Question on switching to LiFePO4 batteries.

Follow-up to WarrenS65:

When it comes to accurate SOC’s, I kinda see the Bluetooth feature mostly as marketing gimmickry, while their real utility is for checking individual cell status…Further, it remains to be seen how the Bluetooth will respond to two batteries in parallel or series connection…My view is there’s no substitute for the credibility of a Victron shunt based meter..

Of all possible features, the Bluetooth feature wouldn’t be high on my ‘must have’ list - JMO

3 tons

DWeikert wrote:
A little late to the thread but just throwing this out there. Instead of 2 100ah batteries is there a chance you would have the space for one 200ah battery? For example -
JITA 12V 200Ah Plus LiFePO4 Battery
Wiring is much easier and solves the problem of trying to balance the cells across 2 different batteries.

My $0.02
Dan

The battery would probably fit but I've already got the batteries. I could just put a jump wire across the positive terminals (like I have on the negative terminals) if I wanted to bypass the positions on the switch (there would be no difference between A/B/Both from an operational standpoint) to alleviate any balancing concerns. But I do like the ability to isolate the batteries from each other if I want.

Thanks

I have 2 206Ah SOK batteries, a Victron SmartShunt, and a Victron Multiplus 3000 inverter/charger. The two batteries are connected in parallel with the negative going to the SmartShunt and the positive going to a battery disconnect switch.
The other side of the shunt and switch are connected to my bus bars with the MultiPlus, Victron Orion DC/DC converter (2 of these), Victron MPPT controller, and the 12V wiring going to the camper.
The SOK batteries have BMS with Bluetooth. I was having "trouble" with the SOC on the two batteries and the Victron all being different. I called CurrentConnected.com (where I bought the batteries and most of the other Victron components), and they had me disconnect one battery then discharge it and recharge it twice, then repeat with the other battery. After this, I reconnected both batteries and everything is working well.
My advice is to buy all your components from one source that will give you good support.
I also have the Victron Cerbo GX and it's connected to my router. I get e-mail alerts when the batteries cross thresholds I've set, but with the solar panels, I haven't had to plug it in since March.

A little late to the thread but just throwing this out there. Instead of 2 100ah batteries is there a chance you would have the space for one 200ah battery? For example -
JITA 12V 200Ah Plus LiFePO4 Battery
Wiring is much easier and solves the problem of trying to balance the cells across 2 different batteries.

My $0.02
Dan

Sterling1 wrote:

StirCrazy wrote:

so, the plot thickens everything I find says 50% or higher and if you're not using them for a long time recharge every 3 to 6 months. I think this is another area where older chemistry myths might be carrying over

Yea, different manufacturers have different recommendations. I just wonder how much difference it makes in the real world.

For someone that really cycles the batteries a lot and is concerned about maximizing the cycle life it may make sense to take extra effort to store them in optimum conditions.

For someone like me who doesn't put a lot of cycles on the batteries storage conditions may not make much of a difference (as long as they aren't stored in a discharged state). They are more likely to die from old age than anything else.

It would just be nice to see how much of an impact storage SoC has on LiFePO4 battery life.

I try not to go by the manufactures but rather from the makers of the cells. What people call manufacturers in this area are really just assemblers. they don't make anything themselves; they just assemble off the shelf components. They may have custom cases made for them, or they might make custom solutions to hold everything together so there is a small possibility they might make a tiny part...

So, I tend to look at CATL, BYD, ELB and EVE cell manufactures, of which, the first three are the biggest in the game, and while EVE isn't as big they are known to be one of the highest quality cells on the market.

StirCrazy wrote:

so, the plot thickens everything I find says 50% or higher and if you're not using them for a long time recharge every 3 to 6 months. I think this is another area where older chemistry myths might be carrying over

Yea, different manufacturers have different recommendations. I just wonder how much difference it makes in the real world.

For someone that really cycles the batteries a lot and is concerned about maximizing the cycle life it may make sense to take extra effort to store them in optimum conditions.

For someone like me who doesn't put a lot of cycles on the batteries storage conditions may not make much of a difference (as long as they aren't stored in a discharged state). They are more likely to die from old age than anything else.

It would just be nice to see how much of an impact storage SoC has on LiFePO4 battery life.

Sterling1 wrote:
….I understand that storing them not fully charged is best;

But I haven't found anywhere on the internet where it quantifies the degradation in life due to starting out storage in a fully charged state.

I could be wrong, but from a distance it seems to me like the answer in which you seek is embedded within your own question - just saying…

3 tons

Sterling1 wrote:
I understand that storing them not fully charged is best. But I haven't found how much degradation it does to be stored in a fully charged state (but not connected to a charger). If it is a 10% degradation in life I I can live with it, but if it is a 50% degradation in life then I'd probably take the extra effort to discharge them for storage.

I haven't found anywhere on the internet where it quantifies the degradation in life due to starting out storage in a fully charged state.

I'll look at my literature for my cells and see if they say anything about how bad it is. like I said for short term I just keep it in my usage range as I run between 10% to 90% and never charge to 100% except the night before, or the day I am going camping I will go to a full charge and balance then reset my BMS to the regular operating range I use, but I am out almost every weekend (I work a 4 day on and 4 day off schedule) but when I am done with it for the winder I do drain it down to 50 to 70 which takes quite a bit. Usually, I just switch the fridge to 12V when I go to bed and then turn everything off the next day sometime. but I'll see if I can find anything that says how bad it is to leave them charged full.

so, the plot thickens everything I find says 50% or higher and if you're not using them for a long time recharge every 3 to 6 months. I think this is another area where older chemistry myths might be carrying over

I understand that storing them not fully charged is best. But I haven't found how much degradation it does to be stored in a fully charged state (but not connected to a charger). If it is a 10% degradation in life I I can live with it, but if it is a 50% degradation in life then I'd probably take the extra effort to discharge them for storage.

I haven't found anywhere on the internet where it quantifies the degradation in life due to starting out storage in a fully charged state.

Sterling1 wrote:


I know LiFePO4 batteries should be stored around a 50% SoC for maximum life, but how important is this from a practical standpoint? I dry camp fewer than 10 times a year. If I were to give the batteries a full charge and disconnect them, top them off before going out, fully charge them when I returned (if they were significantly discharged), disconnect them and leave them that way for my next trip, how much am I really degrading their life? I realize I could boil some water in my microwave to get the charge level down but I wonder if it is really worth it.

I store mine anywhere between 70 and 90. It all depends on where they end up after my last night of camping, but that is during camping season. where I am camping every week or two. When the season comes to an end, I run my cell down to approximately 50% then turn the power off. with a 3% loss per month, I'll be fine till spring. you'll find everyone does things a little different.