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  1. #1
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    Thinking about chargers: technical considerations and practical issues (8A++ Lipos)

    Hi,

    Thanks to your contributions on this forum, I finally opted to purchase batteries with very high amperage to get what I wanted, a very long battery life. Yeahhhh what a good investment!!! Now the workers have worked in my garden with a mini excavator for digging and preparing the construction of a garden shed and terraces, I played almost 2 hours this afternoon crawling and bashing into the holes on the gravel in the mountains of debris with a ... 7600mAh Traxxas (I won at least 10 minutes yesterday at low speed).

    But of course, after receiving these batteries has raised the question of charging time and capacity of my current chargers to load the batteries @1C or 2C (SPC 8.2A coming soon, on the way from USA). I have two Maxxtrax AC 680 +, limited to 6A / 80W output. Until now I was using 4.4A NiMH and2S / 3S 5A Lipo batteries. So my current chargers were suitable for this purpose:

    7,4V (2S) x 5A = 37W
    11,1V (3S) x 5A = 55,5W
    8,4V (NiMh) x 4,4A = 36,96W

    Under the 80W maximum output capacity of my charger.

    Now with the Traxxas 2S 7.4V 7600mAh:

    7,4 (2s) x 7.6 = 56,24 (@ 1C charging) = still ok (is it possible to charge it @ 2C? ), but I'll not be abgle to charge it @ 1C because output is limited to 6A... 80W yes but 6A, wo with a 2S Lipo, I can't use the maximum W value, right?

    And with the SPC 8.2A:

    7,4 (2s) x 8.2 = 60,68W @1C but... 7,4 (2s) x [8.2x2 @ 2C charging] = 121,36W

    If I am satisfied, certainly I'll buy a second pair (for my Savage, because @ 3Sthe Savage flux is just excessive and difficult to controlto be honest).

    So my new batteries are more demanding. I put the question of whether I should invest in new chargers or not. Charging time for 7600mAh @ 6A would be extended by 50% compared to a charger capable of outputting @ 7.6 A. Consequence: 1:30 instead of one hour. As I charge both batteries in parallel, this is ultimately less embarrassing than if I had only one charger, but ... if I go hiking, I'll have to charge 2 or 3 pairs of batteries. This would mean a difference of 1 to 2 hours depending on battery capacity to load ..

    So I plan to spend on a dual output charger with a capacity of 2 x 10A, 150W per output in the event that I would buy the batteries that power applicant (3S with high amperage rechargeable 2C)

    After some research, I found that many different brands of chargers were built on the same basis ... same look, same specifications but different brands. I confess to being hesitant about this kind of product. Sold as expensive OEM with another brand only... Like for example SkyRC = Hitec Ultimate = ... I found 3 or 4 other brands with exactly the same products, but different color... and writings.

    It seems that some manufacturers are really manufacturers, I mean the Source of some products (Ok they probably manufacture somewhere in Asia or India... but engineering is their property, they are not only a marketing company but an engineering company).

    Here is a list of brand that seem to be serious because not content just to put their brand on an OEM product manufactured for 10 different other brands by a supplier in China also responsible for the design of the product.

    (links are links to the manufacturer's homepages, not to resellers so I suppose that I'm ok with the rule 11? If not please remove the links and accept my apologies)

    --- Hyperion: http://www.hyperion-eu.com/products/type/15
    --- Graupner: http://shop.graupner.de/webuerp/serv...11&language=en
    --- Ansmann: http://www3.ansmann.de/cms/en/chargi...e-charger.html

    I already know Ansmann very well because all my AA, AAA, and 9V batteries are NiMh rechargeable batteries from Ansmann, the quality is very high, their ''maxx-e+'' technologie is very efficient (low power loss for NiMh, after a year there is 80% capacity left in a battery that has been charged but not used during a year http://www.ansmann.de/cms/fr/busines...u-battery.html ). I use 2800mAh AA batteries into my Canon 580EXII flash gin and the speed + the autonomy is impressive (I use 4 flash guns with pocket wizard control, and I need power and speed)

    So I am convinced by the quality Ansmann for this type of product, but I'm also curious about the other two brands.

    What do you think?

    A - I have to change the charger and buy a single dual output charger with external power supply (powerful enough course)
    B - I would rather invest my money in a pair of Lipo 8.2mAh or 9.2mAh and keep my current loaders, since I would have time to recharge my batteries back from my hikes
    C - if I change charger, is it better to take out two single or one dual output? With 2x mono outputs chargers, I can reach the 150W on AC with no external PSU. Finally in terms of price, 2x mono output chargers AC + / - = 1x dual outpu charger + 1x DC power supply

    Thanks for your feed back.

  2. #2
    Marshal ksb51rl's Avatar
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    The Hyperion charger line is universally held in high regard. A healthy price tag accompanies these.

    Ansmann (I know of their batteries) and Graupner have very little market share here in the States.

    The iCharger line has some very good and inexpensive to premium-price chargers. Anything from the 206B to the 306B would probably fit your needs fine.

    One of my favorite brands is FMA with their PowerLab 6 and PowerLab 8 models.

    The iChargers and the PowerLab models are single chargers, but there are provisions for parallel charging. For example, the PowerLab 6 will allow parallel charging for up to nine (9) identical packs at one time. However, you would need the correct cables and should make sure you know what you're doing prior to doing something like this.
    Last edited by ksb51rl; 12-01-2011 at 03:26 PM.
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  3. #3
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    Thank you ksb51rl for your reply.

    I already had a look on the iCharger products because I've seen some good feed backs on this forum, but I did not know FMA products. I found the two brands on google, I'll have a closer look at FMA.

    But in Europe, neither FMA nor iCharger are represented by a network of resellers. If I want to buy one, I'll have to buy it from USA or NZ. I can buy locally a 220V AC to DC PSU with european plug, and buy the charger anywhere else thanks to the DC input conection.

    But it does mean: charger + external power supply with a single output, and...

    Quote Originally Posted by ksb51rl View Post
    However, you would need the correct cables and should make sure you know what you're doing prior to doing something like this.
    ...and I don't want make any parallel chargin or something else dangerous because I'm not familiar with that, I want to stick to the KISS approach (Keep It Simple and Stupid/Safe).

    Seems that Hyperion is well know everywhere.

    So I understand in your reply that you DO recommend me an upgrade (buying new charger), isn't it?

  4. #4
    Marshal ksb51rl's Avatar
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    Charger and power supply needs are so case specific, I make few recommendations about what a user should do. I know with my planned purchase (tomorrow) I can charge 4 of my SPC 8000mAh packs at once at their maximum recommended rate. There are much cheaper chargers that can do almost as much, but I am planning on this being my LAST charger ever.
    In my opinion, an 80W charger is pretty weak. The difference between the PowerLab (PL) 8 and the PL6 is 344W of maximum power (1344 watts vs. 1000 watts, easy math.) That's 4.3 times the AC 680's maximum output.
    I suppose my best recommendation to you is to get something you will not grow out of anytime soon. To me that means my charger should:
    charge a.) up to four 2S OR 3S; b.) 8000mAh capacity or more packs (and packs are only getting larger), c.) at at least a 2C rate; and d.) be able to discharge unused packs down to storage level at least at a 50W rate.

    Many others prefer multiple smaller chargers. There's nothing wrong with a whole lineup of them.
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  5. #5
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    Long Term Investment. I do agree with you. You're right. I'll wait a little bit and invest in a very good charger. Maybe not my LAST charger ever because I hope that I'll be alive longer than my charger But I'll invest the appropriate budget to make sure having a long term solution, scalable, reliable, safe and powerfull enough to comply with future requirements (I'll probably buy a second one, my wife appreciate the Summit and my litlle daughter is already playing with the truck itself, not with the RC but with the truck (she's 18 month old ^^)

    Thanks for your advise.
    Kind regards

  6. #6
    Marshal ksb51rl's Avatar
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    Get some other advice too. Unlike with medical professionals, these second opinions don't cost you anything.
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