DC extension cable

[Bill]

Mr. Wright's question about mobility scooter batteries has poked me into asking this again.

1) I have a 12v towbar winch, which I need to cable to the front of the Disco. 2) This vehicle tends to sit for weeks unused, so I'd like to be able to plug in a charger in the garage and run a cable out to the car to put it on charge in the inevitable rain. 3) I seem to be the only family member with a charger. Last time I had a flat battery I had to ring round to recover the chargers. I seem to have lost the 2 mains extension reels that they borrowed with the chargers.

It seems to me that something like a 30foot length of cable with something like Anderson connectors on each end and a few adapters to croc clips etc would be a useful thing to have handy. I gather Anderson connectors are used to charge mobility scooters.

Winch current draw depends on the load, but apparently can range from

10A up to 90A for short periods.

2 questions: These connectors are said to be reversible. I can't get my head round whether there could be any problem if they were lent out. If the extension cable were connected the wrong way round, it would presumably have + on black and - on red, but this would be corrected in the adapters?

My guess is that either 4mm 41A or 6mm 53A stranded cable would be good enough for the intermittent winch current in the open air, but I'm not clear what size connectors would fit, or how easy this cable would be to carry, store or handle.

Has anyone done this sort of thing?

[Colin Stamp]

What's the rated output of the charger? The cable from the garage to the car shouldn't need to carry more than that. Only the cables from the winch to the car battery will need to carry the full winch current.

If your charger is one of those start-and-charge things, then it'll be able to tax the extension cable more heavily, but only very short-term. Then your enemy will be voltage drop rather than cable current rating, so the length becomes important.

Cheers,

Colin.

[Huge]

Anderson connectors are hermaphroditic (IOW, they all fit together - there are no male & female connectors). It is impossible for them to be connected "the wrong way round". What is possible is to wire them the wrong way round, but providing both ends of the extension are wired the same way round, it shouldn't matter. But if you want the cable colours correct, I suggest you follow the standard;

[Andy Wade]

Be careful, if we're talking about an ordinary single-phase transformer-plus-bridge-rectifier type of charger (no smoothing of the DC output) the RMS output current in the cable will be significantly more than the mean DC current, due to the peaky waveform.

I'd advise rating the cable at least a factor of two above the rated mean DC output, to play safe. Voltage drop considerations may dictate that an more in any case.

[Peter Parry]

All I have come across use 3 pin XLR.

[Bill]

It looks a though some use XLR and some these Anderson connectors, but I've never delved into this before, and don't know anyone with a scooter.

XLR's were my original thought as I could just select a mic cable for the charger operations, but I don't think that the 15A rating is enough for the winch.

[Colin Stamp]

That's a bit further than I'd go - I'm guessing the number on the front of that type of charger will be measured by whatever scheme makes it highest, to the point of outright fraud. Still, as you say, better safe than sorry.

Indeed. Particularly if it's an "Intelligent" charger, voltage drop will be critical.

On the other hand, it could be a "charger" like this...

In which case, you could probably use a mile of bell wire ;o)

Cheers,

Colin.

[Bill]

My chargers are just some cheap automatic things from Wickes or Aldi (I hate and never understand the row of LED's), and the old little 6A selenium rectifier one which had a nice meter on the front until my daughter dropped it. It never bothered me that the case had melted above the rectifier.

[Bill]

Thanks, that looks very useful. I'm still not sure how the hermaphrodite thing works in practice, but I do think I'm getting more stupid with age.

I think a 40A cable rating ought to be OK, so all I need to do is match the cable to the connector size.

The other item I've needed to power was a tyre pump for the boat trailer at some distance from the car. When I used an Aldi 3-way cigar socket cable as an extension lead, I burnt my hand on the plug as I pulled it out of the socket. The fuse had just blown and the cable was turning nicely crisp.

[tony sayer]

In article , Bill scribeth thus

There are bigger ones around the EP series or the Speakon connectors are good...

[The Medway Handyman]

AAMOI they can be made m/f.

I used to sell Wetrok scrubber drier machines. The batteries were connected to the machine via Anderson connectors. The connector from the batteries had a pin & the connectors from the machine and the charger had a hole. This was to prevent the charger being connected directly to the machine and it's electronics.

I recall one cheapskate, know it all, contractor refusing our quote to replace a set of batteries, claiming he could get a better price elsewhere. The cheap supplier fitted normal Anderson connectors and the operator connected the charger directly to the machine - burning out about £600 worth of circuit boards etc.