12v solar charger.

FrostyDog

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Dec 14, 2016
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Hi Folks, just starting on this venture and am looking for some advice/opinions. We're setting up a 32ft 5th wheel to run on solar. Everything is setup to run on 12v and don't particularly want to go changing to 24v. Can someone advise me on a reliable controller/charger for charging a 500Ah pack we want to make out of 18650's. Thanks.
 
FrostyDog said:
mike said:
Many of us are using the PCM60X. It will charge 12v, 24, and 48v systems. It gives you room for change too in case you ever do decide to step up to 24v or 48v.
http://www.mppsolar.com/v3/pcm60x/

Thanks Mike. I'll check them out. How do they handle abuse from rough conditions?

I've only had mine for a couple of months. It seems to be built pretty solid. What kind of abuse, temperature? Mine seems to operate fine well below freezing. It was 11F this morning and it was still operating fine. I haven't experience summer temps with it yet though.
 
500Ah is a large battery - how many panels are you intending to install ?

Almost everyone who does what you are doing underestimates their consumption, and dramatically underestimates what is required to keep a battery above its minimum DoD.
 
mike said:
Many of us are using the PCM60X. It will charge 12v, 24, and 48v systems. It gives you room for change too in case you ever do decide to step up to 24v or 48v.
http://www.mppsolar.com/v3/pcm60x/

Pretty sure it only does 15v on an equalization charge. for a 4s pack hes not going to get near 16.8
The Xantrek c60 is about a third of the price and does up to 17v on a 12v setup, 34v for 24v and 68v for 48v

kind regards
 
3nergE said:
mike said:
Many of us are using the PCM60X. It will charge 12v, 24, and 48v systems. It gives you room for change too in case you ever do decide to step up to 24v or 48v.
http://www.mppsolar.com/v3/pcm60x/

Pretty sure it only does 15v on an equalization charge. for a 4s pack hes not going to get near 16.8
The Xantrek c60 is about a third of the price and does up to 17v on a 12v setup, 34v for 24v and 68v for 48v

kind regards

You don't ever equalize charge a pack of 18650s. What are you trying to charge? A 48v string should be 14 packs in series, a maximum of 58.8v. Where are you getting 68v from? Same with 24v... your calculations are way off.
 
mike said:
3nergE said:
mike said:
Many of us are using the PCM60X. It will charge 12v, 24, and 48v systems. It gives you room for change too in case you ever do decide to step up to 24v or 48v.
http://www.mppsolar.com/v3/pcm60x/

Pretty sure it only does 15v on an equalization charge. for a 4s pack hes not going to get near 16.8
The Xantrek c60 is about a third of the price and does up to 17v on a 12v setup, 34v for 24v and 68v for 48v

kind regards

You don't ever equalize charge a pack of 18650s. What are you trying to charge? A 48v string should be 14 packs in series, a maximum of 58.8v. Where are you getting 68v from? Same with 24v... your calculations are way off.

Just supplying maximum voltages per the settings. The main consideration is the voltage range of the charge controller.
I wasnt suggesting equalizing cells, just pointing out that the PCM60X only does 15v on an equalization charge @ 12v

If he was to use the PCM60X then 16.8v would not be acheivavle on a 4s setup 3s increases current 25+% and is not recommended for a 12v rig. The xantrex controllers can easily charge a 4s pack and therefore reduce inverter side currents substantially (really recommended @12v) since using low voltage runs into cable sizing issues due to current


Additionally the PCM60x only has a 3v range @ 12v - ie 12v-15v (15v under equalisation)
So the PCM60x will only be suitable for 3s @ 12v, and not sure what it would think about the battery being at 9v, likely it would just charge, but again, a 3s setup will induce huge currents and need some serious cable sizing considerations (especially with a 500Ah pack)
 
mike said:
Okay, I see what you're saying. I guess it depends on your pack specs. I haven't seen many people doing is the way you're describing. It's usually 7s for 24v and 14s for 48v. I suppose it depends on your specific needs.

Everyone doing 12v does either 3s or 4s, thats the consideration here.

7s for 24v is considered by most the best on LA charge controllers as lead acid sits in the range of 21-30v
Otherwise you use as many cells in series as possible to reduce current and hence wire sizing (think ebikes)

Similarly at higher voltages the main consideration with lithium is hitting the charge controller and inverters ideal voltage range.

kind regards
 
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