Issue Report from Assembly


#1

In the interest of spreading knowledge about possible failure modes and assembly problems I am sharing my experiences.

1. Surface Module Holder - Mirror Image Assembly Possible:

It is possible to assemble this in a mirror image (we did). Despite having a puzzle like design to prevent incorrect assembly we put it together and glued it before testing it with the circuit board. It's glued now, and can't be used at all.

Solution: I'd recommend disassembling the communications module first and then using the board for the surface module as a guide to make sure you don't assemble it backwards.

2. Battery Tube - Easy to Short:

The + wire exits through a hole in the - terminal plate. We removed the + end cap to add batteries. The stress on the wire pulled on the plastic cover which separated at the - terminal side causing a short. This is a big problem because that end is epoxied in, so basically we have to throw away the whole battery tube and build a replacement. We are looking at what it will cost to get access to a laser cutter to make the fancy end caps.

Solution: It might be wise to run the + terminal wire outside of the battery tube rather than inside.

3. Battery Tubes Are Opened Very Often, But Very Hard to Open (wire as a battery pack for in-place recharging):

The battery tube is very hard to open for something that is being opened and closed every time. The battery holder should assembled with two additional wires in-between the battery connections (balancing wires). The end caps should take into account for this. There should be a standardized RC charging adapter in the main electronics package.

Solution: Basically we should set it up as a battery pack and run a standardized RC recharging connector out of the main electronics assembly. I am just looking into how to do this safely, anyone have any suggestions?

4. Batteries are Expensive - No Backup Waterproofing:

The RC community shrink-wraps battery packs which could be sealed with caulk. If the housing flooded additional water protection would be very nice.

5. End caps with syringe hole: It is not clear why this is left open, or how one is to seal it properly to achieve the 300' depth rating.


#2

Quantumquark,

This is really great feedback- thank you!

For #1, I definitely agree. There are already two blurbs about that in the instructions (in step 76) but it would probably be good to include a photo. I did that part of the instructions kind of hastily.

#2-- Interesting idea. I haven't heard of the wire stripping at that point aside from you and it's very convenient for everything to be well enclosed, but that's something I'll look out for in the future. Just to clarify- do you have a v2.4 or a v2.5 design?

#3 I agree that it would be much nicer to charge the batteries in their packs... not only for ease of charging, but also because it would allow the battery packs to be sealed by even better means. For instance, if the tubes were only opened when the batteries became cycled enough to need replacement, it would be practical to fill the tubes with mineral oil. This would keep the batteries from being damaged as easily if dropped (that tends to destroy batteries because it sheers of their internal circuit board), would allow the tubes to go deeper, and makes them more impervious to leaks. The problem with charging (as you described) is that each battery needs to be balanced in the pack, so wiring to each battery junction is needed and each of those wires would need to be routed out of the pack or to an additional circuit board inside the pack. Additionally, charging lithium batteries can be dangerous, so I'd rather leave that circuitry to the professionals. Like you, I'd be very interested to hear other people's ideas for how to approach this problem. I tend to agree with you that the best way of doing might be to use an off-the-shelf balanced charger for the pack and just break out the wires going to each battery to a standard terminal. I'd love to keep the conversation going about the best way to do all that.

4. Agreed. At this point, it's really more a matter of ease-of-use considering that we don't yet have a good method for on-board charging

5. The plunger from he syringe should be placed back into the endcap (but the shaft of the plunger is shortened so it is just shy of poking past the face of the outer endcap disk, but there is still enough to grab onto with your fingers). Now that I'm looking through our Dozuki instructions, I can see that I never added a photo of that.. I just said "Remove inner plunger rod from syringe and set aside in clean place" in step 9. I'll try to add that photo when I get back from my travels (I'm visiting family right now).

Okay, once again, thank you for these comments- this is exactly the kind of feedback we need. Keep them coming!

Eric

P.S. Do you need more topside adapter pieces? Write me at eric@openrov.com and we can coordinate.


#3

Hello Eric,

Thank you for your thoughtful reply! I am very impressed by the many clever solutions you and the community have come up with.

Answer: I have a new 2.5

#3. Have you considered including a battery opening tool with the ROV kit?


#4

Additional Item:

7. Battery End Cap Assembly Order: My suggestion: solder first, glue second. Don't use gorilla super glue.

The assembly instructions indicate that one should glue the battery terminals with gorilla super glue or super glue then solder the wire to them. I would suggest doing that in reverse, my soldering iron melted the super glue causing the battery terminal to slide off the plastic end cap. Also the gorilla super glue we got would not bind to the plastic after having been melted, so we had to go with classic super glue.


#5

One more to add:

The end cap syringe hole orientation. It was difficult for me to determine the use of the syringe hole. As a result I mounted mine inverted assuming that the string would be held in place by the internal plastic structure of the electronics tube. Silly I know but seriously when you don't even know why you are adding this thing or how it's used it can be confusing.


#6

These a great suggestions. I’m working on the new instruction set for 2.6 now (which is very similar) but I’ll be sure to make some changes based on your points.

Thank you very much for the feedback!

E