Lipo or Nimh

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1 hour ago, Rogerborg said:

From the charger's point of view, it's easier.  With lipo, it knows what voltage the battery should be, so it won't (if it's half decent) over-charge it.

 

With nimh, it has no idea and just has to pump in energy until it sees the resistance spike - and it has to charge at a high rate in order to see that spike.  If it misses it (hellllo, Nuprol) then it'll charge and charge and charge and...

 

With NiMH constant current is supplied as long as the battery voltage increases, and charging stops when the voltage begins to drop. This drop is quite small & can be very tricky to detect though, so many chargers also include failsafes such as a voltage based cutoff, timer based cutoff, and/or temperature cutoff.

 

LiPo uses the normal CC/CV charge algorithm as per other Li-Ion chemistries - provide constant current for the first stage, up to the full charge voltage (4.20V in this case), then maintain constant voltage while decreasing the current supplied until it drops off below a certain threshold. Where LiPo gets more complicated though is balancing & cell/pack health. You *can* charge them without balancing etc, but it greatly increases the risk of self-immolation in use...

 

They're both a little more complex than that in practice, but that's the gist of it. If you want a lengthy read on battery tech, this is a good resource: https://batteryuniversity.com/

 

1 hour ago, Rogerborg said:

A V2 or V3 trigger trolley is about £5.  It's not rational to fit a mosfet that costs two or three times that just to protect the trigger contacts.  Yes, you can get higher current flow, but if you're dicking with the wiring you can stuff 16awg in there anyway.  Mosfets are nice, but you don't need them.

 

A good power MOSFET and a couple of resistors only costs £2-3 and it's very simple to put together. It's well worth it IMO, not just to protect the trigger contacts but to improve efficiency & trigger response, reduce occurrences of cutoff lever lockups on semi-auto, increase ROF and prevent it dropping off over time (the decline is so gradual you won't notice it over time, but use an AEG for a while without a MOSFET and then simply clean the switch contacts and the difference will be night and day. It's even worse if you use semi-auto a lot).

[Rogerborg]

53 minutes ago, Ad_ said:

A good power MOSFET and a couple of resistors only costs £2-3 and it's very simple to put together. It's well worth it IMO

 

Oh, I actually agree, I've just made a bunch of them.  Whether it's worth it if you're not already set up for soldering is perhaps the issue, versus the cost of some 16awg and replacing the trigger contacts every so often.

 

Not that I'd want to put anyone off getting fluxed, I'd highly recommend it, but it's not for everyone.

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40 minutes ago, Rogerborg said:

 

Whether it's worth it if you're not already set up for soldering is perhaps the issue, versus the cost of some 16awg and replacing the trigger contacts every so often.

 

Well if someone's going to be replacing the trigger contacts and putting in some 16awg they'll need to be set up for soldering anyway... might as well put in a MOSFET too while they're at it

[Adolf Hamster]

plus it's worth mentioning that whilst replacement contacts are generally easily available, at least for the common platforms, you run the risk that an aftermarket part might not quite fit the box properly, for example the COL might not trip or the trigger might not reset.

 

[Rogerborg]

On 22/08/2020 at 00:58, Ad_ said:

 

Well if someone's going to be replacing the trigger contacts and putting in some 16awg they'll need to be set up for soldering anyway... might as well put in a MOSFET too while they're at it

 

That's... a darn fine point, actually.