift battery cell explode on me tonight! Scared the bejeepers out of me as it sounded like a canon shot.

Watered the batteries approximately 9 days ago using distilled water. Didn't think I overfilled, but I've never found directions on how full to fill these things. Had some off-gassing/steaming The next day and then nothing until yesterday where I noticed the characteristic smell and saw ever so faint off gasing for about 20 minutes.

I've used my generator to bring the power levels back up to around 52 or 53 volts and usually into the upper '80s or lower '90s percentage All this week. Only one time did it read over voltage, I have a separate thread asking questions on that from more than a month ago....

Today, as usual, never enough sun to power these DC solar trailers, I fired up my generator with the DC solar trailer reading at 40% capacity and if I remember correctly 47.1 volts being read from the midnight classic controller. When I heard the bang I immediately shut off my generator and can see a damaged cell through the lid that covers the forklift batteries. Sunny Island is reading 53% while the midnight classic controller is reading 53% at 53 volts. Unit is still on and still powering my dwelling.

So what the heck did I do wrong?
How the heck do I clean this up? Baking soda and water?
Is it possible to replace just a single forklift battery cell?

When I say I rely on this thing, this is my soul source of energy, is this thing still safe to use?

ANY help is appreciated, but I am still a complete noob so please forgive if I cannot answer all of your questions! Please and thank you!

 

[rhino]

Not able to answer what you did wrong but wondering how big is your battery in watt hours? How old is the battery?

 

[Hedges]

Yes, cells can be replaced, if they can be mechanically disconnected and removed.

Do you have one battery, or two in parallel?
Are the cells linked by bolted connections, or do cast links join them?

You can disconnect one cell, configure Sunny Island for 46V nominal rather than 48V nominal.
You would have to also adjust Midnight Classic to match the new voltage.

After battery has been disconnected and left to sit for a number of hours, check each cell voltage. Check each cell specific gravity. To determine if they diverge, or are close enough to work together.

If caps protect cells from contamination, I would hose off and scrub first, then rinse with baking soda to neutralize what remains.

 

[Nobodybusiness]

As the title says, I had a forklift battery cell explode on me tonight! Scared the bejeepers out of me as it sounded like a canon shot.

Watered the batteries approximately 9 days ago using distilled water. Didn't think I overfilled, but I've never found directions on how full to fill these things. Had some off-gassing/steaming The next day and then nothing until yesterday where I noticed the characteristic smell and saw ever so faint off gasing for about 20 minutes.

I've used my generator to bring the power levels back up to around 52 or 53 volts and usually into the upper '80s or lower '90s percentage All this week. Only one time did it read over voltage, I have a separate thread asking questions on that from more than a month ago....

Today, as usual, never enough sun to power these DC solar trailers, I fired up my generator with the DC solar trailer reading at 40% capacity and if I remember correctly 47.1 volts being read from the midnight classic controller. When I heard the bang I immediately shut off my generator and can see a damaged cell through the lid that covers the forklift batteries. Sunny Island is reading 53% while the midnight classic controller is reading 53% at 53 volts. Unit is still on and still powering my dwelling.

So what the heck did I do wrong?
How the heck do I clean this up? Baking soda and water?
Is it possible to replace just a single forklift battery cell?

When I say I rely on this thing, this is my soul source of energy, is this thing still safe to use?

ANY help is appreciated, but I am still a complete noob so please forgive if I cannot answer all of your questions! Please and thank you!

No idea what happened.

You need to figure out if you can cobble together what you have left to make 48V batteries.

If you can make a 48vdc battery with what’s left then you will be ok.
Not as much capacity but able to run.
Probably have to use the generator a bit more but won’t be dead in the water.

As for the battery that exploded disconnect it and haul it out best you can.

You can’t just wholesale throw baking soda in the compartment because it might get down in other active cells.

Clean up best you can, rinse it down with water while being careful not to get any baking soda in active batteries.

Next steps after that really depend on Budget, location and what you already have there.

 

[Dude77]

Hello again, if you can see the time I'm posting this follow up you can tell how much this is on my brain! It's 2:30 in the morning and I've been tossing and turning.

The batteries in question are GNB Platinum classics.... If memory serves they're supposed to be 468 amp hours. The DC solar trailer is a 2016 model. I don't know the year of the batteries but I would assume it's close. (Edit: tag says 510 AH)

Haven't summoned the courage yet to flip the cover to the battery embankment yet as I cannot find my face shield..... But I will post a pic of what I can see from the side in the next post

 

[Dude77]

 

[Dude77]

 

[Dude77]

 

[Dude77]

As I post this I guess my biggest question is wondering is this set up still safe to charge using my generator?

Anything I can do to make it safer if so? Like keep that cell that popped dry or should I add water again?

When I say I'm a noob, I can't emphasize that enough.

 

[Hedges]

Whatever popped the last cell could pop another. What is its electrolyte level now?
Any chance it was plugged vent cap, and simply pressure buildup caused a problem?
There other explanation would be ignition of hydrogen.

Can't operate in series with a bad cell.
I suppose with all vent caps off you could ensure plates are covered with water, charge to full, top off with water. See if cell still good.

I think you have two 48V batteries in parallel.
If cell is bad, need to take it out of circuit. Not worth replacing for such as old battery.
The pictures I'm finding show plastic covers over busbars between cells. Are they bolted, can you remove jumper to isolate the cell and bypass it?
If so, change both batteries from 24s to 23s, reconfigure Sunny Island to 46V nominal, change settings in Midnight Classic similarly.

The single good cell isolated from other battery could be kept at float with a suitable power supply, for future use.

Other choice would be rearrange as one battery with 24 cells, but that would be losing 50% of capacity not 4%.

 

[Dude77]

For how loud the bang was I'm assuming it was hydrogen getting ignited.

I will try to snap some better pictures in a bit.

What you're saying about isolating The bad cell makes absolute sense, as does pulling or isolating a cell from the other battery to make it 46v....... However there's the quandary, I literally do not know how to do that.

 

[Hedges]

Examine busbars. Can they be disconnected by unbolting?

If so, keep insulators on other busbars (including second busbar on same cell), used insulated handle wrench, disconnect battery from load. Wear face shield. Remove any metal jewelery. Then disconnect.

Either jumper around with cable, or move cells so missing cell at the end. Very heavy, probably easier to make new cable.

If cast busbars not bolted, you may be able to cut, drill, tap. Or solder/weld lead (make sure no more outgassing while doing that.

But did cell disassemble itself? If not, if just a gas bubble burned, maybe still usable. Also have to wonder what caused the spark.

 

[Dude77]

I'll attach pictures in the next post. Absolutely no idea what caused the spark. Solar trailer I can't say as isolated but essentially it goes fifth wheel travel trailer with about a 15 ft gap to the solar trailer, then about an 8 ft gap to a shipping container, The shipping container is what? 8 ft wide? The generator is on the other side of the shipping container....

The power cable from the generator runs under the shipping container to the solar trailer, no gaps in any of the connections

 

[Dude77]

 

[Dude77]

 

[Dude77]

 

[Dude77]

I'm assuming these are the bus bars you're talking about? The cap is off and they look like they are a whole unit, don't think I'm going to be popping these off easily

 

[OzSolar]

Probably was no spark, I'm guessing that cell had a thermal runaway. That tiny array on those trailers was totally incapable of properly charging them so that cell probably developed an internal short. Since it couldn't convert amps into chemical energy (battery charging) it only was able to to use those amps to make heat. Blamo!

Those cells are welded together in the factory. Sadly, that's not a process that can easily be done in the field so that entire 48v battery is out of commission. No harm in trying since that it is a goner.

If that trailer is like most I've seen they have two 48v batteries paralleled with Anderson connectors so you can unhook the bad pack from and keep using the other one.

Your cells are most likely well below the 40% your Inverters think they are.

Do you have a quality hydrometer? The cheap ones at the auto parts stores will do in a pinch but you really need to get a good one if you plan on taking care of FLA batteries properly. This one is my favorite but I also like to use a refractometer.

Keep us posted!

 

[Dude77]

Thank you for the info. Any idea on just what the heck I do once I disconnect that problematic battery? I mean I'm assuming I would have to reconnect it to complete the circuit somewhere. Also I would then no longer be at 48 volts? Or would I still be? Anything I need to change at the SMA or at the midnight controller? And if so how?

Many many thanks in advance

 

[Dude77]

Here is what the midnight is reading when I took those last pics. Looks like it's still charging on its own? SMA says 53% capacity....

If I disconnect one of the whole batteries, I'm assuming I would still be at 48V? But my amp hours would be cut in half?