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12V battery only charging to 13.4

Depending on your environment, and it feels like yours is semi-outdoors, corrosion can occur on and between current-carrying conductors. Something like https://www.amazon.com/NO-OX-ID-Special-Electrical-Contact-Corrosion/dp/B00HDF9EXE can help both improve conductivity and prevent corrosion. On the other hand, any silicone grease will protect from corrosion and be squeezed right out of the interface if you bolt (or crimp) copper to copper. But see 'terminal torque' above.
Thank you for the link! I will get it ordered. It is semi outdoors
 
The reason for welding cable is it is very very flexible - high number of copper strands inside of it.

THHN and most cables used for house wiring have a small number of strands and are very very stiff. This means you can apply a lot of force when bolting it down.

Well, ideally cables are restrained as close to the connection as possible and have a fuse within 7 inches - this comes from the ABYC (american boat and yacht) standard - good to live by when there is vibration possible. Stationary still good for strain relief - you don't want a super heavy cable hanging from a fragile connector. Another reason to put both bolts into each connector. So in your case I would probably put a clamp around the wire so it is attached to the roof of the cavity and flows down. This way the clamp holds up the weight of the cable verse the battery terminal.

NOTE - car jumper cables and car battery jumper cables are not used in power systems. Many times they are CCA... copper coated aluminum.... and they are rated at 100amps - but only for 10 seconds. Certain to create hot spots and potential fires if used continuously. If you are unsure if yours are that - take a spare piece of cable and pull a single strand out - if the end looks silver while the strands look copper it is probably CCA....if you can't tell hold a lighter under it and if it whisps and disappears right away it is CCA... if it heats, gets red hot... then gradually curls back it is copper...


NOTE - edit above - added the words that are underlined
 
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take a spare piece of cable and pull a single strand out - if the end looks silver it is CCA
have you never seen tinned copper? this is a bad statement, the only way to tell is to burn it or scrape it. you guys are really getting out in left field here.

1200ah and they can't make it through the night, and you guys think its a top balance issue? she hasn't provided a single screenshot of anything to make any real clear answers, having her rip apart a battery bank right now is a total waste of time, insulators in a non moving environment is a non issue.

you may be shocked to know that almost every service entrance wire in the USA is made of aluminum and is just fine.
 
I wasn't suggesting that was the issue with charging -

To me the lack of balancing is the root problem with not fully charging. The other likely suspect is the charger

No bottom balance means no checking that each cell will actually take a charge and cycle fully.
They probably will, but there is always a chance that a cell is seriously short and bringing down its parallel mates.

Not top balancing - I would expect this to shave the top by 20% until it happens naturally from just cycling.

A loose/dirty/oxidized connection from not having all of the bolts installed or torqued proper count cause once or more cells to not take a full charge and bring down a grouping of cells. Slow to charge and others hit full first and stop charging. Then when you discharge it hits bottom first and you get an undervolt disconnect.

It was clear from the answers and the pictures she posted that she had made some questionable choices all through the build. So my novel and the wire type comments were to cover all of the bases on the battery build. The comments also covered some things that just plain appear to be risks I wouldn't take sleeping on top of the batteries.

All of the items are easy to correct but a number of them are issues that could go from everything normal and happy to flames in a matter of minutes


and I edited the earlier comment to add a few words - sometimes the fingers are faster than the brain - they are underlined and indicated as an edit for later folks that come by
 
i agree with what you said, but when she makes comments like things were shorting with the lead acid batteries before this, people need to step back and find the actual problem. you can tune and tweak the system when its operational, but no power 4 days speaks to a much larger issue
 
I was reading the logs in my BMS app and I saw one over voltage error. Couple days ago.
If you could identify which 4P set is causing the over volt that would be good to note. If there is another 4P pack that is lower than the rest, that might be your strongest (most capacity) set. Perhaps swapping 2 cells from the weaker and stronger sets would balance the capacities.
Obviously it would be best to capacity test each cell (i've done this and it takes weeks) but you can balance the sets with enough observations and good notes.

Can you post screenshots of your BMS settings? That sounds like a good place to check, i haven't seen info or questions on that front.

Similarly, when the charging appears to stop, you should check the BMS to see if there are any charge amps coming in. A huge battery like you have will spend a LOT of time in the flat part of the voltage curve and without checking the current it may look like nothing is happening.
 
@MedicineMom



Do you have a DMM (digital multimeter) , or better yet - a clamp meter that reads DC voltage? They can be as cheap as $30 and get what you need to do...

Do you know how to use it to read ohms, AC and DC volts and current?

note - if you don't own one, this should your next purchase. If you don't know how to use it then some youtube time is in your future.

With the DMM we can help troubleshoot the issue down to the bad component.

You can't trust the BMS when trying to figure out issues and you will need to take readings at various places around the setup.
 
i agree with what you said, but when she makes comments like things were shorting with the lead acid batteries before this, people need to step back and find the actual problem. you can tune and tweak the system when its operational, but no power 4 days speaks to a much larger issue
Except that "batteries running down because of a short somewhere" isn't really a thing, is it? Too big a load, or something that's on unexpectedly, but a 'short' is either going to trip a breaker, blow a fuse, or start a fire, not run my battery down faster than I expect.
 
Except that "batteries running down because of a short somewhere" isn't really a thing, is it? Too big a load, or something that's on unexpectedly, but a 'short' is either going to trip a breaker, blow a fuse, or start a fire, not run my battery down faster than I expect.
I said find the problem, I didn't say I agreed its a battery issue, she has no idea what the issue is, and clearly we don't yet either.
 
Do you have a DMM (digital multimeter) , or better yet - a clamp meter that reads DC voltage?
You misspelled AMPS. She needs a clamp-on DC ammeter.

I've had good luck with https://www.amazon.com/gp/product/B08CX6VHWV ($70 with coupon), though it's not as accurate or fancy as my Fluke 87-IV with separate Hall effect Fluke clamp-on ammeter, it costs an order of magnitude less.
 
You misspelled AMPS. She needs a clamp-on DC ammeter.

I've had good luck with https://www.amazon.com/gp/product/B08CX6VHWV ($70 with coupon), though it's not as accurate or fancy as my Fluke 87-IV with separate Hall effect Fluke clamp-on ammeter, it costs an order of magnitude less.
I have one just like that. It's kind of old and has provided weird readings, so we bought a second one, but they didn't have any with the clamp.
 
I said find the problem, I didn't say I agreed its a battery issue, she has no idea what the issue is, and clearly we don't yet either.
Yeah not a clue. I did gain some knowledge on re-doing it properly. Maybe that is playing a part in the problem. It has been a consus here the batteries are not being properly charged. So that is one problem to solve. I suspect there is an issue with the converter, or a short somewhere. Possibly both. It states it charges with 60amps at 14.64V. I have not found either of those things to be true.
 
@MedicineMom



Do you have a DMM (digital multimeter) , or better yet - a clamp meter that reads DC voltage? They can be as cheap as $30 and get what you need to do...

Do you know how to use it to read ohms, AC and DC volts and current?

note - if you don't own one, this should your next purchase. If you don't know how to use it then some youtube time is in your future.

With the DMM we can help troubleshoot the issue down to the bad component.

You can't trust the BMS when trying to figure out issues and you will need to take readings at various places around the setup.
I have two. One without a clamp meter. But it seems like the clamp isn't working properly on the other one. I can probably order one. Where would I start testing? We've done quite a few. In two days we are going to take of the main negative, turn breakers off, turn them on one by one and run each circuit and see what we come up with.we already did this test minus running each circuit. The biggest draw we got was 0.04.
 
The reason for welding cable is it is very very flexible - high number of copper strands inside of it.

THHN and most cables used for house wiring have a small number of strands and are very very stiff. This means you can apply a lot of force when bolting it down.

Well, ideally cables are restrained as close to the connection as possible and have a fuse within 7 inches - this comes from the ABYC (american boat and yacht) standard - good to live by when there is vibration possible. Stationary still good for strain relief - you don't want a super heavy cable hanging from a fragile connector. Another reason to put both bolts into each connector. So in your case I would probably put a clamp around the wire so it is attached to the roof of the cavity and flows down. This way the clamp holds up the weight of the cable verse the battery terminal.

NOTE - car jumper cables and car battery jumper cables are not used in power systems. Many times they are CCA... copper coated aluminum.... and they are rated at 100amps - but only for 10 seconds. Certain to create hot spots and potential fires if used continuously. If you are unsure if yours are that - take a spare piece of cable and pull a single strand out - if the end looks silver while the strands look copper it is probably CCA....if you can't tell hold a lighter under it and if it whisps and disappears right away it is CCA... if it heats, gets red hot... then gradually curls back it is copper...


NOTE - edit above - added the words that are underlined
They are THHN cables. Good idea with the hanging support. They are copper, but we have extras we can run this test with. How else can I top balance without another power source?
 
Except that "batteries running down because of a short somewhere" isn't really a thing, is it? Too big a load, or something that's on unexpectedly, but a 'short' is either going to trip a breaker, blow a fuse, or start a fire, not run my battery down faster than I expect.
I am thinking like a bent or ancient cable could cause power loss. Which in time could be an issue. My BMS is saying a short is somewhere, but I can't see it anywhere. No fuse has burnt out and luckily no fires yet.

But it does seem silly that little power loss would be putting us in the position we are in.
 
If you could identify which 4P set is causing the over volt that would be good to note. If there is another 4P pack that is lower than the rest, that might be your strongest (most capacity) set. Perhaps swapping 2 cells from the weaker and stronger sets would balance the capacities.
Obviously it would be best to capacity test each cell (i've done this and it takes weeks) but you can balance the sets with enough observations and good notes.

Can you post screenshots of your BMS settings? That sounds like a good place to check, i haven't seen info or questions on that front.

Similarly, when the charging appears to stop, you should check the BMS to see if there are any charge amps coming in. A huge battery like you have will spend a LOT of time in the flat part of the voltage curve and without checking the current it may look like nothing is happening.
I will pay more attention over the next day, but it appears as though cell 1 and 4 have the most issues. I'll post some photos of the BMS.

Will once talked about some cheap device to test capacity. One I found has terrible reviews. It appears as though the charging never stops. I have never seen it below 20 with the generator on. Today we had sun, but it was still losing 9-14amps. Three phones, a notebook, and one light bulb was the most I had going, the furnace was off.
 
Some of these settings I have not messed with.
 

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your comment about breakers concerns me, DC side of the world at least in that era was fuses. breakers are for the AC side of the world. can you take a photo of the fuse/breaker panel, and a screenshot from the bms. and photo of the charger wiring to the batteries.. please provide a photo of the actual model number of the charger as well

Hope I didn't mis speak! I am posting a photo of the breaker panel in the RV, and I just posted BMS screenshots. I'll have to wait for daylight to get the converter photo.
 
Where are you measuring the current? If the converter is on and supplying loads, and you are measuring converter current it may never go to zero.

If (only) the battery is drawing current and still hasn't hit 100% SOC, then keep charging.

We measured at the converter output terminals like the guy at intellipower said to do. There is 2 negative and 2 positive, so I measured them both. 14.03 and 13.99.
 
As long as it's still taking current, it is not full.
When it is full at a particular charge voltage, 14 volts, current will decline to zero.
When the current declines to zero at a particular charge voltage then they are full.
That makes sense! So in that case it would be the converter?? It claims to charge with 60 amps at 14.64 but I haven't got those readings.
 
Yes, sorry for the acronyms, sometimes I spell them out and sometimes I assume...

Not sure who would have recommended that, I'd go with 3.6 or 3.65, at least till they get balanced.

Yes, when any one cell hits COVP (or CUVP on discharge) the BMS will at least disable charging, if not take the entire battery offline, until it's 'woken up' by the appropriate procedure, which varies depending on BMS and protection engaged.

I can almost read the part number of the JK(?) BMS, but if you could tell us exactly what one you have, maybe someone with the relevant experience could help with settings. Is it active or passive balancing? I don't think there's a passive balancer anywhere that'll balance 1216AH 'cells', and the usual 2A active balancers will take a week to fix a 25% imbalance...

4P on 304AH cells is going to take a lot of charging and a lot of balancing until you know it's right. I'd have built four individual 304AH batteries, at the very least for ease of access and maintenance. That thing's gotta weigh 300 pounds, and the cells aren't even restrained. In fact, it doesn't even look like there are separators between the cells?

Please tell me this isn't a mobile setup...

Please post pictures of the intererconnect wiring and (especially) the fuses.
I will change my charge settings. The BMS is a JK B2A8S20P. It is not mobile. I can try to get some photos of the wiring between the cells(right?) and the fuses. My BMS is a 1 amp I didn't notice until we put it in. It appears as though there is a charging issue.
 
Change battery capacity to 1200

change start balance to 3.4

cell ovp to 3.63
soc 100 to 3.62
ovpr to 3.6
Max Balance Current to 2A

what size wire is run from the converter to the batteries, and what is the distance.

are you turning your inverter on and off multiple times a day?

take a picture of the first bms screen where it shows amperage. with the converter off, and your normal loads you use running. then turn off all the loads and take a photo of that

you need to try to get some heat in this bay, incandescent light bulbs or some furnace heat, you are on the bleeding edge of it shutting off.
 
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cell ovp to 3.63
soc 100 to 3.62
ovpr to 3.6
These are very aggressive for trying to troubleshoot.

If it was my battery, I would set charge voltage to 13.9 volts and verify that you can fill the battery with that charge voltage first.

I think you were being too impatient with your charging, OP.
50% starting SOC leaves 600 ah more to put in.
If you are only getting 20 or 30 amps out of your converter that means 20 or 30 hours worth of charging. With no loads.

Cell to cell imbalance will only expose itself above 3.45 volts per cell.
 

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