Ruston Gas turbine cranking battery

[RRaghunath]

Normally, the cranking batteries in automobiles are VRLA batteries that run about 3years on average and need no water top-up.

How about using Sealed Ni-Cd battery for cranking? The requirement is for Gas turbine cranking with battery size of some thing like 230Ah (Ni-Cd) for two crank capability. The location is in the desert with temperatures crossing 50degC at times.

Appreciate if you can share your opinions / experiences!

Thanks.

 

[VEBill]

I had a NiCd battery in my old 1972 Dodge Dart for many years during the 1980s. It was surplus from helicopter service. It worked very very well. On the coldest days (-35C) it cranked over at full speed and started instantly.

Can't comment about turbines.

 

[qassure]

Hi rraghunath
sealed cylidrical ni-cads or low maintenance ni-cads has long life and more efficient. but the peak current requirement decides the selection of batteries. Ni-cads are capable of delivering up to 10C rate (10 times of their Ah rating) for about 20 seconds and 25C rate for about 2 seconds. the is no much change in the efficiency of the battery at 50 degree C.
--QA

 

[ScottyUK]

Big Ni-Cads are hugely expensive compared to a broadly equivalent lead-acid cell. If you don't need specific properties of the Ni-Cad or to avoid certain characteristics of lead-acid (e.g. weight) then lead-acid is normally the better choice from an economic point of view. Have you priced up a 230AH Ni-Cad? Last time I priced big Ni-cads was as an option for a UPS system and they were about 3x the price of an equivalent vented lead-acid.

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Sometimes I only open my mouth to swap feet...

 

[MikeHalloran]

I worked briefly in a Ni-Cd plant. Many folks there built their own car batteries out of cells that had failed FAA qualification tests. They worked just fine, but they'd be very expensive to build from new cells.

( You need 11 x 1.2V Ni-Cd cells to make a practical '12V' car battery. The car system will overcharge ten cells, or die trying. )

( It's a good idea to cover the intercell links of such a battery. The short circuit current of NiCd cells that size is sufficient to melt a dropped wrench. )



Mike Halloran
Pembroke Pines, FL, USA

 

[RRaghunath]

Thanks everyone for sharing.

ScottyUK,
My assessment also is that Ni-Cd are 3times more expensive. But, you know any organisation which specifies Ni-Cd for cranking applications!

 

[ScottyUK]

What the customer specifies, the customer can have... at a price!

The only Ni-Cad cranking batteries I'm aware of are on a couple of fire pumps, and these somewhere around the 60AH size. I don't know why these were originally spec'd as Ni-Cad, but much of this plant was designed by US engineers and we've kinda surmised that the Ni-Cad cranking battery must be from a US standard. If anyone can shed any light I would be interested.

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Sometimes I only open my mouth to swap feet...

 

[qassure]

Ni-cad cells are costly, at the same time it has long life.
it is mostly used aircrafts, metro tarins etc, due to the requirement of high starting current. presently, SAFT (France) is manufacturing Ni-cad batteries for every application which includes electric cars.
--QA

 

[zeusfaber]

Aero applications used to be split down the middle - some aircraft having lead acid, others wet NiCd - to the point where every RAF Battery Shop used to come in two halves - an acid half and an alkaline half (might still do for all I know).

The main argument in favour of NiCd was that after it had been cold-soaked to something like minus 40 (F or C), you stood a better chance of getting a cranking current out of one than from a Lead Acid battery - and since all our current front-line aircraft were specified in the days when we thought the next war was going to be fought somewhere cold,that's what they got.

A.