LIFEPO4 - lithium battery

[Gobi King]

Anyone here have any experience with lithium fe batteries?

18650 vs bigger 32650

Bms and a charger ??


My trolling motor is 12v with max draw of 50 A

DIY LI doable ?

[Tiddlerbasher]

I've a lot of experience with 18650s but only the standard Lion ones. I use them mainly in torches and portable power packs.
The Lions I use are mainly 3000mAh. For 50 amp your gonna need an awful lot. I have never played with LIFE04 batteries.

[Gobi King]

Here is my confusion or questions:

1. How do you charge them when you have a BMS tied to them?
2. Do I need a spot welder? which one?
3. What do you use as DC power for charging?

50 A is max, I nearly never go full throttle on my trolling motor, mostly use it to GPS lock or troll 1.1 mph for walleye.
Average draw is 10A

[Ron Jones]

There are videos on the Tube about building something this size. I would definitely use a spot welder, any of the entry level ones would work for this. An MPPT would take care of the charging and discharging. This is if you are set on DIY.

There are off the shelf SuperCaps this size, but you don't save anything over a deep cell AGM or Li.

It would be a lot of fun, and quite the conversation piece.

Ronald Jones

[Gobi King]

I have a 100 Ah flooded right now,
I can add another 100 Ah flooded in parallel and get 100 Ah useable total.

Convo - lol, sure is, LI is still the hen's teeth. But my interest is useable charge, aka the juice.

48v battery pack and then step down?

Spot welder - another tool that I will never use again,

MMPT for charging ?


batt -> bms -> mmpt [what feeds mmpt charge controller?]

[MarkT]

They're even starting to power submarines with lithium batteries.  Replacing the AIP with lithium batteries.  You're getting closer to state of the art!

[David Hall]

I've been looking at them as a new setup for my boat.  I currently run lead acid- 29 series starter battery and two 31 series house power, my interest peaked when I took notice of the batteries my grandson uses on his kayak.  I think that They are amazing.

[Gobi King]

Nuclear subs with LIFEPO4 batts,

The Nordhavns have a diesel hybrid drive system, only if they made a smaller one for my Crestliner 


After binge watching some UTUBs more concerns and questions:

1. Temp - Michigan is cray cray when it comes to temps, we have 39F morning in summer sometimes.  LTO seems to be the way to.
2. KISS - Larger cells and few of them to achieve desired voltage and capacity will be the ticket but that gets expensive.
3. Used Batts - quite a few guys are selling used batts off. I need to find some LTOs

Voltage - 48V seems to be the ticket, I just have to  step down it for my 12 V system

Charging - Biggest obstacle for me is the charging power source

1. Bennie method - genny, use my 800W hb el cheapo and run to charge.


BMS -
I found the answer to my BMS question - for large current draws, some guys don't run that through the bms but they use the bms to control a relay/disconnect when the voltage reaches cut off (LVC).

So using this method I can have a 50A bms and still use the battery bank to run a motor that draws 100A peak.

Aliexpress - all the new batteries seem to be on Aliexpress, what the charge, I wonder why we don't have a local distributor. Paying $300 for DHL for $300 in batteries seem very wasteful.


I found a pack in Bensalem PA, anyone close?

[Gobi King]

Finally had a minute to bounce some thoughts and check suggestions by solar guys.

Cells -
I was a little click happy, maybe it is the covid cabin fever.

-12v LiFEPO4 premade packs, 3 of them. Use will be for Daiwa Tanacom electric reels and sonar in my folding porta bote.

- 36v A123 LiFEPO4 cell 9 AH pack, need a bms for this guy but this was just an impulse buy, not sure what the heck I will do with this one.

- 8 x 280AH LiFEPO4, this will give me a measly 560AH of battery capacity for my mighty trolling motor.
I bet ya I can troll all the way to Wisconsin and fish with Crow ;-)

The best part is that PER my calculations, the 560AH of cells will fit my 2x31d batt storage compartment [well we shall see]

now to source waterproof BMS, I think I will go with 150A 4S bms


Charging, well boyz et girlz, I am stuck, my LI charge pumps out an earth shattering 5A, hmm, the city will ticket me if I keep the boat on my driveway that long

What can I use to get 50A @ 14v? old server power supplies?

I have ATX power supplies, if I add a voltage regulator inline, I should be able to get that ?

[jzman]

not sure if it will work for your application, but the two-wheeled cart 12v lead car battery chargers do 40-50 amps.  they are not too expensive but they are for lead acid chemistry.  you especially cant set it and forget it unless you are charging and relying on a good BMS (even then dont).  Best to use this charger for maybe 70-85% charge then top off with a charger meant for LiFePO4

[Gobi King]

not sure if it will work for your application, but the two-wheeled cart 12v lead car battery chargers do 40-50 amps.  they are not too expensive but they are for lead acid chemistry.  you especially cant set it and forget it unless you are charging and relying on a good BMS (even then dont).  Best to use this charger for maybe 70-85% charge then top off with a charger meant for LiFePO4

it depends on output voltage, I need 14v to 14.4 v output.

A waterproof charger will be better, as I have to charge them outside. Maybe 2x 30a 12v Chargers, everything I see is a lot of $$$$.

I have old manual chargers, I think they do 20A max, I am going to check the voltage on those for bulk charge step.

[Dominick]

How hard is it to take the battery out of the boat.. If it is no big deal bring the battery in and get yourself a battery tender and always keep it hooked up when not in use.  Dominick

[Gobi King]

How hard is it to take the battery out of the boat.. If it is no big deal bring the battery in and get yourself a battery tender and always keep it hooked up when not in use.  Dominick

Dom, the battery is accessible, but it weighs around 80 lbs, my shoulders are not what they used to me.

280Ah Li batt will be around 50lb plus bms and case.

yes, I do carry out the starting batt, which is around 40lbs,

Now, if I was married, my wife would probably help me carry the 80 lb battery out after every fishing trip and charge it for moi 

[Dominick]

Now, if I was married, my wife would probably help me carry the 80 lb battery out after every fishing trip and charge it for moi 

Hey don't say that.  It's cheaper tp pay someone to do it each time you need it.     Dominick

[Tiddlerbasher]