how to trick pcb board

[chowpay]

Hi guys,

Building converting a battery for a friend but running in to problems. The light setup he has is http://www.bikelights.com/Products/solo_logic.htm with a nicad battery 7.2 L&M sells a 11.4 lion.

What I did was order a lion 11.4v from all-battery.com, opened the nicad pack and replaced it with the lion (which fits like a glove btw)

So it works sometimes but when its fully charged it wont even turn on.

My friend's theory is the PCB protection on the board, when I first plug it in spikes to 12,8v which the pcb thinks is a short so it shuts the battery off.

I know the battery works though I use it to power other lights and is fine. But the solo logic is finky

Anyway for me to get this to work, or trick the PCB?

Thanks!

 

[OddOne]

Hi guys,

Building converting a battery for a friend but running in to problems. The light setup he has is http://www.bikelights.com/Products/solo_logic.htm with a nicad battery 7.2 L&M sells a 11.4 lion.

What I did was order a lion 11.4v from all-battery.com, opened the nicad pack and replaced it with the lion (which fits like a glove btw)

So it works sometimes but when its fully charged it wont even turn on.

My friend's theory is the PCB protection on the board, when I first plug it in spikes to 12,8v which the pcb thinks is a short so it shuts the battery off.

I know the battery works though I use it to power other lights and is fine. But the solo logic is finky

Anyway for me to get this to work, or trick the PCB?

Thanks!

One, you're probably tripping the pack's protector circuit's current limit when powering the light up on a full charge.

Two, you do not want to tamper with or disable Li-ION protection boards. Li-ION batteries have enough of a propensity toward "venting with flame" (read: "exploding") as it is, with a properly functioning protection circuit. Monkeying around with it is tantamount to converting the batteries into small explosives.

oO

 

[chowpay]

I heard something like turning the light on and off fast will trick the chip. I couldnt get this to work. Is there anything I can do to lower the voltage output or control it so the battery doesn't shut itself off?

Looks like the manufacture ships a 11.4 Li-ion version .. I just cant see why the one i'm making wouldnt work consistently ?

Thanks

 

[hopkins]

Add a resistor in series to lower the output current when first turned on.
and a switch to short this Resistor once the light fires. (haha)
Make sure the resistor and switch are rated to handle the power
disipation and current.

Please wear breathing protection if the battery 'vents with flame'
so as you fight the fire you do not breathe toxic fumes. Also a camera
to capture the moment!!!:laughing:

 

[chowpay]

:thumbsup:wow thats really helpful ...


Then again partially my fault so let me rephrase my question.

Why would a manufacture battery pack that has the exact same voltage as this one work. While this one wont work unless I drain some of the power first?

 

[hopkins]

You question is 'why?'
I think the answer is that lithium batteries will burst into flames
when discharged wrong or overcharged wrong. Research Li-ion battery.

Note: Here in California a home burned down yesterday caused by a RC car
battery & charger. The boy did not think there was any danger but there was!


The PCB protection inside the Li-ion will try to stop you from doing the wrong
thing. Watch this youtube video of a lithium ion battery fire caused by
people doing the wrong thing to the battery on purpose:

http://www.techeblog.com/index.php/tech-gadget/how-not-to-test-your-computer

You should believe that this will happen to your battery when you force it to
operate wrong. Be ready for explosion, fire, and toxic gas.

Question: how will you make a phone call to the Fire Dept for help when you are blinded by the exploding battery pack?

 

[chowpay]

Once again GREAT ANSWER!!! ... to a question no one asked.

If you read what I said my question is :

" Why would a manufacture battery pack that has the exact same voltage as this one work."

Not why it would blow up if I force it to work.

So i ask this question again. Basically, I'm just trying to figure out the difference between the two packs. The 11.4v manf one and the all-battery 11.4v one.

 

[SilverFox]

Hello Chowpay,

Welcome to CPF.

It sounds like your pack has a high current protection that is lower than the starting current of your light.

Different protection circuits incorporate different values for the high current shut off. If the pack is designed around a specific application, the values used for low voltage cut off and high current shut off can be adjusted to work with the application. Another battery pack with different values may not work.

Tom

 

[chowpay]

Ah thanks that was the kind of answer I was looking for.

Is there any way to replace the PCB board with a different one? I'm just not sure where to get a different board at.

Thanks

 

[hopkins]

Oh! Sorry. They made it that way because its the only way they know how to. In the future they'll get better.

Here is why:
Lithium ion battery have one of the best energy-to-weight ratios, no memory effect, and a slow loss of charge when not in use. They can be dangerous if mistreated and unless care is taken their lifespan may be reduced. Although originally intended for consumer electronics, Lithium-ion batteries are growing in popularity with the defense and aerospace industries because of their high energy density.

lithium atoms are very small compaired to nickel and cadmium atoms so can
pack a lot more of them into a battery thus making it more powerful.

The anode of a conventional Li-ion cell is made from carbon, the cathode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent.

The underlying chemical reaction that allows Li-ion cells to provide electricity is:Li(1-x)CoO2+Li(x)C6 =C6+LiCoO2 which tells you why they burn at over
1000 degrees when 'venting with flame'

It is important to note that lithium ions themselves are not being oxidized; rather, in a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, Co, in LixCoO2 being oxidized from Co3+ to Co4+ during charging, and reduced from Co4+ to Co3+ during discharge.

A particularly important element for activating Li-ion batteries is the solid electrolyte interphase (SEI). Liquid electrolytes in Li-ion batteries consist of solid lithium-salt electrolytes, such as LiPF6, LiBF4, or LiClO4, and organic solvents, such as ether. A liquid electrolyte conducts Li ions, which act as a carrier between the cathode and the anode when a battery passes an electric current through an external circuit. However, solid electrolytes and organic solvents are easily decomposed on anodes during charging, thus preventing battery activation. Nevertheless, when appropriate organic solvents are used for electrolytes, the electrolytes are decomposed and form a solid electrolyte interface at first charge that is electrically insulating and high Li-ion conducting. The interface prevents decomposition of the electrolyte after the second charge. For example, ethylene carbonate is decomposed at a relatively high voltage, 0.7 V vs. Li, and forms a dense and stable interface.

So its an electro-chemistry difference, basically at the SEI.

 

[hopkins]

...but chowpay , you indicated in your original post that you were aware
of the answer Silverfox just gave. How could you not be?
The new battery did not work with the light. You told us all.

 

[SilverFox]

Hello Chowpay,

I believe you can build your own protection circuit and use whatever values you want to. However, you will have to do some testing on the batteries to make sure they can handle the protection values you select. If you make the wrong choices, you may end up with "explosive" results.

There are very few assembled protection circuits available to the general public. Most applications that utilize Li-Ion cells have a custom designed circuit that is specific to a single application.

Tom

 

[chowpay]

I was wondering could this be a possible solution. ... Now I can leave the current pcb board intact. heres my idea:

The pack currently holds 6 cells to achieve 11.1 volts. If I remove 1 of these cells It would drop voltage to 9.45 but it would still run better than the nicad 7.2 it came with.

This should also solve the problem with the power spike. What do you guys think would this be a viable option?

Thanks

 

[hopkins]

Maybe. Can you cut the pack open and post a picture of all
the insides? Give us an idea? The site you got the battery from shows it
contained in blue plastic.

 

[hopkins]

Hi chowpay. Please note that each cell is 3.7volts in your 6 pack.
Do the math and look inside at the connections.

 

[SilverFox]

Hello Chowpay,

You have 11.1 volts with 6 cells. If they are Li-Ion cells, each cell is a nominal 3.7 volts. This means that you have 2 parallel strings of 3 cells. If you remove one pair of cells, your voltage should be down to 7.4 volts.

You also have to run your figures through Ohms law. I believe that if you reduce the voltage, the current increases.

Tom

 

[hopkins]

Hi chowpay - can you confirm that this is the Li-ion batterypack you bought:

Li-Ion 18650 11.1V 4400 mAh Rechargeable Battery Pack with PCB Protection LI18650-111V4400 for $46
You are doing great to save the cost of $275 Li-ion for the Solo Logic
from that site.

Also does your friends Solo Logic bike light switch on High 1st, them Medium
and Low or the reverse order: low, medium high ?

Also can you measure the current with a meter on startup with the old 7.2v battery pack?
How many amps? Confirm the math: W=E * I , 13watts=7.2volts * 1.8amps
Can you confirm approximate 1.8amp value ?
New Li-ion batter pack current should be 1.17amps. The new pack can do this easy!

Your new 11.1v Li-ion should be able to give 1.5C continuous current which
is 6.6amps! (spec for the cell configuration inside the pack)

Solo Logic lamp spec says it can detect low voltage battery packs and
will Not turn on to save the battery. Very smart.

Can you solder all the connections between the new Li-ion battery pack and
the Solo Logic light to see if poor connections are causing a voltage drop ?
That could be why the Solo will not turn on. Its smart.

I have had problems like this using aligator clips that make poor connection
and add resistance. Twisting wires together is fine for low currents but not
the huge current the Solo Logic draws. Crimping connectors/sockets on is best so you can remove it to recharge.

Let us know. We want to help.:welcome: