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Old May 14, 2008, 07:30 PM
Not your average DiggsyBear
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Raleigh, NC
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Batteries for charging at the field or installed in a trailer

There was a good discussion going on in another thread that was off topic about this and I wanted to start a thread here so we could continue on. I am primarily interested in a way to charge my Lipos and such while at a fly in or just a couple of days away from AC power. I have a trailer and want to install a few big bricks in there that would allow me to charge for a few days without recharging the main bricks.

I am considering a couple of options.

1 Golf Cart batteries. A friend of a friend uses these in a motor home and says they serve his purpose well, and are designed to run very low without damage.

2 Deep cycle marine batteries. Also designed to run pretty low, but not sure if they are safe in enclosed areas.

OH, UPS pacs are something else I would consider and am curious about. Just not sure where to get them. But I know the interruptible Power Supplies for large server racks will go down to almost zero charge and bounce back.


So, what are you guys using? What worked well and what didn't? And what did it cost?

Thanks,
Diggs
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Old May 14, 2008, 07:46 PM
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250AH or 190 AH " U-Boat batteries " that everydayflier uses
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Old May 14, 2008, 07:56 PM
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Aside from actual German U-boat batteries is there a good source for these hall woo?
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Old May 14, 2008, 08:57 PM
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USA, AK, Houston
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I personally wouldn't deal with a battery that big since they are heavy and dangerous. If it where me I would just get a very quiet small honda generator and a nice big marine battery. Every evening just charge up the marine battery using the generator and a charger. It's simple, and you get AC in case you need it.

I would get a EU2000i

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Old May 14, 2008, 09:08 PM
Not your average DiggsyBear
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Raleigh, NC
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Wow, that generator is about $300 less than I have invested in my trailer. While I would love to have one, the funds just won't allow for it. I can snag a pair of batteries for around $150. However, I hear the advice and maybe I can save up for the generator. I would love to have one!!

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Old May 14, 2008, 09:29 PM
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Haralson County GA. USA
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Quote:
I am primarily interested in a way to charge my Lipos and such while at a fly in or just a couple of days away from AC power.
Sorry but that tells us nothing ,well nothing useful.

If you fly 6oz. foaamies with 2S 600 mAh LiPolys and fly 6 times a day just use your car/truck battery.

If you fly 4S 3300 mAh LiPolys then you may need one ,two or more 125Ah Deep cycles depending on how many flights.
I fly 3,4 and 5S A123 2300 mAh packs and I can fly / charge a dozen mixed packs and never use more than approx. 20% from my two 125Ah (250Ah total) deep cycles.



Charles
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Old May 14, 2008, 09:46 PM
Not your average DiggsyBear
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Quote:
Originally Posted by everydayflyer
Sorry but that tells us nothing ,well nothing useful.

If you fly 6oz. foaamies with 2S 600 mAh LiPolys and fly 6 times a day just use your car/truck battery.

If you fly 4S 3300 mAh LiPolys then you may need one ,two or more 125Ah Deep cycles depending on how many flights.
I fly 3,4 and 5S A123 2300 mAh packs and I can fly / charge a dozen mixed packs and never use more than approx. 20% from my two 125Ah (250Ah total) deep cycles.



Charles
Well, I was making it kinda general for the other people discussing this.

Personally, I fly a variety of things. I would say I mostly use 3S 2100 Lipos, but I also use a fair amount of 4S 4000~6000mah and 3S 3600mah packs. But I also fly many 3 and 2S 900~1300 packs. So I am all over the board. Depends on the condition of the day. At SEFF I was charging mainly the larger packs. I would say 3 of the 4S packs a day, and 4 or 5 of the 3S 3600's.

On a big day
# of charges - pack size
3 - 4S 4000mah
2 - 4S 5000mah
6 - 3S 3600mah
5 - 3S 2100mah
5 - 2S 900mah

I really can't see using more than that in a day. And that would be unusual, but the max I expect to ever run in one day.

I would be installing these in a covered cargo trailer and have heard that deep cycle marine batteries emit a toxic gas when being charged. Dunno if that is true, or if it is so slight that it would be cause for concern.

Any advantage to batteries designed for a golf cart? Safer? Would they handle being drained better?

Anything else I should consider? OH, I would like to run a light or two off these for short periods as well. Small light typicall for a trailer light. Never checked the size of it, but looks a lot like a clear xmas light. Probably 7~15 watt I would guess.

Thanks for the info.
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Old May 14, 2008, 10:04 PM
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Hi,

For a day trip to the field, I use one 205 AH WalMart deep cycle battery. I fly 2S 5000 up 10S 2200's. Never a problem. For contest or flyins, I have two to four of these 205 AH batteries in parallel . Last year at the Nats four of us shared the four battery set up for a week and never charged while on the trip. These batteries cost around $75, Everstart Marine Deep Cycle.


Ric
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Old May 14, 2008, 10:30 PM
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I have used jump-start batteries with some success. My Pops has a big one for jumping vehicles at his shop and my brother and I have used it continuously for a whole weekend with no issues.
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Old May 14, 2008, 10:46 PM
Sparky "Electrics Rule"
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If you deep cycle them they are not going to last. We had three at our field last less than 6 months.

Quote:
Originally Posted by bildo baggins
I have used jump-start batteries with some success. My Pops has a big one for jumping vehicles at his shop and my brother and I have used it continuously for a whole weekend with no issues.
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Old May 14, 2008, 11:25 PM
PGR
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Quote:
Originally Posted by Diggs
I would be installing these in a covered cargo trailer and have heard that deep cycle marine batteries emit a toxic gas when being charged. Dunno if that is true, or if it is so slight that it would be cause for concern.
Conventional lead-acid batteries produce hydrogen gas when they're charged. Hydrogen isn't toxic but in high concentrations it's not life-supporting.

But it's extremely flamable (think Hindenberg). In enclosed spaces it can be extremely explosive.

Normal charging of healthy batteries doesn't produce much hydrogen, though, and it rises instead of sinks so it doesn't tend to concentrate enough to be a problem as long as there's some ventilation.

To bypass this problem entirely, use sealed lead-acid batteries (SLA). These are also commonly known as gel batteries. They don't leak anything under normal use and can typically be mounted in any position like on their sides or even upside down.

My personal favorites for storage batteries (RVs, golf cars, etc) are the Optima D31 Yellow Tops. The D31 is a 75AH SLA that will provide excellent starting current and a nice, flat voltage curve at moderate loads and they can be repeatedly discharged to 10.5V without harming the battery.

They're not cheap, though.

I have a D31T in the trunk of my car for charging packs at the field. It's hooked to the car's charging system via an RV isolator relay so it's getting charged while the engine is running but isolated from the car's electrical system when the engine is off. That prevents me from discharging the starting battery under the hood.

I always go to the field with all my packs charged so I rarely need to charge more than 6 to 8 packs at the field. My typical pack is 2100-2500 mAh and 3-5 cells. The D31 charge 8 of 'em without any noticeable drop in voltage. I'm sure it will do more, but I haven't found the need to yet.

And just for the record, the battery under the hood is also an Optima. It's been charging battery packs and starting my car for over 6 years now and it shows no sign of reduced capacity.

Pete
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Old May 14, 2008, 11:45 PM
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I don't know much about batteries but as Bob Vincent said in the other thread, we charged 3s and 4s ( 2200 mah minimum) batteries for four days on my new Everstart Deep Cycle Trolling battery. It cost $65 and I bought a charger just for it too. Took it home, it showed 80% so I put it on the charger. It was done in about 20 minutes. Loaded it up for SEFF. Never charged it at SEFF and we flew the crap out of everything. We had over 15 planes there. I still haven't charged it but will be interested to see how long it takes to get back to capacity.
I'll use it in my shop with the Xtrema charger once in awhile just to keep it active.
It sure is handy just to sit on the tailgate and not have to mess with power stations.

J
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Old May 15, 2008, 09:43 AM
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Melbourne, Australia
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4S 2200 takes about 27Wh to charge which drawn from a nominal 12V Pb means 2.25Ah. If you charged 10 packs a day for four days that would be 90Ah drawn from the battery. Either you didn't charge that many, or my maths is wrong or it was a 450AH battery to be only 20% discharged!

I am not questioning anything you said, just struggling to understand how it worked out that way ?
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Old May 15, 2008, 11:33 AM
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Hey Diggs, after you have picked your batteries and when the funds permit it. You should slap one or two solar panels on the top of your trailer. Put in charge a controller and you have yourself a quiet low maintenance setup that goes anywhere. Great podcasts keep up the good work.
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Old May 15, 2008, 06:40 PM
Not your average DiggsyBear
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Quote:
Originally Posted by Marty H.
Hey Diggs, after you have picked your batteries and when the funds permit it. You should slap one or two solar panels on the top of your trailer. Put in charge a controller and you have yourself a quiet low maintenance setup that goes anywhere. Great podcasts keep up the good work.
Marty H.

I saw someone at SEFF doing something similar and thought about all that space I have on top of my trailer that gets blasted with sunlight. I would do it if I could find some on the cheap!!

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