Home Battery questions - smart chargers and standby switching?

[Carbon]

I would like to make a set-and-forget home battery system to cover brownouts, and the occasional blackout of a few hours duration, and rare major outage (110 AH deep cycle AGM battery , ResMed DC/DC converter to AS10), AND it has to look pretty

The two main aspects I am not sure about
1. how to set up a battery so I can plug it in the wall and pretty much forget about it (or do batteries need to be regularly cycled?) Is plug and forget charging covered by using a smart charger/ multistage charger?

2. How to just leave it all turned on and have it automatically keep going if the power browns out/ stops completely?
Does one need something that can automatically switch power draw for the CPAP from mains to the battery (i.e. to make this like a standby UPS on steroids). Is such a thing even needed, or can you just assume it just sorts itself out in a straight line drawing off the battery with the CPAP while still on charge, with the smart charger maybe catching up during the day on any nett overnight battery discharge?

And the "looking pretty" bit is to keep the missus happy - can all this stuff be fitted neatly in an off-the-shelf battery box?

I guess my other much simpler option is to cover 90% of my issues with a normal computer UPS, destroy the alarm, and just be happy I can cover anything up to 10 minutes without any annoying beeps to wake me.

[Grover64]

Carbon

There are several ways to skin this cat. Primarily you could run the equipment of the DC converter connected to the battery with a smart charger connected to to the battery as well. A 110 A/hr battery would need a decent charger and to best look after the battery it should have at least 3 stages to the charger and be specifically designed for the charging profile of an AGM battery ( not expensive nor difficult to find). Secondly you could run an inverter 12vDC to 240 AC and similarly connect a charger to the battery. This would be a bit more expensive and likely that the inverter will make some noise and efficiency is not as good.

Lastly as you suggest a UPS without an alarm would do the trick. There are UPS made for medical equipment and they rate a UPS for an Airsense 10 at 600 VA / 360 Watt Maximum Uninterruptible Power Supply will provide 1 hour 10 mins. The UPS I saw on the interweb was USD299. I did notice a site in Aus selling the Defender 1200 VA for AUD 199. This would be the option that I would probably choose IMO.

Cheers

[OMyMyOHellYes]

Stay away from UPS units. Nothing more than small batteries with inverters. Avoid inverters. Inverters bad.

It is expensive, but I could propose an elegant solution that includes a 12 V battery, a West Mountain Super PWRgate 450 (PG40S), and a small radio power supply that can put out 14.5 V (most do 13.8 and can be adjusted for higher). It is not cheap, but it is truly a *Ronco "Set it! And forget it!" solution. The PWRgate switches automatically between the power supply and the battery when voltage drops and switches back when voltage comes back. (like an over the counter UPS, but without the power robbing inverter, and with a battery big enough to actually get you through the night. Or two) It also maintains the battery so you don't have to worry about maintenance (battery will still need to be changed out down the road, somewhere probably between 7-10 years just because batteries, even when maintained, don't last forever).

*As seen on TeeVee!!!

OMMOHY

[pholynyk]

To expand on OMMOHY's reply, a computer UPS has very limited capacity; perhaps half an hour. I recommend reading through PaulaO2's thread below: http://www.apneaboard.com/forums/Thread-...ery-backup and particularly the thread by Foss referenced within it: http://www.apneaboard.com/forums/Thread-...up-Battery

Both will give you the background and details you need to create you backup system. Making it pretty is up to you and your wife.

[Grover64]

Stay away from UPS units. Nothing more than small batteries with inverters. Avoid inverters. Inverters bad.

It is expensive, but I could propose an elegant solution that includes a 12 V battery, a West Mountain Super PWRgate 450 (PG40S), and a small radio power supply that can put out 14.5 V (most do 13.8 and can be adjusted for higher). It is not cheap, but it is truly a *Ronco "Set it! And forget it!" solution. The PWRgate switches automatically between the power supply and the battery when voltage drops and switches back when voltage comes back. (like an over the counter UPS, but without the power robbing inverter, and with a battery big enough to actually get you through the night. Or two) It also maintains the battery so you don't have to worry about maintenance (battery will still need to be changed out down the road, somewhere probably between 7-10 years just because batteries, even when maintained, don't last forever).

*As seen on TeeVee!!!

OMMOHY

I think this looks like a great system and as you suggest much better than a UPS. Cant see them for sale in Australia I will have a look and see if there is anything similar.

[FrankNichols]

Most people think of UPS associated with Computer systems, but they are available for all kinds of equipment - such as sump pumps. Some have much larger storage capacity and can run a CPAP machine a lot longer. That is not to say that a DIY system of inverter and battery and ... could not be better and more efficient etc, but not everyone likes to fiddle, some just want a plug and play solution. Another possibility that costs a bit more, if you are concerned for instance with storms in your area causing long term power outages (think Hurricane and days to a week) you may want to look into a small generator (if all you need is you CPAP) and a separate circuit for just your CPAP on it.

[Grover64]

I nice off the shelf option available in Aust could be the Waeco RAPS 36 Coolpower. It is a nice looking power box with a 36 Amp/hr battery inside and all the connections etc to allow it to be charged from 240v . Just plug your cigarette lighter plug on the DC DC converter from RESMED into it. It is a nice unit that can then be portable and taken with you say camping etc (too big for the plane) and be useful for other pieces of equipment.

Cheers

[OMyMyOHellYes]

I think this looks like a great system and as you suggest much better than a UPS. Cant see them for sale in Australia I will have a look and see if there is anything similar.

Best bet - find somebody knowledgeable that is hooked into ham radio if you are thinking about this. Everything is available through ham radio channels (that was not an intentional pun).

OMMOHY

[Carbon]

Thanks everyone for the input. Those various setups are impressive.
After further discussion with she-who-must-be-obeyed , a very major factor is aesthetics, so what I will run with is....

1. UPS with alarm disabled - annoyingly limited by software to 8 minutes vs the 30min I figure it would last, but this will nevertheless silently cover the brown-outs causing no-flow wakeups 3-4 times/week.

2. ResMed PowerStation II travel battery (already owned) all set to go in bedside drawer for occasions of >8 minute blackout - probably a few times a year. Will need to run with humidifier off.

3. My workplace walking distance away has full emergency power system. I can charge up the PowerStation II on their AC power each day in a disaster scenario.

[archangle]

Most battery chargers, including many so-called "trickle" or "float" chargers will shorten the lifetime of a lead acid battery if left connected 24/7. In particular, many of them may be OK for months, but they somehow fail to go into "standby" mode.

I've found the Schumacher SE-1-12s is one that doesn't tend to eat batteries. Family members and I have used them on probably a dozen car or marine batteries and got an average of 5 or more years of life out of the battery. We've also ruined 4 or 5 batteries with other "maintenance" chargers.

BTW, it's not that Schumacher brand chargers are better than others. I'm just familiar with this particular model in real world use over many years.

To get an even better long term life from your battery, put the charger on one of those mechanical weekly timers you plug into the wall that cuts the power on and off on a programmable schedule. Set it, for instance, to run 8 hours one day a week if it's a "standby" battery.

The timer does two things. First, there are fewer hours for the charge current to damage the battery. Second, it resets the electronics of the charger in case it gets "confused" and doesn't drop back to standby mode.

As for leaving the charger connected all the time, this is somewhat concerning. Some chargers do strange things like put a high frequency voltage on top of the the DC voltage. There's also the possibility of voltage spikes or noise and such that won't hurt a battery, but might mess up your CPAP if it was connected. It's probably unlikely for this to be a problem, but it's possible. I'd be comfortable using Schumacher SE-1-12s this way.