battery cable size

[user 23166]

can anyone tell me what's the best gauge battery wire with insulation rating to buy to connect 2/ 6 volt 225 AH batteries in series parallel and then to connect  them to a 45 amp converter charger please? :-/
all of this in an area no bigger than 2' x 2'

Thank You,

 

[highdesertranger]

depends on the length and the amperage. punch the numbers into this,

http://circuitwizard.bluesea.com/

as far as the type of wire, I like marine rated wire. Ancor brand for me.

highdesertranger

 

[rayrey]

Is all you are going to do is charge them? I ask because the cable between the batteries has to handle your biggest loads or combination of loads. So if your inverter calls for 2 gauge you will need at least 2 gauge between the batteries.

I plugged in 12 volt, 45 amps and 1 foot, it said 12 gauge. ...yikes. I would not be sending 45 amps through 12 gauge or even 10.

 

[jimindenver]

Is all you are going to do is charge them? I ask because the cable between the batteries has to handle your biggest loads or combination of loads. So if your inverter calls for 2 gauge you will need at least 2 gauge between the batteries.

I plugged in 12 volt, 45 amps and 1 foot, it said 12 gauge. ...yikes. I would not be sending 45 amps through 12 gauge or even 10.

 

[Weldman]

That’s cause it assumes you are using 105 degrees Celsius Ancor wire not the usual 75 or 90 degree Celsius wire.
Ancor wire ampacity chart
You need minimum at 90 degree Celsius rated wire 2 gauge

 

[user 23166]

depends on the length and the amperage.  punch the numbers into this,

http://circuitwizard.bluesea.com/

as far as the type of wire,  I like marine rated wire.  Ancor brand for me.

highdesertranger

Hi HDR, I did that, thx....now I'm
having a hard time finding cables less than 2 feet long :-/

 

[user 23166]

Is all you are going to do is charge them? I ask because the cable between the batteries has to handle your biggest loads or combination of loads. So if your inverter calls for 2 gauge you will need at least 2 gauge between the batteries.

I plugged in 12 volt, 45 amps and 1 foot, it said 12 gauge. ...yikes. I would not be sending 45 amps through 12 gauge or even 10.

Hi Jim,
My load will be less than 60 AH's a day, and I'm not going to use an inverter, just a converter charger, not sure the amp rating I want yet

 

[user 23166]

That’s cause it assumes you are using 105 degrees Celsius Ancor wire not the usual 75 or 90 degree Celsius wire.
Ancor wire ampacity chart
You need minimum at 90 degree Celsius rated wire 2 gauge

Hi Weld, was this meant for Jim or me?

 

[highdesertranger]

for the wire size 60AH per day really means nothing. you need to figure out the largest load that a wire is expected to carry. this goes both ways weather discharging or charging. so you need to figure out what size converter and your largest drawing item.

which brings up another question. is the converter going to be your only charge source? is it a new smart converter or an old dumb converter?

highdesertranger

 

[user 23166]

By far my biggest draw is going to be my resmed airsense 10 CPAP @ 33Ah a night.
I'll be getting a smart converter, I'm thinking maybe 35 amps, but the converter charger will only be when I can't get enough solar

 

[Qxxx]

I find the answers here to all be highly confusing, and completely off the mark. The real question is how many Amps does the CPAP draw, and how many Watts. This page says typical 53W and 104W peak for the Airsense 10:
https://www.easybreathe.com/AirSense-10-AutoSet-CPAP-Machine-with-HumidAir-p4381.html

I'm not sure how peak factors into normal use, but 53W at 12V is **ONLY** 4.4A, and nothing like 45A.

53W/12V = 4.4A

Then, if you're running off a 12V-to-120VAC inverter, factor in a bit of inefficiency, and then the typical draw will be maybe 5A, or 60W from the 12V batteries.

You don't need 2 gauge wire, and a common 300W inverter should be fine. Use the wires that come with it to connect to your batteries. I'd say best get a "pure sinewave" inverter to be safe, rather than the cheaper "modified" sinewave type.

So, now once you know the amperage draw, you can compute the AH in use, or

5A * 8Hr = 40AH draw from your 12V batteries over night.

That is consistent with your numbers, but the Amps are wrong. W=V*A, A=W/V, and AH=A*Hr.

EDIT: the other thing is Watts relate to power draw, and are "consistent" across different voltages. So, 60W=12V*5A is roughly 120V*(1/2 A). There is a fudge factor in relating AC to DC, but this gives you a usable estimate.

 

[highdesertranger]

ok like I said for the wire size disregard the amp hours. concentrate on the amps in other words how many amps does it draw?

the C-Pap seems fine I am assuming that 33Ah is over an 8 hour period. that would make the draw a little more than 4 amps. is that a 12v C-Pap or a 120v?

so far 35amps from the converter is the largest number. use that for your wire size.

how much solar?
how big is the battery bank?

highdesertranger

 

[Qxxx]

"so far 35amps from the converter is the largest number. use that for your wire size".

Again ... NO!

35A*12V = 420W, not 53W. It's just a little air pump. A 420W air pump would blow your lungs to pieces.

 

[user 23166]

I find the answers here to all be highly confusing, and completely off the mark. The real question is how many Amps does the CPAP draw, and how many Watts. This page says typical 53W and 104W peak for the Airsense 10:
https://www.easybreathe.com/AirSense-10-AutoSet-CPAP-Machine-with-HumidAir-p4381.html

I'm not sure how peak factors into normal use, but 53W at 12V is **ONLY** 4.4A, and nothing like 45A.

53W/12V = 4.4A

Then, if you're running off a 12V-to-120VAC inverter, factor in a bit of inefficiency, and then the typical draw will be maybe 5A, or 60W from the 12V batteries.

You don't need 2 gauge wire, and a common 300W inverter should be fine. Use the wires that come with it to connect to your batteries. I'd say best get a "pure sinewave" inverter to be safe, rather than the cheaper "modified" sinewave type.

So, now once you know the amperage draw, you can compute the AH in use, or

5A * 8Hr = 40AH draw from your 12V batteries over night.

That is consistent with your numbers, but the Amps are wrong. W=V*A, A=W/V, and AH=A*Hr.

EDIT: the other thing is Watts relate to power draw, and are "consistent" across different voltages. So, 60W=12V*5A is roughly 120V*(1/2 A). There is a fudge factor in relating AC to DC, but this gives you a usable estimate.

that page is a bit misleading, this is the page that tells you exactly how many AH's my cpap will draw.

www.resmed.com/us/dam/documents/articles/198103_battery-guide_glo_eng.pdf

I have the airsense 10 with humidifier and climate line air hose...my pressure setting is 15

I don't need an inverter, i'm buying a converter from resmed that I connect directly to my batteries.

:thumbsup:

 

[Elbear1]

"so far 35amps from the converter is the largest number. use that for your wire size".

Again ... NO!

35A*12V = 420W, not 53W. It's just a little air pump. A 420W air pump would blow your lungs to pieces.

33 amps total over 8hrs at night.

 

[user 23166]

ok like I said for the wire size disregard the amp hours.  concentrate on the amps in other words how many amps does it draw?

the C-Pap seems fine I am assuming that 33Ah is over an 8 hour period.  that would make the draw a little more than 4 amps.  is that a 12v C-Pap or a 120v?

so far 35amps from the converter is the largest number.  use that for your wire size.

how much solar?
how big is the battery bank?

highdesertranger

I have 2- 225AH interstate 6 volt batteries, and I'll start off with 1-100 renogy solar panel

cpap is 120v, but with this product from resmed...
www.1800cpap.com/resmed-dc-converter-for-the-airsense-10-and-aircurve-10-machines?gclid=

I can connect it directly to my battery bank, no inverter necessary.

Everyone is apparently under the assumption I will be using a DC to AC inverter , so I guess I wasn't clear in my initial question, my bad.

To clarify, the only 120volt draw I have is my cpap, but I am buying a converter from resmed so I can connect my cpap directly to the batteries...all my other draws will have 12 volt plugs.

So I believe all I need is to know is what battery gauge I need to connect 2-225AH batteries in series parallel, and then to an AC to DC converter charger that I'll be adding in a couple months, so that I can charge battery bank from a generator or shore power...please correct me if my line of thinking here is wrong.

 

[Qxxx]

33 amps total over 8hrs at night.

Oh lord .... 33 AH over 8Hr, not Amps.

 

[user 23166]

Qxxx, I knew what Elbear meant :sleepy:

 

[Qxxx]

that page is a bit misleading, this is the page that tells you exactly how many AH's my cpap will draw.

www.resmed.com/us/dam/documents/articles/198103_battery-guide_glo_eng.pdf

I have the airsense 10 with humidifier and climate line air hose...my pressure setting is 15

I don't need an inverter, i'm buying a converter from resmed that I connect directly to my batteries.

:thumbsup:

Excellent. Just for reference, it might have saved a lot of flailing around if we'd had the PDF reference a while back . Just saying.

However, the file actually gives specs for 6 or 8 different devices. On looking at the last unit on page 7, Airsense 10 with ClimateAir and humidifier (yes/no??), it shows 5.37A at pressure 16, or 65W. IOW, right what I estimated.

Buying the 12V DC-DC converter is a good option. Other things you'll notice, on page 5, it indicates using a 300W inverter, again just what I said. And on page 3, it shows the DC-DC converter you are apparently buying. You'll notice how "thin" those wires are, not hardly 2 gauge. Now you got it all. Have fun and keep on trucking.

 

[Elbear1]

I have 2- 225AH interstate 6 volt batteries, and I'll start off with 1-100 renogy solar panel

cpap is 120v, but with this product from resmed...
www.1800cpap.com/resmed-dc-converter-for-the-airsense-10-and-aircurve-10-machines?gclid=

I can connect it directly to my battery bank, no inverter necessary.

Everyone is apparently under the assumption I will be using a DC to AC inverter , so I guess I wasn't clear in my initial question, my bad.

To clarify, the only 120volt draw I have is my cpap, but I am buying a converter from resmed so I can connect my cpap directly to the batteries...all my other draws will have 12 volt plugs.

So I believe all I need is to know is what battery gauge I need to connect 2-225AH batteries in series parallel, and then to an AC to DC converter charger that I'll be adding in a couple months, so that I can charge battery bank from a generator or shore power...please correct me if my line of thinking here is wrong.

Youre going to have problems with that setup. Once you break them batteries in youre going to need 500w or more.

The advice you always hear of you draw say 35 amps and thus you need 35 amps in solar to replace it is horrendously false. The batteries dont charge linearly like that. The older they get the worse it becomes. Size battery to needs then size solar to battery. I.e. you need to charge about 1/8th (c10 + load) your bank.... 22.5a + load = 500w to achieve 14.8v and even then you will struggle without perfect sun and a backup source.

A small lithium battery might be better for you than a bunch more panels. They are nearly linear like that.

P.s. youre wiring in series. Series-parallel would be if youre hooking up 4 6v to be 12v. 2 in series plus 2 in series then those would be paralleled for 12v 450ah.