advice pls, with Battery Charging query.

Thread Starter

Poor old sod

Joined Jul 25, 2017
163
i have a pair of 50AH batteries with bolt on terminals. i want to connect both 10A-20A cont charging wires across both batteries in series, and 30A brief discharge wires onto one battery. max imballanced discharge 50AS over 2hrs. i hope normal charging will restore ballance. max discharge either battery 45%. terminals normally only removed when changing battery. both circuits will have connectors between battery and loads. pls indicate suitable wire sizes, ring terminals, and charge line connectors [XLR?]. i will use anderson connector for 30A cct.
 

Irving

Joined Jan 30, 2016
3,127
50Ah batteries will be typically M6 rings, easily good enough for 100A continuous. Continuous 20A charge, 12AWG for a metre will get mildly warm, longer cables go to 10AWG. 10AWG will support 30A discharge; I use for 120A <10sec with no issue. All cables sheathed with 200°C rated silicone. XLR as used on wheelchair charger only good to 8A. Anderson SB50 good to 75A+ continuous.

Unbalanced batteries charged in series won't self balance - either need balancer circuit or separate chargers or consider swapping 12v discharge alternately from both batteries.
 

Ian0

Joined Aug 7, 2020
6,286
XLR is a balanced line audio connector. Don't use it for anything else.
If you had just spent £500 on a microphone and you plugged it into a socket only to find it was not a microphone socket, but was a power socket that damaged your microphone, how happy would you be?
Anderson SB50 is a power connector for batteries.
 

MisterBill2

Joined Jan 23, 2018
13,115
Certainly using an XLR three pin connector for anything except low level audio is poorly advised. In fact, it is REALLY A DUMB IDEA. Just because somebody got away with it once does not make it any less totally wrong!!
 

Thread Starter

Poor old sod

Joined Jul 25, 2017
163
Certainly using an XLR three pin connector for anything except low level audio is poorly advised. In fact, it is REALLY A DUMB IDEA. Just because somebody got away with it once does not make it any less totally wrong!!
in common use as gopher charge leads- on psu >Gopher also many e-scooterrs, i believe. 24v >=8A DC
 

Ian0

Joined Aug 7, 2020
6,286
in common use as gopher charge leads- on psu >Gopher also many e-scooterrs, i believe. 24v >=8A DC
It also means that any pre-made leads will have the current carrying capacitor for low-level audio (i.e. next to nothing).
About 10 years ago Neutrik decided that they were going to address the issue with the XLR being used for power, and develop a DC power connector similar to the Powercon, but nothing became of it. I suggested that they simply reverse the keyway on the standard XLR, and use the same pins, but nothing became of that either.
Cliff makes a connector similar to a Speakon for DC power, but it isn't widely used.
https://www.cliffuk.co.uk/products/cliffcon/pole4.htm
 

Irving

Joined Jan 30, 2016
3,127
Like it or hate it, XLR is the defacto standard for wheelchair/mobility scooter 24V chargers up to 8A - pins 1 (+) & 2 (-) are power, pin 3 to (-) is used as a motion lock to prevent movement while on charge.
 

Ian0

Joined Aug 7, 2020
6,286
Like it or hate it, XLR is the defacto standard for wheelchair/mobility scooter 24V chargers up to 8A - pins 1 (+) & 2 (-) are power, pin 3 to (-) is used as a motion lock to prevent movement while on charge.
Fortunately the Venn diagram of wheelchair users and professional microphone users doesn't show much overlap. [edit] I just hope that none of the wheelchair users decide to buy a male-to-female XLR cable as a charger extension lead.
 

Ya’akov

Joined Jan 27, 2019
6,550
Just because somoine made a mistake doesn‘t mean you should repeat it. One way you can tell the XLR was not designed for high current is that unless you modify the strain relief attach wires of suitable ampacity is veryh difficult or impossible.

Since you already plan to use Powerpole connectors it seems most reasonable to use the for this connection as well. The Powerpole Pak connector housings will let you assemble up to 4 pin latching connectors using power poles. It’s more secure that the usual roll pin placed between the mated connector, and it provides a lot more to grip for plugging and unpuggling.
 

MisterBill2

Joined Jan 23, 2018
13,115
No matter how many people do something really dumb, that does not make it any less dumb. The first fool to burn down a nursing home by using a microphone extension cable for charging should certainly catch a lot of grief for intentional stupidity. That #24 super-flex wire is not good for even one amp steady current.
 

ericgibbs

Joined Jan 29, 2010
16,361
pls indicate suitable wire sizes, ring terminals, and charge line connectors [XLR?]. i will use anderson connector for 30A cct.
hi Bill,
The TS is using the XLR Connector with a battery charger interconnetcion modification.
Not as a microphone extension cable.
E
 

MisterBill2

Joined Jan 23, 2018
13,115
With an XLR connector the very largest wire size I would use is #20 wire. For some brands you might be able to get #16 into the terminals if they are clean and you are really careful. But I would not even try.
 

Irving

Joined Jan 30, 2016
3,127
With an XLR connector the very largest wire size I would use is #20 wire. For some brands you might be able to get #16 into the terminals if they are clean and you are really careful. But I would not even try.
The wheelchair chargers I have use what appears to be standard 13A 2-core PVC-insulated mains flex. Works perfectly. And wheelchair users have been doing so for at least 40 years. The XLR was chosen, I guess, because its a latching connector and big/robust enough for someone with limited dexterity to manhandle into the socket on the chair. And relatively cheap compared to alternatives.

1664731845046.png
 

Irving

Joined Jan 30, 2016
3,127
From Wikipedia - my highlights:

The XLR connector is a type of electrical connector primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between three and seven pins. They are most commonly associated with balanced audio interconnection, including AES3 digital audio, but are also used for lighting control, low-voltage power supplies, and other applications. XLR connectors are available from a number of manufacturers and are covered by an international standard for dimensions, IEC 61076-2-103.[1]

[...] The XLR could accept 14 AWG (1.6 mm or 0.063 in) wire with a current-carrying capacity of 15 amps

Though it may have been designed for balanced audio, its original use was actually for loudspeaker connectivity, and there is no standard that says they are just for balanced microphones... the IEC standard above is referenced by over 30 other standards for LV power supplies, lighting equipment, wheelchair chargers and a host of other non-audio applications.
 
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Ian0

Joined Aug 7, 2020
6,286
and stage lighting equipment.
The standard for DMX is the 5-pin XLR - though low-end lighting manufacturers used the 3-pin when they were cheaper and not available in pcb-mount version, much to the annoyance of PA companies.
(Though the PA companies refused to work alongside a certain lighting company who decided to use 3-pin XLRs for the mains connection to spotlights)
 

Irving

Joined Jan 30, 2016
3,127
The standard for DMX is the 5-pin XLR - though low-end lighting manufacturers used the 3-pin when they were cheaper and not available in pcb-mount version, much to the annoyance of PA companies.
(Though the PA companies refused to work alongside a certain lighting company who decided to use 3-pin XLRs for the mains connection to spotlights)
Yes, I read that the DMX spec expressly forbids the use of 3-pin XLR connectors...

[...] The three-pin XLR connector is commonly used for DMX512, on lighting and related control equipment,[8] particularly at the budget / DJ end of the market. However, using three-pin XLR connectors for DMX512 is specifically prohibited by section 7.1.2 of the DMX512 standard.[9] Use of the three-pin XLR in this context firstly presents a risk of damage to the lighting equipment should an audio cable carrying 48-volt phantom power be accidentally connected, and secondly encourages the use of cable following analogue audio specifications for DMX, which can lead to signal degradation and unreliable operation of the DMX network [wikipedia]
 

Ian0

Joined Aug 7, 2020
6,286
A
Yes, I read that the DMX spec expressly forbids the use of 3-pin XLR connectors...

[...] The three-pin XLR connector is commonly used for DMX512, on lighting and related control equipment,[8] particularly at the budget / DJ end of the market. However, using three-pin XLR connectors for DMX512 is specifically prohibited by section 7.1.2 of the DMX512 standard.[9] Use of the three-pin XLR in this context firstly presents a risk of damage to the lighting equipment should an audio cable carrying 48-volt phantom power be accidentally connected, and secondly encourages the use of cable following analogue audio specifications for DMX, which can lead to signal degradation and unreliable operation of the DMX network [wikipedia]
As a 48V phantom power supply is limited by it 6.8k resistors to about 7mA, all that is required to protect the DMX inputs is a 12V 400mW zener. (I actually used a 45Ω 265V PTC thermistor and a transorb, which will withstand connection to the mains)
However, the TS thought he would use an Anderson connector, and whilst the applications of the 3-pin XLR is a worthwhile discussion in itself, I fear that we may have drifted off topic.. . .
 

Dumb-ton

Joined Oct 16, 2022
5
A

As a 48V phantom power supply is limited by it 6.8k resistors to about 7mA, all that is required to protect the DMX inputs is a 12V 400mW zener. (I actually used a 45Ω 265V PTC thermistor and a transorb, which will withstand connection to the mains)
However, the TS thought he would use an Anderson connector, and whilst the applications of the 3-pin XLR is a worthwhile discussion in itself, I fear that we may have drifted off topic.. . .
i am the op. [had email probs.] thx for diiscusssion. the gopher will have 2x 6A inteli chargers in parallel, to provide small charge on flat grround as range extender, driven by sml genset with their own XLR connectors. 24v to 12v 360w buck boost converter provides 12v for usb ports, rev. camera and 22A for m'bike starter solenoid and 250w motor to pull recoil starter cord. 2x 12v central locking actuators operate choke/primer, and fuel tap. i can pick up this genset, but nothing heavier. it will be behind the seat, chargers underneath it.
 
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