Emergency lighting battery replacement

[Wiz]

We quoted to rip a cb unit with wet cells and didn't get the job , however we were called out to by the housing trust  a few weeks later after the company who had undercut us , had done their funky stuff.
I had to cut the battery supply first then power off the 240v as the planks had left the wet charger in and installed sla batteries.
The housing manager face turned white as I told him to stand outside in the corridor , while we shut it down.
The batteries were fit to explode , the mind boggles.
We then got the job to put it right.

Everyone in this industry needs to be very aware of the above problem.

Most charging circuits designed for wet batteries are purposely built to be a bit 'rough' in their charge characteristics. This actually helps a wet battery to work efficiently by keeping the plates clean. However if you connect a Sealed Lead Acid battery to a wet lead acid charger you will get the problems mentioned above. Quite simply the 'rough' charging characteristics will destroy the SLA batteries and could overcharge them with potentially dangerous explosive results!

You can always charge wet batteries from a SLA charger without dangerous problems but you are likely to get a reduced life/poor performance from the wet batteries.

Always remember:

- The right battery charger is required for every battery.
- Never connect SLA batteries to a wet battery charger (unless it's instructions say you may do so)
- Preferably avoid connecting wet batteries to a SLA charger (unless it's instructions say you may do so)

[Tom Sutton]

Although BS 5839 part 1 recommends using batteries of a type having a life of at least four years under normal working conditions, most service engineers take this to mean that all batteries should be replaced after 4 years no matter their condition

But are they right Wiz especially if we are talking about EL?

[Wiz]

Although BS 5839 part 1 recommends using batteries of a type having a life of at least four years under normal working conditions, most service engineers take this to mean that all batteries should be replaced after 4 years no matter their condition

But are they right Wiz especially if we are talking about EL?

tw, I appreciate the original posting was about emergency lighting batteries. IMO the topic had changed to discussion about batteries in general and I added some info. My sentence you highlight clearly mentions BS5839 which is the fire alarm standard. You previously posted information about the recommendation in the Emergency lighting standard - which was spot on.

In case there is still any confusion about what I was trying to say, I would confirm that I have found it would be pointless installing a good quality 10 year life SLA battery in a fire alarm system because another fire alarm engineer may subsequently automatically replace them after four years, no matter their condition, under the belief that BS 5839 recommends batteries are replaced every 4 years.

I believe both the fire alarm and emergency lighting BSs recommend/infer that system batteries are replaced when they are no longer capable of doing the job they were intended to do!

[Tom Sutton]

Thanks Wiz I fully appreciate the subject has been widened and welcome I it, the more well informed information available the better I like it, I just wanted to be clear in my own mind. However my interpretation was that that the person requiring my enquirer to change his batteries did not fully understand the BS and was acting on the bit about SLA batteries incorrectly, as the batteries were NI Cad. I think your last paragraph sums it all up for me.