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Old 03-15-2017, 01:38 PM   #1
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Default Dragonfly lithium batteries

Anyone have any experience with Dragonfly lithium batteries? Their 100Ah 12v battery looks very similar to the StarkPower 100Ah battery but is $899 instead of $1099 and has a 3 year warranty instead of 1 year.

It has a BMS with high/low voltage protection, high/low temperature protection and cell balancing. The StarkPower BMS does not mention temperature protection.

Batteries - Dragonfly Energy

https://starkpower.com/product/stark...12-volt-100ah/
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Old 03-17-2017, 10:58 PM   #2
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It is intriguing to me! I would like to know what happens when the engine generator gives it 14.7 volts. Does the BMS reduce it?

Does the BMS heat it using it's own energy so it can be charged below 32F? Lots of questions. $900 still above my threshold but getting closer.

I have known several in the motorcycle world that went lithium. Ended up a waste of money when they failed. Maybe they weren't taken care of properly but I'd hate to fail a $900 battery early. Would certainly like to hear of a successful user.
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Old 03-19-2017, 01:22 AM   #3
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I don't see where they claim low temperature protection. I see high temp in their BMS description. Of course this battery, just like all the other drop-in types, doe not have any kind of internal heating system.

Note their wording is very careful. They don't make any cells. Virtually all cells are manufactured in China. Whether they use a high grade, or off spec cells we don't know. They probably assemble these batteries in Reno as they claim.

FWIW, I own about 7 of the Stark 125 AH batteries. They are phenomenal and have been trouble free. They do have a high temp cut-off, along with the other BMS features. They won't allow more than 15v charging. I've never seen more than 14.6 out of my alternator.

In the Industry, they refer to these outfits that use the low-grade cells and an off the shelf BMS board "sticker boys". Basically all these types of batteries are the same inside, and only the external label with their branding differentiates them. Not sure that these folks are not one of those.

Even my $7000 Lithionics battery does not have a low-temp disconnect if that tells you anything. The only ones I've heard of doing that are doing so with a Silverleaf system, which is outside a BMS box.
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Old 03-19-2017, 02:11 AM   #4
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Quote:
Originally Posted by wincrasher View Post
I don't see where they claim low temperature protection.
On the BMS features page it says "High/Low Temperature Protection".

Supposedly Dragonfly is developing a new manufacturing approach that led one of the big Chinese lithium cell manufacturers to invest in them to gain access to it.

University alumni revolutionize renewable power companies in Nevada

"Dynavolt's chairman, Lewu Chen, said that the investment in Dragonfly Energy, which is their first U.S. investment, gives them access to technology that is expected to lower their manufacturing costs"

That article also implies they manufacture their own cells:

"Dragonfly Energy intends to expand their pack manufacturing capabilities in Nevada in addition to expanding cell manufacturing"
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Old 03-19-2017, 02:17 AM   #5
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Quote:
Originally Posted by rectalogic View Post
On the BMS features page it says "High/Low Temperature Protection".

Supposedly Dragonfly is developing a new manufacturing approach that led one of the big Chinese lithium cell manufacturers to invest in them to gain access to it.

University alumni revolutionize renewable power companies in Nevada

"Dynavolt's chairman, Lewu Chen, said that the investment in Dragonfly Energy, which is their first U.S. investment, gives them access to technology that is expected to lower their manufacturing costs"

That article also implies they manufacture their own cells:

"Dragonfly Energy intends to expand their pack manufacturing capabilities in Nevada in addition to expanding cell manufacturing"
But is it on operating or charging. Note the temp range -4 to 160. My guess is the upper range limit is on 160. But I'd not run a battery over 100, let alone those kind of temps.
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Old 03-19-2017, 02:31 AM   #6
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I think -4 is also the low temp damage temp the davydd had been told by ARV? That would also include storage that cold. Charging would still be at 32* cold side limit, I would think.

Note that it said expand their "pack" manufacturing capabilities, so it could, or could not, include making the cells that go in the packs.
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Old 03-19-2017, 03:19 AM   #7
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Note that it said expand their "pack" manufacturing capabilities, so it could, or could not, include making the cells that go in the packs.
After that it says "in addition to expanding cell manufacturing" which implies they currently do some cell manufacturing and plan to do more. They could also be expanding from zero cell manufacturing.
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Old 03-19-2017, 04:18 AM   #8
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Well, I'd have to talk with them to determine what is BS and what is true. Cell manufacturing, answered honestly would mean actually making the cells from the ground up with all raw materials. But in actuality, it probably does not mean that here. It could mean any level of post production work from already manufactured cell material.

That is assuming they are using prismatic cells. Could be that this is a cylindrical cell setup. .
Reading between the lines, it looks to me like an assembly operation only.
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Old 03-19-2017, 12:30 PM   #9
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We all know that the battery manufacturers will cherry pick information to to make themselves look better and others less good, and Dragonfly is certainly no exception there. Here is how the do a cost analysis against lead acid batteries. I think, at least to some extent, companies can be judged by the accuracy of their claims, especially about other products that they are comparing to.



Lots of claims there that stretch, like 300 cycles at 50% for lead acid, when it is easy to get 1100 cycle rated ones. And of course the urban legend, IMO, 50% rule. Plus the show using 100% of the lithium capacity.

The little bit of reading I did on them indicates a PHD started Dragonfly, and his big push is in a more economical way to make lithium cells, by altering how a few steps are done in manufacturing them. The price decrease does not seem to be in affect yet, though, as $999 for 100ah is not exactly cheap.
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Old 03-19-2017, 12:50 PM   #10
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Here is what they say about the BMS. Doesn't look like any low temperature things.

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