Moddifing La Crosse BC-700?

Is it possible to modify La Crosse BC-700 so I becomes BC-900/BC-9009 (support higher current values)?

I think that the controllers are the same in all three.

Can someone post pictures of the PCB of BC-900/BC-9009?

I'm not a master of electronics but I think it's possible, just changing few elements or am I wrong?


Sorry for my English.

Even if you dropped all the right components in there, wouldn't you still need to modify the firmware? How are you proposing to do that?

mexusbg said:

Is it possible to modify La Crosse BC-700 so I becomes BC-900/BC-9009 (support higher current values)?

I think that the controllers are the same in all three.

Can someone post pictures of the PCB of BC-900/BC-9009?

I'm not a master of electronics but I think it's possible, just changing few elements or am I wrong?


Sorry for my English.

Click to expand...

the firmware chip is fused in the pbc, you can't remove it without destroy it

you can only change the whole mainboard, but remember that the bc900 need a 3V 4A power supply, the bc700 have a smaller psu if i remember well

Doesn't the firmware chip act just as a switch.
Other components limit the current?
For example change 700mA output to 1000mA (not in the menu) by changing a resistor/adding more transistors or changing it with higher value one.

So that It could charge faster big batteries (I don't need more than 1A current anyway).

1A is good balance to not ruining your cells. But I think 700mA is perfect for charging eneloops!.

Now higher cap cells they just don't last anyways (enegizer 2500 lol.)

With cells like that they are nothing more than to waste your time.

I am doing a test on 6 energizer cells to see how fast they discharge per day. Enegizer claims 6 months. Reality its been almost a week and the cells already halfway discharged of just sitting there.

Is there any good hi cap cells that can reach at least 100 cycles and yet still perform like the eneloops? I guess the only time I would use the 1A charge rate if you really need the cells

I also have a AlkaXline charger that supports 1-2 * AA/AAA, current:
1*AA=1600mA
2*AA=800mA
1*AAA=800mA
2*AAA=400mA.
I relay don't like this charger. But still very compact for traveling. Fast charging (it's pity that it doesn't have option to change the charging current)

I am curious about one thing? is the bc-700 identical as the bc-9009 itself?? the only difference i see is that

BC-700 3v 2.8A (4x700 Firmware V36 Whats new in this version???)
BC-9009 3v 4.0A (4x1000) Firmware V35)

I am assuming La crosse is going by max charging currents to best match the output specs of both AC adapters.

If you'll notice, when you charge 4 batteries at once you only get about 699ma charging current or so. If you're only charging 1 or 2 batteries, I've seen upwards of 715ma. If the power adapter only outputs 2.8A, that's exactly 4x700ma. Something tells me that's where the 700ma limit is...

Has anybody stuck a BC900 power supply onto a BC700?

BatteryCharger said:

If you'll notice, when you charge 4 batteries at once you only get about 699ma charging current or so. If you're only charging 1 or 2 batteries, I've seen upwards of 715ma. If the power adapter only outputs 2.8A, that's exactly 4x700ma. Something tells me that's where the 700ma limit is...

Has anybody stuck a BC900 power supply onto a BC700?

Click to expand...

Funny how you say this. on my BC900 when using the 700mA rate. all 4 channels are 699-702.

BatteryCharger said:

Has anybody stuck a BC900 power supply onto a BC700?

Click to expand...

Either it will do nothing different (most likely case) or it will blow up. There is nothing to be gained either way. Because of course having an additional 1.2A available from the power supply won't change how much the device draws.

And errr... for anyone who happens upon this thread, screwing with the power supplies on any LaCrosse charger is not something you want to be doing unless your insurance is paid up.

By the way, the 2.8A @ 3V figure has nothing to do with the fact that 4x700mA is also 2.8A. It's coincidence. They are different voltages. More power is coming out of the wall than is being sent to your cells. Which is the way it has to be in this universe.

core said:

They are different voltages More power is coming out of the wall than is being sent to your cells. Which is the way it has to be in this universe.

Click to expand...

I quite don't follow?

core said:

Because of course having an additional 1.2A available from the power supply won't change how much the device draws.

Click to expand...

Yes and no. It depends on what is limiting the device, which, apparently none of us have quite figured out. It may in fact be the power supply amperage.

core said:

By the way, the 2.8A @ 3V figure has nothing to do with the fact that 4x700mA is also 2.8A. It's coincidence. They are different voltages. More power is coming out of the wall than is being sent to your cells. Which is the way it has to be in this universe.

Click to expand...

I'm fully aware of ohms law and the law of conservation of energy. The "voltage overhead" is what the charger runs on, the LCD display, etc. The batteries are only getting roughly half of the voltage from the 2.8 amp power supply, but they're still getting the FULL 2.8 amps. It's not a coincidence, the charger would not be able to charge 4x700ma if it only had a 2.5 amp power supply.

If it had a 4 amp power supply would it charge at 1 amp each? I don't know, has anyone tried?

MAYBE there is another part limiting the current, MAYBE not...I don't think anyone has figured that out yet.

one way to find out is I can first take a reading without any cells just to make sure the voltage matches on the drive bay (idle) and then start adding cells one by one and take another reading for different charge rate and see what the multimeter reads. and then take another reading by removing cells one by one with combination of charge rates and see how much voltage is left over.

My theory is that if the ac adapter is 3V the charger is getting exactly 3V and top of that (4x1000) 4.0A (not from the AC outlet but the adapter only). This type of setup is to simply things resulting smaller ac adapter. But I think this can be risky that if you use a third party adapter and the voltage is slightly higher than it should well you know the rest no need to revisit the melting stories lol. As for the C9000 charger AC adapter is 12V going to the charger and then gets step down again to 2 volts (thinking the charger itself does this correct me if I am wrong here) where it goes to the cells (final stage). This setup is good and reliable but the down side its one bulky adapter and charger lol. Well the charger is big for other reasons.

Again this is all theories and what I think is the reason why La crosse went that route.

Now this does not mean its drawing 4A from the AC outlet its much lesser than that maybe 1/2 A maybe??

And core is correct I don't think this charger has any voltage overhead at all.

Stay tune for the results!

BatteryCharger said:

The "voltage overhead" is what the charger runs on, the LCD display, etc. The batteries are only getting roughly half of the voltage from the 2.8 amp power supply, but they're still getting the FULL 2.8 amps.

Click to expand...

Sorry, but you are way off base here. The charger doesn't have "voltage overhead". It requires excess power for all the trinkets you mentioned. Not voltage.

It's not a coincidence, the charger would not be able to charge 4x700ma if it only had a 2.5 amp power supply.

Click to expand...

Again, wrong. It could very easily deliver 2.8A to the batteries with only a 0.5A power supply depending on the supply voltage. And that is precisely what a car battery charger does. Set your car battery charger to 75 amp engine start and do you think it's sucking 75A out of your wall socket? LOL no of course not.

You may be familar with V=IR, but apparently not P=IV.

Presuming the BC-700 could be modified to match the charging current of the BC-900, there's a very good chance it would experience the same type of failures as the BC-9x series if they share major components.

According to forum member Russel in this post, the BC-700's 3.0 volt, 2.8 ampere power supply actually outputs 3.153 volts, which places its output voltage in the same neighborhood as that of the out-of-specification BC-9009 power supply which further exposed the BC-9x series vulnerability to melt-downs.

Cautionary reading for owners of the BC-9x and owners of the BC-700 considering a modification to raise its charging current:

http://www.candlepowerforums.com ... post1550244
.

core said:

It could very easily deliver 2.8A to the batteries with only a 0.5A power supply depending on the supply voltage.

Click to expand...

This is ASSUMING the BC700 has the built in high efficiency DC-DC converter to convert higher voltage/lower amperage into the opposite. I have yet to see anybody demonstrate this...

Something tells me they wouldn't use such an odd 3v, high amperage power supply if the BC700 was going use a DC-DC converter as well. Might as well go with a normal 5 or 12 volt power supply.

Let's see...

Four NiMH AA cells charging at 2.8 amps:

4(cells)*1.4V*2.8A = 15.68 Watts

15.68W/115V = 0.136A

0.136A/.5(50% efficiency) = .272 Amps at 115 volts from the wall socket.

But:

15.68W/3V = 5.23 amps

So, ½ Amp at 115 volts would supply enough power to charge 4 NiMH cells at 2.8 amps. (assuming 1.4 volts per cell)

But, the AC adapter that comes with the BC-700 wouldn't be able to supply 5.23 amps (or more depending upon efficiency) at 3 volts.

--------------------

Let's look at some BC-700 numbers:

4(cells) * 1.4V (nominal charging voltage) * .700A (charging current) = 3.92 Watts

3.92W / 3V(AC adapter output) = 1.31 Amps

1.31A / .5 (50% efficiency) = 2.62 Amps

So, about 2.62 Amps at 3 volts required at the BC-700 charger input in order to charge four NiMH AA cells at 700mA.

As I understand it the BC-700 has a linear mode regulator rather than the more efficient switching mode regulator, that is why I am guessing at 50% efficiency. The AC adapter has an actual output of up to 2.8A at 3V, so I don't think that I'm too far off.