K2 vs. StarkPower LiFePo4 batteries

Reading the blurb referenced it would seem that the A123 batteries (which
are available from http://www.buya123batteries.com) seem to have the best
protection / charging electronics they only rated at 5Ah although this
should provide better performance than a 7Ah SLA.

The higher power batteries do not seem to have all the tricks in the
electronics.

Interesting note: although A123 is a US company using MIT derived
technology, they are owned by the Chinese!


At 17:37 04 February 2015, Charlie M. UH & 002 owner/pilot wrote:
On Wednesday, February 4, 2015 at 12:08:54 PM UTC-5, jfitch wrote:
On Tuesday, February 3, 2015 at 3:50:28 PM UTC-8, Dave Springford
wrote:
I'll preface my remarks with the statement that I sell K2 batteries.

The K2's are made in the USA, not Chinese knock-offs. K2 pays a fee
to
the patent holder while the knock-off's do not. K2 has also had their
batteries UL certified and listed.

These items account for some of the price difference.

The K2 also have a higher Watt-hour rating at 123 vs 115 for the
Stark
and the K2 are rated for 25 amp continuous discharge vs 15 for the Stark.
The K2's also have a better temperature range.

In my opinion, the K2 is a superior product and is worth the extra
cost.

I sell K2 batteries with the protection module for $150 US and
chargers
for $30 US and will have some on hand at the Seniors at Seminole Lake.
For
any one interested in purchasing a K2, contact me at the address below.

Dave Springford
dave at foxonecorp dot com

I don't believe anyone is building cells in North America for the
consumer market. These are all coming from China. It makes no sense at
all
to build the BMS boards here either. So as a point of differentiation
between vendors, there is nothing in it.

As an avid "Electric RC'er", while you are likely correct that most cells
come from a limited number of places, where they end up can be a case of,
"Give me cells" vs. "I don't want seconds/low performers".....
Price is not always a guarantee (there is a "very high priced" LiPO hobby
vendor that has performance numbers similar to "mid level" vendors.....),
but it can help out as well as "post sale support".

Not saying anything for/against any vendor mentioned here, just a
different
view.

On Tuesday, February 3, 2015 at 3:33:38 AM UTC-8, wrote:
We have been selling the Starkpower battery for more than a year now. Started out very cautiously - selling only a few to a few of our steady customers. We have now sold several hundred with no complaints. They really are great and are exactly the same size as the battery they replace.

One caution is you must use the special charger (inexpensive) that shuts off when the battery reaches a fully charged state.

Tom Knauff
Knauff & Grove, Inc
Ridge Soaring Gliderport

www.eglider.org

Can one charger charge two identical starkpower batteries in parallel?

Ramy

I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:

Can one charger charge two identical starkpower batteries in parallel?

Ramy

On Tuesday, April 14, 2015 at 7:29:58 PM UTC-4, JS wrote:
I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:

Can one charger charge two identical starkpower batteries in parallel?

Ramy

Please take questions of this sort to the manufacturer of *your* batteries. The right answer is going to depend on the details of internal construction. And there are going to be some cautions if not an outright admonishment against this.

LFP batteries have very low internal resistance, so batteries in different states of charge will pass a very large current when connected in parallel until their voltage is equalized. If your batteries are fused as they should be (right on the terminal), you stand a fair chance of blowing fuses if you hook together batteries in reasonably different states of charge.

Here's a *great* time to ignore the "well, it worked for me" replies. It'll work acceptably well right up to when it doesn't.

My $0.02.

Evan Ludeman / T8

....And the chargers are very inexpensive. I have 2 LiFePO4 batteries
and two chargers.

On 4/14/2015 5:44 PM, Tango Eight wrote:
On Tuesday, April 14, 2015 at 7:29:58 PM UTC-4, JS wrote:
I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:
Can one charger charge two identical starkpower batteries in parallel?

Ramy
Please take questions of this sort to the manufacturer of *your* batteries. The right answer is going to depend on the details of internal construction. And there are going to be some cautions if not an outright admonishment against this.

LFP batteries have very low internal resistance, so batteries in different states of charge will pass a very large current when connected in parallel until their voltage is equalized. If your batteries are fused as they should be (right on the terminal), you stand a fair chance of blowing fuses if you hook together batteries in reasonably different states of charge.

Here's a *great* time to ignore the "well, it worked for me" replies. It'll work acceptably well right up to when it doesn't.

My $0.02.

Evan Ludeman / T8

--
Dan Marotta

On Tuesday, 14 April 2015 17:44:48 UTC-6, Tango Eight wrote:
On Tuesday, April 14, 2015 at 7:29:58 PM UTC-4, JS wrote:
I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:

Can one charger charge two identical starkpower batteries in parallel?

Ramy

Please take questions of this sort to the manufacturer of *your* batteries. The right answer is going to depend on the details of internal construction. And there are going to be some cautions if not an outright admonishment against this.

LFP batteries have very low internal resistance, so batteries in different states of charge will pass a very large current when connected in parallel until their voltage is equalized. If your batteries are fused as they should be (right on the terminal), you stand a fair chance of blowing fuses if you hook together batteries in reasonably different states of charge.

Here's a *great* time to ignore the "well, it worked for me" replies. It'll work acceptably well right up to when it doesn't.

My $0.02.

Evan Ludeman / T8

Damn you Evan, the voice of reason and logic. I just checked K2 website and nothing posted but a charger is only $40. Seems to be cheap insurance for for $125+ battery.

No an excuse but this is the setup that came with the plane I bought. Buy beware but I should have known that.

On Tuesday, 14 April 2015 17:44:48 UTC-6, Tango Eight wrote:
On Tuesday, April 14, 2015 at 7:29:58 PM UTC-4, JS wrote:
I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:

Can one charger charge two identical starkpower batteries in parallel?

Ramy

Please take questions of this sort to the manufacturer of *your* batteries. The right answer is going to depend on the details of internal construction. And there are going to be some cautions if not an outright admonishment against this.

LFP batteries have very low internal resistance, so batteries in different states of charge will pass a very large current when connected in parallel until their voltage is equalized. If your batteries are fused as they should be (right on the terminal), you stand a fair chance of blowing fuses if you hook together batteries in reasonably different states of charge.

Here's a *great* time to ignore the "well, it worked for me" replies. It'll work acceptably well right up to when it doesn't.

My $0.02.

Evan Ludeman / T8

Damn you Evan, presenting common sense and logic. I looked on the K2 website and nothing mentioned about charging in parallel. However chargers are $50 buck, cheap insurance.

Not an excuse but this setup came with the plane I acquired. Buyer beware, but I should have checked the setup. yup ordered a second charger today. Thanks Evan.

Ron

On Tuesday, April 14, 2015 at 8:23:29 PM UTC-4, Ron Gleason wrote:
On Tuesday, 14 April 2015 17:44:48 UTC-6, Tango Eight wrote:
On Tuesday, April 14, 2015 at 7:29:58 PM UTC-4, JS wrote:
I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:

Can one charger charge two identical starkpower batteries in parallel?

Ramy

Please take questions of this sort to the manufacturer of *your* batteries. The right answer is going to depend on the details of internal construction. And there are going to be some cautions if not an outright admonishment against this.

LFP batteries have very low internal resistance, so batteries in different states of charge will pass a very large current when connected in parallel until their voltage is equalized. If your batteries are fused as they should be (right on the terminal), you stand a fair chance of blowing fuses if you hook together batteries in reasonably different states of charge.

Here's a *great* time to ignore the "well, it worked for me" replies. It'll work acceptably well right up to when it doesn't.

My $0.02.

Evan Ludeman / T8

Damn you Evan, presenting common sense and logic. I looked on the K2 website and nothing mentioned about charging in parallel. However chargers are $50 buck, cheap insurance.

Not an excuse but this setup came with the plane I acquired. Buyer beware, but I should have checked the setup. yup ordered a second charger today.. Thanks Evan.

Ron

No trouble!

So the next consideration is switching in flight. Same concerns apply...

I've never been able to figure out a good way to get a back up battery in my 20, so I have just one big honking 12AH battery. But if I had a dual LFP battery system, I'd use (appropriately rated) low voltage drop diodes to prevent back feeding the low battery with some mongo current during switchover. With my luck, I'd blow the fuse on my good battery....

-Evan / T8

On Tuesday, 14 April 2015 18:41:54 UTC-6, Tango Eight wrote:
On Tuesday, April 14, 2015 at 8:23:29 PM UTC-4, Ron Gleason wrote:
On Tuesday, 14 April 2015 17:44:48 UTC-6, Tango Eight wrote:
On Tuesday, April 14, 2015 at 7:29:58 PM UTC-4, JS wrote:
I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:

Can one charger charge two identical starkpower batteries in parallel?

Ramy

Please take questions of this sort to the manufacturer of *your* batteries. The right answer is going to depend on the details of internal construction. And there are going to be some cautions if not an outright admonishment against this.

LFP batteries have very low internal resistance, so batteries in different states of charge will pass a very large current when connected in parallel until their voltage is equalized. If your batteries are fused as they should be (right on the terminal), you stand a fair chance of blowing fuses if you hook together batteries in reasonably different states of charge.

Here's a *great* time to ignore the "well, it worked for me" replies. It'll work acceptably well right up to when it doesn't.

My $0.02.

Evan Ludeman / T8

Damn you Evan, presenting common sense and logic. I looked on the K2 website and nothing mentioned about charging in parallel. However chargers are $50 buck, cheap insurance.

Not an excuse but this setup came with the plane I acquired. Buyer beware, but I should have checked the setup. yup ordered a second charger today. Thanks Evan.

Ron

No trouble!

So the next consideration is switching in flight. Same concerns apply...

I've never been able to figure out a good way to get a back up battery in my 20, so I have just one big honking 12AH battery. But if I had a dual LFP battery system, I'd use (appropriately rated) low voltage drop diodes to prevent back feeding the low battery with some mongo current during switchover. With my luck, I'd blow the fuse on my good battery....

-Evan / T8

Switching in flight is covered, similar to what you describe. I have the opposite situation; currently 2 batteries but ability to add 2 more (front of stick and in tail) that are wired and plumbed.

Thanks Evan

From the StarkPower website:
"Unlimited packs in parallel at 12V but only with individual 12V chargers on each battery."

http://www.starkpower.com/spnews/energystoragebatt/

On Tuesday, April 14, 2015 at 6:41:54 PM UTC-6, Tango Eight wrote:
On Tuesday, April 14, 2015 at 8:23:29 PM UTC-4, Ron Gleason wrote:
On Tuesday, 14 April 2015 17:44:48 UTC-6, Tango Eight wrote:
On Tuesday, April 14, 2015 at 7:29:58 PM UTC-4, JS wrote:
I have used and charged two 10AH LiFePO4 batteries in parallel sans probleme.
Jim

On Tuesday, April 14, 2015 at 2:48:04 PM UTC-7, Ramy wrote:

Can one charger charge two identical starkpower batteries in parallel?

Ramy

Please take questions of this sort to the manufacturer of *your* batteries. The right answer is going to depend on the details of internal construction. And there are going to be some cautions if not an outright admonishment against this.

LFP batteries have very low internal resistance, so batteries in different states of charge will pass a very large current when connected in parallel until their voltage is equalized. If your batteries are fused as they should be (right on the terminal), you stand a fair chance of blowing fuses if you hook together batteries in reasonably different states of charge.

Here's a *great* time to ignore the "well, it worked for me" replies. It'll work acceptably well right up to when it doesn't.

My $0.02.

Evan Ludeman / T8

Damn you Evan, presenting common sense and logic. I looked on the K2 website and nothing mentioned about charging in parallel. However chargers are $50 buck, cheap insurance.

Not an excuse but this setup came with the plane I acquired. Buyer beware, but I should have checked the setup. yup ordered a second charger today. Thanks Evan.

Ron

No trouble!

So the next consideration is switching in flight. Same concerns apply...

I've never been able to figure out a good way to get a back up battery in my 20, so I have just one big honking 12AH battery. But if I had a dual LFP battery system, I'd use (appropriately rated) low voltage drop diodes to prevent back feeding the low battery with some mongo current during switchover. With my luck, I'd blow the fuse on my good battery....

-Evan / T8