3 pin Molex extension cable?

April 17, 2016 3:17 PM

The 6-AA removable battery pack inside my bluetooth speaker is attached to the unit's power supply by a 3 pin molex connector. I'd like to get a molex extension cable so I can keep the pack outside the unit. Do these exist?

I have bought an extra battery pack (to backup the one whose juice has become depleted when I'm out with it), and for ease of use I'd like to just get a molex m-to-f extension cable and have the battery pack sitting outside the unit when in use, rather than having to remove/insert the battery pack into the tight-fitting compartment, and then have to seal it up with screws every time. (The battery pack only gives around 2 hours of playtime, so that would be way too much screwing/unscrewing, since I use this almost every day.) Can anyone provide some kind of ID for the molex connector in the photos, and how likely is it that I will find a ready-made m-to-f extension (say, in the 9 - 12 inches range)?

Here are some pics:

Picture 1
Picture 2

The scan with the ruler (in cm) of the molex connector coming out of the battery pack I did myself, the other pic(s) are from manufacturer documentation. I suspect that what I am looking for might be available from some eBay or amazon seller from China, but without having any kind of ID for the molex connector(s), there's not much I can do. If I do have have/get an ID for the molex, will I be able to find an extension cable for sale online? (And, if not, how much should I expect to pay an electronics person to make one for me?)

Thanks in advance for all pointers and suggestions!

posted by tenderly to Technology (9 answers total)

Best answer: Looks like a standard LiPo battery cable; e.g. the 3-pin version here should work (you'll find tons of them on eBay, AliExpress etc as well).
posted by effbot at 3:25 PM on April 17, 2016

Best answer: FWIW (& for future reference for anyone stumbling across this), it's not a molex connector. It's a JST connector, XH series (or similar) e.g. JST-XHP-3.
posted by Pinback at 4:35 PM on April 17, 2016

Best answer: These are about 10x more expensive than what they should be, but here it is on Amazon with Amazon Prime: 1, 2, 3
posted by suedehead at 8:43 PM on April 17, 2016

Response by poster: Thanks for the info and links, folks!

As should be obvious from a glance at the pic of the battery pack I posted, this Li-PO connector is attached to a Ni-MH battery pack (6 x AA), clearly not the type of battery with which it is usually associated, or for which it was designed; need I have any concerns about using one of these extension cables to power and to recharge (via the speaker when plugged in to the wall) the battery pack? I assume this is simply the type of connector the manufacturer decided to use for this device, and it makes no difference that the batteries are Ni-MH and not Li-PO.

BTW, I also saw there at Amazon that they are selling "Fireproof Explosionproof Lipo Battery Safe Bag for Charge & Storage"; are Li-Po batteries more prone to overheating and exploding than Ni-MH, or should I be concerned about charging and storing my Ni-MH battery pack "in the open (more or less)"?

I know next to nothing about batteries, cables, and such, and wouldn't want to brick the unit or destroy the battery pack by making a foolish mistake that would be an obvious no-no to anyone who knows the ins-and-outs of these things. So if there's anything potentially risky I should know about before acquiring and using one of these cables, please do let me know.

Thanks once again!
posted by tenderly at 9:31 PM on April 17, 2016

Best answer: Yup, battery type makes no difference. While in the US they're mostly known as connectors for LiPo batteries (thanks to their ubiquity on R/C packs), elsewhere they've been pretty common on NiCd & NiMH packs (e.g. in cordless phones etc.) for 20+ years.

From memory the connector itself is rated to 250 volts / 3 amps, so in your speaker it's almost certainly operating well within it's rating.

LiPo (& most lithium cells in general, especially rechargables) are somewhat prone to catastrophic self-destruction (i.e. smoke & spitting fire) if physically/electrically maltreated e.g. bent, crushed, overcharged, discharged too fast, etc. The consumer types generally have a monitoring chip built into the cell/pack to mitigate that. However in some cases e.g. R/C models, high currents are needed and rapid recharging desirable - so the monitoring chip is left out.

I hesitate to say that things like fireproof charge/storage bags are overkill or a solution looking for a problem - because the problems are real and dramatic - but (IMO) they're certainly trading on the fear of potential LiPo fire/explosion.

NiCd & NiMH cells have considerably less energy density & their contents nowhere near as flammable, so the risk is minimal. Don't stab them or throw them into a fire though...
posted by Pinback at 9:56 PM on April 17, 2016

Response by poster: Thanks for the additional info, Pinback.

Is there are substantial difference between a JST-XH and a JST-EH that might impact its suitability for my purpose (i.e. both using the battery connected via the cable to power the unit as well as to be itself recharged via the unit)?

I found this JST-EH listed on eBay:

RC-2S-Lipo-Battery-3P-JST-EH-Plug-Balance-Charger-Cable-Extension-Lead-22cm

Any reason why that would not work?
posted by tenderly at 3:11 PM on April 18, 2016

That eBay link is a little confusing - the listings says EH, but the pic sure looks like an XH (or similar; see note below) to me. The main difference is the EH series has latches/locating tabs on the short ends of the plug and the socket is open on one long side, while the XH is shrouded on all 4 sides & has the latches/locating tabs on one long side.

Since they don't seem to know the difference, it might be a crapshoot what you end up getting from that particular seller. But searching eBay for 'JST XH 3 pin extension' brings up a few (e.g. "5 x JST 2.5 XH 3-Pin Connector Extension Wire Male to Female Length :200mm") that look to be the right thing.

Note: I'm not 100% sure it's an XH on your speaker (though it sure looks like it) - for a start, XH is a wire-to-board series and so the line socket you show in your 2nd pic (with sides that surround the plug) doesn't 'officially' exist. It's pretty common for the sockets to be misused though (by soldering wires to the PCB terminals & insulating with heatshrink), I know there's various knockoffs that are compatible but vary just enough to get around JST's patents, and the XH style is very commonly used for both the sensing connection on R/C battery packs and the actual power connection in things like cordless phones, portable speakers, etc.

Also, double-check the pin spacing - XH is 2.5mm, while some similar ones are 2.0mm. Luckily, I don't think there's anything similar in 0.1" (2.54mm) pitch…
posted by Pinback at 12:48 AM on April 20, 2016

Response by poster: Thanks for checking back in, pinback!

I was just considering putting in an order for this "2.54XH" 30cm cable (since I could use the extra length; most of the JST cables seem to be only available in 20cm lengths, and I assumed––wrongly, it would seem––that "2.54XH" was just another variation on or name for JST-XH) as seen here:

Lipo-Battery-Charger-Silicone-Wire-Balance-Extension-Cable-2S-3Pin-3S-4Pin-4S-5Pin-8S-9Pin-2.54XH-30cm

Your last comment, "Luckily, I don't think there's anything similar in 0.1" (2.54mm) pitch…" suggests that this "2.54XH" is not simply another designation for JST-XH, and would not be suitable. I measured the pin spacing on the connector on my battery pack, and it's definitely not 2.0mm, since the distance from pin 1 to pin 3 is 5mm, so I think we can safely say it's a 2.5mm JST-XH (especially since you say this connector is commonly used for both sensing connections and actual power connections). So that is what I will order.

If, for some reason, the JST-XH cable I get fits, but for some reason is not suitable, what would be the most likely outcome?

1. battery will not recharge and battery will not power speaker with extension cable; no lasting damage or harm (all functionality restored when extension removed)
2. battery pack is destroyed but speaker is unharmed
3. speaker is bricked but battery pack is unharmed
4. both speaker and battery pack are no longer usable

Thanks again for taking the time to help me navigate these unknown waters!
posted by tenderly at 2:13 AM on April 21, 2016

Response by poster: Thought I'd wrap this AskMe up (for the benefit of anyone with a related issue who may come across this in the future) by letting y'all know that I ordered the Li-Po Battery Balance Charging Extension Wire Cable that effbot linked to above (got three for three dollars, shipped for free from Laos), and I have used it with my battery and speaker to both charge and play with no issues.
posted by tenderly at 4:10 AM on June 4, 2016