160 ah batteries only last 1 hr???

[Watch_Cowspiracy]

I got 4 used 40ah lithium iron phosphate batteries, wired in parallel. 400 watts of solar. During the day, I can run my 100 watt AC freezer without a problem, but about an hour after the sun goes down the battery voltage drops to 10.5. I'm not using any power except the freezer. What could I be doing wrong? Did I get scammed with dead batteries?

 

[highdesertranger]

did you check that 100 watts or is that from the specs?

what's the duty cycle?

I would check the power consumption of the freezer and the how much the inverter is drawing and go from there. I know very little about Lithium batteries so I will let others chime in.

highdesertranger

 

[Watch_Cowspiracy]

100 watts rated. Measures about 400 w on startup, then hovers between 30-90 watts while running. Probably 100% duty cycle because it's 90 degrees out and had room temp food in it. But still, that shouldn't be depleting the batteries so fast. I measured the inverter's draw awhile ago, don't remember off the top of my head exactly but it was peanuts compared to what 160 ah of batteries should handle.

 

[tx2sturgis]

My first question is: 

Do these lifepo4 batteries have a built-in or outboard BMS? Are they 14.4 volt packs or what?

Reason I ask is, you say they are used, but we dont know if they are a DIY kit, or off-the-shelf cells with no BMS or what.

Without knowing all of that information, we, as the reader, can't assume we know the fully charged pack voltage, and whether or not you have cells that are top-balancing correctly. Some lithium batteries and the associated BMS are not rated for parallel connections.

Also, is your solar controller rated for lithium? Or are you using a lead-acid charger for the lithium pack?

And as HDR points out, the freezer might or might not be, 100 watts, continuous, or intermittent, and is that including the inverter losses? How big is the freezer? A tiny dorm-sized freezer versus a 5-10 cu ft deep freeze unit...those are two different things. Are you in a hot urban or desert environment or a cool shady mountaintop? 

Are the solar panels flat mounted on a roof, or shaded for at least part of the day? 

Was it all working fine for months and then simply failed, or did the system do this from day one?

We just need more information to be sure.

But, it sounds like your 160 ah bank is undersized if you are running a large capacity AC freezer (like a residential deep freezer) thru an inverter with a heavy load on the batteries 24/7.

 

[Gypsy Freedom]

i dont mean to infer a mistake, but are you sure you have 4 times 40 amp hour 12 v lifepo4 batteries. or do you have 4 times 40amp hour lifepo4 cells. there are a lot of those running around on the used market right now.

maybe post up a link/picture or model/specs so we know what we are dealing with

a simple test you could do is to disconnect all loads and let your solar charge up the battery back fully. then check the voltage several hours after charging has stopped. if the voltage drops much with no load, i would be suspicious of the condition of the batteries

if they seam to be holding under no load. getting a battery monitor that measures and records amp hours would be my next step. at the end of the day when they are fully charged (assuming here that they get fully charged) reset the counter and see how many amp hours are drawn from the battery by the time they get real low like you are seeing

with more info about what you have we might be able to further explore what is going on. could be an issue with load or charging but hard to say from available info

 

[Watch_Cowspiracy]

Thanks all for the replies, sorry for the delay I've been out of service for awhile. These are the batteries. http://valencetechstore.com/u112rt.html IIRC they have an internal BMS and do seem to hold a charge. The charge controller is a 40 amp mppt that is supposed to work with lithium batteries. I've never used a lead acid charger with them.

I have since gone to the auto parts store and picked up a lead acid deep cycle battery. I'll probably just take these to a recycling center and eat the $500.

Also, special mention to XERTYX. While I appreciate the impassioned reply, If you'd follow the instructions of my screen name, watch www.cowspiracy.com you'd understand why anyone who considers themselves to be an environmentalist would never stock their freezer with animal products. Beyond burgers perhaps (a plant based burger that has fooled professional taste testers).

 

[Gypsy Freedom]

ya, those batteries are supposed to be drop in replacements. once they are charged and holding a charge, did you try to run your fridge then? if so how long did it take for the batteries to drop down to the low voltage?

is the fridge working well into the night now with the new battery?

if you are just going to scrap the other lithiums, i would love to get a hold of them to tear them apart maybe see what went wrong. what part of the world are you in?

 

[Groovy2]

4 X 40 ah batteries wired in Parallel make a battery that is 3.6 volt total
and 160ah ( not what you have )

4 X 40 ah batteries wired in Series = 13.6 volts
But its still a 40 ah battery - (this is what you have )

When connecting your batteries in Series you are Adding the voltage
while maintaining the Same capacity rating in amp hours

 

[Groovy2]

opps I am wrong I assumed you had 3.6 volt cells -
after looking at link to your cells it should be 160 ah 
4 cells wired in parallel -

 

[tx2sturgis]

Thanks for the update on the battery configuration.

If you'd follow the instructions of my screen name, watch www.cowspiracy.com you'd understand why anyone who considers themselves to be an environmentalist would never stock their freezer with animal products. Beyond burgers perhaps (a plant based burger that has fooled professional taste testers).

The above reply about hamburger meat helps drive home my earlier post about how we tend to 'assume' things based on our own experiences with it.

Even just a casual assumption that we all store and eat meat, can be wrong.

 

[highdesertranger]

jeez, I am on the road traveling from one camp to another for one day and I come back to this.

I deleted a whole bunch of posts for bickering, being snarky, for quoting those posts and for just plain being an ass.

stay on topic and try to offer help to the original poster or don't post.

highdesertranger