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UPS - Lead Acid Batteries - Charging Questions

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Last Modified: 2020-06-19
Hey Talented Experts:
Can someone point me to a site or video that discusses the "MUST DO" and "MUST NOT DO" with regard to using lead acid batteries. I'm new to using them and know nothing.

I've got a UPS that uses them and want to ensure I get the most out of their use.

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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
Make sure you replace them, based on manufacturers recommendations.

as for use of the batteries, this will be documented in the UPS manufacturer's instructions.

How old is the UPS ?

How old are the batteries ?

Batteries should be replaced every two years.

Author

Commented:
Hi Andrew:
Brand new batteries. Brand new UPS.
Is there any rule about always/never fully charging the lead acid batteries?
Or
Is there any rule about always/never fully discharging the lead acid batteries?

Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
UPS should handle all that.
andyaldersaggar maker's framemaker
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Commented:
There is an ideal charging method, https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery describes it, however as Andrew has said the UPS looks after the batteries better than you or I could. Seems odd that you have even taken one out of the UPS.

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Commented:
Hi Andy:
I am working on a project for a small --very small-- manufacturing facility and I'm making the UPSs.
BTW, batteryuniversity is a great site.  Thanks!!!!
VMware and Virtualization Consultant
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David Johnson, CDSimple Geek from the '70s
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Commented:
Don't forget proper ventilation. Lead/Acid batteries give off hydrogen gas when charging. This is an explosion hazard in a confined space.
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
and temperature monitoring and alerting, or you'll be rushed to the hospital like I was with hydron sulphide poisoning...

when a UPS went bad, and charged and boiled a lead acid cell in the datacentre!

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Commented:
Ugggh.  The Lead acid batteries I inherited in this project are not charging.  Not charging at all. These things have been sitting around for over a year.  Could they be useless?

Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
Yes, once the battery voltage drops to a very low voltage they'll not charge.

You need a good charger to recover them, or know the special way to overcome the issue.

never a good idea to keep batteries lying around without float charging.
David Johnson, CDSimple Geek from the '70s
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Commented:
do you have a hygrometer and measure the specific gravity?  https://www.powerstridebattery.com/blog/what-is-a-hydrometer-and-how-do-i-read-one/
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
Sealed! you would have to force the tops off!

Sealed Lead Acid Batteries are maintenance free!

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Commented:
Hi David/Andrew.  I ain't got one of those hygrometers!

What kind of special charger do I need to bring these back to life?




Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
one that can recovery batteries, or try to recover batteries.

a CTEK or NOCO .

But there is no guarantee that it will recover the battery.
David Johnson, CDSimple Geek from the '70s
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Commented:
Is there any rule about always/never fully charging the lead acid batteries?
They should always be fully charged.
Is there any rule about always/never fully discharging the lead acid batteries?
Never fully discharge.

u cant let batteries sit for 4-5 months without charging them. They sulphate and u cant fix that. The batteries would not be any good, thats why they dont charge.
https://batteryuniversity.com/learn/article/how_to_restore_and_prolong_lead_acid_batteries
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Commented:
Lead acid batteries must be maintained it a charged state for storage, even the sealed ones.  If you haven't bee keeping a float charge, those batteries are dead and you need to replace them.  All lead acid batteries start to sulfate when they go below 80% charge, shortening the life of the lead acid battery.  You need to top up the charge at least once a month to keep it above 80% charge while it's in storage.

While lead acid batteries can theoretically last 5-7 years, they have very little charge at the end of the 5th through 7th years, basically dead for UPS purposes.  If your UPS is above 80% load, you must change out your batteries every 2 years, or their won't be enough charge to keep your systems up long enough for a safe shutdown cycle.  You may be able to keep it as long as 3-4 years if your UPS stays below 20% usage.

For every full discharge event that drops your batteries below 80%, you should subtract 3-6 months off the life of your battery depending on how deep the discharge was.  I worked at a site that had nearly quarterly outages from a corrupt utility and I had to replace the batteries at least once per year, depending on the UPS, or there would not be enough battery charge to allow for a safe shutdown.

You can buy individual batteries for about half the price of a UPS pack and connect them up yourself if you're familiar with basic electric wiring.



andyaldersaggar maker's framemaker
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A very low trickle may recover lead-acid batteries but it's probably not worth it since you would then be designing and testing a UPS with batteries that do not behave like normal ones. https://batteryuniversity.com/learn/article/elevating_self_discharge describes how they go dead on the shelf.
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
They sulphate and u cant fix that.

Well, if that's the case...

my CTEK chargers have a de-sulphate mode, and that fixes them!

CTEK are intelligent chargers! they don't just whack volts and amps in.... they have 8 modes of charging....

during COIV-19 whilst all my motors are off the road, they are all connected to CTEK chargers and the batteries.....ensuring they are topped up....and cycled...and pulsed charged

https://www.ctek.com/
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Commented:
That only works because you aren't using or needing the batteries.  You have to super slow charge them to de-sulphate them.  That basically means 7-10 days of charging and downtime while charging them.

https://patch.com/maryland/elkridge/how-to-revive-or-desulphate-a-lead-acid-battery
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Commented:
i have recovered 0 V batteries  with a trickle charger -  but it takes days....
you can shorten the charging after an hour or 2, when the voltage is showing 14 V again- and use the normal charger

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Commented:
Thank you all for amazing insights and tips on this issue. 
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