crowTrobot
New Member
Probably not the normal route. But I would like to at least look at it.
Probably not the normal route. But I would like to at least look at it.
How does this differ from a BMS?I do have a balancing charger that ensures all the cells are charged to the same level.
How does this differ from a BMSI do have a balancing charger that ensures all the cells are charged to the same level.
I can be done despite many doomsayers.
Our 4 cell 300Ah Sinopoly LiFePO4 motorhome/engine starting battery has survived 10 years of fulltime travel without any inbuilt BMS circuitry.
I can be done despite many doomsayers.
Our 4 cell 300Ah Sinopoly LiFePO4 motorhome/engine starting battery has survived 10 years of fulltime travel without any inbuilt BMS circuitry.
My "BMS":
No charging source exceeds 14.1V at the battery terminals at which point the battery pack is always 100% SOC without any absorption time regardless of my usual charging currents according to both the series installed Victron and Junctek shunt based battery monitors.
75A alternator, 50A solar and rarely used 30A mains powered battery charger.
20% SOC loud alarm and Victron BatteryProtect 12.5V disconnect. Never triggered in day to day use.
Unlike apparently hundreds of fellow forum users cell balancing has never proved necessary for the last 10 years. Sure I occasionally check but again despite being informed multiple times that cell capacities will drift excessively they have not, well at least for my battery or the 280Ah EVE battery that I paralleled about 18 months ago.
I have observed up to a c40mV deviation on the odd occasion but as a test a few years ago forcing all cells to within 1mv required a few seconds at 30A. Certainly no useful energy added to any cell.
I'm almost convinced that sometimes perfect cell balance is perhaps just a psychological satisfaction thing?
Forcing the battery to 14.5V about a year ago. Near enough for me.
I must check again soon.
Click to enlarge.
Balancing chargers I have seen charge each cell individually to the correct voltage (3.50?)How does this differ from a BMS
Balancing chargers I have seen charge each cell individually to the correct voltage (3.50?)
They would provide no other protection.
The balancing chargers I have seen are for small battery hobbyist to fly a model plane or run a model car etc.
Some fancier balance chargers will stop charging momentarily to measure the cell voltages. This takes wire resistance out of the equation.
Keep your eye on Battery Hookup. They often have things like this.Probably not the normal route. But I would like to at least look at it.
No obsession here. Some others seem obsessed in their cell voltages being identical.It's been well established that YOU are far more obsessive than the average human BMS.![]()
No obsession here. Some others seem obsessed in their cell voltages being identical.
Our Victron system settings have remained unaltered for the last five or so years.
It all ticks over on its own without adjustment or intervention.
Sure I keep an eye on things and hopefully not too many others have blind faith in their often the cheapest BMS available operating perfectly for the next 15 years without checking occasionally.
I have no such faith for our perhaps unique and frequent 700A plus peak starter motor current draw requirements.
14.1V maximum, 10 minutes absorption and 13.45V while the sun still shines "float" is very easy and works for our now 10 year old fulltime RV use battery.
The "human BMS" is all but idle these days.![]()
Thank you for confirming my previous post unless you consider careful occasional battery monitoring is some form of obsession.Uh huh.
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Are lithium ion batteries better than lead acid?
I found mine are pretty quiet. But maybe that's my old ears? ?? In my case can't hear over the ringing in my ears.diysolarforum.com
That's what we're saying. Most people would start off saying they're going to do exactly what you do (play BMS onPerhaps I incorrectly assumed most others would do likewise?
Thank you for confirming my previous post unless you consider careful occasional battery monitoring is some form of obsession.
Perhaps I incorrectly assumed most others would do likewise?
If not I gladly plead guilty to all obsession charges.
If I built a battery with no BMS, I'd build it with cells that have a high discharge / charge rate. For my Lithium Iron Phosphate batteries, I have topbrand that can charge discharge at 2C or 3C. The higher C discharge the better.
There could be a good reason to not have a BMS, like on a wheel chair crossing the street and the power dying as acceleration is needed to get out of the way of a car and not trip the BMS that stops the chair dead in its tracks. The risk your taking is the battery pack catches on fire as soon as the wheel chair is out of the way.
Personally, think building a lithium battery without a BMS is a terrible, terrible idea that gets worst as the battery gets older. If you know what you're doing its probably a terrible idea. Might not be so terrible if you can accept the loss of the equipment and all the other damages, that point only a bad idea.