My battery backup setup

[GeoffD]

The power went out a week and a half ago. This finally prompted me to get myself a battery backup setup for my spare ResMed S9 AutoSet.

ML35-12 Mighty Max 35 amp-hour AGM wheelchair/scooter battery ($63.99 on Amazon)
ResMed 12v-24v DC-DC converter ($84.95 from an online DME)
0.75 amp Battery Tender Jr.($27.69 on Amazon)



With a deep cycle AGM battery, you're supposed to be able to draw the battery down to 20%. With a 35 amp-hour battery, that gives me 28 amp-hours of usable power.

According to the ResMed battery guide, with the slimline hose and no humidifier using my settings, it draws about an amp at 12v. I should be able run it on the boat for 3 days and not need to worry about killing my boat's battery bank. With the heated ClimateLine hose and the humidifier running, I should get most of a night out of it.

http://www.resmed.com/us/dam/documents/a...lo_eng.pdf

[OMyMyOHellYes]

Good to go. Just remember to ditch the pictured humidificator.

OMM

[truetopath]

Man that's a gnarly set up!

[justMongo]

I like it. You might want to put an Ammeter inline with the CPAP 12-24 Volt converter positive lead and test the actual current pulled.
Most DVMs can measure current in the range of interest. My Fluke certainly can.

[player]

You could have wired 2 12 volt batteries together to give you 24V instead of 1 battery and the $85 12V to 24V converter... This would double your battery life, and save you $21.

[archangle]

You could have wired 2 12 volt batteries together to give you 24V instead of 1 battery and the $85 12V to 24V converter... This would double your battery life, and save you $21.

That apparently doesn't work. There's a third wire on the connector with some undocumented signal. The S9 won't work unless it sees the signal. Someone reported that they monitored it and it was some sort of serial data signal.

I don't know of any source for the connector, either. You'd have to cut the connector off of an existing ResMed S9 power brick or adapter.

[justMongo]

Also for 24 Volts there are 12 lead-acid cells in series. The Voltage will vary depending upon state of charge from about 25.2 to 23.4 -- the converter compensates for that.

[Mark Douglas]

The power went out a week and a half ago. This finally prompted me to get myself a battery backup setup for my spare ResMed S9 AutoSet.

ML35-12 Mighty Max 35 amp-hour AGM wheelchair/scooter battery ($63.99 on Amazon)
ResMed 12v-24v DC-DC converter ($84.95 from an online DME)
0.75 amp Battery Tender Jr.($27.69 on Amazon)



With a deep cycle AGM battery, you're supposed to be able to draw the battery down to 20%. With a 35 amp-hour battery, that gives me 28 amp-hours of usable power.

According to the ResMed battery guide, with the slimline hose and no humidifier using my settings, it draws about an amp at 12v. I should be able run it on the boat for 3 days and not need to worry about killing my boat's battery bank. With the heated ClimateLine hose and the humidifier running, I should get most of a night out of it.

http://www.resmed.com/us/dam/documents/a...lo_eng.pdf

What kind of boat?

[OMyMyOHellYes]

I like it. You might want to put an Ammeter inline with the CPAP 12-24 Volt converter positive lead and test the actual current pulled.
Most DVMs can measure current in the range of interest. My Fluke certainly can.

Remember, when it comes to multi-meters, if you find one that works well, it's a Fluke.

OMMOHY
Model 87 V

[justMongo]

What kind of boat?

Nothing too big...