Upgrading NiMH AA's in dvd player battery pack

[Dan]

I was recently given a portable DVD player for signing up to DirctTV. I
didn't expect it to be the best one on the market (smallish screen for 1
thing) but I thought it would be good for watching a movie during frequent 2
hour plane trips I have to take. Plays fine, decent picture, BUT the
batteries crap out after a little over 1 hour (you'd think at a minimum the
thing would be good for one 2 hour film). So I opened the battery pack & as
I suspected, found 7 NiMH AA cells, marked 1300 mah. I see that NiMH AA's
are available up to around 2700 MAH. Swapping out the cells is
straightforward, but I'm wondering if the current charger would be up to the
task of feeding them. Looks like a fairly decent circuit (multiple ic's,
anyway) which includes a thermistor taped to the cell pack. Whether this is
how the circuit senses a full charge or whether it's an overheat detector, I
don't know. But again, the circuit does appear to be a bit more
sophisticated than those I've seen for drills, etc, which do rely on the
crude temp method to indicate a full charge. Might this charger be able to
handle cells of 2X the capacity of those the unit came with? How could I
test this, short of actually buying & installing the higher amp cells? A
measure of charging current with the present cells, maybe?

TIA

Dan

 

[Charles Schuler]

I was recently given a portable DVD player for signing up to DirctTV. I
didn't expect it to be the best one on the market (smallish screen for 1
thing) but I thought it would be good for watching a movie during frequent
2 hour plane trips I have to take. Plays fine, decent picture, BUT the
batteries crap out after a little over 1 hour (you'd think at a minimum the
thing would be good for one 2 hour film). So I opened the battery pack &
as I suspected, found 7 NiMH AA cells, marked 1300 mah. I see that NiMH
AA's are available up to around 2700 MAH. Swapping out the cells is
straightforward, but I'm wondering if the current charger would be up to
the task of feeding them.

Should be fine.

Looks like a fairly decent circuit (multiple ic's,

anyway) which includes a thermistor taped to the cell pack. Whether this
is how the circuit senses a full charge or whether it's an overheat
detector, I don't know.

Overheat.

But again, the circuit does appear to be a bit more

sophisticated than those I've seen for drills, etc, which do rely on the
crude temp method to indicate a full charge. Might this charger be able
to handle cells of 2X the capacity of those the unit came with?

Should be fine.

How could I

test this, short of actually buying & installing the higher amp cells? A
measure of charging current with the present cells, maybe?

No need to test.

 

[PhattyMo]

I was recently given a portable DVD player for signing up to DirctTV. I
didn't expect it to be the best one on the market (smallish screen for 1
thing) but I thought it would be good for watching a movie during frequent 2
hour plane trips I have to take. Plays fine, decent picture, BUT the
batteries crap out after a little over 1 hour (you'd think at a minimum the
thing would be good for one 2 hour film). So I opened the battery pack & as
I suspected, found 7 NiMH AA cells, marked 1300 mah. I see that NiMH AA's
are available up to around 2700 MAH. Swapping out the cells is
straightforward, but I'm wondering if the current charger would be up to the
task of feeding them. Looks like a fairly decent circuit (multiple ic's,
anyway) which includes a thermistor taped to the cell pack. Whether this is
how the circuit senses a full charge or whether it's an overheat detector, I
don't know. But again, the circuit does appear to be a bit more
sophisticated than those I've seen for drills, etc, which do rely on the
crude temp method to indicate a full charge. Might this charger be able to
handle cells of 2X the capacity of those the unit came with? How could I
test this, short of actually buying & installing the higher amp cells? A
measure of charging current with the present cells, maybe?

TIA

Dan

The charging circuit itself _probably_ limits the current to some "safe"
value,so there's _probably_ no worries about frying the
charger,overcharging the cells,etc.
It will just take 2x as long to fully charge..

 

[Dan]

The charging circuit itself _probably_ limits the current to some "safe"
value,so there's _probably_ no worries about frying the
charger,overcharging the cells,etc.
It will just take 2x as long to fully charge..

Thanks for the replies, I'll give it a try.

Dan