Topic: Need advice on LiFePO4 batteries (Read 2738 times)

April 16, 2021, 06:14:35 AM

One of the kids is (finally) going to take one of the kayaks cluttering up my garage home. It's fully rigged so she also gets my battery box and I'm building a new one.

I'm seeing the prices for 12v 10amp LiFePO4 batteries are dropping to nearly reasonable costs, but I can't claim to understand them.

I'm only after a battery, not a package like the Wilderness System battery pack. A LiFePO4 battery that looks like an SLA battery is cheaper than those kinds of units and I have skills, but I have questions.

Who makes a good, reliable LiFePO4 battery? What brand(s) should I consider? What kind of maintenance charger do they need? Those kinds of questions.

April 16, 2021, 06:46:30 AM #1

Quote from: Tinker on April 16, 2021, 06:14:35 AM

One of the kids is (finally) going to take one of the kayaks cluttering up my garage home. It's fully rigged so she also gets my battery box and I'm building a new one.

I'm seeing the prices for 12v 10amp LiFePO4 batteries are dropping to nearly reasonable costs, but I can't claim to understand them.

I'm only after a battery, not a package like the Wilderness System battery pack. A LiFePO4 battery that looks like an SLA battery is cheaper than those kinds of units and I have skills, but I have questions.

Who makes a good, reliable LiFePO4 battery? What brand(s) should I consider? What kind of maintenance charger do they need? Those kinds of questions.

I look for LiFePO4 batteries with the following: BMS built in to prevent over charging and over heating, cylindrical cells vs prismatic cells as prismatic are more vulnerable to overheating and failure due to increased hardware and less airspace in the battery, a minimum of a three year warranty

I've used Amped, Dakota, and ReBel batteries and all have served me well. I prefer the ReBel batteries as they have built in bluetooth that allows you to monitors the battery's charge, # of cycles, and temperature.

You do need a charge specifically designed for lithium

April 16, 2021, 07:01:56 AM #2

I run the Hobie department at Outdoor Emporium in Seattle and we sell the Dakota Lithiums. I use a 23ah one for my 9" fish finder and have no issues. I've also sold tons of 10ah Dakota's and have only one come back for warranty. They've also got an 11 year warranty which is nice.

Kevin

April 16, 2021, 07:08:36 AM #3

Quote from: uplandsandpiper on April 16, 2021, 06:46:30 AM

I look for LiFePO4 batteries with the following: BMS built in to prevent over charging and over heating, cylindrical cells vs prismatic cells as prismatic are more vulnerable to overheating and failure due to increased hardware and less airspace in the battery, a minimum of a three year warranty

I've used Amped, Dakota, and ReBel batteries and all have served me well. I prefer the ReBel batteries as they have built in bluetooth that allows you to monitors the battery's charge, # of cycles, and temperature.

You do need a charge specifically designed for lithium

I've never heard or read anything about cylindrical vs prismatic cells before now. Thank you, I appreciate it.

Quote from: kredden on April 16, 2021, 07:01:56 AM

I run the Hobie department at Outdoor Emporium in Seattle and we sell the Dakota Lithiums. I use a 23ah one for my 9" fish finder and have no issues. I've also sold tons of 10ah Dakota's and have only one come back for warranty. They've also got an 11 year warranty which is nice.

Thank you, Kevin. That's helpful.

April 16, 2021, 03:22:10 PM #4

Got this one in the mail today ordered from chet on NCKA, 17.5AH. it's about 50% the weight as my 9AH SLA, 75% the size and nearly twice the capacity. Actually more than twice the capacity because drawing down SLAs below 50% damages the battery.

The battery is only good as the cells and BMS (battery management system the circuit board on the right of the cells). Good cells are generally brands you've heard of Samsung, LG, Sanyo, Panasonic - the ones pictured appear to be Samsung 35E 18650's in 5P3S configuration. Lithium cells need to have their voltages in balance which the BMS takes care of along with the other duties uplandsandpiper mentioned. There are two ways of charging: bulk and balance charging both of which need a lithium CCCV charger. Bulk charging puts power in the battery back from the main terminals - like this battery pack, dakota lithium, battleborn - it's more practical. The BMS then distributes the voltages to each cell/parallel group to make them a more even voltage. Balance charging charges each cell or parallel group individually, you'll see this this in RC batteries at hobbyking.com with the main positive and negative wires and another set of wires (balance leads) that go to a balance charger like an imax b6. It's generally better for the battery to be balance charged.

Thank you for subscribing to battery facts.

April 16, 2021, 04:17:16 PM #5

Yes, I know of Chet but have never seen one of his finished battery packs. Thanks!

I'm a retired EE. When I retired, lithium batteries weren't in general use and were never used in the area of my discipline.

April 16, 2021, 04:40:53 PM #6

Quote from: Tinker on April 16, 2021, 04:17:16 PM

Yes, I know of Chet but have never seen one of his finished battery packs. Thanks!

I'm a retired EE. When I retired, lithium batteries weren't in general use and were never used in the area of my discipline.

Yeah he says to never open them, but that's the first thing I did as the degenerate I am. His battery pack looks legit. Don't really agree with the type of connections he used, which appears to be soldered zinc wire. I'm okay with the zinc but the soldering transfers heat to the cells which can affect the lifespan. Typically these packs are connected with zinc strips and spot welded. I also don't agree with his choice of a 15A fuse, I'll probably wire in a 3A between the fish finder and battery pack.

The BMS is 40A and since the cells are 8A continuous discharge making for 40A continuous discharge out of the pack. So I could swap out for a 40A fuse, hook up an inverter, and mount my 450watt Jimmy Buffett Margaritaville machine to the kayak, which would be nice on hot long days in August.

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Topic: Need advice on LiFePO4 batteries (Read 2738 times)

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