Surf PI power question

[neptune769]

Hi Everyone,

Placed my order today for the Surf PI kit. I have some questions about the batteries. I would like to use Li-Ion cells. But if I use 3 cells that is 11.1 volts nominal and 12.6 peak. A 4 cell pack is 14.8 nominal and 16.8 peak. I assume the 3 cell pack is to low. My question is will the Surf Pi handle the 16.8v? I thought I saw a post somewhere in the forum that discusses this. But I can't find it or remember what is said. If someone can point me in the right directions I would appreciate it.

Regards,
Dennis

[Carl-NC]

The regulator can handle well above 17v, but the 555 timer is limited to ~15v. There may be a higher voltage rated 555, not sure, or you could kludge in 2 or 3 diodes to the ground pin.

[ApBerg]

Hi Everyone,

Placed my order today for the Surf PI kit. I have some questions about the batteries. I would like to use Li-Ion cells. But if I use 3 cells that is 11.1 volts nominal and 12.6 peak. A 4 cell pack is 14.8 nominal and 16.8 peak. I assume the 3 cell pack is to low. My question is will the Surf Pi handle the 16.8v? I thought I saw a post somewhere in the forum that discusses this. But I can't find it or remember what is said. If someone can point me in the right directions I would appreciate it.

Regards,
Dennis

The surf works nice on your 3 cells , 11.1 volt ... current the surf take's is ca 50 mA

[chemelec]

According to my National Data Book, an LM555 is 18 Volts Maximum.

[Carl-NC]

The LM555 is bipolar... I know on some PI designs the bipolar 555 won't work, it needs the CMOS version. Just something to watch for.

[neptune769]

Thank you all for your input. I found another post that said the LMC555 is a CMOS good to 18v. Could that be used without any other modifications? The pins are the same but that is all I know. The reason for all this is because 4 18650 Li-Ion cells makes for a better configuration in my housing without having to make a dummy cell.

Thanks again,
Dennis

[mickstv]

The recommended voltage on the LMC555 is 15 volts, going past the recommended voltage will either stress the component or blow it up. Just do what Carl said, use a few diodes in series to reduce the voltage to the 555.



Mick

[neptune769]

The recommended voltage on the LMC555 is 15 volts, going past the recommended voltage will either stress the component or blow it up. Just do what Carl said, use a few diodes in series to reduce the voltage to the 555.



Mick

Hi Mike,

I must be going crazy or something, I could have swore that when I looked at the Datasheet for the LMC555 it said 18v. I must have wanted it to say it than and my mind made it that way. I'll see about cramming some diodes in.

Thanks,
Dennis

[Qiaozhi]

Hi Mike,

I must be going crazy or something, I could have swore that when I looked at the Datasheet for the LMC555 it said 18v. I must have wanted it to say it than and my mind made it that way. I'll see about cramming some diodes in.

Thanks,
Dennis

.

[neptune769]

Hi Folks,

I knew I saw a 18v somewhere. It was the TLC555. I just don't know if it would work. I only know a little about electronics not enough to know what to look for to be able to substitute something. Sorry for all the confusion.

Regards,
Dennis

[jap]

You did not mention Li-Ion cells ma-h if we assume the cell of 1000 ma-h and consumption 50 ma----- you used 20h ---: So you'll still using 3 cells will be safe in use and i have seen one of the sites used in the 3 cells.

best time

j.

[neptune769]

You did not mention Li-Ion cells ma-h if we assume the cell of 1000 ma-h and consumption 50 ma----- you used 20h ---: So you'll still using 3 cells will be safe in use and i have seen one of the sites used in the 3 cells.

best time

j.

Thank you, I had planned on 61850.

[porkluvr]

Hi Folks,

I knew I saw a 18v somewhere. It was the TLC555. I just don't know if it would work. I only know a little about electronics not enough to know what to look for to be able to substitute something. Sorry for all the confusion.

Regards,
Dennis

My Signetics shortform "555, 556 Timers" handbook states 18V Absolute Maximum. But that does not mean it is a good idea to power NE555 with 18V. Instead, should use something lower so that you have some headroom in case of an accidental over-voltage. Using 15V would let the device work under a lot less stress, and thus probably last longer.
So then, a 15Vmax device should probably be operated at around 12V for it to have some safety headroom.

Some engineers like to push the edge of the limits for one reason or another. Their designs will make it out the door but then fail sooner than a more conservative design would.

[neptune769]

My Signetics shortform "555, 556 Timers" handbook states 18V Absolute Maximum. But that does not mean it is a good idea to power NE555 with 18V. Instead, should use something lower so that you have some headroom in case of an accidental over-voltage. Using 15V would let the device work under a lot less stress, and thus probably last longer.
So then, a 15Vmax device should probably be operated at around 12V for it to have some safety headroom.

Some engineers like to push the edge of the limits for one reason or another. Their designs will make it out the door but then fail sooner than a more conservative design would.

I see now thank you.

[golfnut]

I currently run my surf on Makita 18v Li Ion corldess packs with no problem.

I realise I was over the limits on paper, but it was a small risk considering the cost of a few blown parts.

The convenience is a week or more of detecting from each battery and 40min charges.

Heavy though, I have the battery in my coat to make it do able. Whod of thunk it.

S