Series or Parallel - rebuilding salvaged board.

[Vapaneezer Scrooge]

I think I already know the answer to this but safety first I thought I would double check.

I stripped a broken mod I was donated for parts, Modefined LYRA 200 watts, the main part I want to use is the superb board to make a 3D printed mod using this.

Like a dick I stripped it a while ago and binned everything else so can't remember if it was series or parallel, but I'm 99% sure it was standard SERIES, so am I right in saying the input Voltage with 2 x 18650 batteries will be 8.4 Volts? (they read just shy of 4.2 volts each)

The board is straight forward enough to solder and protected, power in positive & negative, power out positive & negative, though there is 1 wire I am not sure what to do with, there was a thin wire that went to the battery door spring loaded pin, labelled 'BM' is this needed? if so does anyone know where I should wire it up to?

I will chuck up a photo of the board if required once I soldered on some new wires.

Finally, I'm no expert and just starting building, I've made a simple single cell mech which was fine and wired up a simple DNA board single cell which is about my level of experience, I've plenty of common sense so won't leap to conclusions which is why I am reaching out to your experience - ANY advice appreciated.

 

[Vapaneezer Scrooge]

Sorry forgot another question, the wire used in the original circuit is a thinner gauge than the 16 AWG I was going to use, I'm guessing it's more like 20 AWG, is this okay to use on a regulated mod?

**EDIT** just measured it and it's 18 AWG - I would prefer to use this as the board has just enough room to route the existing wire on the underside, wider would give me mounting clearance issues.

 

[STAVROS EVDORIDIS]

the thicker wire should be better but 18 awg should be enough.you can always bent it acordingly and solder it after that to make it easier.Lyra and pretty much every dna 200 mod s batteries are in series

 

[nordelen]

Yeah, the Lyra was a series mod mate.

 

[Vapaneezer Scrooge]

Any ideas about the extra wire? should I just send it to the bottom battery connection?

 

[shale84]

Any ideas about the extra wire? should I just send it to the bottom battery connection?

Hehe,seems that you have same problem like me.
I belive that thin wire is "signal" wire that somehow makes board work in series setup.
I too have an old board that I tried in both series and parallel in "normal" way (2 wires on board and 2 wires out on 510) but it didn't work and I can't find where's that 5th wire going

 

[nwhornet]

DNA boards have a balance wire to control charging. There's a schematic on Evolv forums so may be of some help. I know the Lyra isn't DNA but it looks like it shares many characteristics.

 

[red5]

If you watch djlsb on YouTube he always says that extra wire/pin in the battery door compartment is for "battery monitoring and balanced charging"... I'm guessing it's somehow monitoring the voltage difference between the 2 battery's and without the wire present it's not able to do this and is shutting itself down on the assumption that something is wrong with one or both of the battery's.

 

[Vapaneezer Scrooge]

Thanks all, Battery monitor makes sense

Stripped 2 more mods yesterday and they all featured this wire going to the base plate, so I assume the wire can either go to the base of the battery circuit or can I add a jumper wire to Battery + terminal on the board?

I won't be using the mod to charge the batteries so I might block off the USB port.