PandaSoup

How many Amps should I charge these at? I'm at 3.8 right now and it takes forever with this many.

flyinwalenda

My Feedback: (5)

7 amps is good but don't go above 8 amps.

RustyUs

Holy cow. What are those packs being used in? Charging one of them packs @ 3.8 amps would take approx. 2 hours. The price to pay for higher capacity.

trax de max

Have you looked into parallel charging,
It'll be good to charge from storage to full, but from used to storage you may need to charge up separately, Also will depend on your chargers specs

RustyUs

The normal recommended charging method for LiPo batteries is a 1C charge rate. Meaning those packs you have could be charged @ 7.6 amps...provided you have a charger that will put out that kind of amperage.

There are packs out there that state they are capable of 2C,3C even 4C charge rates. I don't recommend charging above a 1C charge rate to fast charge a LiPo battery. Doing so could shorten battery life cycle. That's a debate for some people, and I don't want to get into the discussion of the effects of "super charging" a high capacity LiPo pack in 20 minutes.

PandaSoup...what you got there, is the best way to go...you have more than enough packs to rotate for a full day of RCing (unless you have a RC that uses two packs at a time).

PandaSoup

It's for a project at work. The batteries are for a Traxxas Summit Chasis, but the GoPro itself and servos for the arm and GoPro are also being powered by the batteries.

We also didn't want to risk storing batteries in our work vehicle in the hot sun, so we just purchased batteries to leave at locations that the Summit is most used.

How long can these sit without use before needing a charge?

I'm using a Tenergy TB6, it goes up to 5A.

Should I use and charge all of these a few times before letting them sit on a shelf?

ETA: they need to be stored at full capacity so that they are usable right away when needed, so what is the best way to maintain them?

flyinwalenda

My Feedback: (5)

You should read this and get up to speed on Lixx battery pack basics..
http://www.rcuniverse.com/forum/rc-c...batteries.html

LiXX packs should never be left fully charged for a few weeks. Some say days but if I'm not going to be using them within a weeks time I put them in storage mode. You should always store the packs at 50% capacity (storage mode) . Store them this way and they will last years. Store them fully charged and it will shorten their lifespan and lower their "C" rating output. The charger you are using has an auto-storage mode setting.
Always balance charge when charging too.

PandaSoup

There's no balance port on these new batteries.

The Summit is used for emergency response, so we can't keep batteries at 50% because we don't have time to sit and charge them when it is needed. LIfespan isn't a huge issue because we can always buy more batteries, so if that's the only issue with storing them charged then that's fine.

I could make a procedure to go out and drain the batteries a bit every couple of weeks and then recharge them, is that a good idea?

flyinwalenda

My Feedback: (5)

Looking at your pic more closely it seems you bought the new ID LiPo's from Traxxas. For some reason they redesigned their packs with a special balance circuit wiring that uses the main plug to both charge and balance. In order to properly charge and balance them you will need to get a Traxxas ID Lipo charger.
A weekly maintenance schedule of discharging them down to storage level and recharging is better than leaving them charged and sitting unused for weeks at a time.

PandaSoup

I heard they are coming out with an adapter to plug into a normal balancing port.

Running the Summit for a few hours a week on company time sounds like a good plan to me.

chuckk2

7600mah lipos - 1C - up to 7.6A Leave at 3.8-3.85v per cell for storage. Do Not leave fully charged, or the Lipos will be damaged.
Your charger may not be able to charge at that rate, a lower rate is fine, other than the time.
My largest charger can charge 5 lipos at that rate per port, for a total of 10 using parallel charging. (DPL-8)
From storage, with balancing, the time is between 1/2 and 3/4 of an hour for 10 charged in parallel.

chuckk2

So, Is it possible to leave two Lipos charged to 50% at each location? That way you might be able to use them in parallel, and still have enough run time.

trax de max

the adaptor plug is #2938

Rv7garage

My Feedback: (10)

Sounds like someone jumped into Lipo technology without doing their research. Lips are not a good choice for storing fully charged.

chuckk2

"There's no balance port on these new batteries".
A two cell only needs the addition of a center tap lead. It looks like that's the third smaller pin in the connector.
It would be fairly simple to make an adapter to use the common 4 button chargers with separate power and balance connectors.

Where things get messy has to do with a battery that has an internal protection circuit.
Some of the just above toy helicopters came with such a circuit inside a lipo. Trying to charge a conventional same cell count lipo
(no protection circuit) with the included charger could result in damage to the lipo.

We had a fairly recent small batch of cylindrical batteries come in for a project.
One of them would not charge properly. Investigation showed that the protection circuit was faulty.
We were able to charge the cell, but the protection circuit went up in smoke during the charge.

trax de max

The adaptor, http://www.ebay.com/itm/TRAXXAS-2938...25268685&rt=nc

PandaSoup

How long can they be stored full before damage is an issue, and what kind of damage?


Is the traxxas summit ran in parallel off the shelf? I don't want to mess with factory wiring, unless it's really easy and not risky to the chassis electronics.

Thanks

Do you mean research, or googling? I did a bit of both, though most of the battery research was done by our robotics and battery engineers (though our battery engineers are working on completely different batteries. Crazy small batteries, so they couldn't help much except for with explaining how they worked. ). It was pretty fun to watch and participate. They hooked the Summit up to a bunch of devices that measured the draw of all of the servos and the GoPro and motor under different loads while the arm was lifting things and the camera was looking around, while everything was static, and all of the above at different speeds and weight loads. Getting towed around the parking lot by the Summit while sitting on a cart was probably the most fun.

Based on that research and some googling, we decided that LiPos would be our best bet.

I'll look around for our research notes and share what I can.


Thanks

flyinwalenda

My Feedback: (5)

Already covered that in post #7.

Kipp Louis

suitable is 7. 6A, if at all with your charger in case that's impossible and then demand the item with the max possible although you will need to charge more than once since the charger end as soon as the charger stop to your max mah.

DrV

My Feedback: (2)

Lots of good advice but also lots of misinformation. Current high discharge lipos will not get damaged by 2c or even 3c charging using high quality charger with a balancer. However you will damage lipos when stored fully charged and may also cause fires. Please read the following.

http://www.rcgroups.com/forums/showthread.php?t=1330647

RCoffroadracer

some say 60-70% some say 50-60%.
. here is max amps. they recommend 60-70%
http://www.maxamps.com/lipo-care.php

trax de max

The storage state is just a range. It's easier to work out 50% than it is to figure out 60% or 70% for most people.
Full is bad, empty is bad, in between is good. I kinda know why max amps say 60-70% while pretty much everyone else says 50% http://www.lithipedia.org/#/safety/4571708997