Replace Lead Acid with LiFePO4 Li Time

[pdaddy]

Currently have a 200w roof mounted panel and 200W renogy solar suitcase panel. My controller is the GoPower GP-PWM-30-UL (BLUETOOTH®-ENABLED - LITHIUM COMPATIBLE). 1000w inverter (which I plan to upgrade to 2000w at some point. Currently have 2 100ah Lead Acid severe duty batteries.

Question is, I just want to get rid of the lead acid batteries and get one Li-Time 12v 230ah LiFePO4 battery with low temp protection (since I live in CO and like to camp in early spring and late fall). Anyone have this battery? Any concerns on just doing a swap? Am I missing any considerations? Eventually, I want to add 2 more 200w roof panels for 600w total on the roof and also add a second Li Time 12 230ah battery. Thanks in advance.

 

[Crowz]

Make sure you pick the LFP setting and that's about all you can do. I would make sure you heat the lifepo4 batteries even with low temp cut off. They don't like being frozen.

But the key thing to me would be upgrading to a mppt charger vs the pwm one you have. That upgrade will really help you to get the most out of your panels.

 

[pdaddy]

Make sure you pick the LFP setting and that's about all you can do. I would make sure you heat the lifepo4 batteries even with low temp cut off. They don't like being frozen.

But the key thing to me would be upgrading to a mppt charger vs the pwm one you have. That upgrade will really help you to get the most out of your panels.

Thanks. I guess I can get a couple of the heating pads for the battery box. Any suggestions on the MPPT controller? I haven't really looked around yet.

 

[Crowz]

The ones I use are kind of expensive so lets wait and see if someone chimes in with other options too.

This is what I use which works with 12v and 24 volt setups and is pretty bullet proof in all weather temperature wise. Mine spent most of their lives in a truck tool box I had laying in the backyard and worked fine.

https://www.amazon.com/gp/product/B00YCI48F4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Its $179 but there may be good options for less than that. You need to also purchase the display panel and cable or you can use a network cable and hook it to a laptop to program it.

Again not the cheapest but I have 2 of them and have run them for many years flawlessly.

 

[Tomthumb62]

The ones I use are kind of expensive so lets wait and see if someone chimes in with other options too.

This is what I use which works with 12v and 24 volt setups and is pretty bullet proof in all weather temperature wise. Mine spent most of their lives in a truck tool box I had laying in the backyard and worked fine.

https://www.amazon.com/gp/product/B00YCI48F4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Its $179 but there may be good options for less than that. You need to also purchase the display panel and cable or you can use a network cable and hook it to a laptop to program it.

Again not the cheapest but I have 2 of them and have run them for many years flawlessly.

For only a few dollars more, $214 will buy you a Victron 30A MPPT. No screen or cable needed extra to buy, just use the free VictronConnect app to see status and programming. I just bought one from InvertersRus for less than that. I just called and they gave me a good deal when I asked if they had any coupons available.

Yes it’s 30A vs 40A, but with my 600W of panels, I never reach more than about 24A on a 12v system. Flat roof mounted panels has a lot to do with that on our camper.

I replaced a Renogy 30A controller with the Victron one. Night and day difference. I had considered the Epevers but I’ve heard they often have a hard time finding the MPPT point and keeping it and thus waste a lot of watts.

Victron SmartSolar Bluetooth MPPT Solar Charge Controllers

Victron SmartSolar Bluetooth MPPT Solar Charge Controllers are the gold standard for battery charging. LiFePO4 lithium batteries too!

invertersrus.com

 

[Rednecktek]

The HQST controllers have always served me well turning Solar DC into Battery DC and they support bluetooth if you can't see the screen easily. And they're only $120 for a 40a.

I've learned to steer clear of EPEvers over the last couple years.

 

[pdaddy]

Thanks everyone. I had heard really positive things about the Victron and I'm excited to switch to an MMPT.

I'm also still trying to wrap my head around wiring series vs parallel on the roof top panels when I add two more. Do I want series wiring with 36 volts at 16.67 amps or do I want parallel wiring with 12 volts and up to 50 amps (in which case I'd need to get a 50 amp controller?) And again, the long term plan is to have two LiFePO4 200a batteries for 400 total. Plan to do a lot of dry camping for up to 5-7 days.

 

[Rednecktek]

Remember that the amp rating of a controller is the OUTPUT rating. I.E. a 20a controller will only put out 20a to the batteries regardless of how much solar panel you've got attached to it.

The big benefit of using MPPT is that you can run higher voltage panels into it and it'll auto-magically transform that into battery voltage. Both have pro's and con's though.

All Series -
Pro's: Highest working voltage requiring smaller cable
Con's: can easily over volt a controller. When a controller SAYS 100v MaxPVInput, it MEANS 80v! 101v is Right Out! One panel gets shaded and the entire string is nerfed.

All Parallel -
Pro's: If one panel is shaded the rest are still working fine
Con's: LOTS of wires and really thick ones at that by the time you get down to the SCC. The SCC may not be able to use all the amperage available to it. Fuses required for 3+ panels on each string.

Combination - 2s2p Example
Pro's - Gains the higher voltage to work better under lower light conditions, with only 2 strings no need for fuses on each one, if 1 panel is shaded the other pair/string is still working fine. Multiple panels can be used in each string as long as all the strings are about the same specs.
Con's: All the panels need to be pretty close to the same specs for Vmp and Isc or the entire string will be nerfed to the lowest common denominator.

A napkin math example of options to help understanding:

Let's say you bought 10 of the ElCheapo Generik 100w solar panels. The specs are 22Voc, 20Vmp and 5a Isc. Let's also say you bought the RenoEverST 60a SCC with a 150v PV Input limit.

If you tried to put all 10 panels in series you'd have a VoC of 220v and 5a which puts the voltage WAY outside the acceptable range, smoke, fire, angry wife happens.

On the other end if you put all 10 in parallel you'd have a VoC of 22v and 50a. You decide to cheap out and not use a combiner box for all of those and just use 10AWG wire for everything because you got a Great Deal on a spool of it. Well, that wire is only rated for 30a so when you get blazing pure skies your wires catch on fire, smoke, and angry wife happens.

OK you tell yourself, you're going to get the HonkinHuge wire and a 10 port combiner box with fuses, so there! OK, you've just spend many hundreds of dollars on equipment but assuming the HonkinHuge wire even FITS into the terminals on the SCC, it may not be able to utilize anywhere near that many amps so it just throttles the whole system. No fire, no smoke, but it's really dark and cold now and the angry wife has arrived.

So, what's a guy to do with these 10 panels? Well, how about stringing 5 of them together in series which gets you 110v and 5a which is well within the "Happy Range" of the SCC. Now, do it again and put a Y-splitter on both sets and bring that 110v (in series you add the voltages together) @ 10a (because in parallel the amps add together) and now you're getting 1100 watts out of your panels. You don't need fuses because as far as the system goes, what you have is 2x 500w panels in parallel. No smoke, no fires, the AirCon and coffee maker both still work in the morning and the wife is happy.

More importantly, the CAT is happy, and that's the IMPORTANT bit. ?

A few things to remember:

Amperage rating is the amps the controller can put out.

PV Input voltage is a HARD number. Like granite hard, or teenager stubborn hard. Good practice is to keep your voltages at 80%-ish because panels generate a bit more voltage when they get really cold.

12v panels, 24v panels, that's all just Marketing Speak. What it means when you see "12v Panel" is "I generate enough voltage to charge a 12v nominal system, but not enough to charge a 24v system." Likewise, a "24v Panel" can generate enough voltage on its own to charge a 24v or 12v system, but not enough to charge a 48v system. It's all just "Marketing-ese".

Solar panels don't PUSH power into a system, the batteries feed a load and ASK the SCC for power to replace it. The SCC then goes and ASKS the panels for power which it then GIVES to the batteries as much as it can. Don't worry that your 1.21Jiggawatts of panels are going to fry your battery, the battery will only take what it needs and leaves the rest to do nothing. Kinda like having extra guys on the job site, the more you have the more can be accomplished at once, but at a certain point people are just standing around doing nothing.

Does that all help?

 

[pdaddy]

Yes. Good info especially on the pro's/con's of parallel vs series. Shade is a constant issue because we tend to camp under heavy forest canopy in Colorado...maybe need to re-think that strategy (which was born out of lots of tent camping and looking for shade). Also why I got the 200w solar suitcase with 50 ft extension cable. With your information, I like the idea of 2s2p and I could put a total of 4 200w panels on the roof.
And based on what you shared, my SCC can remain at 30 amp because it doesn't matter how much amp/volts are coming into it, it will regulate what goes out. So on a 30 amp scc, I could have 50-60 amps coming in but only 30 will go out.
If I do decide to upgrade to a 50 amp SCC, then I'd need to rewire from the SCC to the battery because right now it's only 10 gauge.

 

[Rednecktek]

With 4x 200w panels you have a potential of 800w out of it, so if you decide to upgrade your controller I'd recommend at LEAST a 60a if not an 80a controller for a 12v system, otherwise you're leaving potential power on the table.

Yes, you can continue to use a 30a controller but 2x panels is maxing that out so 2 more panels would just be a waste of money without the SCC to go with it. If you do upgrade the SCC, keep the old one in the loop and use it exclusively for that briefcase. Your batteries won't care how many chargers are connected to it and they'll just ignore each other and plug right along.

You've got over 2700Wh of batteries going in there, an average day is about 4 hours of really usable sun, so you'd need 690w or 60a of charging for all 4 hours to refill that battery from empty.

 

[Tomthumb62]

With 4x 200w panels you have a potential of 800w out of it, so if you decide to upgrade your controller I'd recommend at LEAST a 60a if not an 80a controller for a 12v system, otherwise you're leaving potential power on the table.

We have 600W 12v on a 30A controller. Except for about 3-4 weeks in June and July, we never get that much production. Average max is 22A. In large part due to flat roof mounted panels. Only 200W of our panels are portable suitcase angled to the sun. So it would be a waste of money to buy anything more than a 40A charger in our use case (camp trailer) but yes we’re “throwing away” wattage in high summer but have no more battery to charge or loads to run. We’re good. In fact I’m just about to replace a Renogy 30A controller with a Victron 30A. I expect production to improve slightly due to better MPPT tracking but main reason is the Renogy keeps overcharging our lifepo4.

 

[pdaddy]

With 4x 200w panels you have a potential of 800w out of it, so if you decide to upgrade your controller I'd recommend at LEAST a 60a if not an 80a controller for a 12v system, otherwise you're leaving potential power on the table.

Yes, you can continue to use a 30a controller but 2x panels is maxing that out so 2 more panels would just be a waste of money without the SCC to go with it. If you do upgrade the SCC, keep the old one in the loop and use it exclusively for that briefcase. Your batteries won't care how many chargers are connected to it and they'll just ignore each other and plug right along.

You've got over 2700Wh of batteries going in there, an average day is about 4 hours of really usable sun, so you'd need 690w or 60a of charging for all 4 hours to refill that battery from empty.

I calculated I only use about 70 to 100 amp hours per day. So maybe not even worth adding a second 200ah battery?

 

[Tomthumb62]

I calculated I only use about 70 to 100 amp hours per day. So maybe not even worth adding a second 200ah battery?

You’ll be glad for that extra battery once you hit a couple of days of clouds or rain. It goes quick when you have no charging source.

 

[pdaddy]

With 4x 200w panels you have a potential of 800w out of it, so if you decide to upgrade your controller I'd recommend at LEAST a 60a if not an 80a controller for a 12v system, otherwise you're leaving potential power on the table.

Yes, you can continue to use a 30a controller but 2x panels is maxing that out so 2 more panels would just be a waste of money without the SCC to go with it. If you do upgrade the SCC, keep the old one in the loop and use it exclusively for that briefcase. Your batteries won't care how many chargers are connected to it and they'll just ignore each other and plug right along.

You've got over 2700Wh of batteries going in there, an average day is about 4 hours of really usable sun, so you'd need 690w or 60a of charging for all 4 hours to refill that battery from empty.

Good point. As far as keeping the old SCC and looping it in for the briefcase...the briefcase has it's own SCC already. And I have a "Solar on the Side" port from GoPower wired for 30 amps that makes a direct connection to the battery (it's nice because I don't have to remove the battery cover and use cable clips to the batteries themselves) from the briefcase.

 

[Richard Reid]

Yes. Good info especially on the pro's/con's of parallel vs series. Shade is a constant issue because we tend to camp under heavy forest canopy in Colorado...maybe need to re-think that strategy (which was born out of lots of tent camping and looking for shade). Also why I got the 200w solar suitcase with 50 ft extension cable. With your information, I like the idea of 2s2p and I could put a total of 4 200w panels on the roof.
And based on what you shared, my SCC can remain at 30 amp because it doesn't matter how much amp/volts are coming into it, it will regulate what goes out. So on a 30 amp scc, I could have 50-60 amps coming in but only 30 will go out.
If I do decide to upgrade to a 50 amp SCC, then I'd need to rewire from the SCC to the battery because right now it's only 10 gauge.

 

[Richard Reid]

I think you may have misread something about the voltage. The voltage is a hard number. Overvoltage cannot be regulated between the solar "in" and the battery "out". It's a good way to see the "magic smoke". You can go over in amps. Amps are pulled, volts are pushed. Your house wiring is 120v. It passes through everything and is constant. Your volts are being pushed by whatever your power supply is. Amp get pulled. Each appliance require and "ask' for a specific amperage. It's the reason that the same 120v that powers your electric water heater can also power that little led light without blowing it up.



I'm a newbie with electricity and even newbier with solar but that's how someone explained it to me.



I was told that the only time overvolting your CC is when you wanted to switch out your ipever to get a Victron and your wife wouldn't let you. Lol



Good luck