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Extending output cable of auto battery charger/maintainer

Ed Sowell

Aug 1, 2016
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I have a Schumacher SE-5212A-CA battery charger/maintainer with 14AWG DC output cable. To reach the battery while in the car from the charger on a shelf on the adjacent wall, I need to extend the cable about 3 feet. I'd either splice or replace with a longer cable. I'm concerned that this might affect the "sensing circuits" in the charger.

Anyone here have thoughts on the matter?

BTW, I sent the question to Schumacher and got a reply from customer service: "The cable is 14AWG." No help at all, I can read that off the cable!
 

Martaine2005

May 12, 2015
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Extending or replacing the wires wont affect it. You are only extending by about a metre (3').
Same for extending the mains input, some people will connect to an extension cord.

Martin
 

bertus

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Nov 8, 2019
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Hello,

Extending the cables by 3 feet, the voltage drop will be 0.9 Volts per cable so 1.8 Volts over the pair.
I used this online calculator:
https://www.inchcalculator.com/voltage-drop-calculator/
I used 3 feet and 12 Volts and 50 Amp (the max the charger can give).

User thicker cables will reduce the voltage drop.

Bertus
 

Bluejets

Oct 5, 2014
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If it's a "smart charger" chances are the charger interrupts the charging routine on occasion to take any readings thus making a change in cable size irrelevant.
Charger may well be rated at 50A but yet to see one charge at such a high constant rate.
 

Ed Sowell

Aug 1, 2016
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Thanks!
Martin, I'd rather add to or replace the output cables than relocate the charger and drag an extension cord.
Blujets, I think it could be a smart charger but not sure.
Bertus, most usage would not be recharging a dead battery so it wouldn't often be at 50 amps. And I expect under that extreme condition a 0.9 volts wouldn't have much effect.
 

Bluejets

Oct 5, 2014
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Martin, I'd rather add to or replace the output cables than relocate the charger and drag an extension cord.
Using a mains extension would be the normal accepted method, however if you must and intend to replace the entire length of LV leads, then go heavy.
Maybe also invest in a pair of HD clamps while you are there.
Most of these have poor quality clamps anyhow.
 

Ed Sowell

Aug 1, 2016
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If it's a "smart charger" chances are the charger interrupts the charging routine on occasion to take any readings thus making a change in cable size irrelevant.
Charger may well be rated at 50A but yet to see one charge at such a high constant rate.
The Schumacher literature says it is microprocessor controlled to optimize charging rate. Doesn't use the term "smart charger."
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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Schumacher has a web page of FAQs (Frequently Asked Questions) that perhaps @Ed Sowell should read.

Responders here might want to check this page too.

Based on what little information has been provided so far, I would suggest extending the existing battery cables with 14 AWG insulated wire. If the charger becomes "hinky" at the distance extended, either use a shorter distance or a larger wire size: 12 AWG or even 10 AWG. I have used 4 AWG welding cable for my home-built "dumb" charger, which was capable of some 200A short-circuit output current, but that seemed a little extravagant even for very conservative me. My welding cable was removed to my day job laboratory, supposedly "on loan" but never returned to me. I now get by with a 4-wire 12 AWG cable, paralleling the red plus white and black plus green wires. The "new" battery charging cable may not start a diesel truck engine (I haven't tried that yet) but it charges an automobile battery PDQ (Pretty Damned Quickly).
 
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