Questions on NiMH Batteries

Thanks to all.

It looks like NiMH batteries are out of the question for me. I have a
10 Ah LiFePO4 drop-in replacement as my main battery and am very happy
with its performance. I'm looking for LiFePO4 cells (and BMS) for
protection that can fit in my tail battery box. The dimensions of the
drop-in box a

Length = 58 cm
Width = 3.5 cm
Height = 6.5 cm

No luck so far, but I'm continuing the search. I could also build up a
pack for a separate box which I've installed behind the seat back. Its
dimensions a

Length = 36 cm
Width = 4.8 cm
Height = 10.8 cm

Any suggestions would be most welcome. I've been searching the net, but
nothing yet satisfies my specific needs.

Dan

On 2/26/2015 8:16 AM, Pierre Vav wrote:
Hi,

I have a pack of 11 9ah Nimh 1,2 v as a backup battery in the tail of my Lak17.
They have the same format as alkaline D cells.
I use a RC charger that automatically detects the right number of elements.
At end of charge, voltage is arount 16,2 volts, but drops quickly to under 16. Also cable length drops voltage to something usable by instruments (15v).

As it is a backup battery, I use it after the main 9ah pb is lowered down, so voltage is ok.

I never had any problems with these batteries. But they are old now, and i plan to replace them with lifepo4.
also nimh auto discharge force me to derig the tail very often. With Lifepo4, If I do not use the backup, no need to derig.



--
Dan Marotta

It looks like this will fit the bill for me:
*http://www.bioennopower.com/products...tery-pvc-pack*.
It's a 12v 12 Ah soft pack with BMC and charger. It appears it will
slide right into my tig welded covered aluminum box where it will be
padded with foam and secure from any stresses.

It will be a simple matter to pull it out and take it home for
charging. I'll simply reload the (mostly) dead lead batteries back into
the tail box for weight and balance purposes. They won't be connected
any more.

On 2/26/2015 10:13 AM, Dan Marotta wrote:
Thanks to all.

It looks like NiMH batteries are out of the question for me. I have a
10 Ah LiFePO4 drop-in replacement as my main battery and am very happy
with its performance. I'm looking for LiFePO4 cells (and BMS) for
protection that can fit in my tail battery box. The dimensions of the
drop-in box a

Length = 58 cm
Width = 3.5 cm
Height = 6.5 cm

No luck so far, but I'm continuing the search. I could also build up
a pack for a separate box which I've installed behind the seat back.
Its dimensions a

Length = 36 cm
Width = 4.8 cm
Height = 10.8 cm

Any suggestions would be most welcome. I've been searching the net,
but nothing yet satisfies my specific needs.

Dan

On 2/26/2015 8:16 AM, Pierre Vav wrote:
Hi,

I have a pack of 11 9ah Nimh 1,2 v as a backup battery in the tail of my Lak17.
They have the same format as alkaline D cells.
I use a RC charger that automatically detects the right number of elements.
At end of charge, voltage is arount 16,2 volts, but drops quickly to under 16. Also cable length drops voltage to something usable by instruments (15v).

As it is a backup battery, I use it after the main 9ah pb is lowered down, so voltage is ok.

I never had any problems with these batteries. But they are old now, and i plan to replace them with lifepo4.
also nimh auto discharge force me to derig the tail very often. With Lifepo4, If I do not use the backup, no need to derig.



--
Dan Marotta

--
Dan Marotta

On Thursday, February 26, 2015 at 4:06:54 PM UTC-5, Dan Marotta wrote:
It looks like this will fit the bill for me:* http://www.bioennopower.com/products...ery-pvc-pack.*
It's a 12v 12 Ah soft pack with BMC and charger.* It appears it will
slide right into my tig welded covered aluminum box where it will be
padded with foam and secure from any stresses.



It will be a simple matter to pull it out and take it home for
charging.* I'll simply reload the (mostly) dead lead batteries back
into the tail box for weight and balance purposes.* They won't be
connected any more.




On 2/26/2015 10:13 AM, Dan Marotta
wrote:




Thanks to all.



It looks like NiMH batteries are out of the question for me.* I
have a 10 Ah LiFePO4 drop-in replacement as my main battery and am
very happy with its performance.* I'm looking for LiFePO4 cells
(and BMS) for protection that can fit in my tail battery box.* The
dimensions of the drop-in box a



Length = 58 cm

Width = 3.5 cm

Height = 6.5 cm



No luck so far, but I'm continuing the search.* I could also build
up a pack for a separate box which I've installed behind the seat
back.* Its dimensions a



Length = 36 cm

Width = 4.8 cm

Height = 10.8 cm



Any suggestions would be most welcome.* I've been searching the
net, but nothing yet satisfies my specific needs.



Dan




On 2/26/2015 8:16 AM, Pierre Vav
wrote:



Hi,

I have a pack of 11 9ah Nimh 1,2 v as a backup battery in the tail of my Lak17.
They have the same format as alkaline D cells.
I use a RC charger that automatically detects the right number of elements.
At end of charge, voltage is arount 16,2 volts, but drops quickly to under 16. Also cable length drops voltage to something usable by instruments (15v).

As it is a backup battery, I use it after the main 9ah pb is lowered down, so voltage is ok.

I never had any problems with these batteries. But they are old now, and i plan to replace them with lifepo4.
also nimh auto discharge force me to derig the tail very often. With Lifepo4, If I do not use the backup, no need to derig.







--

Dan Marotta




--

Dan Marotta

Hi Dan,

Even if you're only using the old LA batteries for ballast (in the tail)..... I would NOT recommend it.
LA (Lead Acid) batteries will suffer from "plate sulfation", basically the "battery form of rust". This causes the battery plates to swell, sometimes a LOT. This can cause the pack to wedge itself into a fixed compartment as well as crack the case letting out the small amount of electrolyte contained within to go "where ever it wants" (basically down.... attacking anything,like steel..... "control cables/rods anyone?").

Take this info from an "Ex UPS battery monitoring person" with ~15 years in the industry. I have seen batteries explode/crack cases more than once.

You want weight, get lead bricks, please DON'T use old LA batteries..........

UmmmmK?!
;-)

Thanks for that great advice, Charlie! I will find lead bricks or shot
which I can load into the box. Bricks or sheet will be better, of course.

On 2/26/2015 2:34 PM, Charlie M. (UH & 002 owner/pilot) wrote:
On Thursday, February 26, 2015 at 4:06:54 PM UTC-5, Dan Marotta wrote:
It looks like this will fit the bill for me: http://www.bioennopower.com/products...ttery-pvc-pack.
It's a 12v 12 Ah soft pack with BMC and charger. It appears it will
slide right into my tig welded covered aluminum box where it will be
padded with foam and secure from any stresses.



It will be a simple matter to pull it out and take it home for
charging. I'll simply reload the (mostly) dead lead batteries back
into the tail box for weight and balance purposes. They won't be
connected any more.




On 2/26/2015 10:13 AM, Dan Marotta
wrote:




Thanks to all.



It looks like NiMH batteries are out of the question for me. I
have a 10 Ah LiFePO4 drop-in replacement as my main battery and am
very happy with its performance. I'm looking for LiFePO4 cells
(and BMS) for protection that can fit in my tail battery box. The
dimensions of the drop-in box a



Length = 58 cm

Width = 3.5 cm

Height = 6.5 cm



No luck so far, but I'm continuing the search. I could also build
up a pack for a separate box which I've installed behind the seat
back. Its dimensions a



Length = 36 cm

Width = 4.8 cm

Height = 10.8 cm



Any suggestions would be most welcome. I've been searching the
net, but nothing yet satisfies my specific needs.



Dan




On 2/26/2015 8:16 AM, Pierre Vav
wrote:



Hi,

I have a pack of 11 9ah Nimh 1,2 v as a backup battery in the tail of my Lak17.
They have the same format as alkaline D cells.
I use a RC charger that automatically detects the right number of elements.
At end of charge, voltage is arount 16,2 volts, but drops quickly to under 16. Also cable length drops voltage to something usable by instruments (15v).

As it is a backup battery, I use it after the main 9ah pb is lowered down, so voltage is ok.

I never had any problems with these batteries. But they are old now, and i plan to replace them with lifepo4.
also nimh auto discharge force me to derig the tail very often. With Lifepo4, If I do not use the backup, no need to derig.







--

Dan Marotta




--

Dan Marotta
Hi Dan,

Even if you're only using the old LA batteries for ballast (in the tail).... I would NOT recommend it.
LA (Lead Acid) batteries will suffer from "plate sulfation", basically the "battery form of rust". This causes the battery plates to swell, sometimes a LOT. This can cause the pack to wedge itself into a fixed compartment as well as crack the case letting out the small amount of electrolyte contained within to go "where ever it wants" (basically down.... attacking anything,like steel..... "control cables/rods anyone?").

Take this info from an "Ex UPS battery monitoring person" with ~15 years in the industry. I have seen batteries explode/crack cases more than once.

You want weight, get lead bricks, please DON'T use old LA batteries.........

UmmmmK?!
;-)

--
Dan Marotta

On Thursday, February 26, 2015 at 5:23:56 PM UTC-5, Dan Marotta wrote:
Thanks for that great advice, Charlie!* I will find lead bricks or
shot which I can load into the box.* Bricks or sheet will be better,
of course.


I like these shot bags. Mix-n-match to get the weight that you want. Easy to swap out if you have someone heavier flying the ship.

http://amzn.com/B0034ZECX4

On Thursday, February 26, 2015 at 5:23:56 PM UTC-5, Dan Marotta wrote:
Thanks for that great advice, Charlie!* I will find lead bricks or
shot which I can load into the box.* Bricks or sheet will be better,
of course.




On 2/26/2015 2:34 PM, Charlie M. (UH
& 002 owner/pilot) wrote:



On Thursday, February 26, 2015 at 4:06:54 PM UTC-5, Dan Marotta wrote:


It looks like this will fit the bill for me:* http://www.bioennopower.com/products...ery-pvc-pack.*
It's a 12v 12 Ah soft pack with BMC and charger.* It appears it will
slide right into my tig welded covered aluminum box where it will be
padded with foam and secure from any stresses.



It will be a simple matter to pull it out and take it home for
charging.* I'll simply reload the (mostly) dead lead batteries back
into the tail box for weight and balance purposes.* They won't be
connected any more.




On 2/26/2015 10:13 AM, Dan Marotta
wrote:




Thanks to all.



It looks like NiMH batteries are out of the question for me.* I
have a 10 Ah LiFePO4 drop-in replacement as my main battery and am
very happy with its performance.* I'm looking for LiFePO4 cells
(and BMS) for protection that can fit in my tail battery box.* The
dimensions of the drop-in box a



Length = 58 cm

Width = 3.5 cm

Height = 6.5 cm



No luck so far, but I'm continuing the search.* I could also build
up a pack for a separate box which I've installed behind the seat
back.* Its dimensions a



Length = 36 cm

Width = 4.8 cm

Height = 10.8 cm



Any suggestions would be most welcome.* I've been searching the
net, but nothing yet satisfies my specific needs.



Dan




On 2/26/2015 8:16 AM, Pierre Vav
wrote:



Hi,

I have a pack of 11 9ah Nimh 1,2 v as a backup battery in the tail of my Lak17.
They have the same format as alkaline D cells.
I use a RC charger that automatically detects the right number of elements.
At end of charge, voltage is arount 16,2 volts, but drops quickly to under 16. Also cable length drops voltage to something usable by instruments (15v).

As it is a backup battery, I use it after the main 9ah pb is lowered down, so voltage is ok.

I never had any problems with these batteries. But they are old now, and i plan to replace them with lifepo4.
also nimh auto discharge force me to derig the tail very often. With Lifepo4, If I do not use the backup, no need to derig.







--

Dan Marotta




--

Dan Marotta


Hi Dan,

Even if you're only using the old LA batteries for ballast (in the tail)..... I would NOT recommend it.
LA (Lead Acid) batteries will suffer from "plate sulfation", basically the "battery form of rust". This causes the battery plates to swell, sometimes a LOT. This can cause the pack to wedge itself into a fixed compartment as well as crack the case letting out the small amount of electrolyte contained within to go "where ever it wants" (basically down.... attacking anything,like steel..... "control cables/rods anyone?").

Take this info from an "Ex UPS battery monitoring person" with ~15 years in the industry. I have seen batteries explode/crack cases more than once.

You want weight, get lead bricks, please DON'T use old LA batteries..........

UmmmmK?!
;-)





--

Dan Marotta

NP, glad to add something worthwhile.
;-)

Been shopping for lead for the past couple of hours and finally settled
on lead ingots. I've ordered 10 pounds and, if they don't simply slip
into the battery box, they can be easily cut to fit. I'll be replacing 6
lb of batteries and moving the dry CG aft from 73% to 79%. I have
enough capacity in the tail ballast tank to move it further aft as I like.

The shot bags looked nice, but their form factor would not fit into the
box which is very long and thin. I also considered lead shot which
would have required me to line the battery box with aluminum foil and/or
plastic wrap, pour in the shot, and then pour in epoxy to stabilize the
load. The walls of the battery box are thin fiberglass and I would not
have wanted any flexing to release shot into the lower fin area.

All's well now - just waiting for Christmas to arrive!

On 2/26/2015 8:22 PM, Charlie M. (UH & 002 owner/pilot) wrote:
On Thursday, February 26, 2015 at 5:23:56 PM UTC-5, Dan Marotta wrote:
Thanks for that great advice, Charlie! I will find lead bricks or
shot which I can load into the box. Bricks or sheet will be better,
of course.




On 2/26/2015 2:34 PM, Charlie M. (UH
& 002 owner/pilot) wrote:



On Thursday, February 26, 2015 at 4:06:54 PM UTC-5, Dan Marotta wrote:


It looks like this will fit the bill for me: http://www.bioennopower.com/products...ttery-pvc-pack.
It's a 12v 12 Ah soft pack with BMC and charger. It appears it will
slide right into my tig welded covered aluminum box where it will be
padded with foam and secure from any stresses.



It will be a simple matter to pull it out and take it home for
charging. I'll simply reload the (mostly) dead lead batteries back
into the tail box for weight and balance purposes. They won't be
connected any more.




On 2/26/2015 10:13 AM, Dan Marotta
wrote:




Thanks to all.



It looks like NiMH batteries are out of the question for me. I
have a 10 Ah LiFePO4 drop-in replacement as my main battery and am
very happy with its performance. I'm looking for LiFePO4 cells
(and BMS) for protection that can fit in my tail battery box. The
dimensions of the drop-in box a



Length = 58 cm

Width = 3.5 cm

Height = 6.5 cm



No luck so far, but I'm continuing the search. I could also build
up a pack for a separate box which I've installed behind the seat
back. Its dimensions a



Length = 36 cm

Width = 4.8 cm

Height = 10.8 cm



Any suggestions would be most welcome. I've been searching the
net, but nothing yet satisfies my specific needs.



Dan




On 2/26/2015 8:16 AM, Pierre Vav
wrote:



Hi,

I have a pack of 11 9ah Nimh 1,2 v as a backup battery in the tail of my Lak17.
They have the same format as alkaline D cells.
I use a RC charger that automatically detects the right number of elements.
At end of charge, voltage is arount 16,2 volts, but drops quickly to under 16. Also cable length drops voltage to something usable by instruments (15v).

As it is a backup battery, I use it after the main 9ah pb is lowered down, so voltage is ok.

I never had any problems with these batteries. But they are old now, and i plan to replace them with lifepo4.
also nimh auto discharge force me to derig the tail very often. With Lifepo4, If I do not use the backup, no need to derig.







--

Dan Marotta




--

Dan Marotta


Hi Dan,

Even if you're only using the old LA batteries for ballast (in the tail).... I would NOT recommend it.
LA (Lead Acid) batteries will suffer from "plate sulfation", basically the "battery form of rust". This causes the battery plates to swell, sometimes a LOT. This can cause the pack to wedge itself into a fixed compartment as well as crack the case letting out the small amount of electrolyte contained within to go "where ever it wants" (basically down.... attacking anything,like steel..... "control cables/rods anyone?").

Take this info from an "Ex UPS battery monitoring person" with ~15 years in the industry. I have seen batteries explode/crack cases more than once.

You want weight, get lead bricks, please DON'T use old LA batteries.........

UmmmmK?!
;-)





--

Dan Marotta
NP, glad to add something worthwhile.
;-)

--
Dan Marotta

Hey Dan -

Why not just use water for tail ballast and not have so much weight up high? Possibly a freezing problem at altitude?