NIMH Batteries

Dear List,
It is time to replace one of the battery packs for my sailplane. I
currently use packs consisting of 7 2.5V SLA batteries to make a 14V
pack. This has worked very well for me in the past but the AH on these
cells is somewhat limited. I would like to ad a transponder and
possibly some type of collision avoidance device so I am looking to
upgrade the power supply. I have seen Nickel Metal Hydrate batteries
that come in 12V and 10 to 14 AH sized the same as the SLA batteries
alot of the glider people are using. There is a company in the UK ,
ATSI, who markets these NIMH batteries for aviation use. My question
is does anyone on the list have any experience with these or any other
12V NIMH batteries for glider use. I dont mind using the sealed lead
acid batteries but the NIMH has many advantages . And yea, I know
price isnt one of them.
Thanks

I dont mind using the sealed lead
acid batteries but the NIMH has many advantages . And yea, I know
price isnt one of them.
Thanks

NIMH?!? If cost doesn't frighten you, then why not LiFePO4?
http://www.valence.com/products/batt...es/u-charge_xp
http://www.valence.com/sites/all/the...ta%20Sheet.pdf
http://www.valence.com/products/batt...es/u-charge_rt
(integrated battery maintenance version...)
http://www.valence.com/sites/all/the...ta%20Sheet.pdf
Kick a$$ batteries with 1/4-20 threaded connections to boot...but
certainly not cheap. Just talked to a nice lady there at Valence, and
for reference:

40 amp/hr is $800 (U1-12XP, their battery which is the same size as a
12v 12 amp/hr lead brick but half the weight)
24 amp/hr is $600 ( U1-12RTL, same size/weight as above but with
built in battery management system)
Both series are claimed to be able to be charged on most standard lead
acid chargers (set for AGM/GEL cells)

-Paul

On Dec 4, 12:45*pm, sisu1a wrote:


*40 amp/hr is $800 (U1-12XP, their battery which is the same size as a
12v 12 amp/hr lead brick but half the weight)
*24 amp/hr is $600 ( U1-12RTL, same size/weight as above but with
built in battery management system)
Both series are claimed to be able to be charged on most standard lead
acid chargers (set for AGM/GEL cells)

-Paul

Paul, thanks for the links, I never knew these existed . If one can
actually get "Thousands of cycles" then these would be much more
affordable than the steep initial cost might sugest. Have you been
using one in your plane ?
Thanks

On Dec 4, 11:11*am, K M wrote:
Dear List,
It is time to replace one of the battery packs for my sailplane. I
currently use packs consisting of 7 2.5V SLA batteries to make a 14V
pack. This has worked very well for me in the past but the AH on these
cells is somewhat limited. I would like to ad a transponder and
possibly some type of collision avoidance device so I am looking to
upgrade the power supply. I have seen Nickel Metal Hydrate batteries
that come in 12V and 10 to 14 AH sized the same as the SLA batteries
alot of the glider people are using. There is a company in the UK ,
ATSI, who markets these NIMH batteries for aviation use. My question
is does anyone on the list have any experience with these or any other
12V NIMH batteries for glider use. I dont mind using the sealed lead
acid batteries but the NIMH has many advantages . And yea, I know
price isnt one of them.
Thanks

I assume the reason you hand made a 7 cell SLA battery is you needed
the higher voltage for some fussy electronics? Modern electronics
should work fine on the voltages output from a conventional 6 cell SLA
battery - of course until the voltage falls below a critical point.
Was there a particular device that needed the higher voltage? Without
that need just using that volume to accommodate extra battery capacity
and a standard 6 cell battery will be easier and cheaper. Of course
another reason might just be you have strange space requirements and
fitting in 7 cells of a particular size was the best way to go.

If you have got voltage sensitive equipment NiMH offers the benefit of
a flatter discharge curve than lead-acid (in addition obviously to
more Ah/volume). Of course that can also bite in making it less
obvious what the remaining battery capacity is.

Darryl

On Dec 4, 12:02*pm, K M wrote:
On Dec 4, 12:45*pm, sisu1a wrote:



*40 amp/hr is $800 (U1-12XP, their battery which is the same size as a
12v 12 amp/hr lead brick but half the weight)
*24 amp/hr is $600 ( U1-12RTL, same size/weight as above but with
built in battery management system)
Both series are claimed to be able to be charged on most standard lead
acid chargers (set for AGM/GEL cells)

-Paul

Paul, thanks for the links, I never knew these existed . If one can
actually get "Thousands of cycles" then these would be much more
affordable than the steep initial cost might sugest. Have you been
using one in your plane ?
Thanks

If you could live long enough to utilize even a thousand cycles,
maybe. I get 4 years service from my 14 volt (10 ah 2v glued to 10 ah
12v) pack, for around $80.00. To meet the same $/yr figure I'd have
to fly another 30years, which is unlikely.

On Dec 4, 12:11*pm, K M wrote:
Dear List,
I have been thinking of using 10 of these 10,000 mAh NiMH batteries
for a separate transponder circuit in my sailplane. Light weight, 1000
cycles and only moderately expensive. Use 10 or 12 depending upon your
needs. Packs and connectors are easy to fabricate.

http://www.all-battery.com/dsizeseri...batteries.aspx

I have one of their 3200 mAh pre-made packs and capacity was as
advertised.



It is time to replace one of the battery packs for my sailplane. I
currently use packs consisting of 7 2.5V SLA batteries to make a 14V
pack. This has worked very well for me in the past but the AH on these
cells is somewhat limited. I would like to ad a transponder and
possibly some type of collision avoidance device so I am looking to
upgrade the power supply. I have seen Nickel Metal Hydrate batteries
that come in 12V and 10 to 14 AH sized the same as the SLA batteries
alot of the glider people are using. There is a company in the UK ,
ATSI, who markets these NIMH batteries for aviation use. My question
is does anyone on the list have any experience with these or any other
12V NIMH batteries for glider use. I dont mind using the sealed lead
acid batteries but the NIMH has many advantages . And yea, I know
price isnt one of them.
Thanks

Would that be 100,000 mAh?

Sounds like a lot but maybe not for a glider with a 15000 mm wingspan.

2NO

On Dec 4, 2:07*pm, Tuno wrote:
Would that be 100,000 mAh?

10 cells of 10,000mAh capacity in series is still 10,000mAh capacity.
Only the voltage increases. I don't know why the spec is in mAh
instead of Ah, perhaps because the capacity of D type cells used to be
less than 1Ah?

Andy

Slightly hijacking this thread:

Can anybody recommend a reliable manufacturer of NiMH batteries.

I've tried a variety of makes of 2 - 2.4 Ah AA cells for running digital
cameras and have to say I'm far from impressed.

I have two good chargers (a Vencon which is mains driven and controlled
by a PC and a Pro-Peak Prodigy II which runs off 12v and designed for
field charging RC aircraft batteries). Both are peak chargers and can
record the mAh during charge and test discharge.

I've yet to try a NiMH brand that comes near its rated capacity. Most
show an, ahem, spectacular drop in capacity during subsequent cycles.

I've never had any of this nonsense from NiCd cells: they 'just
work' (unless made by GP).

Bottom line: unless I can find a brand of NiMH that does what it says on
the tin there's no way I'm going to spend good money on using them to
replace SLAs or trust them to last out a decent xc flight.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Dec 4, 3:21*pm, Martin Gregorie
wrote:
Slightly hijacking this thread:

Can anybody recommend a reliable manufacturer of NiMH batteries.

I've tried a variety of makes of 2 - 2.4 Ah AA cells for running digital
cameras and have to say I'm far from impressed.

My experience with NiMH in digital cameras is similar. I have gone
back to using disposable alkaline cells in my DSLR.

Andy