diy solar

diy solar

Valence U27-12XP 12 volt 138Ah

I’m new to all this, but for those of you that are familiar with the U27-12XP, can I run these in parallel with my Victron Solar MPPT and not bother with an external BMS, or do I need to purchase some sort of battery Managment system for their use?
 
I was getting a little concerned that cells were getting a little out of balance. One module showed 33 mV difference. When I checked this AM all 16 cells were within 3 mV of each other. I don't know what is acceptable. Is 33 mV a lot or not much. Anyway balancing seems to be working well.
 
Logdigital said:
I’m new to all this, but for those of you that are familiar with the U27-12XP, can I run these in parallel with my Victron Solar MPPT and not bother with an external BMS, or do I need to purchase some sort of battery Managment system for their use?
Click to expand...

I've only been using them for about a month now. Everything seems to be working just fine. Don't have the solar hooked up yet. So far I'm only using Victron Multiplus and bus alternator for charging. I see no reason for the MPPT to have different results.
 
somewhereinusa said:
I was getting a little concerned that cells were getting a little out of balance. One module showed 33 mV difference. When I checked this AM all 16 cells were within 3 mV of each other. I don't know what is acceptable. Is 33 mV a lot or not much. Anyway balancing seems to be working well.
Click to expand...
My software shows the spread limit to be 10mV.
 

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I just added two more batteries for a total of 6 in parallel. I now have 828 Ah with a projected usable of 662. The last two had less than 10 cycles each. It took a couple of days for everything to even out and show basically the same module, cell voltages and state of charge as the first 4.
I haven't discharged them very far as I'm again at the location with really crappy 15A service, however with the hybrid inverter I'm able to pretty much use what I want.
I have noticed that when bulk charging the cell spread often goes over the 10 mV set on the Valence software, this doesn't seem to trigger the cell balancing, I'm not sure what does trigger it. When discharging and the charger is at the end of the absorption cycle all cells are in the 2 to 5 mV spread range. Don't know if this is normal, can anyone with other LiFePo4 cells and the ability to log it confirm?
 
I noticed mine were in balance mode this afternoon, two out of four cells on each battery were over 3400mv (IIRC) and were highlighted blue whilst on bulk charge.
 
somewhereinusa said:
I just added two more batteries for a total of 6 in parallel. I now have 828 Ah with a projected usable of 662. The last two had less than 10 cycles each. It took a couple of days for everything to even out and show basically the same module, cell voltages and state of charge as the first 4.
I haven't discharged them very far as I'm again at the location with really crappy 15A service, however with the hybrid inverter I'm able to pretty much use what I want.
I have noticed that when bulk charging the cell spread often goes over the 10 mV set on the Valence software, this doesn't seem to trigger the cell balancing, I'm not sure what does trigger it. When discharging and the charger is at the end of the absorption cycle all cells are in the 2 to 5 mV spread range. Don't know if this is normal, can anyone with other LiFePo4 cells and the ability to log it confirm?
Click to expand...
In watching mine charge/discharge, the balance function doesn't go active till the cell spread is over 50mV even though the max cell spread is set at 10. I'll have to go back through some logs to see more details. There may be a time element involved where there needs to be a certain spread for a certain amount of time before balancing gets turned on.
 
I read where these batteries are "drop" in but also reading that external software is used to install/balance/maintain them.
I'm considering buying 2 of the 138AH ones to replace the 2 exisiting FLA's.
Am I correct in asuming that I can simply unbolt the fla's without having to balance, test ,etcs and connect up the Valences(parallel) To me "drop-in" means it is like changing the battery in your car(i.e. unbolt the old one and bolt in the new one).
 
I have several these (U27-12XPs) in my RV and they have been working perfectly for several months now. I read that these are not a good idea to get due to not having a BMS and to stay away from them. I thought they did have a BMS inside. Are they not protected at all with their internal electronics? Over/Under volting, temperature etc? If not, what are you guys doing that are running these?

Hopefully I didn't waste a bunch of money trying to get a good deal..

John
 
I have 4 of these 135 ah batteries. Will be following this thread, and inquiring about getting the necessary parts, wiring, and software for external monitoring. All 4 of mine only had around 40 cycles, so I'm hoping these will last a long time.
 
Happy Holidays every one! Special cudos to Will who put this forum up for us. I thought I was being smart and saving about $700-$800 on each 12V battery by buying the Valence u27-12xp-12-volt-138ah aftermarket. I though that they had internal BMS, BUT the only functioning part of the stock BMS board from Lithiumwerks/Valence is the Balancing function. Cliffman is correct in that there is no other protection. I don't know if the guys using the OEM Valence software are able to rename/renumber the cell pack so that limits and ranges can be changed. I spoke to Matt at Lithiumwerks Tech Support who educated me, after buying 6 of these beauties, that Lithiumwerks/Valence does not offer BMS Programming for these specific batteries in the RV Battery Aftermarket Arena. Matt also highly suggest that these packs be protected with an external BMS for all the "gotta have protection." I've taken two of these cases apart and have not figured out a way that the case can be disassembled without destroying it.
I have a BMS Board, recommended by Will, coming from China and plan to build or assemble my own case while I'm waiting for the BMS to get here. I guarantee my case won't be as pretty. It's too bad, because they are the best looking and probably the best built Cases out there. Matt also relayed that the Valence U1-12RT 12.8v 40Ah Lithium Iron Magnesium Phosphate Batteries DO have a working BMS.
Note: After seeing the internal wiring, there is no way to access the internal cells using the communication cables. Again, Too bad. If we pull together, we can do this. Any recommendations or solutions?
 
My Go Power IC-3000 has the all the protection that I need. No, it's not full proof but good enough as my DC load is so minimal it's not a concern.
 
Any recommendations or solutions?
Click to expand...
I'm working on one that uses external sensors, should be acquit for what I need monitored. I have all the bits and pieces now, I think, just have to get it all wired and the code written.
 
I'm more computer illiterate than savy. Plus I have a sizeable DC demand starting with a residential fridge, +. Any chance of getting the software?
 
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