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Old 07-16-2007, 01:33 AM
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Re: A123 Batteries for Dummies.

I think we are saying the same thing. sounds good. make an adapter that brings center voltage to jack signal wire, and cut signal wire to the rx. OR place a separate jack. Both excellent ideas. I need to get home and go to work on this. alas uncle sammy has other ideas.

Let me think it through a bit more and I will throw some ideas out to standardize one's fleet of batteries/jacks. Why? it will allow one to have to buy fewer batteries. If you know the weight of all your packs, they become easily interchangeable, may save a few bucks in the long run while you build up the battery fleet.

Technique: Number your battery packs, Date them, and on the planes that you use a logbook on, mark the batts every 100 flights or chargings.... before long we will see how 123s hold up. Id bet very good. No more than we tax the capability of the cells, My guess is the life of these babys will be longer than the plane. at least that's based on my lack of skill.

On my setups from now on, I will plan to make the battery accessable more easily if possible. more to follow as we figure this out. The things I am talking about are simply a matter of conveinence though FWIW..
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Old 07-16-2007, 08:42 AM
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Re: A123 Batteries for Dummies.

The rating is over 1000 cycles -
A guy in Spain posted a review of this claim, using a 30 amp load (as I recall) and then instantly recharging. He said he passed the 1000 mark and they were still right up to snuff. That is one hell of a test. It was posted in RCGroups in Batteries n Chargers .
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Old 07-22-2007, 07:40 PM
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Re: A123 Batteries for Dummies.

First flights on my home-made A123 2S packs.... flew about 70 minutes total, 6 Hitec 5955's, lots of gyrations... had peaked the pack before going with my Cell Pro. Recharge at home showed "70%" remained when it started. It put .895 A into the pack (895 ma), so that is pretty low consumption. Checking the pack between flights, it stayed at 6.60 the whole time. So far, so good.
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Old 07-24-2007, 09:41 AM
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Re: A123 Batteries for Dummies.

My Dewalt battery arrived yesterday. I have it tore down into 5 2s packs. I would like to have two 2s2p packs.

I want to use the balanced charge with the Cell pro charger. Can I balance all 4 batteries independently?
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Old 07-24-2007, 09:49 AM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by Rolling Thunder View Post
My Dewalt battery arrived yesterday. I have it tore down into 5 2s packs. I would like to have two 2s2p packs.

I want to use the balanced charge with the Cell pro charger. Can I balance all 4 batteries independently?
If you build it as a 2s2p pack. The two in parallel will always be balanced with one another. Then the cellpro will only have to balance two 4600mAh cells/batteries. If you need a drawing, I can sketch one for you.
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Old 07-24-2007, 11:18 AM
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Re: A123 Batteries for Dummies.

Have you actually done this?
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Old 07-24-2007, 12:36 PM
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Re: A123 Batteries for Dummies.

I have done this on may Lipos and the theory would be the same.
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Old 07-24-2007, 12:59 PM
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Re: A123 Batteries for Dummies.

The actual problem --is that the charger gets blindsided by the paralled pack.

In the case of the A123 cells --they do not PEAK
they are full at 3.6 volts but continued application of a voltage over 3.6 Volts will cause the cells to rise to whatever voltage is being fed into the pack - one of the two paralleled could be full and one not full and the charger would keep on applying power .
that is a "possibility".
Maybe never happen but IF you futz with trying to balance at full levels -- it will do it. I went through this learning curve --
On the dual A123 packs - the best bet is to simply charge as individual cells ( if you are using the CellProA123 4 cell charger) so a series/ parallel switch could be rigged up.
But IF you had been using these cells --you would see that in actual use - a simple two cell pack will sustain a hell of a lot of drain from even the super servos - far more than your LiPos and because there is no reg being used - you have access to ALL the available current - you are not hindered by a regulator , which uses up energy and when hot , fu-ks up the whole thing ..
Now -if you still insist on parallel packs -- the best bet is to monitor actual use and alternately charge the two packs .
In actual use -so far - I see a simple charger which charges the 2 cells -NO balancer -as a good setup - Once these cells get discharged some-- rather than simply poking the charger at almost "full "levels - they balance up all by themselves
That ain't theory -that is actual experience .
I also use 4 cells in a pack ( in series) -to fly electrics and every time -- the cells charge back up to LESS than .10 V difference (lowest to highest)in the four cell packs .
Ask the guys using them - and you wil get a good picture of how they work - so far - they are very often confused with the LiIons of higher voltage and LiPos .
they are NOT the same .
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Old 07-24-2007, 07:00 PM
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Re: A123 Batteries for Dummies.

I guess I will skip the balance plug then.

I have to say that I was shocked at how large these cells were. I thought I read somewhere that they are an "A" size cell. I was suprised to open the dewalt pack and see ten 10 gauge shotgun shells. They feel very light for there size.
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Old 07-24-2007, 07:47 PM
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Re: A123 Batteries for Dummies.

Aerobob, Thanks for the report. My dewalt pack and cellpro charger will be on my doorstep when I get back from vacation. Can't wait to try them as receiver packs.

Craig
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Old 07-24-2007, 10:20 PM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by Rolling Thunder View Post
I guess I will skip the balance plug then.

I have to say that I was shocked at how large these cells were. I thought I read somewhere that they are an "A" size cell. I was suprised to open the dewalt pack and see ten 10 gauge shotgun shells. They feel very light for there size.
Actually --using the Cellpro 4 a123 you must use the center tap -
it is no big deal - but I really would avoid trying to do the charge as a parallel setup -

Once you understand exactly how the Cellpro operates - try it ( the parallel) but watch what is happening during charge to each and every cell - this requires you have a setup allowing an outside V meter to be poked in, to see each cell's voltage AS YOU CHARGE.
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Old 07-25-2007, 09:24 AM
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Re: A123 Batteries for Dummies.

Hi guys, great thread and info, have been looking for this for a long time. I just ordered the dapter (like immediately after reading this thread LOL).
I have managed to find a source nearby where I can get the cells individually, but without solder tabs attached. Is there any reason not to solder my own tabs/battery bars to the cells direct? I am assuming that if I follow the same precautions and methods used in soldering nimh packs and Lipo packs, it should be safe?

Thanks guys.
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Old 07-31-2007, 06:04 PM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by dick hanson View Post
Actually --using the Cellpro 4 a123 you must use the center tap -
it is no big deal - but I really would avoid trying to do the charge as a parallel setup -

Once you understand exactly how the Cellpro operates - try it ( the parallel) but watch what is happening during charge to each and every cell - this requires you have a setup allowing an outside V meter to be poked in, to see each cell's voltage AS YOU CHARGE.

I made my decision, I will be a conformist. I bought the Cellpro charge and 5 balance plugs, one for each pair of batteries. I will build the packs as 2s1p. When I disassembled the Dewalt pack I broke the batteries down into 5 pairs so I only have to solder the lead and balance plug onto the tabs.
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Old 07-31-2007, 09:44 PM
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Re: A123 Batteries for Dummies.

If the cells are in parallel, one parallel cell can never be at a higher voltage than the other. They are in parallel. They have to be the same voltage because the postive it connected to positive and the negative is connected to negative. The wire between them will balance the cells. The only problem you can get into is if one cell is damaged and can only say 3 volts then they both will be charged to 3.6v and only 3.6v and then may self balance back down to 3v. The charger does not car if there is 1, 2 or 1000 cells in parallel, it will charge them all the same (1000 cells would take a very long time to charge, 2,300,000mAh).
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Old 08-01-2007, 04:05 PM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by hybris View Post
If the cells are in parallel, one parallel cell can never be at a higher voltage than the other. They are in parallel. They have to be the same voltage because the postive it connected to positive and the negative is connected to negative. The wire between them will balance the cells. The only problem you can get into is if one cell is damaged and can only say 3 volts then they both will be charged to 3.6v and only 3.6v and then may self balance back down to 3v. The charger does not car if there is 1, 2 or 1000 cells in parallel, it will charge them all the same (1000 cells would take a very long time to charge, 2,300,000mAh).

Plus I would not want to pay your electricity bill to charge them or buy the 100 car batteries you would need to field charge them.
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