battery backup recommendations as10/as11

[robbob2112]

Well, been using just the battery and just the ASV on it. I can get 6 nights before the depth of discharge reaches 30% and I need to charge it. In practice i charge after 3 days.

I returned the eco-worthy 10 amp charger and got a li-time 20amp charger. The eco-worthy got to hot to touch after a couple of hours charging. Hot enough to bubble and warp the plastic case. I was beginning to worry about fire risks, but never smelled the plastic actually melt. The other issue is everytime I unplugged it the thing shifted back to AGM vs Li mode. And last the wires were very warm to the touch. I think it was more intended as a trickle charger or for a smaller battery.

The Li-Time charger has a fan, metal case, and 10awg silicone wires with a 50amp powerpole disconnect. They get warm, but not as much as the other charger. The fan is a little loud, but not crazy. So with the larger or even the smaller battery get a charger with a fan and metal case.

The pap machine typically draws 4 to 6 amps from the battery and the 20amp charger runs at 19.5amps so it charges each nights use in about 2.5 to 3 hours.

Ran the concentrator for 5 nights and I can get 2 nights if I take the DOD to 15%.

[robbob2112]

Been using the ASV off the battery nightly for a while now.  And since we love graphs here on the board I figured I'd post a few.

I plugged the new charger into a timer so it comes on everyday and recharges the night's use.  This way it is automatic and I don't have to remember to do it.  I also get to leave the charger cnnected to the battery all the time which means less time bending over to play with things.  My wife isn't happy with the way it looks so I guess I'll build a wooden case to slde it into and hide all the wires.  Of course I have to leave vent holes for the chargers airflow.

If you can't tell from the graphs it takes about 1.25 hours to fully recharge the battery after 10 hours use.

[robbob2112]

One last post - I promise - I completely reworked my backup with a LiTim 100ah mini as my battery and lots of other much smaller components and wire.

See the attached for my wiring diagram an parts list - all from amazon except the inverter is from current connected inverter - fridge not included

Everything in a wooden box with the sockets and a few other things mounted outside. The inverter is not normally connected unless we have an outage.

[robbob2112]

Minor edit to the drawing.  I flipped the battery monitor and cutoff switch so the battery monitor would always be on and I can tell what the charge state is.

Waiting on the real plastic box or to have time to make a wood one.  Until then I have a mock up using cardboard.

Everything is crimped them covered with shrinkwrap inside.  The exception being the shunt.  I coated the nuts and bare metal with liquid electrical tape.  Just not across the shunt itself.

Robert

[robbob2112]

Well, I am returning the shunt/battery monitor.... the other parts of the kit have issues. The buss bars are brass verse copper the are rated 300amps, but calculating everything the are only good for around 250amps. The battery monitor has some deficiencies I am gonna swap for a victron 712 unit.

[Charliejoe]

I have a similar set up for my AS 11, using a new 77Ah (non deep cell) 12 volt battery, but without a trickle charger. It will not power up my machine. If I hook  that set up to my 12-volt car battery, it works well. I am not electrically savvy enough to understand my results. Can anyone explain it to me?

[robbob2112]

I should have come back and added the final pictures - I put the whole thing (except the charger) inside a sewing box we got at the thrift shop for $20.  Looks much better than the cardboard box.

[robbob2112]

Answer a couple of questions and maybe I can help.

A picture is worth a thousand words, post one if you can.

A paper drawn wiring diagram is also helpful if it isn't obvious where the wires go.  Post this as well.

Are you using the heated tubing?  if so what temp is set?
Are you using the heated humidifier?  if so what setting?

For connecting to the battery are you using the official resmed DC/DC converter?  something else?

Is the battery you are running off of fully charged?  
Is is new or old?  
Do you have a meter and can you check that it reads as 12v?



I can tell this much from what you provided so far -  Once it is working - 
For a regular non-deep-cycle lead-acid car battery, it's generally recommended to limit the depth of discharge to around 30% to avoid damaging the battery. So, the usable watt-hours for the lead-acid battery would be:

Usable Wh=12 V×77 Ah×0.30=277.2 Wh

That means with the humidifier turned off and the heated tubing off you can run about 15 hours.  If you turn those on to the default level of 86f and setting 4 you only get about 4.5hrs

[Charliejoe]

thank you a  lot, robbob!

2 photos attached

no heat. no humidity used. AS11 is fairly new.

I've used an IKFD brand dc-dc  converter [in the photo] as well as an official  ResMed dc-dc converter. same specs for each. [2,71A 65.0 W]. same negative  result with each.

battery [in the photo] is brand new, fully charged. meter reading is 13.1 V

if I could get 15 hours of cpap-ing, it would be quite perfect!

[robbob2112]

Have you checked the fuse that is built into the cable?  Pull the fuse and check voltage between the socket side next to the positive and the negative post.  Then put it back and make sure it is fully inserted and try again.  Those inline auto fuses can easily have bad contact.

There is also a fuse inside the plug, screw the end off and it is a little glass fuse.  This doesn't apppy if you use this adapter in the car and it works.

Is the green light on the brick on?

Pretty much has to be a fuse or a bad connection between the socket and adapter.


Your battery is an AGM verse straight flooded lead acid.  The spec sheet says it will do around 18 to 20hrs.