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Getting close and a little nervous! Starting to connect things any insight appreciated.

Jwtravel

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Jul 5, 2021
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So, I am working on a 24v system in my van. Here are some photos and then a run down of what I have done and a few questions.A18FA4AD-804D-4DC9-AE62-6D999958E495.jpegI have a Tracer 24v 40a SCC, a Giandel 24v 2000w inverter, 24v to 12v converter, a 12v fuse block. I have installed a 100amp main fuse. Going to the SCC I have installed a 50a breaker. From the main fuse to the converter I have installed a 25a fuse.B2A475EA-A815-4D87-ABED-FF9705763BF4.jpegI have built a 24v lifepo battery. There are 8 cells wired in series with a Daly BMS. 200ah. My panel array consist of 2 200 watt 24v Rich solar panels. Planning to wire them in parallel unless I get talked out of that. That are rated at a little over 37v.11B34E70-DC79-4E91-B65E-13085026C096.jpegSo, I think the numbers jive but I am a total novice on this DC stuff.
Question 1: Do I need a bolt on fuse at the batteries or is that covered with the main fuse?
#2. Should I have an additional fuse before the inverter in addition to the 100a main?
#3 Does anyone have a link about setting the parameters based on my lithium batteries?

I have searched the web and referred to Will Prowse book, but frankly I’m overwhelmed and now pretty nervous about starting to hook things up. Which brings up question #4, can anyone offer a very basic sequence to start connecting things.
Any insights and criticism appreciated.
 

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Question 1: Do I need a bolt on fuse at the batteries or is that covered with the main fuse?
#2. Should I have an additional fuse before the inverter in addition to the 100a main?
#3 Does anyone have a link about setting the parameters based on my lithium batteries?
#1) I don't see the main fuse. I have my battery protect fuse the first thing after the positive terminal on the battery, and that is followed by a master off switch and this is all located prior to the first busbar. If your "main fuse" is first, and is placed as close to the battery as practical, you have meant the intent.

#2) If your inverter wiring is rated to handle 100 amps, than I would say no. There's a document in the resources section that says you need to fuse every branch so it is fused for the wire. I'm pretty sure your buck converter for the 24 volt to 12 volt side the wire is not rated for 100 amps. Prior to my DC fuse box, I have a 50 amp maxi fuse and holder I installed on a similar line.

#3) parameters of lithium batteries: You're ahead of me there. I'm a couple months from finishing my 12 volt to 24 volt conversion and am using lead acid batteries until then. May help if you mention the type of BMS. Looks like a DEl Green.
 
1. Where is the "main fuse" and what do you mean by "main fuse"? The only fuse I see is between the 24V->12V converter and the bus bar. There definitely needs to be a proper fuse on the positive battery lead close to the battery. Or is there a fuse hiding inside the positive bus bar?
2. A fuse between the positive bus bar and inverter is common. Fuses/breakers protect the wire from overloads. You have a fuse protecting the DC converter, why not the inverter?
4. You already seem to have most things connected. Make sure the SCC is powered by the batteries before you connect the solar panels to the SCC.

What size wires are you using everywhere? The inverter can handle 4000W surges. With a 24V battery that can be over 160A. For that you want 1AWG or even 1/0AWG from the inverter to the bus bars. If the inverter surges to 4000W while the SCC is pushing 40A and you have say 20A of loads from the DC fuse box, the battery wiring would need to handle 220A. That means the battery wiring to the bus bars needs to be 2/0AWG and then the main battery fuse would need to be 250A. This is all worse case. If you know you'll never even come close to the 2000W then you can stick with smaller wires and the 100A fuse. Then the fuse will blow if you put too much into the inverter at some point.

Regarding the panels and whether to have them 2P or 2S I would go 2S if shading won't be an issue and if the SCC can handle the volts. What is the max input voltage of that SCC? The panels have a Voc of 45.4 so in 2S that is 90.8V. If you get into colder temps then that could easily go over 100V. If your SCC only allows 100V max input voltage then you can't go 2S unless you will NEVER encounter temps near freezing. The benefit of 2S is the panels will be able to provide power to the 24V batteries under less ideal conditions, even if only a little. I have 3 panels in 3S with a 24V battery and I start getting useful current flowing into my batteries less than an hour after sunrise. Every little bit helps.
 
Thank you. This exactly what I needed. It’ll take me a minute to digest this info and I will give everyone an update. Thanks again for taking the time to answer my questions. I’m already feeling less overwhelmed and that helps tremendously!
 
1) I guess from your layout you followed a certain guide that's often copied. There is a big difference in a display setup for you tube and what's needed for a safe installation. I would recommend at least a MRBF fuse as close as practical to the battery positive before the cable connection to the rest of the system.

2) I would take the main feed from the battery ( now fused at the battery) to a positive buss bar. From the buss bar feed the inverter and DC to DC converter with fuses/breakers near or incorporated with the buss bar.

3) Parameters. For the charger or for the BMS? A search or a look in the resources section may find what you need. This really needs a new request for advice from you. A post asking for BMS settings followed by a post for charger settings would be the simple option.

There are a number of practical issues with your layout.

The Aili shunt gets quite hot and will not be helped by heat from the inverter.
A similar issue with the thermal breaker in the convection heat flow from the charger.
As suggested ensure the cable sizes are adequate for the current flow and are protected my suitable fuses or breakers.

With the panels, parallel should be OK as the max power volts are quite high, however you may find that series connection gives slightly more power late and early in the day or in very poor solar conditions.

I like the design of the battery box, giving a snug fit to the cells. This is the method I use and suggest the methods using threaded rod compression are excessive.

Don't worry too much about the system, I suggest you limit the high charge voltage to 27.6 or 28 volts.

Mike
 
So, I rearranged some things. I also added a MRBH fuse (that thing is cool).
Everything is up and running.
Thanks for the help folks.
 
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