field power supply

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field power supply

Postby ron stahl » Tue Mar 13, 2012 9:12 pm

As per Mikes suggestion below is a email string that was sent around about the field power supply. I just checked for current pricing and shipping and tried to call Jack to inform him of the total with shipping. I was waiting for a vendor to have one at the Wram show or Lebanon last week since it is still winter even though it does not feel like it.

All of Mikes points are very valid and is why we are going with the IOTA DLS 55 model power supply; that way our smaller generator will power it and then we have no need  to run the 6500 watt larger generator and just waste energy into heat if we are not having a meeting at the field and need to charge the battery bank.  By going with this version we  need about 800-1000 watts to run the power supply. We use a honda 1000 at the jet events to power mine and we have no issues doing so. Lastly if we see we need to have a larger power supply down the road you can daisy chain these units together, but then we would have to run the big generator.

Ron Stahl has sent you this email from my iPad2.

On Mar 13, 2012, at 7:09 PM, "Bagley, Michael" <michael.bagley@windriver.com> wrote:

All,
A couple of points to add in this discussion:
1.)    I would like to suggest that these types of exchanges be copied and ultimately use the new Forums section of the RCMB web page. There is a dedicated topic section just for the field maintenance and building projects. It then provides an archived record of the exchanges for a particular topic for all to view.
2.)    As Ronnie points out, most of the automotive style changers do have very large amount of ripple. This is fine when charging a Lead/Acid primary cell by itself like in an auto repair shop. The charger essentially uses the battery as the DC filter. In the case when you have sensitive chargers like the LiPo chargers used for our flight packs, they are trying to measure/charge the LiPo packs to fractions of a volt and a large ripple component on the DC source could cause problems with this activity. So a Charging unit with additional DC filtering is needed here.
3.)    The charger used for the Electrics charge station should also be sized to match or require less power demands than the smaller generator at the field. This would then not require running the large generator for charging the storage batteries in the station.
4.)    I would also suggest that charging of the storage cells in the station be done during the week, possibly while the field cutting activities are performed. On the heavily used weekend flying sessions coming, a couple of users with large flight packs can consume most of the charger capacity, therefore negating any charging activities on the primary cells in the station.
Regards,
Mike Bagley

From: Ron Stahl [mailto:ronscustommodels@msn.com]
Sent: Tuesday, March 13, 2012 6:36 PM
To: <CharlesWRiley@verizon.net>

Subject: Re: Update of Battery Bank Charger
We do not want a regular battery charger because of the ripple current they produce ( some lipo chargers just will not work if the ripple current is high).I am ordering a 50 amp IOTA automatic battery charger / power supply just like the one  we used last summer from my charger box. We can wall mount it and it never has to be disconnected since it is designed to be installed into a motorhome chassis or boat for battery charging and or running all of the 12 volt equipment when on shore power. I have waited to see if they went  on sale during the winter months and they have not. If the suppliers that have good pricing get them back in during the next two weeks, we will have it for the april meeting. We can use the 50 amp power supply that loaned the club until then.

Ron Stahl has sent you this email from my iPad2.

On Mar 13, 2012, at 3:22 PM, "Charlie Riley" <Charleswriley@verizon.net> wrote:

I check two additional places to day as possible sources for a charger for our electric “friends” (electrics will never work).  I also drew a conclusion that anything under 40 amp charge capacity would not suffice since the only time it will be used is during meetings and special events.  With a bank of 4 large capacity batteries, it makes sense that 10 amps per battery is the minimum charge rate for a three to 5 hour period.
Soooo, that pretty much limits our selection to a unit on wheels.  Before, I was not recommend the wheeled units but since we MUST disconnect the charger when not being used anyway, it would be stored elsewhere in the building and not left buy the batteries, right!

PEPBOYS has a 40 amp unit at $169 while Harbor Freight has a similar 40 amp unit (with 3 hour timer and auto shutoff) for $149.
I recommend we get busy finalizing this purchase given the flying season is upon us and since we will probably miss the purchase before Saturday’s meeting it will be needed for the April meeting.
Charlie
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Re: field power supply

Postby ron stahl » Wed Mar 14, 2012 7:32 pm

All,
 This topic has gotten old quick and so we can out this to bed; Jack and I spoke last evening  since I am in charge of this project and appreciate everyones input about it but since the guys with the most high power electric experience ( Troy, Mike and Myself ) have looked at what we need and not spend a fortune doing so. We decided that a IOTA 55 amp power supply was the right thing to buy  and we were done other than making the purchase and installing it. Just so everyone understands, when my charger box is connected to a battery I am pulling 50 amps to run all four of my chargers for my bigger packs. Therefore as a option when we are down on  battery bank voltage we can run the small generator to charge our bank and plane batteries instead of the 6.5 KW one as we only need 1KW to power the IOTA supply, by using the 6.5 just during the two- four hours at meetings we are not putting enough current back into the battery bank to satisfy the demands that now being put on it by people using it every day. If you flew larger electric planes you would have experienced what most newbies have  and that is they under estimate the amount of power required to field charge when multiple chargers are hooked up. The reason we have 4 batteries is so we can store 400 amps of 12 volt power, so if they are dead to charge them in 2 hours would require a  very expensive charger that when we are having a higher than usual demand could then also be used as a power supply to augment the batteries other wise you drain  a fully charged set of batteries in 1-2 days of use. Lastly all of the chargers I have seen allow for voltages between 10 -16 volts for input voltage so if you make a personal choice to not use the battery bank while the power supply is on that is ok with me, but I would never purchase a charger that did not me to use a power supply for use. I never need a battery at my house to charge my batteries I just use my power supply and charger box that I bring to the field.

Ron Stahl has sent you this email from my iPad2.

On Mar 14, 2012, at 8:59 AM, "Charlie Riley" <Charleswriley@verizon.net> wrote:

I see a MAJOR flaw in any charger that will depend on someone hooking it up and starting the small generator other than when we have a meeting or event gatherings when the electric gurus are there and have a personal interest.  So, whatever generator is purchased HAS to have sufficient output to make a serious impact on the batteries in only a few hours.  Personally, I am not concerned about voltage ripple.  I would not be connecting my charger to the bank if there is a charger connected at the same time. OVERVOLTAGE!
C
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Posts: 7
Joined: Sun Jan 29, 2012 10:53 am


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