Absolutely agree... it’s the back and forth that teases out all the nitty gritty stuff.. just like being down the pub really.... except we don’t get kicked out at closing time..
Batteries keep dying.
- Thread starter Ibid49
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Ibid49
New Member
Generalizations are not wrong, so long as you understand them as generalizations. It only becomes a problem when you incorrectly take a generalization and treat it as an absolute truth. "It's warmer in the summer than in the winter" is a generalization. You just have to understand that sometimes there are days in mid March (technically still winter) that are warmer than some days in mid September (still summer). And also of course, it doesn't apply to the southern hemisphere. But there's nothing wrong with observing or voicing generalizations, so long as they are presented as such. Words like "average" suggest that it's presented as a generalization.
Batteries are not animals. They are a chemical, physical object. You cannot "work them hard" any more than filling up a glass and emptying it out again is working the glass hard. The idea of "working them too hard" stems mostly from Lead Acid batteries where you had to worry about sulfation, and using short, partial charge/discharge cycles was the best way to avoid that. That's not true of LFP batteries. As long as I'm staying within specs of recommended usage, there's no reason not to use the full capacity of my batteries. I don't run them down to zero. I don't keep them at high voltages. They spent the majority of their time in that long, flat plateau of the discharge curve. I protect them from extreme temperature. I don't exceed even half of their C rating (well, sometimes, just barely over half).
Honestly, I would love to have more battery capacity. Two years ago, when I designed this system, I doubled my capacity from my previous system, and then I found that I had use for the additional capacity. And if I doubled my capacity again, I would use that capacity. I would use it for welding or additional cooling in the summer or whatever else I wanted to use it for, because electricity is useful. If you're buying battery capacity that you're not using, you're just wasting money.
The exact quote is "average and not so average person" - that's pretty much everyone and not a 'fair generalization'. Never mind using the word 'vegans' by both you and the person I replied to to indicate all vegans are somehow "stuck in a bubble about how special they are". Generalizations about the weather are also entirely different compared to generalizations of groups of people.
Daddy Tanuki
Solar Wizard
the only generalization here was not directed at you. I have never thought of you in the way i described several people, but it is what it is, a microcosm of humanity as a whole. these days people are rude, they are conniving and they play the victim very well, or they are good at manipulating others to cover their malfeasance.
I can list several threads right here and now where many of the so called experts, and "old timers" on this forum attacked and attempted to drag down other members of the forum (not me, i might add), for no other reason then the people in question felt slighted...like little children on a playground, they gang up on others attempting to harangue the target until the target leaves or bows down to their newly invented god. If this dismays you or angers you then you need to look at the actions of the people I have described.
Daddy Tanuki
Solar Wizard
Sorry, but every non vegan you talk to says the same thing... they (vegans) cannot shut up for more than three seconds about how special they are... so its an apt observation. average refers to some who are not special on this forum and not so average alludes to the more special ones...not all of them, i never assigned a percentage, nor a number.
I have several vegan friends - even on this forum. I must have very different experiences than you. They all know I hunt and fish and have no problem with that, and never bring up the fact that they're vegan any more than I bring up the fact that I eat meat.
In the Victron, do you have bulk/absorb voltage between 28.4 and 29.2?
Please report threads/comments where you see this behavior. I can't be everywhere, but the other mods and I do take these things serious - as does Will.
Daddy Tanuki
Solar Wizard
thats nice...
Not sure if this point was tackled, but do you have a pre-charge resistor? Maybe you hit the BMS over current protection while the caps were charging in the inverter. The short you measure are the (empty) capacitors.
Daddy Tanuki
Solar Wizard
Duly noticed taking it to a PM then.
krby
Solar Enthusiast
I always forget to mention this to people. In my "mobile" battery bank suitcase, the battery switch goes through a pre-charge resistor on it's way to "fully on". On another project, I got surprised by this last weekend by a spark when reconnecting an a converter/charger to a small 12V AGM bank. Since then, I just keep a 20Ω 100W resistor next to the equipment where I can see it.
Ibid49
New Member
Someone else did mention this, but I don't understand the purpose or function. That's not me arguing, I'm professing ignorance. I wouldn't know how to implement that or how to know if it's doing what it should be doing. Can you explain what this does and how to implement it?
The input of an inverter basically is a large set of capacitors. These need to be charged - but for an initial supply of a voltage source, these show as a short circuit, and then quickly charge to the applied voltage. This means you get a large inrush current, possibly more than the battery in normal conditions has to provide (and can thus trigger the over current protection) even if it's only for a relatively short amount of time.
To get around this issue, you first charge these capacitors through a resistor to limit this inrush current, after which you switch the battery as normal. See this thread for example:
Precharge resistor
Hello, I'm buying 4 solar batteries of 51.2v 300a each in China. So each batteries will be 15kw. I told the manufacturer to add a precharge resistor to the BMS. They sent the information of the precharge resistor and they are waitingfor my confirmation. I'm not an expert is this suitable for me?
diysolarforum.com
So you find a power resistor, and place that one with a push button in parallel to your main battery switch. Before you turn on this main switch, you hold the button for x amount of seconds, charging the capacitors (with the inverter off). Then switch the main battery switch, after which you turn the inverter on.
Quattrohead
Solar Wizard
I am surprised that someone that knows so much about everything needed to come on here for help ?
Let's keep things civil.
krby
Solar Enthusiast
UPDATE: I thought Will did a video about this. Found it:
Someone else will probably explain, but I'll give it my best here:
The DC input of an inverter has a set of large capacitors. One great thing about capacitors is they can charge and discharge *REALLY* quickly. But, to the DC source (your batteries), this "really quickly" will look like a short circuit for a very short period of time. So, there will be huge current draw right when you connect them to the inverter. You probably have noticed a spark. Over long periods of time, the spark can degrade the connectors. But in your case, that huge initial surge may also trip your battery's over current protection.
A pre-charge resistor is just a resistor sized so that it won't allow that initial surge of current. I bought a few 20 Ohm 50A resistors on Amazon a while back and I use them for things like this.
You can use the pre-charge resistor a few different ways:
- Manually connect it in series with either the positive of negative when you first hook a source up to an inverter. Wait a few seconds, then set the resistor aside and connect things up without it. The input capacitors of an inverter will self-discharge, but it takes a while.
- Some folks will a battery switch to do this for them. On a 2-pos round switch you the positions are often OFF -> 1 -> 2 -> 1+2. If you wire the switch so the battery + resistor is on 1 and then 2 is just parallel set of wires connected just to the battery then as you turn the switch you go from "off", 1: "resistor + batt" (pre-charges the capacitors), 2: "batt only". Personally, turn my switch all the way to 1+2, which ends up being two parallel connections to the battery, one thru a resistor and one direct. I've done the calculations, and the resistor will see very little current when in this position so I'm not worried heat.
Someone else will probably explain, but I'll give it my best here:
The DC input of an inverter has a set of large capacitors. One great thing about capacitors is they can charge and discharge *REALLY* quickly. But, to the DC source (your batteries), this "really quickly" will look like a short circuit for a very short period of time. So, there will be huge current draw right when you connect them to the inverter. You probably have noticed a spark. Over long periods of time, the spark can degrade the connectors. But in your case, that huge initial surge may also trip your battery's over current protection.
A pre-charge resistor is just a resistor sized so that it won't allow that initial surge of current. I bought a few 20 Ohm 50A resistors on Amazon a while back and I use them for things like this.
You can use the pre-charge resistor a few different ways:
- Manually connect it in series with either the positive of negative when you first hook a source up to an inverter. Wait a few seconds, then set the resistor aside and connect things up without it. The input capacitors of an inverter will self-discharge, but it takes a while.
- Some folks will a battery switch to do this for them. On a 2-pos round switch you the positions are often OFF -> 1 -> 2 -> 1+2. If you wire the switch so the battery + resistor is on 1 and then 2 is just parallel set of wires connected just to the battery then as you turn the switch you go from "off", 1: "resistor + batt" (pre-charges the capacitors), 2: "batt only". Personally, turn my switch all the way to 1+2, which ends up being two parallel connections to the battery, one thru a resistor and one direct. I've done the calculations, and the resistor will see very little current when in this position so I'm not worried heat.
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Q-Dog
¯\_(ツ)_/¯
I have never used a resister on my MultiPlus 3000 (same unit as the OP). Plus BattleBorn says you don't need a precharge resistor on their batteries until the inverter is over 3500 watts. Common sense says since the OP has recovered and restarted from several shutdowns in the past 2 years, lack of a precharge resistor isn't the issue.
I must be doing something wrong as I've never had a battery shutdown in the 3 years I've run my MultiPlus, so I think I will have to let Battle Born and the OP figure this one out.
I must be doing something wrong as I've never had a battery shutdown in the 3 years I've run my MultiPlus, so I think I will have to let Battle Born and the OP figure this one out.
True, but the description of 'measuring a short after connecting the battery, disconnecting the battery for a while and reconnecting fixes it' (paraphrased) seems to indicate something like that happened at least once.
Ibid49
New Member
Ok, that's easy enough. Most of the time, that spark would have happened inside the housing for the battery switch, if at all, but I can see how the sudden surge could have caused some of my head-scratcher issues. Thanks.
