Solar charging batteries

[redneck joe]

a gunnel .......is it like a gunwale 'cept spelt wrong

Please refer to my screen name....

 

[Mc Tool]

Please refer to my screen name....

My Dad taught me how to sail ...........and the correct name ( he was a lawyer ) and function of every bit of rope , handle or boat part .........I just wanted to sail the friggin boat but every regatta started with a lesson and brief test . I dont think it did me any good ...... but its surprising how many boaties dont know the proper name for things nautical .

 

[redneck joe]

Can't speak to much in sail but I know most every other name, redneck spelling notwithstanding. If I don't know name I know what it does.


Back to batteries, I looked at my starting motor today. Dated 2018, lead acid deep cycle. Came as extra with a boat. Sat in my driveway until two years ago, never charged. Works just fine.

 

[airshot]

LifePo4 batteries like a bigger amp charger over a trickle charger to fill them up. Trickle charge is ok once filled, but not for long term. Lipo batteries require a storage charge ( about 50%) for longest life. Keeping one at full charge over time will shorten the life. When folks start using these type batteries they need to re-learn charging practices as they are much different than lead acid batteries ! The real issue is, if they are charged incorrectly...they can catch fire and burn fast and white hot !! The BMS is supposed to catch the wrong charger/system and stop everything....thus why batteries with BMS are so highly recomended...once you understand how to handle them, you will love them !

 

[kd4pbs]

My Dad taught me how to sail ...........and the correct name ( he was a lawyer ) and function of every bit of rope , handle or boat part .........I just wanted to sail the friggin boat but every regatta started with a lesson and brief test . I dont think it did me any good ...... but its surprising how many boaties dont know the proper name for things nautical .

Some fo’c’sle never understand why it is important to be stern about the proper names of boat parts.

 

[redneck joe]

Learn these key voltages for LiFePO4:
13.3V+ (100% charged)
13.1V (~50%)
12.5V (20% - time to recharge)
12.0V (0%, damage imminent)

So having my 5 w charger on for 48 plus hours, only getting 11.6 v on my meter so I appears by not charging them I for a couple years has toasted them? On charge it reads 14.xx.

I did find my 20 w charger but since I had the 5 on so long that shouldn't help will it?

 

[redneck joe]

This is from the product page, it talks about 11.6 being 'disconnected'? Also, recommends 4 to 10A charger.

 

[redneck joe]

Min are in parallel but why does it say to use solar charger to activate BMS

 

[redneck joe]

Here is the charger I've been using, shows at 14.3 when charging where instructions say 14.6 and I can't find anything other than 12V in descriptions. Arggggg!!!!

https://www.amazon.com/dp/B082LV7RKL?ref=ppx_pop_dt_b_product_details&th=1

 

[kd4pbs]

What they're telling you but not telling you is that using a battery charger that can supply a constant voltage at or above 14.6 V is best, as this will activate the battery's built-in management system which will implement the "smarts" needed to properly charge the battery. I'd say that the supply needs to be capable of a few amps at that voltage at least. And yes, if you allowed the battery to go below it's minimum, it will be pretty much useless going forward. Lithium batteries do not like going below a threshold voltage for much of a length of time without being damaged.

 

[airshot]

I was told that these batteries need more than a trickle charger when the battery is low ( below 50%). Once the battery is charged a small or trickle charger will keep it full. My mfgr recomended a 20 amp 14.6 volt charger for my LifePo4 140 ah battery and it works great and it is quick. These batteries do not like me a long slow drawn out charge rate.

 

[cyclops222]

True LIFEPO4 batteries can take UNREAL charge rates with no damage. I have many D sized LIFEPO4 cell batteries for model air planes. rated at 4 amps. I recharge at 20 amps for at least the last 20 years.

 

[redneck joe]

What they're telling you but not telling you is that using a battery charger that can supply a constant voltage at or above 14.6 V is best, as this will activate the battery's built-in management system which will implement the "smarts" needed to properly charge the battery. I'd say that the supply needs to be capable of a few amps at that voltage at least. And yes, if you allowed the battery to go below it's minimum, it will be pretty much useless going forward. Lithium batteries do not like going below a threshold voltage for much of a length of time without being damaged.

But... it sounds like they bms will shut it off to save it? Then reactivate when 11.6 v is achieved?

 

[kd4pbs]

I sure hope so, my friend!

 

[redneck joe]

Well I'm going to put on the 20 w charger for a day or two. The spec says it is 14.4, not 14.6 but we shall see.

 

[kd4pbs]

The BMS takes a wide range of input voltage and makes it work. It will also limit the current to only allow what it is programmed for, so you won't have to worry about maximum current capability of the supply.

 

[redneck joe]

So, on the batteries i ki.led thru neglect. Is there any good use left in them? The trolling motor sucks a bunch of juice I'm assuming but would it have enough to juice a pond pump?

 

[tpenfield]

I've learned a few things the hard way over the past few years with solar and LiFePO4 (LFP) batteries.

- Expect about 65% of the rated watt output from a solar panel . . . A 5 watt panel is not going to charge a decent sized battery any time soon (weeks). Since LFP batteries can take a lot of current, a small solar panel can't really 'get ahead of the game', and the battery drags down the voltage of the solar panel. I think you are seeing that . . .

- LiFePO4 batteries should wake up at 11.5 volts (+/-) and then go up from there, if they have gone into low voltage protection mode.

- I have found the 14.6 volt chargers can bring the LiFePO4 into over voltage protection mode, which will then give a reading of about 12 volts until they 'wake up'. I try to disconnect my chargers when the batteries get into the high 13 volt range (13.8 ish).

- It is OK to trickle charge LFP batteries, but they don't need it as much as lead-acid. Trickle charging should be in the 13.5 volt range.

- Got any parasitic draws on your boat to worry about? You'll want the solar to be able to keep ahead of those.

- Now that the sun has gone lower in the sky, and the daylight hours are less, I am finding that my 100 watt panel (20 watts per battery) is not able to keep ahead of the game and I have to supplement with shore power. This may be a concern for late-season boating.