I need some solder for r/c car battery wires and connectors. 10,12 and 14g wires to posts. Also smaller 22g wires to each other.

I have been working in the electronic manufacturing and repair industry for over 50 years, here are my views:Kester 44 Activated Rosin Core Solder 63/37 (63% tin/37% lead) in .031 inch diameter is the best solder for most all around electronics work. The ratio of 63/37 gives this solder the lowest melting point of all other tin/lead alloys. This allows you to get on the connection, heat it up, solder it quickly and be done without having to heat up the wires and connections way too much. If you need a thicker solder you can look for it in .062 diameter or even .125 diameter. The thicker diameters are good for soldering larger connections (like a 10 or 12 guage wiring points). You can also twist together two or three smaller diameter solder wires to make a thicker solder if you need too. You can get all kinds of these solders at your local radio scrap store in 63/37 and 60/40 ratios, but the impurities in that cheaper solder could make your soldering job a bit more difficult. Also the fluxes that are used in other solders might not work as well as the Kester brand. All of these solders are available in smaller quantities, you shouldn't need a full pound roll unless you are doing a LOT of R/C work. A few things to remember: It is difficullt to make a good solder connection if your iron is not hot enough or if it does not have enough thermal mass to transfer the heat quickly. Best to use a hot iron of 60 to 80 watts so that you can do the soldering quickly. Do not use acid core solder or acid fluxes for electronics work, the leftover acid can can be conductive and can cause electrical leakage and corrosion.There are "No Lead" solders available, but they require more heat to make a good connection. As a beginner, it might be best to use the tin/lead alloy solder and just remember not to eat the solder and not to lick your hands while you are working. Then wash up after your soldering session.For a good solder connection, follow these steps:1. Position your work such that nothing can move while you are soldering the joint.2. Make sure your iron is at full heat and that it is tinned with fresh and shining solder.3. Put the soldering iron tip on the joint.4. Immediately, put the solder wire at a point where it is touching the joint and the soldering iron tip. (This will allow a thermal bridge to be formed between the tip and the joint)5. Now hold both the solder iron and the solder on the joint and when it gets up to temperature, the solder will melt.6. Feed solder into the joint until it is filled and fully wetted.7. Back off.8. Let the solder joint cool without moving anything.9. Inspect the joint. 10. It should be shiney and solid with no cracks or crystallized areas.Hope this helps :)xJoe

Will I need additional Flux, when using this solder ?

No additional flux is normally needed when using Kester 44 Rosin Core solder for normal tasks such as soldering electronic through-hole components to the pads on a printed circuit board (PCB). The type "44" rosin flux itself is an internal part of the solder wire and it will wet, and clean, a metal-to-metal junction when the connection is heated and the tip of the solder wire is applied to the junction. After cooling, the rosin flux may be cleaned from soldered connections with isopropyl or rubbing alcohol and a cotton swab or a Q-tip.

What do 66 and 44 mean? Thousandths of an inch???

Core Size / Flux % by weight #05 0.50% #12 1.20% #22 2.20% #28 2.80% #30 3.00% #40 0.60% #45 4.50% #50 1.10% #58 2.20% #60 6.00% #66 3.30% #70 4.40%

What % is the rosin core, 2% 3%?

Kester Solder designates the number "66" to describe the core size of this solder. "66" core is 3.3%.

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⚙️ Solder smarter, not harder — the pro’s choice for flawless connections!

MADE IN USA QUALITY - Crafted with American precision and reliability for consistent performance every time
MICRO CORE DIAMETER - 0.031 inch rosin core ensures precise, clean soldering with minimal waste
PRECISION ALLOY BLEND - Optimized 63/37 tin-lead ratio for superior conductivity and joint strength
INSTANT WETTING ACTION - Activated rosin flux spreads rapidly for reliable, high-speed production line soldering
TRUSTED INDUSTRY STANDARD - Dominating activated rosin core solder market for over 40 years—join the pros

Kester 44 Rosin Core Solder 63/37 is a premium flux-cored wire featuring a precise 0.031 inch diameter and a proven 63% tin, 37% lead alloy. Its activated rosin flux delivers instant wetting action, ensuring fast, reliable solder joints favored by professionals for over four decades. Made in the USA, this 1 lb spool is engineered for high-performance, production-line efficiency and durability.

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Brand	Kester
Manufacturer	Kester
Country of Origin	USA
Model number	24-6337-0027
Item Weight	19.8 g
Product Dimensions	6.35 x 6.35 x 7.62 cm; 19.84 g
Item model number	24-6337-0027
Item Height	3 Inches
Item Width	2.5 Inches
Are batteries included?	No

Kester 44 Rosin Core Solder 63/37 .031 1 lb. Spool

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