Lipo in parallel / fuses and charging

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kenl
Posts: 153
Joined: Oct 19th, 2013, 8:50 am
Location: South Western Australia

Re: Lipo in parallel / fuses and charging

Post by kenl »

I can understand why you are asking the question, but after my experience of the compartment containing a chemical reaction resulting in an explosion!! I would redesign the ROV or just go to the trouble of taking the batteries out and charging them in a fire safe location, may catch fire but should not explode.
At least that is my understanding of these batteries..
Jaman42
Posts: 94
Joined: Nov 3rd, 2014, 4:19 am

Re: Lipo in parallel / fuses and charging

Post by Jaman42 »

I can certainly understand your concern but can't the explosion issue be solved with a pressure release valve or something like that? If it catch on fire inside the battery compartment the fire will suffocate pretty fast I imagine, so it's the explosion part that could be an issue.
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ROVER3D
Posts: 128
Joined: Nov 9th, 2012, 7:45 pm
Location: Wuppertal, Germany

Re: Lipo in parallel / fuses and charging

Post by ROVER3D »

Hey,
When charging your batteries do you have to disconnect them from your system?
No, i do not (physical) disconnect while charging.
I am just trying to figure out a easy way to charge the batteries without opening their compartment.
The easy way is an external battery connector, wireless activated by magnet contacs. Like on the ROV-Control MAIN-SWITCH 75A coming up in July.

I can understand why you are asking the question, but after my experience of the compartment containing a chemical reaction resulting in an explosion!! I would redesign the ROV or just go to the trouble of taking the batteries out and charging them in a fire safe location, may catch fire but should not explode.
At least that is my understanding of these batteries..
I recommend not to place batteries and electrical components in the same housing.
I can certainly understand your concern but can't the explosion issue be solved with a pressure release valve or something like that? If it catch on fire inside the battery compartment the fire will suffocate pretty fast I imagine, so it's the explosion part that could be an issue.
If you want to load save in closed (airfilled) housing you need to monitor the temperature of the cells while loading. also each cell-(line)-voltage - normally by your charger. I recommend to use max.0,5Ah charging-current. High charging-currents could cause cell damage and fire.

Do not leave your ROV unobserved while charging...in the basement... over night :shock:
Still keep an eye on it!!
Jaman42
Posts: 94
Joined: Nov 3rd, 2014, 4:19 am

Re: Lipo in parallel / fuses and charging

Post by Jaman42 »

Thanks for the input. I found a reasonable priced release valve http://prevco.com/products/accessories/ ... ves/lp-prv, I guess it wouldn't be too hard to make a similar solution by myself either. Or just use a plug that I remove everytime I charge, less work is better thou.
rossrov
Posts: 383
Joined: Feb 28th, 2013, 5:01 pm
Location: Australia

Re: Lipo in parallel / fuses and charging

Post by rossrov »

Some other very interesting stuff on that website. The housing in the scratch and dent section looks very familiar :).

Inadvertently I may have made a kind of pressure safety device on my first ROV. Just a piece of clear acrylic, polyurethane glued onto the outside of an end cap. Intended purpose was to be able to see into that housing and check for water ingress. Just what would let go in the event (e-vent) of an explosion I'm not sure, as the pipe walls were quite thin (90mm downpipe). Also, would not be any good to have one's head in the firing line, so the acrylic would need to be replaced with something non-transparent, then no temptation to look inside :shock: . Possibly a combination of the above sacrificial vent for rapid pressure release and a slower valve so that you might not lose all the internals to water damage. Put ROV in steel tool box to charge??

A while back ROVER3D mentioned LiPos at ambient pressure, in silicone oil. I'm wanting to investigate this approach, keeping in mind safe charging
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