Off Grid Camping Attempt

I think much of this was answered above, however.

"Trickle" just drops back to a current that will slowly charge the battery. There may not even be any "smarts" involved. While it's OK to leave it hooked up for weeks at a time, my experience is that it may damage the battery over a period of months or years.

"Float" chargers use more "smarts" and reduce or stop the current once the battery is charged. They usually "watch" the battery and will go back up to a trickle charge when necessary. There is a lot of marketing talk/hype/outright lies, varying degrees of "smarts," proprietary designs, nonsense, etc.

The marketers' use of terms like "trickle, smart, and float" are often not very meaningful, if not outright fraudulent.

One big difference that practical experience tells me is that even if the charger is "smart" in some sense, they tend to occasionally get "confused" and get stuck in the wrong mode. This can cause it to stick and either damage the battery from overcharge or let the battery discharge.

I've had good luck with the Schumacher SE-1-12S charger. It's not as "smart" as some claim to be, but, for me, it doesn't seem to "eat" batteries the way a lot of them do.

BTW, my impression is that the charger manufacturers have been making a race for the bottom in terms of quality in the past decade or so. Even if the charger appears to be glitzy and smart, they have a tendency to fail outright or lose their minds and stick in the wrong mode. I don't even "trust" other models from Schumacher.

One thing I've done for long term maintenance of rarely used batteries is to put charger on a weekly outlet timer and set it to only run a few hours every week. For instance, I'd set mine to run the SE-1-12S for 8 hours one day a week. That way, the charger gets "rebooted" once a week, and even if it does get stuck in trickle charge mode, it gets a much shorter period of time to degrade the battery.

BTW, there are some claims that claim if you only do trickle charging, the battery will "look" OK, but it won't really be fully charged.

NomoreCrashcart wrote:My next door neighbor gave me a 10 year-old Optima Red Top deep cycle battery. it was completely discharged, but seemed to take and hold a full charge so if it's worth keeping, I'd like to use it as a back-up back-up.

Question: Is it worth keeping, and how can I tell? Should I just hook it up to my back-up Remstar Plus and see how long it runs until it doesn't anymore?

The Optima Red Top is NOT a deep cycle battery - its a STARTING battery. I happen to have two of them; my last set lasted around 6 or 7 years. If you've noticed my comments that not all marine batteries are deep cycle, its these batteries I'm thinking of.

http://d26maze4pb6to3.cloudfront.net/op ... _Sheet.pdf

It will possibly work for you a few times, and might do fairly well if you were able to charge it everyday after modest discharge, but in the long run it isn't a good substitute for a deep cycle battery.

NomoreCrashcart wrote:Thanks for the replies, everyone. It's nice to see the many ways XPAP users have found solutions to maintaining therapy off the grid. My study was in spring of 2000, and my life improved immediately. Fifteen years later, trying to nap or sleep without the machine seems all but impossible. Getting the right set-up, therefore, is extremely important to me and I welcome any and all observations and discussion. Here's what I've got so far...

Thanks to you all, I ordered this new 12V 70AH for use as a primary battery back-up: http://www.amazon.com/gp/product/B004WL ... FO4IXVZNRN
Question: Do I want a charger or a maintainer or both? Model numbers /links to products greatly appreciated.

ALSO, my next door neighbor gave me a 10 year-old Optima Red Top deep cycle battery. it was completely discharged, but seemed to take and hold a full charge so if it's worth keeping, I'd like to use it as a back-up back-up.
Question: Is it worth keeping, and how can I tell? Should I just hook it up to my back-up Remstar Plus and see how long it runs until it doesn't anymore?

Thanks again, all for the forum and your participation.

Best,
Bill

As CapnLoki mentioned the Red Top is not a deep cycle. If t's been on 0 for 10 years, it's probably shot anyway. You won't want to use it to power your cpap anyway. But for auto application you can charge it up and take it to Pep Boy's or the like nd the'll load test it for you. The worst thing for a battery is not keeping it charged.

CapnLoki wrote:Since I tend to be rather conservative on this issue, I'd say 10-20 times a year is really pushing it.

Not 10-20 times per year. 10-20 times total seems to be the level where damage occurs, whether it's in one month or 5 years. The damage also varies depending on how deeply you discharge the battery. Leaving your car lights on will tend to discharge all the way down to zero. Your CPAP or inverter will shut down at a higher voltage and not discharge it as far.

We used to think deep discharges were a lot harder on regular lead acid batteries. I think it's party our experience with what happens as car batteries get old and die on their own. They end up discharging more easily as they age and we tend to blame a few night's discharging for killing the battery when it's really just the age. Then, of course, the sellers are glad to blame the failure on the owner, not the battery and sell us a more expensive battery.

The reason I think they can handle more discharges is from what I read from people doing solar installations who have run actual tests with discharging the batteries deeply.

Just to be clear, a shallow discharge IS better, as is a deep cycle battery. I don't think it kills the battery as quickly as we tend to think, and that most of us CPAPers won't actually run it down deep enough and often enough to matter.

archangle wrote:

CapnLoki wrote:Since I tend to be rather conservative on this issue, I'd say 10-20 times a year is really pushing it.

Not 10-20 times per year. 10-20 times total seems to be the level where damage occurs, whether it's in one month or 5 years. The damage also varies depending on how deeply you discharge the battery. Leaving your car lights on will tend to discharge all the way down to zero. Your CPAP or inverter will shut down at a higher voltage and not discharge it as far.

We used to think deep discharges were a lot harder on regular lead acid batteries. I think it's party our experience with what happens as car batteries get old and die on their own. They end up discharging more easily as they age and we tend to blame a few night's discharging for killing the battery when it's really just the age. Then, of course, the sellers are glad to blame the failure on the owner, not the battery and sell us a more expensive battery.

The reason I think they can handle more discharges is from what I read from people doing solar installations who have run actual tests with discharging the batteries deeply.

Just to be clear, a shallow discharge IS better, as is a deep cycle battery. I don't think it kills the battery as quickly as we tend to think, and that most of us CPAPers won't actually run it down deep enough and often enough to matter.

I'd disagree on a number of points here - an automotive battery will go pretty deep before the voltage drops to the point where an inverter will cut out. At that point a starting battery is suffering damage on each cycle. Its not a case where it works fine 100 times and then fails, its more like it dies 1% each deep discharge. You mention "old age" and that exactly right - old age for starters is caused by several thousand minor discharges. Or several hundred medium. Or a few dozen deep - or some combination of all of the above. I'll admit that 10-20 deep discharges won't kill a starting battery, but it will cause noticeable damage.

But the real point I have is why bother? If its a matter of getting a bit more use out of a discarded starting battery, then sure, why not? But a starting battery is considered possibly unable to start a car when its only discharged 30%, so even minor degradation could prevent a battery from starting a car on a cold morning. It would be foolhardy to run a pump (and especially a humidifier) from a car's starting battery on a camping trip, so I certainly don't want to advocate that in this forum. And even if I'm being overly pessimistic, for this application a deep cycle battery will outperform a starting battery by a huge factor. Since the initial cost is similar, there's certainly no reason to buy starting battery to be used as a deep cycle.