Car Battery Safety in Lab: Risk Assessment

[Gamma]

Hello everyone,
How much of a safety hazard is it to store a car battery inside a classroom/lab? It's a new battery and it is plugged into a charger all the time. I use is only couple of times per year for a demonstration. Thanks!
-Gamma

 

[nsaspook]

If its a 'No Maintenance' sealed SLA battery connected to a proper multi-stage float charger the main danger is from someone dropping it on their foot or shorting the electrical terminals. Storing it in a acid/alkali leak-proof container/liner when not being used would be a good idea.

 

[Gamma]

Yes it is! Thanks so much. Very helpful response! -

 

[Fervent Freyja]

It wouldn't hurt to check and see if there are any guidelines or protocols written for the labs at your university that address this. I've found old paperwork of that sort going through my AST labs' storage closet- they had protocols written down for everything...

You might want to put a warning label on it just in case a student tries to use it and ends up dropping it like nsaspook noted. That or lock it in a cabinet.

 

[Gamma]

Right! Yes, this issue came up because my physics lab is also my physics classroom. We spend lots of time learning and we get thirsty :) Since my room was designated as a lab, recently a rule was brought up to not allow water. In fighting back, we found only hazardous material present is the car battery and I was asked to remove it before allowing food/drinks. Now I have decided, as you said, to store the battery in a small closet area in the room. I will have the battery plugged into a charger continuously to preserve its charge.

 

[FactChecker]

You want to be sure that the charger is a "battery tender", not just a "battery charger". A battery tender will only charge occasionally when needed to keep the voltage up. Also make sure that the closet is well vented so any gas from charging will not build up. It's explosive.

 

[jack action]

I wouldn't worry about storing a car battery, but I would about leaving it on a charger, unattended, all the time.

If the charger malfunctions and the battery overcharges, it will produce hydrogen sulfide, which is poisonous and flammable.

A car (lead-acid) battery in storage is usually monitored to make sure it keeps its charge (i.e. > 12.42 V), and is charged as needed, under supervision (reference). This is usually once every month or two.

 

[nsaspook]

A proper multi-stage float charger is a 'battery tender'.

https://en.wikipedia.org/wiki/Float_voltage

With the appropriate voltage for the battery type and with proper temperature compensation, a float charger may be kept connected indefinitely without damaging the battery.

http://www.batterytender.com/assets/img/static/FLOAT_MAINTENANCE.pdf

 

[tygerdawg]

Ummm...I'll call it quite hazardous.
Our educational lab facility is a big shop. Students were charging up a couple of those expensive deep-draw batteries for a solar powered boat project. I walked in one morning just in time to hear a big POP-Whheeessssssshsshhhhhhh. The students (whose project advisor is a Ph.D. EE) were allowed to overcharge the bank. Boom, it spewed acid all over the place.

I'm the only faculty at my institution that ever spent time in the Real World of Industrial Pain & Suffering. Luckily I'm widely known as a Raging A-hole Jerk when it comes to Shop Safety and insist on all personnel wearing eye protection at all times.

I also teach an Industrial Safety course. One of the topics is material handling, which leads to fork lifts, which leads to "how to charge the batteries." Guidelines are:

• reserve an area away from normal population as much as possible
• protect against spills etc & clean up immediately if done
• always approach with proper PPE
• protect against shorts & sparks because that will lead to other bad things
• provide plenty of ventilation
• proper documentation, training, re-training, and refresher training programs for everybody concerned

Our friends at OSHA have much to say on the subject (search for "batteries and battery charging"):

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=10742

 

[nsaspook]

Fork lift traction batteries are normally flooded unsealed deep-discharged cells that are designed to and will outgas during a normal charging cycle, not recommenced for something like lab duty without OSHA precautions. A typical HOBART 200A+ dumb charger operates in the 'recharge as quickly as possible mode' because the plates are thick (usually of Lead-Antimony) and are designed for this type of abuse so the machines can quickly get back to work. In this case we have a sealed 'No Maintenance' (Lead-Calcium or Absorbed Glass Mat battery plates for low out-gassing and self-discharge) car battery that if used with a typical multi-stage float low-rate charger is very safe with normal precautions.

 

[MullaTheMech]

Get different batteries, car batteries aren't that good anyways.

Don't take the chance of leaving voltage on them. Cap them with plastic or dielectric grease when you're not using it. This is a school you are talking about and not a part shop or garage. Or keep the battery in a fan ventilated area going outside.