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Old May 23, 2010, 12:17 PM
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Goekeli's Avatar
North Hollywood, CA 91606
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Thanks Charles!! I've found them online both new and refurb. Excellent idea and prices!

Joe
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Old May 25, 2010, 12:34 PM
More Motors, More Fun... :-)
nioa's Avatar
Phoenix, AZ
Joined Jan 2008
700 Posts
Regenerative Discharge

Quote:
Environmentally friendly, industry first, regenerative discharge capability of up to 1000w. Unlike traditional methods of discharge, which deplete the output battery’s energy in the form of heat across a transistor, regenerative discharge takes most of that energy and puts it back into the input battery. In other words, when you discharge your LiPo for storage, you will be re-charging your Lead Acid input battery. The total amount of power that you can achieve is limited only by the amount of current that your input battery can accept, or 1000W, whichever is lower.
Question: I plan on using the PL8 with two 12 volt automotive batteries in series (24v). Unless I missed it, can the regenerative discharge feature be used with a 24v lead acid battery?

I think this feature is very intelligent, and very useful. Good to see such great features in a charger.
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Old May 25, 2010, 12:56 PM
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ggcrandall1's Avatar
USA, GA, Marietta
Joined Aug 2005
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nioa,

Yes that is it exactly. When your power source is a lead acid battery, regenerative discharge uses the power being discharged from your test battery to recharge the power source. Depending on the charge state of the power source you may discharge at up to 1000 watts.

When using a power supply to power the PL8 you may only discharge at up to 100 watts.

Glen
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Old May 25, 2010, 01:01 PM
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Orange Park,FL.
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Will 2 Deep cycle 105AH power this charger nicely?
I find a local store that have Interstate Marine Deep cycle 105AH for $85.00ea what do you think.
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Old May 25, 2010, 02:25 PM
More Motors, More Fun... :-)
nioa's Avatar
Phoenix, AZ
Joined Jan 2008
700 Posts
Thank you Glen.

Thinking about my own question, I realized that 1000 watts at 24 volts is about 42 amps. That's alot of juice. 12 volts at 1000 watts yields about 83 amps. 83 amps is alot of current, so I would think that FMA means the 1000 watt discharge to feed a 24 volt battery load.

raypadro, any "automotive" battery will do. I use those cheapy $52 batteries that the Checker, AutoZone's, whatever, sells. In this application, there is not a whole lot of demand being placed on them.

I have even been using batteries "retired" from my vehicles and getting great results. (Most batteries here in Phoenix need to be replaced every 2 years or so due to the intense heat, regardless of the so-called 6 year battery warranties). Even so, these batteries can still provide lots of juice to source our lipo chargers. I just keep them cool, topped off, and fully charged.
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Old May 25, 2010, 04:03 PM
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Haralson County GA. USA
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There is something to be said for using retired car batteries as a home power source as long as you have the capability to keep them from getting to low during charging however IMO you need all the amp. hours you can afford for field use. It is best to use Deep cycles and limit discharge to aprox.50%. Even a 125Ah rated deep cycle is only rated arount 85Ahs at a constant 25A load and as the load goes up the Ah rating goes down.

I have two 125 Ah rated 310 Reserve minutes each which in theory means they can deliver 25amps, for 420 min. or 6 hours. Experience has shown me that even when new they would drop to 11 volts or so under a 35 to 50 max. load when I had several chargers running off and on for a couple of hours. Remember as your supply voltage drops so does the charger;s max. output capabilities. A PL8 drawing 50amps. from mine in series for 24V (1,000 watts) really pulls them down fast.

Most of the ones who fly high power setup use power supplies at the field and if 120AC is not available they use a generator. I can see the time very soon when most field with 120AC will need to add 220AC or atleast add heavier 120AC as most only use 20Amps. breaker for many charging stations and that just will not work with 1,000 watt chargers.

Charles
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Old May 25, 2010, 04:07 PM
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USA, GA, Marietta
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nioa,

Yes, the 1000 watt spec is for 24V. The power is reduced by half with 12v.

I hope I am interpreting your comment to raypadro about being able to use "any" battery correctly. You do need a good deep cycle battery for the PL8 operation. The engineers at FMA destroyed several standard automotive battery in the development of the PL8.

Glen
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Old May 25, 2010, 04:26 PM
More Motors, More Fun... :-)
nioa's Avatar
Phoenix, AZ
Joined Jan 2008
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ggcrandall1,

Yes, thank you.

My comment was too brief. I agree that a deep cycle battery should be employed for large charging situations.
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Old May 25, 2010, 07:32 PM
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Orange Park,FL.
Joined Aug 2007
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Quote:
Originally Posted by nioa View Post
ggcrandall1,

Yes, thank you.

My comment was too brief. I agree that a deep cycle battery should be employed for large charging situations.
Exactly I already have 2 12vPB's from my F-150 truck but seems to loose it charge sooner than they use to .I use this 2 bats for field charge for almost 1 1/2 years and most of the time where fully discharged)I know don't supose to do that )

Right now I'm looking for something that I can use to charge 12s 5000mah and 12s 3000mah with the PL8.I know is a little dificult for me to calculate but can I get maybe 5 or 6 charges at full power with a pair of 105AH Deep Cycle.
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Old May 25, 2010, 07:56 PM
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Haralson County GA. USA
Joined Oct 2004
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You can calculate it but what I have done is measure it.

One example

Quote:
SMC 3S 25C 4400 mAh (2e. 2200 in parallel)
Inspector 146 watts , 11.17 amps. ,4686 mAh(4.686AH)13% more than dlivered to battery. 4.686AH/ 6 cells =0.781AH per cell.
So if I add 10% for 5000 instead of 4400 about 4.9Ah per 3cells X 4 = 19.6Ah per 12S 5Ah charge. 24 volts would half this so closer to 10Ah per charge.

ABove figures using a different charger.

I started a Thread her

http://www.rcgroups.com/forums/showthread.php?t=994490

to help gather data that is helpful for answering how manny Ahs how many watts are needed etc. and could use others input if they have actual measured data.

Charles
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Old May 29, 2010, 06:45 AM
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Melbourne, Australia
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Simple to estimate and compare with Charles' real-world figures.

To charge 12S 5000 lipo takes about 12 x 4 x 5 = 240Wh from the source (assuming 80% discharged lipo and 80% efficient charger).

240Wh from a 12V source means about 20Ah from the Pb per charge cycle.

So for two 105Ah in series (24V) that would be 10Ah per charge cycle.

You don't want to use more than 50% of the rated capacity so that means you could get 5 charge cycles of the 12S 5000 pack from your 24V/105Ah Pb source.
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Old May 29, 2010, 07:46 PM
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Perth, Tasmania, Australia
Joined May 2000
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Quote:
Originally Posted by kgfly View Post
.......so that means you could get 5 charge cycles of the 12S 5000 pack from your 24V/105Ah Pb source.
Should that read 10 charge cycles? (10 x 10Ah)
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Old May 29, 2010, 08:42 PM
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Melbourne, Australia
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No, because
Quote:
You don't want to use more than 50% of the rated capacity...
5 x 10 = 50Ah which is probably a bit more than 50% discharged for a 105Ah Pb at high load. If longevity of the Pb is of no concern then you might get more than 5 x 10Ah out of it but perhaps not for long.
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Old May 30, 2010, 03:37 AM
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Perth, Tasmania, Australia
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Quote:
Originally Posted by kgfly View Post
No, because 5 x 10 = 50Ah which is probably a bit more than 50% discharged for a 105Ah Pb at high load. If longevity of the Pb is of no concern then you might get more than 5 x 10Ah out of it but perhaps not for long.
Of course you're right - Don't know why I was thinking 210Ah????
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Old May 31, 2010, 07:57 PM
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Orange Park,FL.
Joined Aug 2007
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Quote:
Originally Posted by kgfly View Post
Simple to estimate and compare with Charle's real-world figures.

To charge 12S 5000 lipo takes about 12 x 4 x 5 = 240Wh from the source (assuming 80% discharged lipo and 80% efficient charger).

240Wh from a 12V source means about 20Ah from the Pb per charge cycle.

So for two 105Ah in series (24V) that would be 10Ah per charge cycle.

You don't want to use more than 50% of the rated capacity so that means you could get 5 charge cycles of the 12S 5000 pack from your 24V/105Ah Pb source.
Thanks Kgfly that's what I'm looking for.
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