Drain battery to install connector?

[DanS1]

I am about to install OSE 8mm Antispark connectors on a Revolectrix 6S Lipo, and common sense tells me to drain the battery before I begin since the soldering iron will inevitably short the battery out in the process. How do you drain these high power batteries safely? Any other tips on the process? Have read the threads on soldering these connectors on and will follow those hints about heat sinks and such. Also have the correct large soldering iron needed. Thanks for your help ---

[johnv58]

Why would the soldering iron short out the battery ? Just do one wire at a time. Also it may be easier to use a torch with that style connector.

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[NativePaul]

If you think you may short the connector when soldering it, please don't do it!

Soldering is a great skill to have in this hobby, but there are much less risky ways to get into it.

There is no shame in asking for help, if you are in a club (highly recommended) there is probably a helpfull clubmate that has the skills and equipment to do it safely and would be happy to help out a newbie by doing it for you (and after this covid crisis is over teach you how to do it yourself safely), or your local hobby store usually offer it as a service for free if you bought the boat and battery there, or for just a few bucks otherwise.

Any good charger will have a (often very slow) discharge mode, but if you discharge a 6s battery worthy of 8mm connectors down low enough to not vaporise a soldering iron tip shorting it out sending little blobs of molten metal flying around you, then you have severely overdischarged it, and may as well give it a week long salt bath and throw it away while it is discharged. Also I would say that it is probably safer to short a powerfull battery than a less powerfull one as one with power in will instantly melt/vaporise the short and as long as you are wearing eye-pro you would probably only have some minor burns to the hands arms and face, but if there isn't enough power to instantly melt the short there is a risk of arc welding the short into the circuit at which point you have an incendiary grenade on a short fuse in your hands (or at your feet as you dropped it, and it rolled under your bench, when it went pop). Personally when I work on LiPos I do it at normal storage charge.

[DanS1]

Thank you for your response and advice. Obviously I need to do some more reading on Lipo batteries, and will do so before proceeding.

[fweasel]

I'm a big fan of the new OSE connectors and use them on my bigger boats. Having a good iron or solder station is a must with these larger connectors, so you seem to be covered there. Because the pins cannot be removed from the plastic housing, melting the plastic is easy if not done correctly. I like to connect the other half of the connector and grab the pin on that side with a vise grips to help dissipate heat. You should use a silver solder with a higher melting pointi and not a high lead content solder. I work on one battery lead at a time, trying to prevent a short circuit before it happens. If the battery is new and it has nothing soldered on to the leads, I leave the positive side taped up and taped to the pack itself, until the negative lead is completed and I'm ready to tin the positive wire.

[DanS1]

Why would the soldering iron short out the battery ? Just do one wire at a time. Also it may be easier to use a torch with that style connector.

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Thanks for your reply. The design of the connector, with both solder barrels adjacent, made me nervous. My soldering training (I was an electronic tech in a former life) taught me to maximize surface area contact with the soldering iron tip, which might short the iron into the other solder cup if it slips. (Murphey bets on it, in fact). I'll just have to be especially careful and solder the second wire from the side, maybe with a piece of carbon fiber between the two barrels for insulation.

[johnv58]

I think I see what you mean. Don't forget carbon fibre is conductive.

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[DanS1]

Thanks for the tips - especially using silver solder. I'll be sure to heat sink the barrels the way you suggest. Would have been nice if the barrels could have been removed for soldering. As it is I'll be extra careful when soldering the second wire.

[DanS1]

Oops. Thanks once again - will find something better.

[NativePaul]

A word of warning when Fweasel said silver solder he meant a lead free tin based soft solder with some small percentage of silver (usual 2-4%), some of which is sold as silver solder. Whereas actual silver solder is a hard solder with a much higher silver content (usually 35-40%) and although highly conductive it is used more normally for mechanical connection rather then electrical connection, it has a MUCH higher melting point and requires a blowtorch rather than an iron.

Basically when buying silver solder make sure you check the melting point and/or the silver content, although for a quick guide (there may be outliers) the stuff you want nearly always comes spooled on a roll, and the stuff you don't want nearly always comes as rods or strips. Having a flux core is also a good sign of it meing what you want too.

[fweasel]

A word of warning when Fweasel said silver solder he meant a lead free tin based soft solder with some small percentage of silver (usual 2-4%), some of which is sold as silver solder. Whereas actual silver solder is a hard solder with a much higher silver content (usually 35-40%) and although highly conductive it is used more normally for mechanical connection rather then electrical connection, it has a MUCH higher melting point and requires a blowtorch rather than an iron.

Basically when buying silver solder make sure you check the melting point and/or the silver content, although for a quick guide (there may be outliers) the stuff you want nearly always comes spooled on a roll, and the stuff you don't want nearly always comes as rods or strips. Having a flux core is also a good sign of it meing what you want too.

Thank you

[1coopgt]

I don't know what size soldering tip you are using but if it fits inside the barrel with the wire in it I would recommend doing it that way and slowly pull the tip out of the barrel as you fill it with solder.

[DanS1]

Thanks for the advice. I will be using "Stay Brite", which is a lead-free silver solder as you suggested. Have used this before, and it comes with its own bottle of flux.