Lithium batteries and hydro power

thomas rubino wrote:Hi all;
For the last year, my current AGM batteries have been dying.
After stalling for ten months, they are now on generator life support!  
Even with the hydro constantly making 100 + watts, after racking up 25 amp hrs or so, the batteries fall into the ten-volt range and my inverters start shutting down.

I have been very interested in switching over to LiFe PO4 lithium batteries.
I have been dragging my feet all summer about "just doing" this.
At one point in the spring, I almost ordered the SOK batteries.
I'm sure glad that I did not!
After spending the last week seriously investigating the details.
I have come to the conclusion that Lithium batteries are not right for my system.
Not to say that it can not be done (it could) but the risk of destroying my very expensive pertinent magnet hydro is just too high.

All lithium batteries are composed of separate cells contained in a case.
Those cells are monitored and controlled by a BMS unit (battery management system) a built-in feature of all large lithium batteries.
I have now learned that when the BMS decides the battery is fully charged it disconnects from the charging source.
It will also auto disconnect for high-voltage and low-voltage, or if it malfunctions.
When using solar charging that is completely acceptable. Solar panels do not care if connected or not.
A hydro system or a wind system does care, they require a constant location to "dump" excess power.
Disconnecting a constant diversion charging source while running will send the alternator into an open circuit voltage this means the output voltage goes very high, which has the potential to melt wiring inside the unit.
At the same time once the load is removed, the hydro will go into an Overspeed condition.
The potential for a catastrophic blowout of my hydro, although low is higher than I care to worry about.

As much as I would like to upgrade to Lithium batteries...
I'm thinking I'll be in Missoula next week buying new AGMs!

Jack Adam wrote:I went with Nissan Leaf batteries.  I have hydro and solar.

With out knowing the details about your system It's hard to say a lot.

thomas rubino wrote:Hi David;
Thanks for the info.
My whole system is just slightly better than one that Fred Flintstone might have had.
All 12 vt, added to many times since 1983. I still have one run of straight 12 vt power thru the house!
It started with one solar panel leaning against the wall with a piece of  Romex wire passed thru a window and vice gripped to a die-hard battery.
530 watts solar, PWM charge controller, the Micro Hydro is a Harris permanent magnet 12 volt running a single nozzle.
I do not know the open circuit voltage.
All very hillbilly but it works for us.
I understand upgrading my entire power system to a high-voltage Mppt setup makes perfect sense.
If I was much younger, I would be foolish to not invest in that.
This system and I have grown old together (40 years!)
I think I'll let the kids decide what they want to do when it's theirs.

I very much wanted to try lithium batteries.
I was willing to take extra steps to do so.
With what I learned about the lithium BMS unit, for now, I'll stick with lead acid.
Maybe batteries will have improved when my AGMs wear out again.

David Baillie wrote:

Jack Adam wrote:I went with Nissan Leaf batteries.  I have hydro and solar.

With out knowing the details about your system It's hard to say a lot.

Hi Jack,
Did you ever post about your system? What controller are you using? I have a thread here: https://permies.com/t/206893/Solar-Projects-good-bad-cutting
Where I would love to see the system or a link to it if you've already posted...
Cheers,. David Baillie

thomas rubino wrote:Hi David;
I very much wanted to try lithium batteries.
I was willing to take extra steps to do so.
With what I learned about the lithium BMS unit, for now, I'll stick with lead acid.
Maybe batteries will have improved when my AGMs wear out again.

Jack Adam wrote:

David Baillie wrote:

Jack Adam wrote:I went with Nissan Leaf batteries.  I have hydro and solar.

With out knowing the details about your system It's hard to say a lot.

Hi Jack,
Did you ever post about your system? What controller are you using? I have a thread here: https://permies.com/t/206893/Solar-Projects-good-bad-cutting
Where I would love to see the system or a link to it if you've already posted...
Cheers,. David Baillie

I'm using an older Outback inverter on my hydro.

I tend to not over share on the internet due to issues I have run into in the past from over sharing on a chat forum years ago.

thomas rubino wrote:Hi Jack;
Thanks for the reply.
Interesting you have no BMS.  Being from a vehicle I assume this is a higher-voltage battery?
I had not given any thought to building my own lithium bank and not installing a BMS.

What kind of maintenance/upkeep do you need to perform?

David Baillie wrote: I totally hear you. I do find the general quality of posters here is higher then the norm and the admins take a more active role then you usually find.

David Baillie wrote:

thomas rubino wrote:Hi all;

and here is a link to missouri wind and solar's all in one package to do it. https://windandsolar.com/midnite-classic-mppt-wind-turbine-charge-controller-board/ That would allow you to do lithium or at the very least get more life from the AGMs.
On the plus side you could double your energy harvest depending on your turbine and battery voltage. Do you have a turbine model number,  its free wheel voltage? and your battery voltage?

This thing looks way too beefy for the miniscule amount of power Thomas is generating.  100W input, where the charger can handler 3KW?  
Why not choose something from among these hybrid systems?
https://windandsolar.com/wind-solar-hybrid-charge-controllers/

Michael Qulek wrote:Part of the problem is clinging to the use of AGMs.  Why not go with flooded lead-acid in stead, and get double the life for half the money?

Steven Murpy wrote:Hello, guys. I wanted to say about  LiFe PO4 batteries. As far as I know, this type of battery is now widely used in portable power stations like EcoFlow. I am not a fan of those battery types, but I am just thinking of a practical point. Moreover, LiFe PO4 batteries have more charging cycles it's up to 3500

Eric Hanson wrote:I don’t know why I didn’t see this thread long ago and what I am about to say might fall into the day-late-dollar-short category.

Has anyone here, including the OP, considered *Building* a battery?  By this I mean acquiring individual battery cells (LiFePo4 being the most common, but other chemistries are available), adding a BMS and wiring them together inside some housing.

I have been involved in building a battery box based on LiFePo4 battery cells for about a year.  I would have had my project finished long ago, but sourcing a supply of my specific sized and dimension battery took some time.

The relevant point here is that if a custom BMS is installed, then the upper and lower charge limits can be adjusted and therefore still take advantage of solar panels working at low and especially high output.

There is definitely a skill set required to build one of these devices, but jumping in and building it helps develop that skill set.  My current project is based on 105 AH cells housed in an ammo box.  Now that I have the batteries I hope to accelerate my project.

My conclusion statement is that LiFePo4 batteries might still be the appropriate chemistry, but it will require building in an appropriate Battery Monitor.  If you are looking for pointers, I can certainly point you towards some possible solutions.

Eric