daveopam

My Feedback: (9)

Guys I needed a large capacity compact pack for an on board ignition. this is on a twin glow. I put a standard 600NiCad on it. It worked Ok but after two tanks of mostly idle on the ground the pack was dead. So I bought two Sanyo 1500NiCads with tabs. Now I need to solder them together. I read some place that to much heat can ruin the battery.
What is the best way to solder these together? Also is there a certain type of solder that will be better to use? Soldering is not my strong suit. I did take two 4.8v packs take them apart and make one 6V pack. This was a year ago and it still works but that is the extent of my battery soldering time.

Thanks for the help,
David

Rodney

Using batteries with the tab already attached makes things much safer. It is when you have to solder directly to the positive terminal on those batteries without tabs that get you in trouble. There is a plastic seal at the positive end which can easily be deformed or ruptured by to much heat which often happens when you solder directily to the positive terminal. Using tabs, the prime precaution is to have adequate strain relief on the connections between cells. I use copper braid (like solder wick) as a connecting wire making sure that it is not under any tension, in fact a bit of slop or play is advisable. I use plain old electical solder with rosin flux. make sure all points to be connected are very clean then use flux and tin the area to be soldered to. After that, just lay on the copper wick and a bit of solder (with flux) and just enough heat to reflow the tinned area.

daveopam

My Feedback: (9)

I think I have it Rodney. One question though. The copper wick, will it be sandwiched between the tab and the post? Or will it be running from the tab to the post? I hope you get what I'm asking.

David

bnrusso

dress the pack tabs in the best direction to link one battery to the other. if the tabs overlap then you can solder them directly, without the braid. When you use the braid it can be placed OVER the top. The braid is helpful if you are going to fold the batteries after soldering into a tube shape as the tab to tab soldering cannot be bent. This is provided that the solder doesn't wick completely across the braid and make it solid.
I recommend adding an insulator UNDER the positive tab to be sure that if you melt the plastic coating at the edge you won't cause a short or potential short from the center tab to the outer metal case. A piece of manilla folder with some scotch tape to hold it in place is fine.This isn't important for the negative end as the sides and bottom are the same. The only reason that the sides are insulates is so the cases from each battery don't touch when they are glued or taped together, depending on the configuration. That would cause a short.

Rodney

If your individual cells have tabs as you stated in the first post, just connect the tab from the positive post on one cell to the tab on the negative post on the next cell. As Bnrusso said, if the tabs overlap, you can just solder tab to tab (after tinning them first of course) or if need for strain relief, connect the negative tab on one to the positive tab on the next cell with the copper braid. The advice to always insulate the braid from the cell body is good, there are many ways to do this by using heat shrink, electrical tape, etc.

daveopam

My Feedback: (9)

Thanks for the help guys. I will give it a try and let you see how it did.

David

richrd

What soldering iron are you going to use. because a liitle 25 W is to small, it takes a long time to heat then battery gets to hot. Its wierd but a big 100W is better so you can very quickly heat solder and get away. Guns have been the norm but its hard to tin these. Thats why tabs are the best because you can heat these wih small irons. Just try to get solder on both parts and then melt together.
Rich

daveopam

My Feedback: (9)

Rich I have two choices. I have a little cheapy. i don't know the wattage. I also have a butane mini torch. It has a soldering tip that covers the flame. I have a big soldering gun but it is working sporadicly. I don't use it enough to replace it. From what you have said I think I will try the butane.
I am hoping to get this done this weekend and then post some pics.
Thanks for the help.

David

daveopam

My Feedback: (9)

Thanks to all who helped. I am not the best at this but for a glow heater battery it should be fine. I am going to wrap it in clear packing tape before it goes in the plane. I wanted to be sure it took a good charge before I did.

Thanks Again,David

richrd

Dave the middle picture left battery pos tab looks a little cold. When the solder does no flow out and turns frosty looking then its called a cold solder joint. Best way to fix is add more flux and solder to joint, you can not reheat a cold solder to fix them due too flux has been all used up, just a litttle solder and that joint will shine.
Rich

daveopam

My Feedback: (9)

I see what you are saying Rich. The solder I use had the flux made into it. I think? So should I resolder it or buy some flux? I have some flux in my shop that came with silver solder. But it is liquid in a small squeeze bottle. I use it for soldering clevises.

David

Rodney

Do NOT use the flux from the silver solder; it is an acid and will cause corrosion unless completely cleaned off (almost impossible to do in a case like you are using it). Get a rosin flux made for electronics.

richrd

Yes flux core solder is what you got it's fine, thats why I said just add a little solder maybe 1/16 to 1/8 inch to get the solder to reflow. Also if you are going to do much soldering get a 50 to 100W iron life will be good to you. If you used your butane then the work you did is great because it's a very hard way to go Iam not sure if I could do better. conrats.[sm=wink_smile.gif]
Rich