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diy solar

Can’t get my espresso maker to work! ?

Wondering if you're willing to share any data. I've got a SAMLEX 2000 watt Pure Sine Wave hooked up with 4/0. I got this to run 1200 watts for three to five minutes, microwave popcorn. I have not done that, but I had the inverter running for a few minutes at 1100 watts output and I measured the temps, and the wires never warmed up, and neither did the inverter. I was pretty happy with that. With the solar panels running, the voltage never dropped, but at night time, voltage draw went from 12.6 to 12.0.
I'd attribute that to your batteries, not voltage loss in the cables. Called Voltage sag. How big (capacity) is your battery bank? I have a decent 560Ah LiFePO4 battery bank. It will run an AC unit for quite a few hours.

Doug
 
How big (capacity) is your battery bank? I have a decent 560Ah LiFePO4 battery bank. It will run an AC unit for quite a few hours.
458 ah, 12 volt flooded lead acid. Depends on the use we get from the RV is if I upgrade to lithium’s. The FLAs are challenged by big loads. No AC for me.
 
I see that as a battery voltage sag issue. Perhaps you can adjust your Low voltage cut off - say 11.8V? Does the voltage bounce back up when your heavy load is gone?

Do also note that lead acid chemistry capacity is labeled in a misleading way. They really only should be cycled down to 50% or less to maximize life cycles. Below, to full rating, will severely impact (reduce) the # of cycles. And the rating is for low loads (usually around .05C to .1C)

So my present 560Ah LFP batteries are nearly twice the useable energy capacity of my old 660Ah AGMs. (usable is 330Ah).
Before I went to a lithium-only house battery, I actually had a hybrid, 280Ah LFP (4 cells) and 660Ah of AGMs in parallel. It worked very well. Mostly, I wanted to drop the weight of the AGMs and free up the storage space. You might consider this architecture. A bit of a compromise, but it won't require you to throw away good batteries.

Some will warn you not to mix the chemistries. But after digging around and some reading, and thinking on it.... I went for it. It worked very well. 80% of the LFP voltage operating range is where the AGMs just float >12.8V. I set my charging scheme for the LFPs and not AGM, but that's OK.
The LFPs do almost all of the work since they have very low internal resistance and then accept almost all of the charge to get back to full. Which is what you want.

Doug
 
As soon as the heavy load is gone, the voltage bounces back.

Unfortunately, the low voltage cutoff is not adjustable. I have really liked the Bluetooth monitoring and the ability to adjust with the battery charger and both solar charge controllers. I do wish that the inverter had that capability. The only setting for the low voltage cutoff is 10.5. I was amazed at the difference in amps between 13 volts and 10.5 volts. Ohms law says its out 20% difference. IMO, if the monitor dips below 12 VDC, that's the point that I want the batteries to stop providing the energy.

I've got time to look at hybrids before the upgrade, and I've seen a couple of theoretical ways to do it, but if I did, I'd be the first on my block to try this, and I'm just not that brave spending my own money. It is tempting to find a way to get 200 more amp hours, whether 12 volt or 24 volt (two to four Battlebornes) and keep my old batteries. Its an expensive mistake if I get it wrong.
 
HMMM. OK. I do think Voltage sag is normal, more pronounced with lead acids. I built my 560Ah bank for about <$2000 with new 280Ah EVE LFP cells (search a thread called Xuba 280Ah cells). Thats cells, BMS, heavy duty contactor relay, etc. $400 or maybe $450 of that was shipping the cells from China. Not efficient, but it is what it is. That'd be $4k to $5k or more for the same capacity from Battleborn. Great product, but there are other ways. A few photos of my new battery bank.

You might look in other areas of the forum for ideas.

I'd never seen another hybrid setup. But mine worked great. Just tie in at the load distribution point.

I also will sell you my 3 x 4D Lifeline batteries for $600. They are only 4 years old and resting voltage after a few weeks is still 12.8V. They've been carefully used and always charged to 100% before storage. I use my camper about 30 days / year.
I found a shipper who could deliver them for $150. I'm confident they'd last another 4 to 6 years. New, they are $1800 to $1900 + tax.

Sorry, all, to derail the thread!
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Doug
 
As soon as the heavy load is gone, the voltage bounces back.

Unfortunately, the low voltage cutoff is not adjustable. I have really liked the Bluetooth monitoring and the ability to adjust with the battery charger and both solar charge controllers. I do wish that the inverter had that capability. The only setting for the low voltage cutoff is 10.5. I was amazed at the difference in amps between 13 volts and 10.5 volts. Ohms law says its out 20% difference. IMO, if the monitor dips below 12 VDC, that's the point that I want the batteries to stop providing the energy.

I've got time to look at hybrids before the upgrade, and I've seen a couple of theoretical ways to do it, but if I did, I'd be the first on my block to try this, and I'm just not that brave spending my own money. It is tempting to find a way to get 200 more amp hours, whether 12 volt or 24 volt (two to four Battlebornes) and keep my old batteries. Its an expensive mistake if I get it wrong.
Measure the voltage on the battery as well as at the inverter when the heavy load is on. If you see > 12V at the battery and really low voltage at the inverter, then the problem is in your wiring (or lack thereof).

A 12V low voltage cutoff voltage is fine for Lithium batteries (10% State of Charge), but is too high for lead acid batteries (a 10V to 10.5V threshold is good for them). Doesn't your inverter have a way to set the battery chemistry?
 
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458 ah, 12 volt flooded lead acid. Depends on the use we get from the RV is if I upgrade to lithium’s. The FLAs are challenged by big loads. No AC for me.
How old are they. One of the things FLAs are good at is handling surge loading. Perhaps your batteries are just worn out. This does happen eventually to every battery pack (including lithium).

F.Y.I. 450 AH of deep discharge lead acid batteries is equivalent in usable capacity to 225 AH Lithium batteriess. Unlike Lithium you really don't want to discharge lead acid below 50% capacity. If you are using starter batteries then understand they are inappropriate for this application and you might have killed them.
 
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How old are they
They were delivered in July, four months ago, and kept on a float charger.

I would say my voltage sag for the load was a couple of tenths of a volt less than a You Tube video I watched for a similarly sized AGM battery bank, so at this point I think a .6 volt sag on a 12 volt 458 Ah FLA battery bank at 80% charge with a C20 rate of 23 amps per hour for 20 hours when I was pulling close to 50 amps with the Puekert Effect considered, is about what is expected.
 
This is it. The manufacturer of the van never envisioned passing 100+ amps through that portion of the chassis. It never even entered my mind you were using the vehicle chassis for the return current path. This is so not a good idea.

Add a separate 1/0 ground wire from the battery negative to the inverter negative and see what happens.
Thank you all. I will try adding adding the negative/ground wire from the first bank Tom the second. It will be the 10’ length. From the second bank the inverter is right next to it and then the inverter is grounded to van body.
 
I built my 560Ah bank for about <$2000 with new 280Ah EVE LFP cells (search a thread called Xuba 280Ah cells).
The cells look like they are mounted edge wise when you put them in their final position.. According to EVE that's a no no. It's ok to lay them on their flat side and stack them. I didn't know if you were aware of this or not. From what I know it has to do with the electrolyte covering the pouches. I don't know how much difference it would make to leave them like you have them.
 
They were delivered in July, four months ago, and kept on a float charger.

I would say my voltage sag for the load was a couple of tenths of a volt less than a You Tube video I watched for a similarly sized AGM battery bank, so at this point I think a .6 volt sag on a 12 volt 458 Ah FLA battery bank at 80% charge with a C20 rate of 23 amps per hour for 20 hours when I was pulling close to 50 amps with the Puekert Effect considered, is about what is expected.
What was the voltage on the battery during this test? If it is much different than the voltage at the load then you have a wiring problem. Do some detective work.
 
The cells look like they are mounted edge wise when you put them in their final position.. According to EVE that's a no no. It's ok to lay them on their flat side and stack them. I didn't know if you were aware of this or not. From what I know it has to do with the electrolyte covering the pouches. I don't know how much difference it would make to leave them like you have them.
Thanks for pointing this out! I asked the question prior too and the answer was they could vary in orientation. But I'm going to reconfirm.

Doug
 
Thanks for pointing this out! I asked the question prior too and the answer was they could vary in orientation. But I'm going to reconfirm.

Doug
Someone asked and received an answer directly from EVE.

 
Try connecting only to the new batteries, you could have a bad cell on the old batteries.... and yes the frame is not made out of copper so it is a poor conductor....
 
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