What The FX Pocket Chrono Should Have Been - Rechargable
- Thread starter heavy-impact
- Start date
3d print a new battery cover and AA dummy batteries, drill a hole for the wires to pass through, connect a 4.5v wall wart power supply and your done.
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That is a single cell lipo battery, but 3200 MAH capacity??? That would be huge. The Chinese must have mis-labled this. Methinks its 320 MAH. Anyway, good idea. Do you have a portable charger that you can hook up to a car battery at the range if it needs recharging?
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It's 3200 milliamp hours or 3.2 amp hours. No need for field charging, I'm sure it would last every day for weeks. I've only charged it one time but I've only put about 400 shots on it.
Here's a 36v li-po battery pack I built from 250 used 4000mah medical battery packs. It measure 9"x9"x9" out of it's case and I get about 80ah out of it on my boat. 42v-30v. Started out with 240 cells but I added 10 more.
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That’s effectively what I’m doing. If I was building this just for myself or SkeeterHawk then I’d just solder the wires to the battery terminals and be done. Once I get this done, my goal is to make it like a module that replaces the battery door with a custom door and hooks up to a 5v wall wart or 5v lithium battery pack. Just got everything in today so I can start prototyping next week.
Once I get something presentable, I’ll post it here.
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@heavy-impact I saw your post and another using a different technique and it got my wheels spinning. Your idea is awesome but if you're still under waranty then it kinda nullifies that if you have an issue. I have lipos laying around all over the place from my R/C days but all are more voltage than the chrono can take. Luckily I have SkeeterHawk to design a step down circuit should I need one... 
Also, I have the same screen name on Thingiverse and found you out there too. My library is kinda boring though.
@bigHUN Your idea is what I'm leaning toward without soldering directly to the board. I've already sourced 5v lipo packs and also a 5v power supply. I need to get the multimeter out and see what the output voltage is on a USB and if it's 5v then any laptop will power the unit too.
As soon as my tennis elbow afflicted right arm decides to let me run a mouse for more than 5 minutes, I'm going to get to work designing.
Also, I have the same screen name on Thingiverse and found you out there too. My library is kinda boring though.@bigHUN Your idea is what I'm leaning toward without soldering directly to the board. I've already sourced 5v lipo packs and also a 5v power supply. I need to get the multimeter out and see what the output voltage is on a USB and if it's 5v then any laptop will power the unit too.
As soon as my tennis elbow afflicted right arm decides to let me run a mouse for more than 5 minutes, I'm going to get to work designing.
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Like many here, I'm also into RC. I wonder if one could solder in a PH2.0 connector so I can use the 1s batteries I already have for my Tiny Whoop.
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I would think it's possible as long at the battery is between 4 and 5 volts. Based on my research, 5v is optimum and anything below 4v, the chrono starts acting weird (missing shots, inaccurate readings, etc). There are posts that discuss an extra set of pads in the unit for what appears to be an external power supply originally designed in to the board. The down side is, if you utilize those, my guess is your waranty is out the window.
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The unit is designed with a voltage range of 2.7v-4.5v as AAA batteries have a working range of .9v-1.5v.
I don't do warranties because I modify everything.
Warranties can not be easily voided as most people think. The burden is on the warranty provider to prove the work you did caused the item to fail. They will try to bluff you but they're really just counting on no one suing to recover the remaining value of a $200 item. If you were file suit the warranty provider would fold rather than spend a lot more money fighting the case. You can read about warranty laws on the FTC website. Those little "warranty void if removed" stickers that manufacturers put on everything were illegal and could not void the warranty if removed.
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I'll have to take your word for the working range as I haven't even put batteries in mine yet so I can't measure the voltage when the unit "starts acting weird". I know the equipment I work on at my day job has an X and Y voltage range but starts acting really strange the closer it gets to the X voltage. In many cases the differewnce between working fine and "WTF is going on with this thing" is as little as 1 volt.
I don't disagree on the warranty (think Magnuson-Moss Warranty Act) but I also like to avoid a fight when I can. Designing something that leaves no footprints will result in the mfg's techs being a whole lot less likely to go "hey wait a minute" vs something obviously modified. I typically modify a lot of my equipemnt also because I can also fix it when it breaks but you, me and others who have that ability are a small minority of the overall population.
I don't disagree on the warranty (think Magnuson-Moss Warranty Act) but I also like to avoid a fight when I can. Designing something that leaves no footprints will result in the mfg's techs being a whole lot less likely to go "hey wait a minute" vs something obviously modified. I typically modify a lot of my equipemnt also because I can also fix it when it breaks but you, me and others who have that ability are a small minority of the overall population.
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Some notes I recorded when I had mine apart:
FX pocket chronograph (PCB marked v2.4)
The high-ish low battery indication level of 3.8V translates to 1.27V per cell, which is an unreasonable level in my opinion for either traditional alkaline batteries or Ni-MH rechargeables.
My solution was to fit a DC socket and power it via a small external USB power bank.
FX pocket chronograph (PCB marked v2.4)
- Low battery indicator triggers when Vbat < 3.80V
- 3.3V regulator is a linear LDO with ~100mV dropout
- 5.0V regulator is a buck/boost.
- Current draw:
- 81mA @ 5.0V
- 89mA @ 4.0V
- 99mA @ 3.5V
- 114mA @ 3.1V
- Most of the current draw is from the Bluetooth connection. With no connection to a smartphone, the current draw is <20mA.
The high-ish low battery indication level of 3.8V translates to 1.27V per cell, which is an unreasonable level in my opinion for either traditional alkaline batteries or Ni-MH rechargeables.
My solution was to fit a DC socket and power it via a small external USB power bank.
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That is awesome information!! I knew the low battery was set pretty high when SkeeterHawk told me his is only good an hour or so of shooting before it needs batteries. No clue what was going through the minds of the people at FX when they decided to go with 3 extremely small batteries to power the unit. My guess is the bean counters made a decision without engineering's input. I wouldn't be terribly surprised if FX comes out with a battery eliminator that looks a lot like what you've done to yours.
Thanks again for the information!!
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3.8 is a good storage voltage for LiPo batteries, so now I definitely want to get in there and see if I can wire a PH2.0 connector.
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On another post (somewhere, I don't remember where), i read that there are 2 spare pads on the ckt board right on the edge that are labeled + and -. You should be able to solder to those pads to make a connection directly to the board. Be aware though that if you use an outside power source that you don't want to have batteries also in the unit as it will likely damage the batteries and you'll end up having a bad day if that happens.
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Tim is correct...there is a place along the edge of the board with a couple of pads for the (+) and (-).
The DC socket I used was from an old USB hub. Its footprint wasn't a match for the existing solder pads but close enough that I could use one of them and drill a hole for the other one, and scrape away a little of the solder mask so I could solder it. After trimming a notch in the plastic housing, it looks like it was made to go there.
I did not make any sort of provision to prevent the external battery pack from charging the AAA cells, so to Tim's other point I never use both simultaneously.
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I've become a Ninja at voiding warranties, so I took my FX Chrono apart tonight to take some pictures for the group and this thread.
Here is a picture as you first take it apart:
Now, here is taking the barrel bracket out:
Extracting the PCB assembly give you this:
Here is a close up of the PCB assembly. Note the Battery connections on the left hand side of the board. I ohmed these out, and they are directly connected to the battery contacts.
Note that my board revision is 3.1, where @nervoustrig had a revision of 2.4.
Here is a close-up of the two boards mounted together:
I soldered a couple wired onto the battery connection so that I could put an oscilloscope in the circuit and monitor the instantaneous current draw during the shot acquisition that @nervoustrig didn't get a chance to in his experiment.
I drilled a small hole in the side of the housing to run the wires through, and installed a tie-wrap just inside to act as a strain relief:
And popped it all back together...
I hope that this helps "take some of the mystery" about what is going on inside this unit. Have a happy New Year!!
Cheers!
Jonathan
Here is a picture as you first take it apart:
Now, here is taking the barrel bracket out:
Extracting the PCB assembly give you this:
Here is a close up of the PCB assembly. Note the Battery connections on the left hand side of the board. I ohmed these out, and they are directly connected to the battery contacts.
Note that my board revision is 3.1, where @nervoustrig had a revision of 2.4.
Here is a close-up of the two boards mounted together:
I soldered a couple wired onto the battery connection so that I could put an oscilloscope in the circuit and monitor the instantaneous current draw during the shot acquisition that @nervoustrig didn't get a chance to in his experiment.
I drilled a small hole in the side of the housing to run the wires through, and installed a tie-wrap just inside to act as a strain relief:
And popped it all back together...
I hope that this helps "take some of the mystery" about what is going on inside this unit. Have a happy New Year!!
Cheers!
Jonathan
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Nice! Has anyone tested the pins in that white socket is see if they are connected to power feed?
I may get mine apart today and check them if I can find my VOM.
I decided to add a female USB with a short cord for power from my external pack.
It will wrap around the fold out prongs then the end will fit under the radar part where that clip is to hold it.
Mostly just staying with my Wife today as She went through a pretty traumatic experence last night!
I may get mine apart today and check them if I can find my VOM.
I decided to add a female USB with a short cord for power from my external pack.
It will wrap around the fold out prongs then the end will fit under the radar part where that clip is to hold it.
Mostly just staying with my Wife today as She went through a pretty traumatic experence last night!
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Good morning, Privateer.
If you are referring to this connector, no I didn't check it for power. If memory serves me, that is a Molex connector that has a really special crimper that costs hundreds of dollars by itself, so I didn't bother when I could just solder onto that open connector.
I'm sorry to hear that!!! Absolutely, stick by that gal's side. We'll be here when she gets better.
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