To buy Valence XP model or not?

[KateLee]

Hi there, I'm debating purchasing used Valence U27-12XP 12 volt 138Ah batteries for battery storage for my off grid home (three strings of 4 at 48v). I'm new to this stuff but also need to be frugal in my purchases. I will need a lot of back up storage given that I live in the desert and air conditioning needs to run all night. I have found 12 of these batteries used for around $400 each which seems to be a good solution for starting up. The equivalent in battleborn would be triple the price. I know you get a lot for the extra cost including that the batteries are new, but is seems like if I could get these to work I would be able to have the storage I actually need rather than going with a 3rd of what I need which is what I would have to do. The equipment I have so far is 24 - 320w Sunpower solar panels, 2 midnight solar charge controllers and 2 SMA Sunny Island 6048 interters.

In the video notes reviewing the 40ah Valence medical batteries Will says "DO NOT PURCHASE THE BATTERY WITH MISSING BMS CABLES!! Or the XP models." I understand that these batteries have and internal balancing system but require the external BMS programed by valence for your particular battery bank configuration. Where my knowledge is lacking is why the proprietary BMS would definitely be necessary. Would it be dangerous or would batteries just not charge properly and there would be a loss in efficiency? Would a non proprietary BMS suffice with the option of hooking up to the Valence software to check the functioning of the batteries as a group?

Any input, thoughts or ideas would be greatly appreciated! Just want to be able to build a good solid system with enough battery storage!

 

[Danny]

Thanks for your post. There is a recent post on Lithium Batteries on Boats FB Group. Where issues are discussed you may want to look at BEFORE you buy theses. I have included a link. I personally would build my own 12v bank or buy a drop in before I ventured into this area. https://www.facebook.com/groups/427372107686109/ .

 

[KateLee]

Thanks for your post. There is a recent post on Lithium Batteries on Boats FB Group. Where issues are discussed you may want to look at BEFORE you buy theses. I have included a link. I personally would build my own 12v bank or buy a drop in before I ventured into this area. https://www.facebook.com/groups/427372107686109/ .

Thank you! I’ve asked to join the group and will take a look. After reading the owner manual on the xp systems I was feeling pretty reluctant and have new been leaning toward the drop in ones. Im still open to building my own though.

 

[morth]

I have a couple on the way to do some testing with, will update here as I figure things out. For a simple system, they may work just fine as they are, but the whole proprietary BMS thing is a real road block for adoption in the second hand market for those who want a bigger system. After going around the house for a week with Kill o watt meters, recording how many KWH would be needed to run various things, I feel like the captain of the boat in Jaws but instead of needing a bigger boat, I need a bigger battery bank....

 

[KateLee]

@morth Sorry to not get back to you sooner. I do need a lot of storage so I had to abandon ship on the Valence batteries because too many other forums confirmed my suspicions that it would be a lot of trouble. Also the user manual I found online confirmed that indeed the external BMS is specific and necessary. If they would just sell it to the general public our problem would be solved. But after talking to them on the phone it seemed like that would not be willing to help out the general public.