Which side of the IC5 connector goes on the battery in ARRMA cars?

The female tube half of the IC5 always goes on the battery side, with the male pin installed on the ESC or charger side. Spektrum sells IC5 as matching Battery and Device halves. This ensures safe polarity and proper Smart function.

How do I avoid melting the IC5 housing when soldering?

Use a hot iron (300–400°C), a wide chisel tip, and finish each solder joint in 2–3 seconds. Always tin both parts before joining, and use a connector jig or helping hands to stabilize the work.

What size heat shrink should I use for IC5 solder joints?

Use heat shrink tubing that slides over the soldered bullet and your wire before shrinking. Thinner tubing may not fit over the soldered ends or provide adequate insulation.

Is it safe to solder IC5 connectors to a fully charged LiPo battery?

No. Always discharge LiPo packs to storage voltage (about 3.8V/cell) before soldering. This minimizes fire risk if a short occurs. Only work on one lead at a time to prevent shorts.

What happens if I put solder on the outside of the IC5 bullet?

If solder is on the outside of the bullet, you won’t be able to seat it in the housing. Forcing it will damage or warp the nylon shell. Only tin the inside of the bullet, and wipe off any excess before insertion.

Are EC5 and IC5 connectors interchangeable on ARRMA ESCs?

You can mate EC5 and IC5 for power only, but Smart telemetry requires IC5 on both battery and ESC sides. Always check fit and polarity before use.

How To Solder IC5 Connectors On ARRMA Batteries And ESCs

Knowing how to solder IC5 connectors is a must for any ARRMA owner running modern Spektrum Firma ESCs or Smart batteries. You need reliable, low-resistance joints, but one slip can melt a housing or fry a battery. Here’s how to get every IC5 solder job right, whether you’re swapping ESCs in a Kraton, or building a fresh harness. This is not another battery compatibility guide, for that, see our dedicated ARRMA battery compatibility hub. Here, you’ll get step-by-step instructions, tool picks for 2026, and exactly how to avoid the three most common mistakes that destroy IC5 plugs. You’ll walk away able to wire your ARRMA safely and confidently, with connections that last.

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Quick Answer: To solder an IC5 connector for your ARRMA, use a hot iron (300–400°C), fully tin both wire and bullet, and insert one battery lead at a time. Female tubes are for the battery; male pins for the ESC. Avoid long heat dwell to prevent melting. Check the polarity marks on the housing before you solder.

IC5 Soldering: What Every ARRMA Owner Needs to Know

Many larger ARRMA models use the Spektrum IC5 connector; Horizon lists IC5 for the Kraton 6S V6’s batteries, for example. IC5 mates with EC5 for power, but Smart telemetry needs IC5 on both the battery and the ESC side.

The IC5’s larger contact area reduces resistance for high-current ARRMA setups. Unlike EC3 or XT60, IC5s are made for heavy-gauge battery wire and won’t bottleneck your Kraton 6S or Typhon’s Firma ESC. But the assembly is less forgiving: too little heat, and you get a cold joint; too much, and the nylon housing warps or fuses, especially if you dwell more than a few seconds.

IC5 Battery vs ESC Sides: Which Half Goes Where?

The battery and ESC (device) sides of the IC5 use different bullet contacts, and mixing them up causes fitment and safety problems. For every ARRMA or Spektrum setup, follow this rule: female tubes go on the battery, male pins go on the ESC or charger lead.

This isn’t just preference. The battery housing (female) prevents accidental shorts, while the device housing (male) exposes the pins for a secure connection. Spektrum sells IC5 as separate Battery and Device halves (IC5 Device and IC5 Battery set, SPMXCA502), so fit the Battery half on the pack and the Device half on the ESC or charger lead. Spektrum’s general EC connector soldering guide (EC2/EC3/EC5 PDF, which does not cover IC5) uses the same convention: female tubes for battery connectors, male pins for charger, ESC or other device connectors.

Getting this wrong means reversed polarity, exposed contacts, or a connector you can’t mate with your charger. Always double-check the polarity marks molded into the housing before soldering anything.

Feature	IC5 Battery Side	IC5 ESC/Device Side
Type of contact	Female tube	Male pin
Goes to	Battery output wires	ESC, charger, or device input
Polarity marks	+ and – on housing	+ and – on housing
Assembly risk	Short circuit if both leads are exposed	Melting if too much heat applied
Backwards compatible with EC5?	Yes, power only	Yes, power only

Essential Tools, Solder, and Iron Settings for IC5

You need the right tools to avoid cold joints or a melted shell. Thick battery and ESC wire draws heat away fast, so a temperature-controlled station that keeps its tip hot is easier to use than a small, low-power pencil iron. Set your iron between 300–400°C (570–750°F), toward the high end for thick wire (Hakko guidance).

Use 60/40 or 63/37 rosin-core solder, 0.8–1.0mm diameter for best flow. A wide chisel tip (2–3mm) transfers heat fast and keeps dwell time short. Helping hands or a soldering jig (like Spektrum’s SPMX-1009) prevent the connector from shifting, and heat shrink tubing insulates exposed joints. Here’s a list of essentials that actually work for IC5 jobs in 2026:

→ Spektrum IC5 connectors, Always use genuine IC5s for Smart compatibility and guaranteed fit; knockoffs may not seat correctly.

→ Hakko FX-888DX soldering station, Lets you dial in the right temp for IC5 bullets, with a stable wide tip. Pricier than entry-level stations, but heats up fast and holds temp better.

→ 60/40 rosin-core solder, Flows easily at 300–400°C, made for electrical work. Lead-free needs higher temps and is harder to use for big IC5 bullets.

→ Heat shrink tubing kit, Pick sizes that slide over your wire and bullet; protects the joint and adds strain relief. Thinner tubing may split if forced over a soldered end.

→ Soldering helping hands / connector jig, Holds both the bullet and wire steady, minimizing the risk of touching the iron to the housing. Not strictly required.

Every one of these tools shortens the time your iron is on the connector, which directly reduces the odds of melting the IC5’s nylon shell.

Step-by-Step: Soldering IC5 Connectors Without Cold Joints

The process is simple, but every step matters. The steps below are general bullet-connector soldering practice, not Spektrum IC5 instructions. Spektrum’s EC connector guide (PDF) covers EC2, EC3 and EC5 only, so check your IC5 packaging for part-specific notes. Here’s how to get it right, with special attention to battery safety:

Prepare the workspace. Work on a fireproof surface with good ventilation. Keep LiPos in a fire-safe container until you’re ready.
Discharge the battery to storage voltage. About 3.8V/cell is ideal (Horizon LiPo guide).
Strip the insulation. Expose only as much bare wire as the bullet’s solder cup can take, so no bare copper shows once it is soldered. For batteries, only strip one lead at a time; insulate the other with tape or heat shrink.
Tin the wire fully. Heat the exposed copper and flow solder until it’s fully wetted and shiny.
Tin the inside of the bullet. Hold the bullet with a soldering jig or pliers; add a small bead of solder inside the cup, none on the outside.
Insert the tinned wire into the tinned bullet. Heat both together and add a touch more solder. Remove the iron as soon as the joint flows and is shiny, not dull.
Press the bullet into the housing. Use a small hex driver or flat screwdriver to push the bullet in from the back, housing face down on a solid surface, until it is fully seated. Tug the wire gently to confirm the bullet stays locked in.
Repeat for the other lead. On battery connectors, make sure the second wire is tinned and soldered with the first one fully insulated.
Check polarity and fit. Verify + and – match the marks on the housing, and that the connector mates smoothly with your charger/ESC.
Cover soldered joints with heat shrink. Shrink tubing provides insulation and extra strain relief.

That’s it: you’ve now got a solid, low-resistance connection without risking a melted shell or a short.

Three Ways to Melt an IC5 Housing (and How to Avoid Them)

The most common IC5 soldering failures all trace to one of three mistakes. Each will either destroy the nylon housing, ruin your bullets, or make future repairs impossible:

1. Too little heat, too long dwell. If you use a weak iron or set the temp too low, you’ll have to hold it on the joint for 10+ seconds before the solder flows. By then, the bullet’s heat soaks into the nylon, warping or fusing the housing. Solution: use at least 300–400°C with a wide chisel tip, and finish each joint in 2–3 seconds.

2. Solder overflow on bullet exterior. If solder gets on the outside of the bullet, you won’t be able to press it into the housing. Forcing it melts or cracks the shell. Always tin the inside only, and wipe excess solder if needed before insertion.

3. Not using a jig or helping hands. Trying to hold the bullet, wire, and iron together by hand is a recipe for shifting and accidental housing contact. A soldering jig (like Spektrum’s SPMX-1009) locks everything in place.

Even experienced hobbyists melt an IC5 housing every now and then, but keeping these three mistakes in mind prevents the most expensive failures.

IC5 Soldering Safety: Ventilation, LiPo Handling, and Fire Risk

Proper safety is non-negotiable. Rosin-core solder fumes are hazardous and can cause occupational asthma (HSE guidance). Always solder in a ventilated area or use a fume extractor, don’t hover over the joint. Wash your hands after soldering.

For LiPo battery soldering, always discharge to storage voltage (3.8V/cell), never full charge (Spektrum LiPo safety PDF). Never let both battery leads be exposed at once; always insulate the unused lead with heat shrink or tape. Work on a ceramic tile or silicone mat, not wood or carpet. Store all LiPos in a fireproof box, and never leave them loose or stacked together.

Set your iron between 300–400°C (570–750°F) as recommended by Hakko (source). Lower temps force you to hold the iron on longer, risking housing melt and a cold joint. Use a chisel tip large enough to transfer heat quickly.

Always check for swelling, heat, or damage before recharging a pack you’ve worked on. If in doubt, retire the pack, LiPo fires are not worth the risk.

Frequently Asked Questions

Which side of the IC5 connector goes on the battery in ARRMA cars?
The female tube half of the IC5 always goes on the battery side, with the male pin installed on the ESC or charger side. Spektrum sells IC5 as matching Battery and Device halves. This ensures safe polarity and proper Smart function.
How do I avoid melting the IC5 housing when soldering?
Use a hot iron (300–400°C), a wide chisel tip, and finish each solder joint in 2–3 seconds. Always tin both parts before joining, and use a connector jig or helping hands to stabilize the work.
What size heat shrink should I use for IC5 solder joints?
Use heat shrink tubing that slides over the soldered bullet and your wire before shrinking. Thinner tubing may not fit over the soldered ends or provide adequate insulation.
Is it safe to solder IC5 connectors to a fully charged LiPo battery?
No. Always discharge LiPo packs to storage voltage (about 3.8V/cell) before soldering. This minimizes fire risk if a short occurs. Only work on one lead at a time to prevent shorts.
What happens if I put solder on the outside of the IC5 bullet?
If solder is on the outside of the bullet, you won’t be able to seat it in the housing. Forcing it will damage or warp the nylon shell. Only tin the inside of the bullet, and wipe off any excess before insertion.
Are EC5 and IC5 connectors interchangeable on ARRMA ESCs?
You can mate EC5 and IC5 for power only, but Smart telemetry requires IC5 on both battery and ESC sides. Always check fit and polarity before use.

Final Verdict

If you run any modern ARRMA, from the Kraton 6S BLX to a 2026 Typhon or Senton, knowing how to solder IC5 connectors is essential for safe upgrades and quick repairs. The process is simple, but demands focus: always use the right side (female tubes on battery, male pins on ESC), a hot iron with a wide tip, and genuine IC5 plugs for correct Smart telemetry. Don’t skimp on safety, discharge packs, ventilate your workspace, and protect every joint with heat shrink.

IC5 soldering isn’t forgiving. Dwell too long, or skip the jig, and you’ll warp a housing or get a weak, high-resistance joint. Many hobbyists try to rush the job. Take the time to insulate each lead, confirm polarity, and keep solder off the bullet exteriors. If you do, you’ll get robust, low-resistance power delivery and avoid the three most expensive connector failures every ARRMA owner dreads.

For a deeper dive into IC5 vs EC5 compatibility, see our IC5 vs EC5 guide. If you’re still deciding on a soldering iron, check our 2026 soldering iron roundup for the top picks in every price tier. Solder once, solder right, and your ARRMA will thank you every pack.

Sources

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