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Old 05-15-2015, 06:19 PM   #81
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Default Re: Wonder what big advances will hit "B"s next

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I know little to nothing about fuel cells. Are there any RVs actually using them? The other thing is you mentioned 10 amps of charge. Is that per hour? If so does that mean 80 hours of charge to be ready for a weekend? That I would not understand especially if using an RV any extended period of time because 10 amps could not keep up with usage. Nor it seems to me can solar with a small footprint of collectors. That leaves generation by generator or engine, and shore power doesn't it to keep up with electrical usage? Either would take but just a few hours.
10 amps of charging will give 240AH per day, 800 amp bank full in just over 3 days. Many folks use in the 100-150AH per day, I think, and many use well under 100AH, as we do even with compressor frig. 240AH a day would be way more than most folks need to stay off grid forever, without solar or driving.

Solar is a good option for those that have reasonable power use. 300 watts can give 100AH per day on good days, and extend an offgrid stay considerably for the 50-100AH per day crowd. If you use 300AH+ per day, solar isn't going to extend you more than a little bit.
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Old 05-15-2015, 06:33 PM   #82
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Default Re: Wonder what big advances will hit "B"s next

I'm aware of all that but if you have 800ah of batteries it would imply a lot more energy use one or two battery Bs provide today. If not, why bother to have that much battery power for a weekend sojourn and why spend 80 hours charging when a few (like driving to your destination) will do? It's the logic that defies me. 10 amps per hour charging just makes no sense. At what size for those 10 amps? What would it take to equal the output of an Onan generator? Or a second alternator that I am finding rather efficient. And if you are parked waiting for a weekend trip shouldn't shore power be more logical?

Yes, it could give you staying power without driving if providing 240 amps. That would mean it would need to run constantly. Also staying in one place in a B is not logical either. That might make sense with a trailer.
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Old 05-15-2015, 07:39 PM   #83
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Default Re: Wonder what big advances will hit "B"s next

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Originally Posted by Davydd
I'm aware of all that but if you have 800ah of batteries it would imply a lot more energy use one or two battery Bs provide today. If not, why bother to have that much battery power for a weekend sojourn and why spend 80 hours charging when a few (like driving to your destination) will do? It's the logic that defies me. 10 amps per hour charging just makes no sense. At what size for those 10 amps? What would it take to equal the output of an Onan generator? Or a second alternator that I am finding rather efficient. And if you are parked waiting for a weekend trip shouldn't shore power be more logical?

Yes, it could give you staying power without driving if providing 240 amps. That would mean it would need to run constantly. Also staying in one place in a B is not logical either. That might make sense with a trailer.
You are putting your energy usage and camping pattern on everyone else. Sorry, it doesn't work that way. Not everyone does just a weekend, and I think the example given was just that, one example. 800ah of batteries, 600 usable would be ideal for a lot of folks, we would love to have it. Even off grid a moderate power user, like us, could go a week, even without solar. Remember not all of us want to move every day, we would not consider a change to a trailer until we got to over two weeks in a place, all the time. It is the way we like to travel, just as you want to be on the go all the time.

I agree you would charge to go most of the time on shore power, if you have it, but what if you have to store off site? I would see the fuel cell as near ideal for staying off grid, and not intended to run stuff that a generator would. It would fill the same purpose as solar, keeping you batteries up. Fuel cells have no problem running continuous from what I have heard.
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Old 05-15-2015, 10:41 PM   #84
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Default Re: Wonder what big advances will hit "B"s next

The EFOY models can run 24/7, and are quiet. One of their target audiences is remote camera emplacements, so intruders can't find the fuel cell and disable it.
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Old 05-16-2015, 12:29 PM   #85
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Default Re: Wonder what big advances will hit "B"s next

I'm not putting my power usage and camping pattern on everyone else. Mlts22 mentioned the 800ah in his initial post on fuel cells along with the lengthy charging for a weekend trip. I simply asked the logic of that. Also I never got an answer as to how much space fuel cells take up in a B for that low 10 amp return or whether anyone is installing them, in any RV for that matter.
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Old 05-16-2015, 02:17 PM   #86
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Default Re: Wonder what big advances will hit "B"s next

I have a question which i've never really understood. does a battery charge at the same rate out?. say a battery is 100 amp hours-if it could accept 100 percent of a charge and the alternator is giving it 100 amps does it charge instantly or does it take 1 hour- 100 amp hours out-100 amp hours in
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Old 05-16-2015, 02:50 PM   #87
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Default Re: Wonder what big advances will hit "B"s next

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I have a question which i've never really understood. does a battery charge at the same rate out?. say a battery is 100 amp hours-if it could accept 100 percent of a charge and the alternator is giving it 100 amps does it charge instantly or does it take 1 hour- 100 amp hours out-100 amp hours in
No for most of that. The battery will recharge at a variable rate, taking large amounts of power for a while if available (up to 5 times capacity per Lifeline claim) and then start tapering once you get to about 80% full. It will then need 2-4 (or more) hours to get the rest of the way to totally full. Depending on the battery and the charge efficiency it will usually take somewhere in the 105% range of AH that were taken out, to be put back in. The differences in charge time and amount needed to get full are why the best charging is done by monitoring current, rather than time.
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