Backpacking, Hiking and Camping - the PowerAdd Pilot Pro

amenite wrote:

drzman49 wrote: Thanks for the link and thoughts. If I were to explore various options on my own, it would be helpful to know how much current in watts and amps it would need to output into the machine. I think that the 560 may be similar to the 760. What are the draws for the 560, and what type of electrical current would a workable battery be able to output in terms of watts and amps? Anyone?

Thanks!

CapnLoki is well versed in this and has taken the scientific approach in the past, see below:

viewtopic.php?t=102179

So most of the data I've taken is is concerned with average current, not the instantaneous load. It turns out that while a pump might have an average load of 0.5 Amp, it actually varies from a bit over zero up over one amp on every breath. And on large leak and startup situations, it can easily go over 2 amps, may even 3 - I don't have a good way of measuring a short spike. This is no problem for a larger lead acid battery which is generally designed to be able to dump 50 amps or more, but Lithium batteries are often designed for more modest loads. They almost always have "Battery Management Systems" that keep the cell charges even and prevent various mishaps. (Not always successful, as Samsung found out recently!) These BMS systems usually shut down the battery when it senses an overload.

We've seen significant differences between different examples of the same model - this indicates that the specs are fuzzy and that CPAPs are not the expected use. Make sure you buy from a vendor that has an easy return policy, and give yourself lots of time to test.

So I've only used lead acid deep cycle batteries with my pump. If I wanted Lithium, I would consider LiFePO4. These are still heavier and more expensive than LiPo, but usually have the advantage of charge/discharge specs that are similar to lead/acid so I know what to expect. If you go this route, don't be fooled by "Pb Equivalent" specs, look for real amp-hours.

thanks...

thinking two batteries, one for camping close to road, like LiFePO4
and one for off road lipoly

questions
1. how do I find the "real amp hours", and read the fake pb equivalent?
2. I'm thinking the machine needs 4 to 5 amps to start up (though average far lower) so the output on the battery has to show a max of 4 to 5 or greater, yes? So a battery (of whatever type) that has an output of 90 watts will gave me 7.5 amps. the poweradd says it has an output of 4.5 amps, which seems adequate (unless the battery is below standard).
3. There's something about the auto shutoff that is hard to figure, hence good return policy.
4. for the LiFePO4, I was thinking any one that is made for a car would do. Is that correct?

Since the poweradd was used several years ago, there are some new similar lipoly batteries that are claiming 50,000 or so mah. Thought I would explore this option for my second off road battery.

Thanks again!

drzman49 wrote:1. how do I find the "real amp hours", and read the fake pb equivalent?

amp/hours are only part of the answer, the real value is watt/hours. as capnloki has said, many of those lithium packs quote AH in the tens of thousands (of thousandths) but neglect to mention what voltage that rating is at. (often at the 3.6ish volts of the lithium cell. to find power output, you have to multiply volts times amps times hours. to get watt/hours.

eg, a 31000mah lithium pack is really a 31ah pack@3.2 volts, or 99.2 watt/hours. whereas a 35ah lead acid battery @12.6v is a 441 watt/hour source. give or take a few watts.

drzman49 wrote:4. for the LiFePO4, I was thinking any one that is made for a car would do. Is that correct?

do they make such a thing?

amp/hours are only part of the answer, the real value is watt/hours. as capnloki has said, many of those lithium packs quote AH in the tens of thousands (of thousandths) but neglect to mention what voltage that rating is at. (often at the 3.6ish volts of the lithium cell. to find power output, you have to multiply volts times amps times hours. to get watt/hours.

I figured their calculations was based on some hidden decision about what the voltage that was being used to calculate, that they would use the lowest voltage, yielding the highest number for marketing, but when I tried to confirm that on some published specs, it did not seem clear at all what they were using to make the calculation. Some batteries publish information that give the watt hours (poweradd says their's is about 118 wh), or enough information to make the calculation of what it is.

For the car battery comment, I think i was looking at various types of electrical vehicles. But for cpap purposes, wondering if any of these would work from the website batteryspace. I'm not sure how some are better than others for cpap purposes.

http://www.batteryspace.com/Li-Ion-Batt ... eries.aspx

http://www.batteryspace.com/12.8V-LiFeP ... -18Ah.aspx

http://www.batteryspace.com/12-8v-lifep ... 200ah.aspx

http://www.batteryspace.com/lifepbatterymodules.aspx

These in particular are marked as "for cpap" but don't know why they would be any better than the others...
http://www.batteryspace.com/search.aspx?find=cpap

drzman49 wrote:For the car battery comment, I think i was looking at various types of electrical vehicles. But for cpap purposes, wondering if any of these would work from the website batteryspace. I'm not sure how some are better than others for cpap purposes.

euh, I wouldn't think any of those would be a replacement for a car battery... but, who knows, certainly many times more expensive

someone recently posted a thread here about a friend that went camping with hobby batteries, they were spendy, but light and powerful. you can search with your favorite search engine, put "site:cpaptalk.com" (no spaces) in the query field along with whatever you're looking for, maybe camping, batteries, hobby, lipo, stuff like that.

drzman49 wrote:2. I'm thinking the machine needs 4 to 5 amps to start up (though average far lower) so the output on the battery has to show a max of 4 to 5 or greater, yes? So a battery (of whatever type) that has an output of 90 watts will gave me 7.5 amps. the poweradd says it has an output of 4.5 amps, which seems adequate (unless the battery is below standard)

iirc someone posted on here they had to connect two powerdds in parallel or the cpap would start then shut down. That would indicate that one could not provide the start up current needed.
Also you never hear about people packing spare fuses with them on their trips.

palerider wrote:

drzman49 wrote:4. for the LiFePO4, I was thinking any one that is made for a car would do. Is that correct?

do they make such a thing?

Quick answer - yes, they are all the rage for starting batteries on motorcycles and jetskis. The "Pb-Equivalent" is a play to this market, since lead acid batteries are deemed to low to start when only 30% discharged. Since LiFePO4 holds a strong voltage even when 80% discharged, they make the claim that for starting purposes they can be very undersized. This argument is meaningless for deep cycle applications, so I would not consider purchasing any battery that didn't include the true Amp-hour rating. BatteryTender markets this style of battery and strongly recommends not using them for deep cycle.

CapnLoki wrote:

palerider wrote:

drzman49 wrote:4. for the LiFePO4, I was thinking any one that is made for a car would do. Is that correct?

do they make such a thing?

Quick answer - yes, they are all the rage for starting batteries on motorcycles and jetskis. The "Pb-Equivalent" is a play to this market, since lead acid batteries are deemed to low to start when on 30% dischargered. Since LiFePO4 hold a strong voltage even when 80% discharged, they make the claim that for starting purposes they can be very undersized. This argument is meaningless for deep cycle applications, so I would not consider purchasing any battery that didn't include the true Amp-hour rating. BatteryTender markets this style of battery and strongly recommends not using them for deep cycle.

well, he did say "car" not bike/jetski. little motors, I could see.

Back to the discussion, I read that lithium phos batteries, with a given shelf life, and given cost, payoff if used a couple times a day, but do not pay off when used once or twice a month. While li poly have fewer cycles, may be better payoff if used less regularly. That for a relatively lightweight alternative for off road camping trips and such.

Making the poweradd (to arrive today) a relatively lower cost li poly alternative, particularly in reference to the heavily marketed "cpap battery" show.

I tried my new dbpower li poly jump starter battery with 18000 mah on both my m series and series one, and it powered me easily through the night on the m series (plugged directly into the machine). Poweradd should give me two nights, combined good for my three night kayak camping next month.

drzman49 wrote:Back to the discussion, I read that lithium phos batteries, with a given shelf life, and given cost, payoff if used a couple times a day, but do not pay off when used once or twice a month. While li poly have fewer cycles, may be better payoff if used less regularly. That for a relatively lightweight alternative for off road camping trips and such.

Making the poweradd (to arrive today) a relatively lower cost li poly alternative, particularly in reference to the heavily marketed "cpap battery" show.

I tried my new dbpower li poly jump starter battery with 18000 mah on both my m series and series one, and it powered me easily through the night on the m series (plugged directly into the machine). Poweradd should give me two nights, combined good for my three night kayak camping next month.

The real issue for me is the the LiFePO4 cell voltage is 3.2 meaning four in series is 12.8, very close to a standard lead-acid battery (six 2.1 v cells in series). They can be used as "drop-in" replacements with the same charge/discharge properties. LiPo has a 3.7 voltage so it doesn't match well with 12v appliances and requires special charging, although they do work well with computers, etc that are designed with LiPo in mind. LiFePO4 is considered much safer than LiPo.

Packs like the PowerAd seem to work though they have issues due to the mismatch. When they are designed for cpaps, the price magically triples.

LiPo has a 3.7 voltage so it doesn't match well with 12v appliances and requires special charging

which brings to the fore, the system one voltage requirements, the lifep04 output voltage, do I need a dc to dc converter, or does the system one accept the variance?

Would seem to be answered by the fact that a car battery outputs variance, and the cord used to connect car battery to machine accepts the normal car battery variance, therefore should work from liifepo4 to system one.

drzman49 wrote:

LiPo has a 3.7 voltage so it doesn't match well with 12v appliances and requires special charging

which brings to the fore, the system one voltage requirements, the lifep04 output voltage, do I need a dc to dc converter, or does the system one accept the variance?

Would seem to be answered by the fact that a car battery outputs variance, and the cord used to connect car battery to machine accepts the normal car battery variance, therefore should work from liifepo4 to system one.

I would be quite surprised if there was any problem using LiFePO4 with a cpap, or any other 12v appliance. My boat system voltage varies from 11.5 to 14.6 and I've never had a problem. Although on the boat I never charge while sleeping (I haven't used shore power in many years) I have run at home while the battery is connected to its BatteryTender charger, which does create a small "over voltage" situation.

The more interesting question would be what happens when you use a LIPo battery at its "native" voltage of 14.8 (for a 4S configuration) or 18.5 (for 5S, used by some computers). Also, for ResMed users with the DC/DC converter, are there particular configurations that are most efficient and cost effective?

found a local lifep04 maker/factory, 20ah batteries, inexpensive, 4 cell with a balancer. Does the balancer facilitate a "deep cycle" equivalence? Wondering how this would compare to a ctc.

http://elitepowersolutions.com/products ... cts_id=146

Got the poweradd today, opened it up, a used torn box, fingerprints all over the battery inside. Selling me a used batter as if it is new...Amazon appears to be doing this more an more often. Didn't bother to power it up, sending it back from whence it came.

May explain why folks keep getting faulty batteries...either poweradd staff or amazon staff are recycling returned items, the cost of "easy return".