I'll have 2 separate 16s batteries with their own chargery connected to a common bus. I wanted to be able to power the entire system (up to 12 kW of draw) on a single battery if I needed to because either battery could become useless for so many reasons (including one of the chargery components failing). Since I live full-time in the RV and have no home, I want to build in some level of redundancy into it.
My Xuba 280s are here! Yay!, 28 killowatts. Now to figure out BMS...
- Thread starter Alkaline
- Start date
I'll have 2 separate 16s batteries with their own chargery connected to a common bus. I wanted to be able to power the entire system (up to 12 kW of draw) on a single battery if I needed to because either battery could become useless for so many reasons (including one of the chargery components failing). Since I live full-time in the RV and have no home, I want to build in some level of redundancy into it.
Haha nice! And I must be blind, I can't find it lol. And I've been working off of version 3 of that doc this whole time. D'oh!
PerfectInsanity
Off-Grid Bus Conversion
Completely understand, as we're in the same situation (once the RV build is soon finished). We're hopefully capping our draw at 9-10kW counting worst-case in-rush currents happening at the same time, so similar situation.
The redundancy factor is what's leading me towards trying to find a middle ground on the cost of the BMSes, as I look at budgeting for it more in line with an insurance policy. The batteries cost X amount. The BMS costs X to protect them. How much is too much? If I went with the Rec, I'd probably have to make them one bank essentially due to cost. That's what's pushing me towards the Tiny, 123Smart, or Chargery, though I need to better tally up overall component costs now seeing the new Chargery options.
FWIW I bought the chargery's direct from Jason at a cost of 170 for each BMS and 80 for each DCC plus. 80 shipping (it arrived in 6 calendar days!) ... total was just under $600 for everything (2 sets of BMS/DCC's), delivered... which is about 20% of the cost of the batteries (and bus bars). Still need to add in wiring, fuses, lugs, etc... My mindset is "this is cheap!" because I was starting with battleborn, moved to SoK ($620 for 12v 100Ah) and then moved to build-my-own. Technically I should include other stuff like the battery tester, power supply, and tools I had to buy for this but ...
I'm thinking about the same number of cells for my setup. What is everyone doing for a battery box? I'm going to be installing this with a grid tie setup so I'd like a NMEA enclosure in case the inspector is picky. Suggestions?
Alkaline
Solar Wizard
Well I still have not figured out what BMS to go with checked all the cells and they are good. On a side note I did not get any bus bars. Anyone know if there are ready made eve 280 compatible buss bars on the market?
This 200A JBD BMS works very well
diysolarforum.com
8s 280Ah scale comparison, I haven't received enough cells to try 16s yet.
Amy always ships busbars and screws in small anti-static bags. Check the photos on Alibaba from Amy, they should be in the photo.
I ordered upgraded 3cm, rectangular wider double busbars for just a few extra dollars.
200A Smart BMS from LLT Power
Hi! Anyone used this BMS from LLT Power: https://www.lithiumbatterypcb.com/product/7s-to-20s-200a-smart-bluetooth-bms/ Model No: JBD-AP20S002 Looks like a good bargain, what your views?
diysolarforum.com
8s 280Ah scale comparison, I haven't received enough cells to try 16s yet.
Amy always ships busbars and screws in small anti-static bags. Check the photos on Alibaba from Amy, they should be in the photo.
I ordered upgraded 3cm, rectangular wider double busbars for just a few extra dollars.
jasonhc73
Cat herder, and dog toy tosser.
Since using the LV5048, use the setting on the LV5048 for the top and bottom. I recommend 53.8V as the top and 50.4 as the bottom (or as close as you can set to those). https://docs.google.com/spreadsheets/d/1SyzKUZ5_KxLB6megSLTXYv_1LlbcFqE4gxMgK8SrMvs/edit?usp=sharing
As for a BMS, ask yourself this, does your setup need a low temp cutoff?
If not, then use a high amp cell balancer like this:
2S-24S BMS APP 2A Balancer Li-ion Lipo Lifepo4 LTO Battery Active Equalizer USA | eBay
Find many great new & used options and get the best deals for 2S-24S BMS APP 2A Balancer Li-ion Lipo Lifepo4 LTO Battery Active Equalizer USA at the best online prices at eBay! Free shipping for many products!
www.ebay.com
I have blasted through 4 different BMS's and none of them offered what I really needed, which is balancing.
Respectfully, I don't feel this is good advice for most people or situations. The primary role of a BMS is cell level management and protection. Cell balancing is a very close second, and low temp cutoff is an optional additional feature.
An active balancer does not take the place of a BMS regardless of whether low temperature protection is needed or not. A BMS is the only component in your system that can protect your system at the cell level. An AIO cannot do this, and neither can an active balancer.
jasonhc73
Cat herder, and dog toy tosser.
I have gone through Chargery, Daly, and AntBMS. While they do all have many features that "might" come into play. So far the balancer of a high power active balancer has provided far more benefit than either of the three BMS's listed. Even the AntBMS rated at 320 amps, has let me down, not once or twice, but four times.
I'm all ears for what you like to use on your setup. Define "most" in your statement. In this case, the OP stated it's for a powerwall with an LV5048. That to me means in a house where freezing isn't an issue.
You can't really compare between the two functions though. First, they are not mutually exclusive, both can be employed in many cases. But more importantly one is a safety feature (and often the second line of defense). So its value is not measured by how much measurable utility it provides on an ongoing basis but on how valuable having that protection is to you. If all goes well, with a basic BMS it just sits there quietly balancing and you never actually use it beyond that, but if there is a problem, its an important layer of protection.
A seatbelt is a good example. It provides no measurable benefit to me on a daily basis, in fact its a minor inconvenience, something like the radio or the cupholder in my truck provides exponentionally more utility to me on a daily basis. But obviously most of us would agree that if we had to choose between seatbelts and a cupholder we would choose the former. Its value is not measured in utility and ideally you will never need to rely on it, but if you do its worth the cost.
In short the purpose of a BMS is not primarily to be useful to you, its to protect your system if a problem does occur (similar to a fuse in this sense)
I've suspected but have no evidence that the AntBMS is current rating is very overrated. Sounds like that was the case for you?
I will attempt to define it in the negative:
My perspective is you should use a BMS unless:
(1) you have an explicit and thought through reason to forego the protections a BMS offers
and
(2) you are experienced and knowledgeable enough to understand how to manually manage/protect your system, understand the risks and responsibilities
and
(3) you understand and are confident in your ability to consistently and actively manage your system in place of the automated protection of a BMS
or
(4) for whatever reason you do not mind the risk of damaging or ruining one or more cells (its a learning project, you are rich, experimenting, etc).
1 + 2 + 3
or
1 + 4
should be true
Apart from the ANT BMS I'm curious what your negative experiences with the Daly and Chargery were?
Last edited:
^ To be clear, the above is only my opinion. I think its pretty prudent and a pretty widely accepted perspective, but I don't want to overstate it.
charlesrg
New Member
- Joined
- Nov 3, 2020
- Messages
- 74
Did you consider an Electrodacus BMS ?
The BMS has good features and can help you with protection.
From my research to protect from over discharge you can use both Inverter for AC loads and a battery protect for DC loads.
For over discharge you can use the MPPT solar to stop the charge.
Now if a cell is way off having a latching relay to kill all loads or all charging is great as that might never happen and there will be no energy loss with the relay.
However such relays cost about $100 per each.
I have not read much on Chargery relays but so far I was looking to use Tyco BDS referred here.
The BMS has good features and can help you with protection.
From my research to protect from over discharge you can use both Inverter for AC loads and a battery protect for DC loads.
For over discharge you can use the MPPT solar to stop the charge.
Now if a cell is way off having a latching relay to kill all loads or all charging is great as that might never happen and there will be no energy loss with the relay.
However such relays cost about $100 per each.
I have not read much on Chargery relays but so far I was looking to use Tyco BDS referred here.
Alkaline
Solar Wizard
Thanks everyone I just ordered the overkill solar 16s BMS they just put up.
jasonhc73
Cat herder, and dog toy tosser.
Chargery is fine, but I have found active balancing to be about 1000 times more useful.
After about 600 cycles on the active balancer, mind you it is only able to work at 1 amp even, not two amps that it is capable. All 8 of my BYD's are under 10 mV all the time, untill I bring the packs under 48V or over 53.6V. That's where the delta really accelerates. Next week with the new 280ah cells arriving, we'll see how active balancing or if even needed.
New cells in a matched IR pack, just like any retailer will maintain their "balance" simply because they all have matching IR.
When I first started figuring out some of the goods of the BMS (AntBMS) it was apparent that it was showing me which cells were "crapola" and why they were removed from where ever they were removed from. The AntBMS only has passive balancing, ie all it does is discharge the highest voltage cell if out of balance.
If you maintain your LiFePO4's in the 90% SOC to 10% SOC, the chance to have cells go "rogue" is practically nill. I have regularly brought the BYD packs down to 47V, with the active balancer the largest V delta is only .180mV. While on the AntBMS the Daly, and the Chargery if I brought the BYD down to 47V, the delta V would be usually in the .760 mV range, once it was 1.1 V. This is where one cell in the entire pack, the dud, was about to hit the 2.5V, I'm a done deal dead cell no man's land.
With active balancing I have brought the BYD's down to 42V several times, just to find out, and they pushed the balancer to its limits and it kept going just fine. After today's cycle the packs are all in the < 0.005 mV delta range, one is just sitting pretty at 0.002 across 16 cells.
Never forget that this is DIY land. If you want to play safe and just get something that works plug and play, by all means, get the off-the-shelf stuff and use em. In the end, the only thing a BMS does is turn off if something is wrong.
Similar threads
