Big Battery Purchase...A Mistake???

[Bigreddogs]

Hi guys - Newto the forum here...

Bought a Big Battery OWL170 Ah for my RV. I wanted SOK’s but they were not in stock and my AGM bank was dead - I need two, but only purchased one to start out with because I wasn’t sure Big Battery was a good decision as a supplier. They have some reviews out there that were not positive and those left me with some concerns and a low comfort level.
Here is the situation. I fully charged the battery, installed it in the RV, turned on the inverter a couple of fans, and some lighting until I show 29 amps discharge through the battery via my Victron 500amp shunt and verify that with the reading off the Xantrex inverter.
After researching/educating myself on LifePo4 batteries over the last 2 years I felt comfortable in my decision to buy LFP over AGM for my replacement batteries, and that my Xantrex model RV2012-B20 - 2000Watt inverter/charger would work ok with it - until I purchase a replacement model.
My Xantrex inverter spec shows efficiency is at 94%. I expect that 170Ah battery should provide 30amps per hour for at least 5 hours at 94%. Or 170Ah x .94 = 159.8/30 amps = 5.32 hours of use. So 5 hours minimum I feel is reasonable to allow for resistance in wiring etc.
I check back each hour to see that after 3 hours the battery is shut down. Quick plug into the charger shows the battery is sitting at 10.9V when connected and the BMS comes back online. So I assume the BMS shut it down at low voltage point. Recharge and run the load test again, this time keeping a close eye on system and as the 3 hour mark gets close I go sit and watch the readings in live time. Sure enough, at 91 Ah discharged load the battery is sitting at 10.5V with 28.78 amps draw down (under load) and dropping voltage like a rock. At 9.6V the BMS shuts it down. Looks to me that this battery is under performing.
BB says keep charging and discharging – it will improve as more cycles are completed. WHAT??? Never have I seen a battery improve with use much less improve by 40%. Anyone out there who can advise me on this? I do appreciate any input at this point.
My equipment:
Shunt: Victron Energy SmartShunt 500 amp Battery Monitor (Bluetooth)
Charger: Victron Energy Blue Smart IP22 12-Volt 30 amp 120V, 3 Output Battery Charger NEMA 5-15, Bluetooth

Battery: Big Battery OWL170 12V 170Ah LifePo4
Distance from battery to inverter/charger is approx. 18” to 20”
cable size is 2/0

 

[MisterSandals]

Bought a Big Battery OWL170 Ah for my RV

So you first bought and are following up with research?

my decision to buy LiPo over AGM

LiPo is lithium polymer, completely different than LiFePO4 (and the fictional LifePo4 life polonium chemistry).

30amps per hour for at least 5 hours

That’s 30 amps for 5 hours or 30Ah per hour for 5 hours.

after 3 hours the battery is shut down.

Can you tell why the BMS shut down? Low cell or battery voltage? Do you have access to BMS data an cell voltages?

BB says keep charging and discharging – it will improve as more cycles are completed.

yea, sounds wrong but if cell level balancing, it “could” help a little.

Anyone out there who can advise me on this?

I would do as BB suggests. If it does not improve to where it meets the specs (or your satisfaction), I would check into their support and return policy.

 

[JWLV]

Lifepo batteries are made up of multiple cells. On a new battery each cell might not be the same voltage as the other cells. It takes several charge/discharge cycles for them to balance out. After that you should get closer to the advertised capacity.

Several cycles means 5, 10, or maybe more. It all depends how out of balance the cells are to begin with.

 

[Bob B]

You haven't mentioned what voltage you are charging the battery to .... Did you search this forum for Big Battery before you bought from them.
What Victron device are you using .... doesn't it give you the SOC, amps in and amps out?

They are blowing smoke when they say the capacity will increase.

 

[Bigreddogs]

Thanks for the replies.

• Researched first then bought - watched many videos and read many articles and reviews and majority of information provided here on this forum.
• LiPo was just me being to lazy to type LifePo4, but that is what I meant
• 30Ah per hour for 5 hours is what I was expecting
• No way to read the BMS so I don't know what setting are but suspect low voltage shut down is around 9.6V since that is where the battery shuts down. Also no way of reading what the cells were at the start of the sessions. BB doesn't have a Bluetooth connect/or any means to connect to the BMS for the end user.
• I am continuing to charge/discharge and am not seeing any improvement at this point. I plan to continue this over the weekend and if no improvement I will be asking for a refund.
• I am charging with a Victron IP-22 set at 14.55V bulk w/13.4V absorption no float charge

Am I being unrealistic to expect 5 hours of use pulling 30Ahr out of a 170Ahr rated battery?

 

[TomC4306]

Uh, no, you aren't being unreasonable to expect to get what you paid for and what they sold you.

 

[sunshine_eggo]

Thanks for the replies.

• Researched first then bought - watched many videos and read many articles and reviews and majority of information provided here on this forum.
• LiPo was just me being to lazy to type LifePo4, but that is what I meant
• 30Ah per hour for 5 hours is what I was expecting
• No way to read the BMS so I don't know what setting are but suspect low voltage shut down is around 9.6V since that is where the battery shuts down. Also no way of reading what the cells were at the start of the sessions. BB doesn't have a Bluetooth connect/or any means to connect to the BMS for the end user.
• I am continuing to charge/discharge and am not seeing any improvement at this point. I plan to continue this over the weekend and if no improvement I will be asking for a refund.
• I am charging with a Victron IP-22 set at 14.55V bulk w/13.4V absorption no float charge

Absorption and bulk should be the same. For the purposes of testing, I would apply a 13.8V float to ensure it's getting topped off.

How is the charger attached to the battery?

 

[OffGridInTheCity]

Yes sir, 170ah @ 12v = 2040 wh 'nominal'. 80% of that is 1632wh. 30a * 12v = 360w. 1632wh / 360wh = 4.5hrs. If you use 13v instead of 12 you get closer to 5hrs.

Can you share the link to what you purchased?

I believe you can take these apart (unscrew the case), at least enough to measure the voltages on the individual cells inside. This would reveal if cells are way out of balance cell(s) causing BMS to do early min/max OR if close voltages - then the cells may not be 170ah each. Maybe look for damage - swelling of cell(s) or something like that. In any of these cases - way out of balance, <170ah, or damage - seems like BigBattery should work with you.

 

[Bigreddogs]

Absorption and bulk should be the same. For the purposes of testing, I would apply a 13.8V float to ensure it's getting topped off.

How is the charger attached to the battery?

Anderson plug comes on the battery and that is what I have on my charger, so I just unplug the battery from the RV and plug it into my Victron charger. This is what I will charge it with until my new Xantrex inverter/charger shows up.

 

[Bigreddogs]

Yes sir, 170ah @ 12v = 2040 wh 'nominal'. 80% of that is 1632wh. 30a * 12v = 360w. 1632wh / 360wh = 4.5hrs. If you use 13v instead of 12 you get closer to 5hrs.

Can you share the link to what you purchased?

I believe you can take these apart (unscrew the case), at least enough to measure the voltages on the individual cells inside. This would reveal if cells are way out of balance cell(s) causing BMS to do early min/max OR if close voltages - then the cells may not be 170ah each. Maybe look for damage - swelling of cell(s) or something like that. In any of these cases - way out of balance, <170ah, or damage - seems like BigBattery should work with you.

Yes you are correct with your math and I should (and will start) using watts instead of amps in my discussions. Big Battery is involved and working with me, I just have never heard of a battery increasing usable current by cycling, but I understand that balanced cells may make difference, not sure it will make up 60Ahrs but may make some difference. dYou can unscrew the case, however it is sealed and removal of the seal will void the warranty.

 

[BobCollins]

Thanks for the replies.

• LiPo was just me being to lazy to type LifePo4, but that is what I meant

LiPo (Lithium Polymer) a composition of a lithium cell.
LiFePO4 (Lithium Iron Phosphate) is the chemical composition of a different lithium cell.

While in no way is one term shorthand for the other, for the applications on this site most, but not all, people here are referring to LiFePO4.

 

[Browneye]

Subscribed.
I nearly bought one of those...supposedly they use new cells, but maybe these units have the 'recertified' cells as well - same as the Battery-Evo ones. The latter brand in similar size is their 180Ah they sell for $799.

A full charge may help, repeated cycling will not. At least that's how I understand it.

Waiting for more on this...

I decided to order 3.2v cells and build my own pack - 230A. Also going into an RV.

 

[Bigreddogs]

I will let you know how this all washes out. I have read many reviews on Big Battery that claim they will work out the issues with the customer. I am hoping that is the case as I don't want to have this drag out to long. If we can fix the issue I'm all for it. It's funny, I haven't had any issues with my Lifeline AGMs other than age. Decided to go this route because of friends who have had such good luck with lifepo4 replacements. So I was hoping the same.

 

[Browneye]

I feel for you. I even got a formal quote from BB, and spoke with Fred at BE on the phone.

I nearly scrapped the project a couple of times and bought AGM's. Less headaches.
Lifeline batteries cost as much as lifepo4's, don't they? Other than Battleborns?

 

[Bigreddogs]

Yes they are expensive but they do last - got 11 years on the first group and 8 years on this set that I'm replacing. Just that they are soooo heavy!

 

[Bluedog225]

Also subscribed. Hope you have a good experience.

 

[Browneye]

Yep. Golf cart batteries for us...the current set are dated 2014, so we've done pretty well. One cell is showing a lower SG, so I tried equalizing the pair with my NOCO charger. It did finalize okay, and they hold a charge, but I think their days are numbered. I think they're about 70lbs each. The new 230A lifepo pack is about the size of one battery, and weighs about 40lbs.

Seems like you're not even getting close to it's rated capacity. You're getting 90 amp-hours out of it before bms shut down?
A lot of times I see in testing they'll run a high-amp load to a certain voltage level and then switch to a lower amperage to sqeeze the last juice out of them. Seems like you're not even getting there.

I would be asking them to replace it. Sooner rather than later. My bet is there's a bad cell in there. Were you able to get a read on each cell voltage at full charge?

 

[OffGridInTheCity]

I understand that balanced cells may make difference, not sure it will make up 60Ahrs but may make some difference. dYou can unscrew the case,

There are likely 4 cells in series in the battery. If cell 1 = 3.2v and the other 3 are at 3.4v, you'll still have a nominal 12v battery, but as it discharges the one that is 3.2v will hit bottom way too soon and the BMS will cut-off as soon as the 1 cell out of 4 hits bottom. This can dramatically shorten the useable power.

For 1 cell to be so 'out of whack' with the other 3 is not good - could mean that it's self discharging (losing voltage over time) more than the others (which is bad) but if it's kind of slower then charging may activate balance and bring it up with the others over time. That's where the suggestion of charge/discharge a few times comes in to play,

But it's not good in my opinion.

 

[Browneye]

^^That is what I think the problem is as well. You got one cell that's bunk.

 

[Philfr]

I will let you know how this all washes out. I have read many reviews on Big Battery that claim they will work out the issues with the customer. I am hoping that is the case as I don't want to have this drag out to long. If we can fix the issue I'm all for it. It's funny, I haven't had any issues with my Lifeline AGMs other than age. Decided to go this route because of friends who have had such good luck with lifepo4 replacements. So I was hoping the same.

Btw
How did you get a 2/0 cable on the BB. Their internal Anderson connector is a SB175 (I thought) and max size cable for that is 2AWG. 2/0 would require a SB350.