Deep Cycle Batteries

[Avix]

I'm looking for some deep cycle batteries to run my 300 watt power inverter for a CPAP respirator for camping/power outages, (as well as a good charger for same that would run off a cars powerpoint)

any comments/ideas/sugestions/what NOT to buys?

thanks in advance.

 

[RussH]

On topic - what kind of flashlight are you running with this?Dont buy auto starting batteries. Dont buy marine batteries. Don't buy an unregulated charger. Regulated chargers are refered to as 'smart' or '3-stage' (2-stage may not be regulated, 'automatic trickle charge doesn't mean anything)

Do buy a true deep cycle battery. Probably most reliable is an AGM battery like the Optima designed for deep cycle use. Note that they have 3 types. In small (auto size or smaller) there are no really good traction (deep cycle) batteries. Other than AGM, golf cart, or floor polisher batteries, you would need to buy a large (4D or 8D) battery to get a suitable deep cycle battery. The cheapest route is two 6v golfcart batteries. Sams usually hase those for $50 or less, but you need two.
For a charger, I like bench power supplies at 13.8v, 4a or 6a @$25-$30. 'Smart' chargers tend to be $65-$100 which is OK if you need 10-15amps. HTH,

 

[Floating Spots]

Check your CPAP for a 12 volt direct input.
Some have it.
If not, you will waste more energy on the two conversions than actually running the thing.

You do need to know how much power it draws, the number of hours its on, and the number of days to estimate how much battery you need.
And it does add up quick....

 

[turbodog]

honda eu1000 generator

 

[Doug Owen]

I guess I have to admit straight up, I'm the only guy that doesn't know what we're talking about. Vas ist ein 'CPAP respirator'? Sounds scary to me....

Anyway, if you need 300 Watts out you're going to have to put more in, like half again if you're at 66% efficiency (not an unrealistic number, IMO). 450 watts from a nominal 12 Volts is close to 40 Amps. Serious power.

Another poster "po po'd" Marine Batteries, maybe they've changed since I knew them, but they used to be deep cycle....

Anyway, what sort of load is this beast?

Doug Owen

 

[springnr]

CPAP machines convert 110v to a dc level so there are dual power machines that operate off 110vac or 12vdc.

A CPAP that will run off 12vdc allows you to run straight off a battery when you go camping.

Another benifit is you can run at home off the battery which is trickle charged during the day. With this setup you can sleep right through a power outage.

CPAP Man has a page showing a battery backup setup.

 

[turbodog]

i'm tellin ya... honda generator...

1000 uses for it in addition to this

buy a cheap marine/deep cycle/etc battery and use the honda twice a day to top off the battery

the eu1000 is a REALLY nice unit
1000 watts ac and also has a dc battery charging plug
PURE sine wave output
super quiet
small
lightweight

 

[gadget_lover]

The Eu1000 has a real good rep among home-power enthusiasts but....

It's very expensive.

The original poster already has an inverter (I think) and will be near a car to charge a battery.

Besides, it's the only toy my wife doesn't want me to have. /ubbthreads/images/graemlins/frown.gif

Daniel

 

[paulr]

CPAP respirator = machine that forces air down your airway while you sleep, used for treating sleep apnea. Leaving a generator running all night while car camping doesn't sound appropriate. A battery makes more sense. The machine shouldn't need anywhere near 300 watts of power though.

I'd look into some gel cells, e.g. batterystation sells them.

 

[Tweek]

I would recommend that you try to operate the CPAP off of the inverter (hook it directly to a car's battery) before you go looking into buying large amounts of batteries. There are some things that just don't like "modified-sine" (more like modified-square!) waveforms. If it works for you, plan on having at least 12AH of battery power for every 1 amp your 120V appliance draws.

This adds up really quickly:

For the below, we'll be using the most commonly available battery suited for the load, a group 27, typically available almost anywhere, ranging in average price from $75-120 or so.

Your average group 27 size marine/rv/deep cycle trolling battery can provide about 80AH of it's 100AH rating before you hit the point where the voltage really sags. So if you are using 1A/120V, count on the inverter pulling at least 11-12 amps. At that rate, your battery would be dead in a little over 6 hours. So, you would need 2 batteries to get through one night.

Now for the fun part: charging!

The easiest way to charge this back up would be to jumper-cable it to your car (don't forget about all the safety issues this can bring up). Also keep in mind that the below figures take into account the fact that vehicle alternators do not put out anything near their full power at idle speeds.

We'll continue to assume that your load used 12AH for 8 hours, for a total of 96AH.

Your typical vehicle's charging system has about 10A or so of charging capacity at idle, with all the vehicle accessories (lights, wipers, fan, etc) turned off. So with that easy numnber, we can count on about 10 hours (and probably close to 1/2 a tank of gas) to recharge the batteries. If we are revving up the engine (to about 2000-2500 rpm), we can get more output from the alternator, which would give us maybe 40A tops available. This would still take 2 1/2 hours to charge and still use a lot of gas.

If you want to use one of the little Honda generators to charge a battery, plan on running it all day, their DC output is only 8A.

The best plan, in either case, is a small generator, like Turbodog recommended. I too would recommend the Honda, although for the money, I would go for the EU2000. Twice the output power, bigger fuel tank, can be paralleled for 220V rigs (lots of RV'ers do this!), and is only about $250 more. You can always use it for other things, such as construction work and power outages. Oh, and even the EU2000 is lighter than just 1 group 27 lead brick... /ubbthreads/images/graemlins/grin.gif

Just my observations, suggestions, and opinions!

Chris

 

[turbodog]

well, the generator with a regular a/c battery charger bring charg time down to a coupla hours

 

[Brock]

Most generators won't run chargers at their full rate. I am not sure about the Honda’s. Don't they use an inverter system? Or am I thinking of something else?

In any case you’re talking about a LOT of batteries if you really need 300w all night. I would suggest at least 2 Trojan T105's (about 70lb each). A good 3-stage charger, about 20 amps, you looking at about $400-$500 for the setup. I would seriously look for a CPAP that could run directly off 12v. As mentioned above the loss will be at least 1/3 of the power stepping it up to 120 then back to whatever the CPAP actually uses.

As far as "marine batteries" goes. They are ok for shallow cycle use, if it is rated for 100 amps and use 20 or tops 30 amps then charge it again your ok. True deep cycle batteries like floor scrubber or traction batteries have plates about 4 times as thick and have a larger reservoir for the acid. The also cost a lot more $, but for good reason. They can stand to be discharged and recharged many more times and they can be discharged further without damaging the battery. So it is cheaper in the long run to a true deep cycle battery, if your actually going to use it a lot.

 

[Avix]

I got the 300 watt inverter as part of a trade, cost me a whole $30.00 worth of some work I did for someone who had one he didn't need. (checked it out first, runs things fine)

RussH: the flashlight that this is about will be all the new flashlights and lanterns I will *have* to buy to go camping, since I can't go camping without this rig.

Foating Spots: the company that makes the CPAP wants $130.00 for the 2 connecting cables for the 12 V Direct Input (they made the input socket extra long to make it propriatary) and I want the ability to run it off things besides the car battery. the inverter also gives me the ability to run other electronics if I need to.

TurboDog: way more than my budget will allow. but when the money becomes avalable, thats high on the list.

Springnr: thanks for that link, it looks quite interesting. the problem is the high cost of the cables. I can spend the same amount and have more flexibility with the inverter setup.

Gadget_Lover: you got it.

Paulr: more than I need, but for $30.00 worth of work (less than an hour) it was worth it.

Tweek: thats exactly the kind of info I am looking for, thank you. I do have a wee bit of a concern about running down the car battery (which is why I am looking at info on other batteries and a recharge system)

ok, actualy power use by the CPAP:
120-240 V~
AC 1.0 A max

56/60 Hz 12V
DC 3.0 A max

class II
Type BF

Inverter:

Prestone PortaPower Jump It 300 Watt DC to AC Inverter

 

[gadget_lover]

The web page mentioned at the start of the thread specifies about 100ah to run all night. It looks like Avix's system can be fairly efficient if run straight off 12V DC.

If you can get one of their connectors to study, you will probably find it somewhere on the net or at your local electronics store. You might also find that grinding the shoulder off a similar connector will make it fit their socket.


Daniel

 

[Brock]

I don't know if they are ever on ebay, but you might find the adapter there.

 

[Tweek]

If your CPAP has a 12V input, you will be in a far better position if you use that to power it. Especially if it only pulls a max of 3A. At that rate, just about any large deep-cycle (I'm using the term in a generic sense right now) battery would run your unit all night, and could be charged back up off the car (idling) in a couple hours time the next day.

If camping for you is going to be a short term thing (a few days duration, once/twice a year) I would just use a generic "deep cycle" battery or two. However, if you plan on doing this a lot, I would second Brock, get some quality batteries designed for the job. Rolls, Surette, Trojan, U.S. Battery, etc all make batteries that will last years more than your typical AC Delco will.

Chris

 

[Avix]

ok, sounds like a little minor surgury and messuring on the CPAP is in order (maybe a photo of the connector), I'll try to get the case open and messure the lenght of the needed plug, I can handle a soldering iron but the electronics stuff is a bit beyond me. might be able to find something and go for the 12V DC. now, sugestion on a charger that will run off a car powerpoint? (prefereably while driving if this is safe)

 

[Bullzeyebill]

Avix, have you considered changing over to a Responics CPAC? One with AC/DC.

Bill

 

[Tweek]

If you want to charge while driving, it's pretty easy to rig a charge cord up. All you need is a cigarette lighter plug, fuseholder, wire (14GA recommended), fuse (10A recommended), pair of battery clips, soldering gear, and a little patience. Make sure to get the polarity right! Cigarette plugs are center positive...

As an alternative, you could get one of the lighter socket-to-lighter socket jumper cable rigs, replace the plug on the end that's for the dead car with the battery clips, and go with that. Might even be cheaper, I don't really know.

How many pins are there in the input connector? Your unit might have seperate sets for AC/DC...

Chris

 

[Avix]

Bullzeye, thats what I have, but they modified the DC conector to require a "special" connector only avalable from them (they made the barrel connection longer so off the shelf won't work), and we're looking at $64.00 for the cable/connector which they don't have in stock localy. This has now become a priority situation (we're going to be without power over the nights this weekend while they FINNALY do major repairs to the local substation)I'm haveing to pick up a power system today. I'm looking at Marine Deep Cycle battery to power the inverter to power the CPAP as a imediate messure.

Tweek. let me go grab my camera....

ok, so that didn't work, I did find 1 connector on a old Rad shack "universal" adapter, that at least fit into the DC plug (the smallest of the 6 with the adapter), but I think I would have to either drill out the hole in the case (which I would rather not do), or cut back the plastic on the barrel of the plug. the CPAP takes 12V 3.0 A max, the adapter puts out 12 V at 800 mA max. so it should be safe to try it, just a mater of figuring out the polarity (again, no indications on the case)