diy solar

diy solar

RV lithium, no solar yet, how to manage charge settings

Have you actually implemented this?
I have it. I have set it up and bench tested the function. Works as designed.
Not installed yet as I am waiting for my cells to be delivered.

I really like the idea of charge, shut off, and restart charging by the set voltages.

Only issue might be if you want to charge some by generator and the voltage is not low enough. Would need to bypass.
 
@time2roll why does the diagram show live and neutral going through the relay.
Wouldn't it be more orthodox to just switch the live wire and leave neutral alone just like a normal mains switch?
 
I agree the diagram is poorly drawn. It is just a single pole, single throw mechanical relay. The relay should interrupt the hot instead of the neutral. That is my plan.
 
I agree the diagram is poorly drawn. It is just a single pole, single throw mechanical relay. The relay should interrupt the hot instead of the neutral. That is my plan.
It's kinda crazy .... they show switching the neutral on a 220VAC circuit .... wonder if they actually do it that way over there .... or are they trying to kill a few of us off...LOL
 
Consider an $8 charge controller with your existing converter. Upgrade to inverter/charger or solar at your leisure.

https://www.ebay.com/itm/122112737703?
Well heck, that seems something like this is all I need to accomplish what I've been looking for. I thought charge controllers could only be used with solar systems. That's where I think I went wrong and down this rabbit hole. Hindsight...

Thanks much. I'll research further.
 
I have it. I have set it up and bench tested the function. Works as designed.
Not installed yet as I am waiting for my cells to be delivered.

I really like the idea of charge, shut off, and restart charging by the set voltages.

Only issue might be if you want to charge some by generator and the voltage is not low enough. Would need to bypass.
Might be a dumb question...for use with the converter/charger, couldn't I just set the restart charging threshold high so that it basically ensures it will kick on anytime shore power is introduced (whether via pedestal or generator) and the state of charge is less than the shut off setting? But this would at least allow setting the shut off to 85%. Basically the converter charger seems to run a charge whenever the battery is less than 100% now. Anything wrong with that thinking?
 
Well heck, that seems something like this is all I need to accomplish what I've been looking for. I thought charge controllers could only be used with solar systems. That's where I think I went wrong and down this rabbit hole. Hindsight...

Thanks much. I'll research further.
Interesting thought to use this to control solar charging. There are similar rated to switch DC power. Of course no MPPT function. Not sure I would want to trust this item due to the possibility of over voltage. The BMS would still provide a backstop. Could work considering LFP needs virtually no absorption time.

My thought on controlling the converter is that converter voltage is typically safe but maybe higher than needed and the float seems too high on most. Others have a boost every day to full voltage. I suspect LFP really prefers to cycle instead of float anyway.
 
I built my own LiFEP04 battery and ordered the Battery Management System (BMS) from https://overkillsolar.com. That BMS allows me to set the upper and lower charge limits from an app on my phone (I think it cost me $6 to upgrade the app to have this ability). Like you, I replaced my charger with one that is compatible with Lithium. I know nothing about the BMS that SOK uses but it might be worth checking into to see if it allows you to change the settings. Also, I disconnected the charging wire from my 7-pin connector to avoid any damage to my truck's alternator while towing.

I'll be installing a 2300 watt inverter but decided not to install an automatic transfer switch nor a converter/charger. Instead, I'll plug the trailer directly into the inverter, resulting in all of my appliances and outlets being hot. With this setup, I'll have to remember to turn off my charger at the breaker box so that I'm not using the battery to charge the battery (a loop that would rapidly drain the battery).

We camp 8 - 10 times a year so this is just simpler for us. If I was full timing or camping every weekend, I'd probably go the route of an automatic transfer switch with a Victron inverter/charger. Eventually, I'll buy a solar suitcase and do some boondocking. But, for now, the 280AH battery will be more than adequate for our 3-day weekends without needing to recharge.
 
I am planning on installing heating pads around my LiFePO4batteries with a themostat to turn on at say 40 degrees and off at 45 ish. Lots of videos out there and the compenents will prolly be less than $40
 
I'm a bit late to this party, But I have a Samlex EVO in our motorhome with two 100Ahr LFP batteries. I just switch to LFP last month, so still learning.

We won't be going out again for about a month, but the motorhome fridge (all-electric) is the shop beer fridge and I like to go take a siesta now an again in it. So I leave it plugged in, but didn't want the battery at full charge while sitting. The EVO won't output 12V if there is no battery connected, so a battery cut-out switch won't work for me.

I was able to lower the Absorption voltage to 13.5V (lowest setting) and the float @ 13.5V as well. That's still higher than the 60% or so suggested storage voltage, but its not full charge either. I pulled the fuse from the solar controller.
 
The built in Smart BMS (replaceable) should prevent over charging and over drawing current from the battery pack. Does SOK have an app for monitoring and adjusting the BMS. My DALY BMS has a cell phone APP that does those things.
 
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