Scary stuff! Lipo's right?
Do you know why this happened? Did you use a balance charger?
My ROV
Re: My ROV
Good to see you (intact) here again Ken. The glued end obviously prevented worse damage by being a weak point. Glad you did not use the threaded rods for that enclosure.
On a lighter note, dunno if you have seen these. Two-way data: http://www.voscom.com/video-ptz-over-fiber-1v1dd.asp
On a lighter note, dunno if you have seen these. Two-way data: http://www.voscom.com/video-ptz-over-fiber-1v1dd.asp
Re: My ROV
It was LiPo batteries, and to be fair I did just about everything wrong leading up to one of the 4 packs exploding. I wasn't balance charging.
As Manhattan has said in his thread, it is a lot work to open up the ROV to remove the batteries. I was being lazy and charging them in situ, which is probably fine when the ROV is being used a lot, and packs are inspected periodically and balanced. I suspect I had a dead cell or the like, all just guessing though.
Anyways I am not upset about it, I'm fine and I learnt a good lesson.
Things for the new ROV:
1) Separate battery pack
2) A tether that is workable, I think this is the biggest single obstacle to happy ROVing on a budget. Cat5 just doesn't make the cut, it's too heavy and when made to float (by whatever means) provides too much drag for our little machines. I'm thinking 2 pair one for video and one for PPM with all data being sent via video overlay.............. Or fiber optic see the next post
3)Easier method of attaching thrusters and keeping the seaweed out of the props
4)A cordless tether reel for quicker setup and all round simplicity
5)A really really bright screen or video goggles that work. I think this is the number 2 obstacle to happy ROVing on a budget.
As Manhattan has said in his thread, it is a lot work to open up the ROV to remove the batteries. I was being lazy and charging them in situ, which is probably fine when the ROV is being used a lot, and packs are inspected periodically and balanced. I suspect I had a dead cell or the like, all just guessing though.
Anyways I am not upset about it, I'm fine and I learnt a good lesson.
Things for the new ROV:
1) Separate battery pack
2) A tether that is workable, I think this is the biggest single obstacle to happy ROVing on a budget. Cat5 just doesn't make the cut, it's too heavy and when made to float (by whatever means) provides too much drag for our little machines. I'm thinking 2 pair one for video and one for PPM with all data being sent via video overlay.............. Or fiber optic see the next post
3)Easier method of attaching thrusters and keeping the seaweed out of the props
4)A cordless tether reel for quicker setup and all round simplicity
5)A really really bright screen or video goggles that work. I think this is the number 2 obstacle to happy ROVing on a budget.
Re: My ROV
Ah.. If you were charging without balancing then it's really not that surprising that bad things happened. Good thing you are ok and that nothing burnt down!
Making the charge plug and balance plug accessible from the outside shouldn't be too hard. A pipe fitting with an o-ring sealed end cap that you can undo to get access to charging and balancing connectors for instance. I have also thought about using a 1" ball valve for this in my build. Open the valve and you have access to the charge and balance port. close the valve and you are good to go. Although they are a bit bulky, they are cheap (even the stainless types) and good for 20-60 bar depending on the standard.
Ofc, separate battery pack will give you more options and flexibility.
Good share of information by the way! very valid points you mentioned.
Making the charge plug and balance plug accessible from the outside shouldn't be too hard. A pipe fitting with an o-ring sealed end cap that you can undo to get access to charging and balancing connectors for instance. I have also thought about using a 1" ball valve for this in my build. Open the valve and you have access to the charge and balance port. close the valve and you are good to go. Although they are a bit bulky, they are cheap (even the stainless types) and good for 20-60 bar depending on the standard.
Ofc, separate battery pack will give you more options and flexibility.
Good share of information by the way! very valid points you mentioned.
Re: My ROV
You don’t need to balance Lipos on every charge. Balancing is required when you pull high discharges sporadically from a pack i.e. multicopters. I don’t think that our application require that high current draw, not even near what a Lipo can handle in terms of discharge. My guess is that you had one cell short itself and that created the bang. I have over 150 Lipo packs of various sizes for other projects and every time I had a fail it was always that a cell shorted.
I am also getting convinced that Lipos are not that suitable for ROV applications which is really bad for me since all I have is Lipo packs. Remember some discussions about Lipos and pressure here on the forum.
Kenl, take a look on this http://eclipsebikes.com/headway-lifepo4 ... -1011.html I think these are really good for underwater use and they are as safe as it gets. Personally I am using Li ion and I think I will go that route. I harvest them from purchased laptop batteries where you get 12 cells (in the 2500-2900mah range) for 2$ / cell. Both Li ions and Life batteries you should balance every time, not because of hazards but for the sake of longevity of the cells.
When I read through your post I believe that we are working almost on a very similar project.
I have some ideas on some of your preferences you stated that I will document in my build log.
I am also getting convinced that Lipos are not that suitable for ROV applications which is really bad for me since all I have is Lipo packs. Remember some discussions about Lipos and pressure here on the forum.
Kenl, take a look on this http://eclipsebikes.com/headway-lifepo4 ... -1011.html I think these are really good for underwater use and they are as safe as it gets. Personally I am using Li ion and I think I will go that route. I harvest them from purchased laptop batteries where you get 12 cells (in the 2500-2900mah range) for 2$ / cell. Both Li ions and Life batteries you should balance every time, not because of hazards but for the sake of longevity of the cells.
When I read through your post I believe that we are working almost on a very similar project.
I have some ideas on some of your preferences you stated that I will document in my build log.