UPS Battery Type for Elevated Room Temperatures
UPS Battery Type for Elevated Room Temperatures
(OP)
Need to specify batteries for a warehouse location, winter temp of 55F and summer temp of 95F, for a UPS application. Reluctant to use convential lead calcium because prior experience in this environment resulted in short service life.
Any recommendations for chemistry, construction, or manufacturer.
thanks
Any recommendations for chemistry, construction, or manufacturer.
thanks





RE: UPS Battery Type for Elevated Room Temperatures
RE: UPS Battery Type for Elevated Room Temperatures
RE: UPS Battery Type for Elevated Room Temperatures
This attitude will not get you much mileage here. Like it or not, Mike's advice is sound. There are more than one mfrs.
Although you may get lucky and some will answer to your liking. Stay tuned.
Rafiq Bulsara
http://www.srengineersct.com
RE: UPS Battery Type for Elevated Room Temperatures
I might suggest that a reduced service life is probably due to lack of maintenance by the user, especially checking and topping up the electrolyte. If these are sealed gell cells, you are doomed.
I would still prefer flooded lead acid cells, the Ah capacity increases with temperature, but the charging voltage absolutely must be reduced.
Something like fork lift batteries would be my choice.
Try to find a properly temperature compensated battery charger with a temperature sensor that can be attached direct to the battery case, it is the electrolyte temperature that is important, not ambient.
I believe this may be the solution to your problem.
From memory, the required compensation is -3mV per cell per degree Celsius.
As your UPS probably has a fairly high voltage battery, the change in charging voltage with temperature can be significant.
If charging rate is quite high, electrolyte temperature is even more important than ambient.
One last thought.
Automotive batteries work in ambient under hood temperatures of around 85C, and at very high charging currents, and they work just fine. So it is possible.
RE: UPS Battery Type for Elevated Room Temperatures
It something I've done on numerous occasions where the ambient temperatures were going to kill off the batteries in quick time.
RE: UPS Battery Type for Elevated Room Temperatures
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If we learn from our mistakes I'm getting a great education!
RE: UPS Battery Type for Elevated Room Temperatures
Australia no longer has any facilities for disposal of these batteries and the last lot I had to get rid of, quite a few years ago, had to be shipped to New Zealand. The client wasn't exactly a happy camper when told the cost of disposal was nearly as much as he was paying for the new set of sealed lead acid.
RE: UPS Battery Type for Elevated Room Temperatures
In a previous incarnation (a long long time ago) I was battery applications engineer at Saft Nife in Australia.
Despite the enthusiasm of our battery sales staff, many customers had to be revived and treated for nervous shock, after receiving an initial quotation for a large bank of flooded nicads.
RE: UPS Battery Type for Elevated Room Temperatures
What about NMH, nickel metal hydride, batteries. I've read that they are being built in stationary class, look like regular lead acid. NiHM is supposed to be heat tolerant.
The other thing is lead acid but with different chemistry or design. I thought I read that lead calcium batteries could be had with different plate thicknesses, and the thicker plates were more forgiving in terms of longevity.
The other thing is lead selenium instead of lead calcium. They are supposed to be more heat tolerant.
Its hard to tell from the manufacturer's literature. They will claim something like "operating range 45-115F..." but any battery will 'operate' at those temperature, I need to know if the life expectancy is going to be reduced.
I appreciate all the input so far.
RE: UPS Battery Type for Elevated Room Temperatures
Battery Ah capacity is always rated at the standard ten hour discharge rate, as the discharge rate increases, the achievable Ah capacity falls off quite dramatically.
The problem being, that not all batteries are suitable for such a very high discharge rate. One of the reasons I suggested fork lift batteries is that they are internally very rugged and capable of this type of short term discharge, and you buy them as individual cells.
I would not worry so much about battery chemistry, as the extreme discharge characteristics you will be demanding.
As stated earlier, I believe money spent on a good quality temperature compensated battery charger will go a very long way to prolonging battery life.
When you initially size your batteries, allow plenty of excess capacity, because achievable capacity to the end point voltage will gradually fall off with time.
If you design it only for ten minutes holdup time, it won't take long to drop to nine minutes, then eight minutes....
RE: UPS Battery Type for Elevated Room Temperatures
Disposal of NiCads is more costly than lead-acid: one of our contractors will remove lead-acid types at no cost to us, while NiCads attract a premium.
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If we learn from our mistakes I'm getting a great education!
RE: UPS Battery Type for Elevated Room Temperatures
95 is nothing to LA batteries - if - you do as suggested and control the charging to the actual battery temperature.
You'd probably be better off using LA with a compensated charger and Hydro caps than breaking new ground in battery applications. That is unless your business is in UPSs, or your application actually sees 130~140F.
Keith Cress
kcress - http://www.flaminsystems.com