Battery Connectors: XT60, Deans, and Why You Standardize
Your new pack's plug doesn't match your car — this happens to everyone. What the connector actually has to do, the common types and their current ratings, why standardizing your whole fleet on one plug ends the problem forever, and the polarity mistake that starts fires.
Updated Jul 22, 2026 · RC Crash Crew
You buy a new battery, it arrives, and the plug does not match your car. This happens to nearly everyone, and the panic that follows — "did I buy the wrong thing?" — is why connectors are worth understanding once, properly.
The plug is not part of the battery's chemistry or its rating. It is just the physical connector someone soldered on, and it can be changed. But which one you standardize on, and how you change it, matters more than beginners expect, because a bad connection is a fire risk on a lithium pack.
What the connector actually has to do
A connector on a power lead carries the full current the motor draws — which on a modern brushless setup can be tens or even over a hundred amps. Everything about connector choice comes back to two things:
- Can it carry that current without heating up? A connector too small for the current gets hot, and heat at a connection is wasted power at best and a melt-down at worst.
- Is the contact solid and consistent? A loose or worn connector arcs, adds resistance, and can cut out over bumps.
A hot connector after a run is telling you it is undersized. Feel your connectors when you feel the motor and ESC.
The common types
| Connector | Rough current range | Notes |
|---|---|---|
| Deans / T-plug | up to ~60 A | Long the hobby standard. Compact, solid. Fiddly to solder, and no housing so you can short it if careless. |
| XT60 | up to ~60 A | The current de-facto standard for 1/10. Bullet contacts in a nylon housing, keyed so it only goes in one way, easy to solder. |
| XT90 | up to ~90 A | Bigger XT for 1/8 and high-power setups. Some have an anti-spark version. |
| XT30 | up to ~30 A | Small XT for micro and light setups, small motors, receiver packs. |
| EC3 / EC5 | ~60 A / ~120 A | Bullet-in-housing, common on some brands' RTRs. EC5 for higher power. |
| Traxxas | ~60 A (varies) | Fitted to Traxxas RTRs. Convenient inside that ecosystem; needs an adapter to use other chargers and packs. |
| Tamiya | low — legacy | The old white/flat plug on cheap and vintage kits. Weak, high-resistance, and outdated. Replace it. |
⚠️ These current numbers are approximate and vary by manufacturer and wire gauge. Treat them as "which league is this connector in", not a spec to run right up to. Size up if you are near the limit.
The real lesson: pick one and standardize
The single most useful thing you can do is choose one connector for your whole fleet and convert everything to it.
Why it matters:
- Any pack fits any car, and any car fits your charger, with no adapters.
- Fewer adapters means fewer connections, and every extra connection is resistance and another thing to fail.
- You stop buying the wrong thing, because there is only one right thing.
For most people running 1/10, that connector is XT60. It is easy to solder, keyed so you cannot reverse it, housed so you cannot short it, and it is what most of the hobby has landed on. Above 1/10, XT90 or EC5. Below, XT30. There is nothing wrong with Deans if you already run it — the point is consistency, not the specific choice.
⚠️ Polarity — get this wrong once and it is expensive
Reversing positive and negative destroys electronics instantly, and on a lithium pack it can start a fire.
- XT and EC connectors are keyed — they physically only mate one way, which is a large part of why they are recommended. You still have to solder them on correctly.
- Deans/T-plugs are shaped so they only go together one way, but you can still solder the pack up backwards.
- The convention: the wider tab / marked side is positive. Check the connector's own markings, and check against the pack before you plug anything in.
When you replace a connector, do one wire at a time — cut, strip, solder, insulate, then move to the other. Never have both battery conductors bare at once. This is the same rule as the soldering guide, and it exists because a LiPo will dump hundreds of amps into a dead short.
Soldering a power connector properly
A power connector is heavy work — thick wire, big metal contacts, a lot of heat needed. A small iron will not do it. See the full method in the soldering guide; the connector-specific points:
- Tin both the wire and the connector cup first, then join them. A blob of solder sitting on top of an unwetted contact is a joint that will fail under load.
- Get in and out fast. Prolonged heat melts the plastic housing and lets the contacts shift, so they no longer line up when you plug in.
- A helping-hands or a connector jig holds the plug still. Trying to hold a hot connector and the iron and the wire at once is how people get burned.
- Heatshrink over each contact and over the whole joint. Slide it on *before* you solder — everyone forgets this once.
- Tug-test every joint when it cools. A joint that pulls apart in your hand would have pulled apart at full throttle.
Adapters — fine short-term, not a lifestyle
An adapter lead (one connector on each end) lets a mismatched pack and car work together today.
- Every adapter adds two more connections — resistance and failure points.
- They are the right answer for a one-off — a friend's pack, a loaner, a shop demo.
- They are the wrong answer permanently. If you find yourself with a drawer of adapters, that is the sign to standardize the fleet and be done with it.
Charger adapters are the common exception: many people keep one adapter from their standard connector to their charger's connector, and that is fine.
Balance leads are not power connectors
The small white multi-pin plug on a lithium pack is the balance lead. It is *not* for carrying current — it is how the charger reads and balances individual cells. See the charger guide.
- JST-XH is the near-universal balance connector. A 3S pack has a 4-pin balance plug (one wire per cell plus a common), 4S has 5-pin, and so on.
- Never draw motor current through a balance lead. The wires are thin and will melt.
- Handle balance leads gently — the thin wires break at the plug, exactly like any wire fatigues at a connector.
The short version
Standardize your whole fleet on one connector — XT60 for most 1/10 — learn to solder it properly, and keep one charger adapter. Do that and the "the plug doesn't match" problem never happens to you again.