Battery life help

[drj130]

The other day I went and picked up this item from AAFES (Army/Air Force Exchange Store)
http://www.amazon.com/Schumacher-IP-125 ... B000TD6S9U
and I was wondering if someone could help me figure out if it will last me about 3 nights on a pressure of 11 using an M Series APAP.

My machine will be in CPAP mode only, and of course no humidifier either.

Thanks,

David

[robysue]

One more variable we need to know: How long do you run the machine during a typical night?

[drj130]

Knowing myself, 4 to maybe 6 hours.

[robysue]

I've gotten 3 nights on my System One Auto BiPAP with the humidifier running on my Sears Diehard Jump Starter battery (http://www.sears.com/diehard-gold-porta ... 871987000P) in the past and I typically sleep about 4 1/2 to 6 hours when the battery was completely charged. I use a DC cable to connect the BiPAP and my pressures are min EPAP = 4, max IPAP = 8

But: By the end of that third night the battery was pretty much completely drained. I try very hard to limit the use to two nights between charging now since the last time the battery got that depleted I had real problems with both charging the battery AND having it blow a fuse in the DC cable.

I think you'll probably be ok since you don't plan on using the humidifier. But bring some extra fuses just in case.

[drj130]

Thanks for the fast response. I was worried that I'd made a mistake with buying this thing. It will work until I get back to the states where there are a heck of a lot more options on an item like this.
I "could" recharge it using my motorcycle, but I'd rather not put that kind of a strain on the girl.

[alexsmom]

I can easily get 3 nights, 7 hours a night from my Duracell 600 Jumpstarter battery. Unfortunately it is about twice the cost of the one you are looking at.

[billbolton]

Jump-start style units use small SLA batteries, which will not last very long at all if deeply discharged. So looking to run for more than one night on any of them is asking for an early demise of the battery

Cheers,

Bill

[khauser]

Bill is correct ... these batteries are kinda small. RobySue has a relatively low (at least compared to me) pressure. At my pressure settings (16-20 auto) I can't get 8 hours from the unit. With the humidifier I can't get 6. The unit I have is the Sears platinum ... actually one step up in size from the Gold.

[Fizzled]

Thanks for the fast response. I was worried that I'd made a mistake with buying this thing. It will work until I get back to the states where there are a heck of a lot more options on an item like this.
I "could" recharge it using my motorcycle, but I'd rather not put that kind of a strain on the girl.

Well, your bike probably doesn't care. Bikes from the 80s to current pretty much all operate at 100% electrical load 100% of the time. Your regulator/rectifier converts whatever the alternator's outputting into bike usable DC, but also stabilizes the voltage by shunting (wasting excess energy as heat).

Essentially, your bike consumes whatever your alternator outputs, if there's an excess of energy being produced it's wasted as heat. Drawing too much could cause issues with a deficit to other components (ECU, etc.), but a 2nd battery is unlikely to do this even if it was completely depleted. However, you probably couldn't get away with just idling the bike, not all MCs produce enough wattage at idle to support all OEM systems without extras.

[Fizzled]

The other day I went and picked up this item from AAFES (Army/Air Force Exchange Store)
http://www.amazon.com/Schumacher-IP-125 ... B000TD6S9U
and I was wondering if someone could help me figure out if it will last me about 3 nights on a pressure of 11 using an M Series APAP.

My machine will be in CPAP mode only, and of course no humidifier either.

Thanks,

David

If you can get your hands on a clamp ammeter or kill-a-watt style meter you can figure it out. I could see exhale pressure relief, pressure, your respiration rate, etc. dramatically altering how much time you could get out of a battery.

Just keep in mind as Bill indicates, discharging 'jumpstart' style batteries to 0% regularly will diminish their effective service life VERY quickly. I wouldn't go below 70% on a regular basis on non deep cycle batteries. If you had a deep cycle battery, you still don't want to completely drain it.

[drj130]

I would love to have a better option than what I'm going to use at this event, but some of the items you all suggest are not easy to carry on a motorcycle. This is what my bike looked like the last time I went.


As you can see, space is limited. I've done some thinking on the repacking, and have made a few changes, but trying to carry a deep cycle battery isn't an option at this time nor is plugging in. In the future I maybe able to carry a deep cycle or even a better setup, but I'll have to do some tinkering. If I do things like this in the future, and if my wife rides with me, I'll have to make changes, else she'll have no place to sit. lol

[CapnLoki]

This is an interesting problem - I don't have the answer but I'll throw in a few thoughts:

Essentially, your bike consumes whatever your alternator outputs, if there's an excess of energy being produced it's wasted as heat.

No, the alternator doesn't produce any "excess" that's wasted as heat. Its the job of the regulator to tell the alternator how much current to produce. (My alternator can produce 100 amps, but I can set the regulator for 0 to 100 Amps and it will still only output up to the loads and the battery's ability to accept a charge.) A MC alternator probably is in the range of 20 Amps, which would "steal" about 1-2 Hp from the engine. Since the add-on battery probably only uses 2-4 Amps to charge, this is a negligible load on the engine. As Fizzled said, the bigger issue is that the alternator probably doesn't "turn on" at idle and you probably don't want to run at a campsite at 3000 RPM for 4 hours to charge up; you'd really have to find a way to charge while travelling.

I'm torn on the issue of battery life with high "Depth of Discharge" (DoD). High quality Deep Cycle AGM batteries can cycle 1000 times to low DoD (perhaps 20% discharge), maybe 500 times to 50% and 300 to 80% DoD, and worse if you go to full discharge. But what about a cheap battery you're likely to get in one of these devices? I wouldn't be surprised if the performance is only a tenth of the quality units, and they certainly do not publish their numbers. To make it worse, each time you discharge more than 80% DoD, you're doing permanent damage so the total capacity is reduced. And unlike wet cells, there are no clever tricks to recover the lost capacity.

On the other hand, If you only got 25 three night cycles from the battery, you might say its a bit pricey but worth it. In fact, a lot of users would be happy if it worked a couple of weekends a year for 5 years, or even just once in a hurricane!

Here's an odd thought: you might do better running the CPAP off of the motorcycle battery all night, and then using the add-on starter battery to start the MC in the morning, if needed. If the MC battery is a basic "starter battery" this would probably wear it down too much, but if its "combined starter/deep cycle" battery with 20+ Ah capacity it could work. The M-series probably uses about .6 Amps so 6 hours is under 4 Ah. Just a weird thought.

[Fizzled]

Not on motorcycle systems. On car systems you're absolutely right, they can vary the alternators output. This results in less parasitic losses and inefficiencies.

MC alternator output is a direct function of RPM. Alternators produce 100% of their ability at a given RPM then waste the excess. The R/R runs cooler when you draw more power for this reason.

If you happen to know someone with a bike take an contactless thermometer and point it at the RR, if you start unplugging things like headlights, etc. you'll notice it gets hotter everything else the same (provided whatever RPM you're at is producing anexcess).

[drj130]

I thought of that as well, but at 100.00 euros a pop, the battery for my motorcycle isn't cheap here. Not to mention how much of a pain it would to pull the battery at night. The cord I have for the M Series to run off DC power also isn't long enough to run from Acc. adapter on the bike inside the tent. I only paid about $50.00 for this small battery and if it only works during this time for my trip, I think that it was money well spent. More so because of the time frame involved for when my trip happens.

Thanks for the suggestions CapnLoki

[drj130]

Okay, I just a few things and this is what I know about my bike:

The electrical system has an output of around 330-345W @ 5000 rpms, and just enough to keep the bike running at idle.
The bike requires minimum of 110W just to idle, which is the draw from lights, coils, etc. in stock set up.
The stock set-up allows me to have about 150W of excess power at highway rpms.

I could recharge the setup I have, but to do it best I would have to be riding. I'm not going to try something like that. Too risky. LOL