Author Topic: multiple chargers (Read 1366 times)

tom hampshire · « **on:** May 04, 2009, 06:54:31 AM »

I have three older non-balancing Lipo chargers, and one new model with the balance feature. Is there any sense in using one of the cheap chargers to bring a pack most of the way up to full charge, and then switching over to the balance charger for the last part of the charge cycle? I'm wondering if the total system cost might be lower with fewer packs and multiple chargers, say 2 chargers and three packs. One charger and five or six packs seems awkward, since you can't charge more than one at a time. Thoughts? Tom Hampshire

Alan Hahn · « **Reply #1 on:** May 04, 2009, 07:39:28 AM »

Well I have 3 chargers!

Two are balancing types, FMA 4s's which are limited to 4A and 4s packs, and the other is an Astro109 non-balancing charger. However it can handle more amps and more packs in series. That being said, my maximum pack voltage is 4s. I carry one of the Cellpro's in my car, so it can be used at the field. For me, the purchase usually because I was offered a deal I just couldn't refuse!

I also bought an Astro Blinky, which costs about $25 and is a balancer that I use with the Astro109. It could be used with any charger as long as the pack has a balancing connector. There are other balancers out there. That being said, as long as you packs are in pretty good shape, you could rotate them through the balancing charger to keep the packs balanced in the long term. However if your pack has a weak cell and typically would be way out of balance after a flight, then you would want to balance it every time to try and prolong the pack life.

So I agree, if you have 4 packs to charge up after a flying session, then having two chargers makes sense. In my case all my packs are typically 2100mAHr packs, so I can charge them at >1C, so the charging time is less (but not a lot) than 1hr a pack. However you still need the AC/DC adapter which can supply the amps to handle the two or more chargers.

Dennis Adamisin · « **Reply #2 on:** May 04, 2009, 09:16:17 AM »

Tom:
First off, I did not know you were flying any electrics - inquiring (and nosy) minds want to know more!

I think that balancing with every charge is important - I think that will especially help with packs that are being used fairly deeply. add-on balancers will do the deed. THe Hobbico Equinox will work as a balancer or can be put in-line with your charger so you can charge through the balance connectors.

That beng said there are wome pretty good balancing chargers available with balancers that just are not that expensive anymore. Depending what you have invested in chargers you might just go all-new...

tom hampshire · « **Reply #3 on:** May 04, 2009, 10:14:39 AM »

Hey Dennis - Here's the airframe. Gieseke Noblur from a moon kit. Super kit, too bad its out of production. Anyhow, if I go with an add on balancer coupled to a cheaper charger, will it slow up the charging process? My initial thought was to charge through the power leads at a fairly high rate to shorten the total charge time, and then correct the imbalance with a balanced charge for the last 25% or so. Do you think that method will damage the batteries? If it is OK, then it looks like I might be able to use as few as 3 packs. Tom H.

Alan Hahn · « **Reply #4 on:** May 04, 2009, 12:12:23 PM »

Tom,
Most of the charging time is typically set by the last ~5% of the charge, where the charger slows down and "creeps" up on the full charge.

If you have plenty of battery capacity, then you can save a lot of time by simply stopping the charge at that point, and flying with a 95% charged pack. The main point is to try and leave the pack at the end of a flight with at least 20% of its full charge capacity. So if you have a 4000mAHr pack, it should have at least 800mAHr equivalent left in after a flight.

The main reason for balancing is to make sure the weakest cell doesn't get over-discharged (lower than the 20% reserve), so if you are flying 'conservatively' with the pack capacity, you can let a balance or two slip by without affecting them a lot.

One comment about the balancers--they don't have a lot of current capacity (typically), so they can take a lot of time to bring everything into balance if things are way off.

tom hampshire · « **Reply #5 on:** May 04, 2009, 01:19:18 PM »

Hi Alan - My electrical skills are adequate, but slow. Please bear with me. As I get it, I could use a deep discharge source battery and charge packs between flights to 95% of capacity. I'm using Neu 5s1p 3900 mah pack, on a Nobler, 550 inches or so, with an Axi 2826/12. So I won't have a very deep discharge. Might it be that I can use this 'quick charge' at the field and not even worry about balancing until I run each pack through the balancer charger at home? Might I be able to charge more quickly by doing this at a high charge rate? I think I can go to the capacity over 100, or 3.9 amps without damage. Does this make sense to you? Tom H.

Rob Roberts · « **Reply #6 on:** May 04, 2009, 01:48:01 PM »

Tom are you sure your older chargers will work with a 5s pack? If the charger is up to it you can check the volts at the balancing tap to make sure your close to balanced before and after each charge.

Rob

Dean Pappas · « **Reply #7 on:** May 04, 2009, 03:09:25 PM »

Tom!
A 5S-3900 pack??? That's a 20-ounce battery. Please tell me you're kidding.
It's okay to balance once every so often.
If you did your at-field charging with whatever is at hand, and then recharged each pack at home with the balancing charger that would be fine.
The motor you are looking for in a Nobler will weigh maybe 3-1/2 ounces like a rimfire 3536-1000 and the battery would be something like a 4-S 2500 mAH job.
A 9-ouncer is available from True-RC

by the way Gang, Tom tried electric before all of you except Mike Palko! He loves to blow up planetary gearboxes.

Dean

tom hampshire · « **Reply #8 on:** May 04, 2009, 04:34:42 PM »

Hi Dean - So sorry, its a 4s1p at 14 oz. My confusion stemmed from buying chargers that would handle bigger packs for compatibility with future projects. I still want to run this setup in a Nobler for experimental purposes. But I have to quibble with you, I don't like to blow up gearboxes. I'm waaay too cheap for that. But it was a good lesson. The principle of gearing down a smaller motor is still viable, just don't try a gearset designed for RC with the short shaft and bearings close together. It will not hang together under our G loads, and you will spend time on your knees looking in the grass for little tiny pinions to put it right with. Tom H.

Dennis Adamisin · « **Reply #9 on:** May 04, 2009, 05:00:24 PM »

Quote from: Dean Pappas on May 04, 2009, 03:09:25 PM

by the way Gang, Tom tried electric before all of you except Mike Palko! He loves to blow up planetary gearboxes.

Dean

An EXPERIENCED breaker of things? One more reason Tom is my HERO!

(really nice looking Nobler too)

tom hampshire · « **Reply #10 on:** May 04, 2009, 05:21:00 PM »

OUCH!

Alan Hahn · « **Reply #11 on:** May 05, 2009, 08:33:12 AM »

Tom,
I think you will have plenty of energy left in the pack after a flight. I use about 1600mAHr from a 4s2100 pack, but it is known that I am frugal

with my electrons.

So yes, I guess that there will be a fair amount of capacity left in your pack. Iif you recharge it at ~4A (1C) to put back ~2000mAHr into the pack, that would be about 1/2 hour to recharge. I wouldn't worry about the last 5-10%. The way the lipo chargers work is to give a fast charge initially until the pack is up at ~90% or so, and then gingerly recharge the last 10% at a low and safe rate. Since you don't really need that last 10% in your setup, you can save a lot of time at the field by stopping early. Then you can charge fully and balance at home.

Dennis Adamisin · « **Reply #12 on:** May 05, 2009, 08:58:10 AM »

Tom:
BTW here is my pending "experiment" with gearboxes, This is an all-metal Astro "Super-Drive that looks to be very robust.

Like Alan, I am using about 1750-1850 mah in my Swinger, and the flight time is a little longer than I need - meaning I could be more frugal with the electrons. At any rate you definetly will not be stressing your batteries due to too-deep discharges!

A 4sx2500 mah pack weighs around 8.5 oz, so if you need to put the Nobler on a diet that would be a fast weight save.

tom hampshire · « **Reply #13 on:** May 05, 2009, 02:32:25 PM »

Hi All - Thanx! for setting me right on the pack capacity... I'll try a 2500 4s1p. Dennis, I'd be really curious as to your results with the gearbox. Have you flown it much? I thought, after only 1 awful time, tha the smart layout was a separate shaft alongside the motor, driven by either gears or a toothed belt, giving max separation between the bearings. Hobby Lobby sold one like that, with a belt, but it was too large for all but the biggest (700 inch) stunters. Tom H.

Dennis Adamisin · « **Reply #14 on:** May 05, 2009, 05:38:42 PM »

Tom:
The gear drive has been run on the ground (looks real promising) but have not flown yet. Hoping to fly pretty soon. WIth some forsesight and the right design the motor and gear drive could almost be hidden in a correctly packaged profile layout - its 1" wide

I'll keep ya posted!

Dennis Toth · « **Reply #15 on:** May 06, 2009, 08:00:27 AM »

Tommy,

I was great to see you at KOI and talk over good times. On the battery front here is a web site that was at one time posted here but a bunch of posts (the end of 08 trough end of March ish) seem to have been lost. I think Crist R was the original poster:

http://progressiverc.com/Research.html

This site gives some good comparison data on different packs, weights, dimensions and approx price and sellers. There are some interesting choices available that are light and low cost. It may be a little dated I don't know how often they update the information.

Since I've been flying ECL I (and others on this board) have been looking at alternative battery options to get the cost under control (IMHO the biggest barrier to expansion of ECL). One thing that seems to hold is that the place to spend the money to get the best is in the charger. A top shelf charger (I have the TP610) can make almost any Lipo battery work very well for our load and style of use.

I am working on a new "35" size ship Red's Galloping Comedian that I think will be a great ECL. My goal is to have the power package under 12oz that would be a close match to the IC package of Fox 35 @ 7 oz, 1 oz tank plus 4 oz of fuel. There have been several motor suggestion in other posts and it looks doable.I want to be able to use an 11 x 5.5 APCE - P, 4S1P 2100mah pack combination for this. We'll see.

Best, Dennis T

Rudy Taube · « **Reply #16 on:** May 09, 2009, 02:44:08 PM »

Hi Tom,

Thank you for being one of the pioneers of ECL. We have all benefited from forward thinking guys like you!

You asked several questions:

1. RE: battery capacity, charge rates, use %, etc. Others have given you all the info. you need. :-)

2. RE: your main question: Is having more chargers more cost effective (in $ and time) than additional batteries? ....... Short Ans.: YES!!!!!

Longer Ans: Like you suggested, the math points clearly to more chargers. Like others here, I use the TP-1010C ( http://thunderpowerrc.com/html/cba-chargers.html ). But I also have several other chargers. Three chargers can keep you flying all day. I highly recommend one super charger and two inexpensive Multiplex $75 chargers ( http://www.hobby-lobby.com/multicharger_lipo_ni_charger_2475_prd1.htm ), or equivalent inexpensive charger.

To address your situation, whatever chargers you have now will do just fine. Like others have said, you can charge to 90% at the field then you can use a balancer at home when you have more time to fully charge and balance your packs. I think that each additional charger is worth 2+ additional battries.

For those who do not already own a charger, there are several new charger/balancer/power supply combo chargers on the market now.
( http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVZA8&P=7 )

With additional chargers (I still always use a separate balancer for every charge on my batteries over 4S/2100mAh, but not always on my smaller batteries at the field). But with three chargers and 4 batteries I can fly all day while still doing a complete 1 hour balanced charge.

3. RE: geared motors. YES, there are big efficiency gains with geared drives for our models. We have tried them in our 40 pound IMAC planes (4 geared Hacker motors running inside a geared ring, and also belt drives). They worked, but they were more trouble than they were worth. Now we have gone to LARGE outrunners that are quieter, trouble free, and very powerful. Even the full scale elec. planes have given up on geared electric power trains and have gone to large outrunners. The lower noise (motor RPM) is enough to go away from geared setups.

With this said, I admire those who are willing to put the time and energy into experimenting on our behalf. There are gains with gears, but the problems seem to overwhelm these gains...... for now? ;-)

Again, thank you for all your pioneering work. We all stand on your shoulders and that has allowed us to be able see into the future of ECL.

Regards,

tom hampshire · « **Reply #17 on:** May 09, 2009, 05:49:44 PM »

Rudy - You are way too generous with praise. All I did was to prove that a lightweight gearbox engineered for motor gliders would not stand up to 10-12 g loadings. My other great finding was that early Lipo's, at a 5C discharge, would not track the electricalc predictions of performance. At that point I decided I'd jumped too soon and left it to others. Hardly a pioneering effort. It does look to me like some of the present big R/C gearboxes might have merit. As with glow, C/L doesn't make a big enough market to drive the engineering, so we get the table scraps from makers aiming at the R/C troops. Anyhow, thanks for your kind words.

Dennis - Enjoyed KOI and seeing you immensely. I'm curious about the reaction to electric OTS. My guess is you will get some flak about it here in webland, but everybody at a contest will be cheering the effort. If it saves even one flying field its a winner. Tom H.

Author Topic: multiple chargers (Read 1366 times)

tom hampshire

multiple chargers

Alan Hahn

Re: multiple chargers

Dennis Adamisin

Re: multiple chargers

tom hampshire

Re: multiple chargers

Alan Hahn

Re: multiple chargers

tom hampshire

Re: multiple chargers

Rob Roberts

Re: multiple chargers

Dean Pappas

Re: multiple chargers

tom hampshire

Re: multiple chargers

Dennis Adamisin

Re: multiple chargers

tom hampshire

Re: multiple chargers

Alan Hahn

Re: multiple chargers

Dennis Adamisin

Re: multiple chargers

tom hampshire

Re: multiple chargers

Dennis Adamisin

Re: multiple chargers

Dennis Toth

Re: multiple chargers

Rudy Taube

Re: multiple chargers

tom hampshire

Re: multiple chargers