William,

August is right, the Blue Ion batteries are rated for 100% DOD so to get
the same usable capacity from an L16 at 50% DOD you'd need twice the
overall capacity. Plus most lithium-ion batteries will last significantly
longer than lead-acid so you have to factor in replacement costs when doing
a life cycle cost comparison.

All reputable lithium-ion batteries will come with a battery management
system (Blue Ion calls theirs a battery management unit) that controls
charging and discharging of the cells to ensure even charging. That's why
you can run many more in parallel because the BMS will make sure the cells
are evenly charged. The only limit to units in parallel with lithium-ion is
the manufacturers maximum. You still need to make sure the parallel cables
are the same length. With most lithium-ion batteries you need to order the
battery at the nominal voltage of the system. For example, if you have a 48
V system you need a 48 V battery, you can't (usually) use two 24 V
batteries in series with lithium-ion.

Thanks,
Will
-- 
*Will White*
Curriculum Developer


e: w...@solarenergy.org
w: www.solarenergy.org
p: 802-272-3092

NABCEP Certified PV Installation Professional
# 093006-34

On Wed, Jul 24, 2019 at 9:22 AM August Goers <aug...@luminalt.com> wrote:

> Hi William - Yea, your kWh calculation is correct. However, the 16 kWh
> Blue Ion is comparable to eight L16 (6 volt x 333 Ah each) batteries, not
> one - nameplate rating. Typically you can go way deeper discharge with the
> lithium products, so the Blue Ion might be more comparable to sixteen (or
> even more) L16 batteries in the real world.
>
> I can't speak to the parallel battery issue you raise with Blue Ion or
> other similar batteries such as Discover - it would seem like their
> engineering team could help with that.
>
> August
>
> Luminalt
>
>
> On Tue, Jul 23, 2019 at 4:59 PM William Miller <will...@millersolar.com>
> wrote:
>
>> Friends:
>>
>>
>>
>> I am a complete newbie to any lithium technologies, so please forgive
>> some newbie questions:
>>
>>
>>
>> I am used to working in amp hours.  If we are looking for a battery bank
>> in the range of 100 kWh, this converts to about 2,083 amp/hours at 48 VDC.
>> Is my arithmetic correct?  An on-line calculator seems to confirm this.
>>
>>
>>
>> The biggest Blue Ion 2 battery is 16 kwh.  At 48 VDC this is about 333
>> amp/hours.  This is like an L16.  To get 100 kwh you would need to parallel
>> 6 strings of the 16 kWh batteries.  I would never do this with L-16s.  Is
>> anyone worried about circulating currents in this type of installation?  Is
>> there technology to prevent one string from cannibalizing another?
>>
>>
>>
>> Here is another, more academic question below:
>>
>>
>>
>> In case I am using a term I made up (which is often the case), I define
>> circulating currents as currents flowing between parallel strings without
>> any outside influence.  For example, if you disconnected all charging and
>> loads from an array with two parallel strings, unless the strings were
>> absolutely identical in electrical characteristics, there would be some
>> current flowing between the two strings.  In my opinion this is the
>> Achilles heel in parallel strings.  Also my opinions:  2. The more strings
>> you have the more chance there will be debilitating circulating currents.
>> 3. The older the batteries, the more the electrical characteristics will
>> vary and the more likely you will get higher circulating currents.
>>
>>
>>
>> It is my theory that if you can measure the circulating currents, or the
>> difference between parallel battery strings at any point in the operation
>> of same, you can get a read on the health of the strings.  The more the
>> operating or idle currents diverge, the more one string will discharge the
>> other string.  I guess this is some part of a battery management system.  I
>> am guessing for the Blue Ion 2 to work in 6 parallel strings, they need to
>> monitor and control this difference in currents.
>>
>>
>>
>> We just installed a flooded battery array (2 strings of 4 Deka M6100-33
>> batteries).  My plan is to retrofit the installation with a 1000A/100mv
>> shunt in the negative leads of both strings.  With a DVM I can spot check
>> the circulating currents to learn about the battery health.  In fact I have
>> a remote monitoring system
>> <https://millersolar.com/MillerSolar/Portfolio/Commercial/Cal_Trans/Remote/Remote_Control.html>
>> with some spare ports that can log these values.  Might be an interesting
>> experiment.
>>
>>
>>
>> I appreciate any input on the viability of the Blue Ion 2 or other small
>> battery systems in multi-string installations.  My customers are asking for
>> new technology, but I instinctively avoid parallel battery strings.
>>
>>
>>
>> William Miller
>>
>>
>>
>>
>>
>>
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com
>>
>> CA Lic. 773985
>>
>>
>>
>> Quote of the month:  “As they age, batteries transition from energy
>>
>> storage devices to energy consuming devices.“ W. Miller
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] *On
>> Behalf Of *Lou Russo
>> *Sent:* Saturday, July 20, 2019 1:50 PM
>> *To:* RE-wrenches
>> *Subject:* Re: [RE-wrenches] Large Off-Grid Residential System
>>
>>
>>
>> Blue Ion 2.0 with Outback or SMA. Works every time.
>>
>> Blue Planet's tech support is great, the warranty is even better.
>>
>>
>>
>> Aloha,
>>
>>
>>
>> Lou Russo
>>
>> l...@spreesolarsystems.com
>>
>> 808 345 6762
>>
>> Spree Solar Systems LLC
>>
>> CT-34322
>>
>>
>>
>>
>>
>>
>>
>> On Sat, Jul 20, 2019 at 10:36 AM Jay <jay.pe...@gmail.com> wrote:
>>
>> Hi Marco,
>>
>>
>>
>> Is the max surge 7kw, which is what is listed on line?
>>
>>
>>
>> Jay
>>
>> Peltz Power
>>
>>
>> On Jul 19, 2019, at 3:10 PM, Marco Mangelsdorf <ma...@pvthawaii.com>
>> wrote:
>>
>> Seven to eight Tesla Powerwalls will get you that assuming that the
>> service entrance is no bigger than 200A.
>>
>>
>>
>> marco
>>
>> On Friday, July 19, 2019, Jason Szumlanski <
>> ja...@floridasolardesigngroup.com> wrote:
>>
>> What are current popular options for battery based systems in the 100kWh
>> range? Preferably Lithium.
>>
>>
>>
>> Also, what inverter pairing is suggested with total stacked capacity of
>> 36kW, 120/240V?
>>
>>
>>
>> This is slightly larger than some of the systems I have worked with
>> recently. I'm a bit out of the loop, particularly on the battery side of
>> things.
>>
>>
>>
>> Jason Szumlanski
>>
>> Florida Solar Design Group
>>
>>
>>
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-- 
*Will White*
Curriculum Developer


e: w...@solarenergy.org
w: www.solarenergy.org
p: 802-272-3092

NABCEP Certified PV Installation Professional
# 093006-34

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