Wiring Diagram: Is this safe?

[ShockingResults]

I have a power station, two 51.2V LFP batteries, a DC charger, and an AC charger. This setup will be loaded into a vehicle and the DC charger connected to the vehicle's alternator. I want to...

• use the DC charger to charge the power station directly.
• use the DC charger to charge the batteries directly.
• use the LFP batteries to recharge the power station -- as needed.
• be able to charge/discharge the batteries individually or (if balanced) in parallel.
• be able to isolate, disconnect, and 'individually' remove the power station and each LFP battery (for AC charging outside of the vehicle) on occasion.
• be able to reposition components inside the vehicle and reconnect (with extension cables) on occasion.
• buy cheap cables instead of making them, if possible.

Attached is a wiring diagram. Is this safe? Is this effective?


--- Edit ---
All wires are 10 AWG, except for the pair of 12 AWG 'ring terminal to MC4' output cabels that came with the DC charger.

Each LFP battery will be charged at a fixed 58.4V and <10A max, with potentially <20A max total if running parallel. The power station accepts up to 60V but a maximum 15A and 500W through each of its two XT60i ports.

Here are links for reference...

• "1-2-Off" switch: https://www.amazon.com/dp/B07TZ191YL
• MC4 Fuse: https://www.amazon.com/dp/B0D38G8XDH
• LFP Batteries: https://www.amazon.com/dp/B0DC6R9XY7
• DC Charger: ETAKER F1000 Pro
• Power Station: EcoFlow Delta 2 Max

 

[time2roll]

Not sure MC4 is the best connector for power cables. Do you need to pull all this apart frequently? Wire size and expected amps are not shown.

https://www.customcableusa.com/products/custom-battery-cable-marine-grade-by-the-foot

 

[chrisski]

Recommend Anderson power pole strong enough for your amperage. When things branch off, use a bus bar, not a y cable.

More importantly, need some sort of dc converter to limit the charge from the alternator.

The actual parts used and wiring size will determine safety. Don’t know what a one two off switch is, but if it’s the blue sea switch, this is not rated to be switched on off under load.

 

[ShockingResults]

Not sure MC4 is the best connector for power cables. Do you need to pull all this apart frequently? Wire size and expected amps are not shown.

https://www.customcableusa.com/products/custom-battery-cable-marine-grade-by-the-foot

Yes, I want to be able to isolate and 'individually' relocate the power station and/or batteries for AC charging (outside of the vehicle) on occasion. Also, this setup would allow each component some 'modularity' to be repositioned inside the vehicle, with plug-and-play extension, as needed.

All wires are 10 AWG, except for the 12 AWG positive and negative ring to MC4 cables that came with the alternator charger.

Planning to charge each battery at 58.4V 10A max, potentially 20A total in parallel. The power station accepts 500W max and up to 60V through one of its xt60i ports.

Each LFP battery is only 25Ah. So, I believe the 30A fuse (with its 33kA AIC) coming off each battery will still work to stop a 'worst-case scenario' short circuit.

I updated my first post to include several of these points.

 

[ShockingResults]

Recommend Anderson power pole strong enough for your amperage. When things branch off, use a bus bar, not a y cable.

More importantly, need some sort of dc converter to limit the charge from the alternator.

The actual parts used and wiring size will determine safety. Don’t know what a one two off switch is, but if it’s the blue sea switch, this is not rated to be switched on off under load.

Thank you for these tips, I'll look into it. What would be the advantage of a bus bar in this scenario?

I updated the first post to include links to the "alternator charger", "1-2-Off" switch, and other items referenced in the diagram.

 

[chrisski]

The switch may be good for on/off, but not disconnecting under load. If this is brass, I’d skip it.

For the busbars, they handle more amperage. MC4 are 30 amps or less and are for DC connections for solar panels to charge controller.

30 amps is only 360 watts of charging and will take forever to recharge a battery.

 

[time2roll]

Lots of Power Poles, Anderson connectors, and related distribution can be found here:

https://powerwerx.com/

At this level of 20 amps or less these should be easy crimps to make your own cables. Duplex wire should keep the wires less tangled.

With a fuse off each battery the setup seems fine to me. I use the Power Poles / Anderson connectors and highly recommend them over MC4.

 

[ShockingResults]

The switch may be good for on/off, but not disconnecting under load. If this is brass, I’d skip it.

For the busbars, they handle more amperage. MC4 are 30 amps or less and are for DC connections for solar panels to charge controller.

30 amps is only 360 watts of charging and will take forever to recharge a battery.

The power station and alternator charger can each be 'turned off' at the device to remove load. The 1-2-Both-Off switch is meant to allow me to change circuits to battery 1, battery 2, both in parallel, or batteries off. When the switch is "off" there is still a complete circuit from the alternator charger to the power station; there is no physical disconnect switch for this circuit. Load would be shut off at each device before using the switch to make any circuit changes.

If everything is connected, but input to the power station is shut off at the device, would it be safe to use the alternator charger to charge the LFP batteries? Or, would it be best to also physically unplug the (xt60i) connections from the power station before charging the batteries? Same questions for charging the power station from the LFP batteries: can I just leave the alternator charger 'connected' but 'turned off' at the device?

The expected maximum load is 58.4V @ 20A (1168W). On that note, perhaps I can also parallel/split each of the two XT60i inputs at the power station to get (500W x 2 = 1000W) charging by using both inputs simultaneously?

 

[chrisski]

If everything is connected, but input to the power station is shut off at the device, would it be safe to use the alternator charger to charge the LFP batteries?

No. You still need to put a dc to dc converter in line with charging a lithium battery.

 

[time2roll]

No. You still need to put a dc to dc converter in line with charging a lithium battery.

Did you click on the link in the OP? The "alternator charger" is a DC charger

 

[chrisski]

Did you click on the link in the OP? The "alternator charger" is a DC charger

No did not click on the link.

I went with his block diagram.

If that 1000 watt charger is hooked to the battery, I would want to wire it with wire and connectors that is capable of handling 1000 watts which is thicker than 10 gauge, even if he planned to go only to 20 amps.

Also, seems like the charger is 500 watts max for battery and 500 watts for solar for 1000 watts total.

 

[ShockingResults]

No did not click on the link.

I went with his block diagram.

If that 1000 watt charger is hooked to the battery, I would want to wire it with wire and connectors that is capable of handling 1000 watts which is thicker than 10 gauge, even if he planned to go only to 20 amps.

Also, seems like the charger is 500 watts max for battery and 500 watts for solar for 1000 watts total.

I will recreate the wiring diagram this weekend -- with some updates and clarifications.

The DC "alternator charger" has a maximum output of 12-60V and 40A / 1000W. However, without connecting the charger to solar, it will be limited to 500W max input from the vehicle's alternator. The device came with 12 AWG 'ring terminal to MC4' output cables; all other cables are 10 AWG. So, I will just have to be careful never to set the charger to lower voltage and >20A.

The system should be capable of 20A at any voltage, which is a maximum of 1168W at 58.4V. However, the power station and charger are each limited to 1000W max in any case.

I had not considered the power station potentially drawing >20A from the LFP batteries to maintain its 1000W max input as the battery's voltage drops. Planning to limit loads to 20A max, but would want this setup to be foolproof as possible. The battery’s BMS cuts off at 36.8V, which means a theoretical maximum load of (1000W / 36.8V =) 27.18A going from the batteries to the power station. However, the entire battery to power station circuit has 10 AWG cables and rated for at least 30A... So, I think I'm safe on this point as well?