If the amp hour rating of the batteries is the same, then you definitely see less voltage sag with Northstars.
I would guess that even if you replaced your 520 amp hour batteries with 420 amp hour Northstars, they still will have less voltage drop.
I would install them in two strings, each independently charged with a 25 amp charger, and balanced with a 1 amp balancer. I'd also monitor them for voltage either manually or automatically, for interest and to record their performance.
The Northstar Blue is the most efficient battery I have worked with.
Efficiency can really be approximated by how long the battery has to be in absorption before the battery is fully charged, and how much current it takes to keep it in absorption. Take the energy in kilowatt hours of the absorption period, and divide that into the kilowatt hour capacity of the battery, and you will quickly understand the inefficiency of the battery. If you really wanted to be scientific about it, then divide the kilowatt hour consumed by the battery, by the kilowatt hours returned to the battery and that will be the efficiency of the battery. Since Northstars are more efficient, they require less time and current in absorption to get them fully charged.
To go even further into this discussion, each battery has two categories of efficiency, that being efficiency during partial state of charge operation, and efficiency to go through a full discharge - charge cycle. The Northstars have very high efficiency during partial state of charge (PSOC) operation.
Then combine that with a deeper discharge too. The Northstars can be run between 20 and 90 percent up to 500 times or so and can be regularly cycled through this range if necessary. Other Batteries can only cycle between 50 and 80 percent for 500 times or so. The efficiency of the Northstar rivals that of a Lithium Battery at certain points on the charge curve. Overall, because of the Pure Lead, and now Carbon being added, these batteries are definitely superior to anything else I have seen.
But the most important factor of these batteries are they are of an intrinsically safe design. That is hard to find in an electrochemical storage device.
James
James Lambden
The Electric Propeller Company
625C East Haley Street,
Santa Barbara, CA
93103
805 455 8444
james@electroprop.com
www.electroprop.com
The Electric Propeller Company
625C East Haley Street,
Santa Barbara, CA
93103
805 455 8444
james@electroprop.com
www.electroprop.com
On Sep 13, 2018, at 9:26 AM, clh5_98@yahoo.com [electricboats] wrote:
James,one other thing I've been thinking about. In your experience, will I experience less voltage sag at higher currents with the NorthStar batteries? If so, it seems that this could help some from an efficiency standpoint by requiring less current for the same power setting. My current bank is at 520 aH, do you think that increases in efficiency will somewhat make up for the loss of capacity if I go to 400 aH of NorthStars? Also, I do intend to have 2 parallel strings of 4 batteries tied to a common bus, just like I currently have with my T-145s. I have each string feeding through a disconnect switch so I can isolate each bank for maintenance, or if something goes wrong.Chris
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Posted by: James Lambden <james@electroprop.com>
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