Charge controller advice please

Spazmor

Spazmor

New member
Joined
Mar 15, 2018
Messages
26
Hi everyone,

Just wondering if you guys have any suggestions for my off grid system. I have a design in mind but I'm stuck on charge controller & inverter. I like the PIPs (for the price 5048MS) but as Peter has highlighted they float charge with CCCV and I believe that isn't good for Li-ion.

I'm building a powerwall (prob 6kw total) but batteries are coming in very slowly so initially will use AGM.
I already have the following:

Roof mounts, cable, breakers and fuses

Solar 2.2kw
12 x 185w (36.2v, 5.11A), mono, $400.
In 3s4p... or is it 4s3p
So 108.6v, 20.44A total

Batteries 15.3kw
256 x 60w (12v, 5Ah) AGM, $0
In 8p4s8p? to make 48V

18650s Soon hopefully
thinking 80p14s

Thinking it would be economical to build one system that is Li-ion compatible
A 3 or more Kw inverter should do the job. Max charge rate for the AGMs would be about 64A
 
I wouldn't worry too much about the float charge. Set it low enough and amps going into your battery will be insignificant. Eventually the sun will go down and you won't have any more charging.The only time float charging can be detrimental is if its connected 24/7 (from ACmains)always charging, eventually it will top off the battery.
Example just set your bulk to stopbefore its fully charge and when it switches tofloat it willtrickle chargeit at 1 or 2 amps which is insignificant for a 14s80p lithiumbattery pack. The battery will never get fully charge that way, maybe 90 or 95 percent which is good for li-ion.

The charge controller doesnt even have to be lithium compatible, get one that can handle your solar panels max voltageand the 48 volts your battery pack has. But one thing that is important is it has to be programmable, you need to be able to adjust the bulk/absorb and float voltage. My opinion is get one that you can program directly from the unit. Some require an add-on dongle to program. My view on that is how many times have you lost the remote on your TV, without that dongle you can't do any adjustments. If the PIP 5048 meets your requirements and price range go with that.

Below is a diagram of my solar system hookup. On my system I use a overvoltage relay that disconnects the solar panel if the voltage of the battery goes too high. Very important for li-ion battery packs. There is no way to overcharge my battery pack. The controller, overvoltage relay and battery BMS would all have to fail at the same time. With this overvoltage relay I can use any charge controller, the relay will disconnect the panel if battery voltage ever gets too high. This will prevent the float charging from somehowovercharging your lithium, the relay will disconnect the panel before that happens.
For me the overvoltage relay is the heart of the system, I wouldn't charge lithiums without it. They sell different overvoltage relays 0-40, 0-60, 0-99 volts, all less then 10 dollars. Since you will be handling higher amps, you might need a bigger relay (then the 30 amp I use)or as they are calledhi-amp solenoid (contactor).


image_vkzudt.jpg
 
I would go for a quality solar controller such as for instance a Victron. The solar controller is by far the most important part of your system, and a good controller will give better yields and take better care of your batteri., Controller should be programmeble as to the caharging levels etc.
Then you can get awy with a cheaper converter. Alternatively a combi unit.
 
A PCM controller would work fine.
 
I would not go with AGM as it will work out very expensive per kWh cycled through the batteries and you will not get very much life out of them. Think of the delay in buying the AGM as an investment in more money to buy Li cells with... the urge to powerwall quick with AGM will cost more. Save, delay, invest.

CCCV is only an issue if your CV is set close to the maximum cell voltage and your BMS can't deal with the bypass current of a full charge, which creates the potential for imbalanced cells to be over charged.
 
jonyjoe505 said:
image_vkzudt.jpg
Click to expand...


The 5048MS has "Adjustable Bulk/Float charging voltage" according to their website. Not sure if it is configurable through the LCD or if you need to use a computer dongle.
I was going to use them gently I thinks someone recommended between 3.8-3.2V?

I'm only able to visit the property where this will be on weekends ATM. I imagined I would disconnected when I leave as I don't want to leave it unsupervised yet and it could be up to 6 weeks before I can get back there. It's tragic ;(

I like the look of your overvoltage disconnect. I will look into it.

Thank you JJ

DK100 said:
I would go for a quality solar controller such as for instance a Victron. The solar controller is by far the most important part of your system, and a good controller will give better yields and take better care of your batteri., Controller should be programmeble as to the caharging levels etc.
Then you can get awy with a cheaper converter. Alternatively a combi unit.
Click to expand...

The Victron I saw IIRC were the blue units weren't inverters, the charge current I need for my AGMs is quite high and for my needs still around half the cost of the PIPs.
If I can make the PIP work with lions by changing the charging program then don't you think they're better value? IDK
Is there something specific that the Vicrtons do better in regards to charging lions?

I suppose one negative is that the PIP could present a single point of failure for inverter & charger.

daromer said:
A PCM controller would work fine.
Click to expand...

Yes, these look a good fit for mine. I actually had the PCM60X specs PDF open. I'll still need an inverter. I do like the idea of separate devices. It would give me more flexibility if I wish to upgrade/add down the track. Also small redundancy benefit if inverter failed I can still use small spare car inverter I have until replacement arrives. If PIP failed I may be stuck with no way to charge.

completelycharged said:
I would not go with AGM as it will work out very expensive per kWh cycled through the batteries and you will not get very much life out of them. Think of the delay in buying the AGM as an investment in more money to buy Li cells with... the urge to powerwall quick with AGM will cost more. Save, delay, invest.

CCCV is only an issue if your CV is set close to the maximum cell voltage and your BMS can't deal with the bypass current of a full charge, which creates the potential for imbalanced cells to be over charged.
Click to expand...

I agree. I wouldn't be happy to pay market price for AGMs.
I already have these. They were salvaged from being recycled for scrap. I'm hoping they'll last long enough for me to build HBPW
 
jonyjoe505 said:
Since you will be handling higher amps, you might need a bigger relay (then the 30 amp I use)or as they are calledhi-amp solenoid (contactor).


image_vkzudt.jpg
Click to expand...

I've had a bit of a look for a contactor but seems they're commonly for 12 and 24v loads. Any ideas where I might find one for my panels?
It'll be around 20.44A, 108v DC.
Bonus if it's in Mini Circuit Breaker form
 
Spazmor said:
jonyjoe505 said:
Since you will be handling higher amps, you might need a bigger relay (then the 30 amp I use)or as they are calledhi-amp solenoid (contactor).


image_vkzudt.jpg
Click to expand...

I've had a bit of a look for a contactor but seems they're commonly for 12 and 24v loads. Any ideas where I might find one for my panels?
It'll be around 20.44A, 108v DC.
Bonus if it's in Mini Circuit Breaker form
Click to expand...

How about this one? http://store.evtv.me/proddetail.php?prod=p115bda you have to use 7.5-16V to control the contactor. Spec Sheet - http://www.gigavac.com/sites/default/files/catalog/spec_sheet/p115.pdf
 
For solar you can use Schneider 2pole breakersor the cheaper ones here

Above can also be added a shunt trip to that you can remotely trip.


I have some on my page what I have been using.
 
Sorry I should have said relay. I would like to have overvoltage trip on panels like Jonyjoe was referring to. 20.44A, 108v DC.
And I have a breaker box that I'd like to fit it into if possible so was hoping there was an affordable MCB device but still couldn't see what I was looking for.

Daromer, Yes Schneider seemed good value for me and good brand. I deal with the company at work regularly. I had already bought my breakers. I had gone with Schneider 63A 250V DC for $24AUD for Batteries. May upgrade this in future.
Schneider DC 250v 32A 2pole $22AUD for Solar.
And ELS 32A 240V AC $4.80AUD x 2 for 240v Supply
 
Every morning, Our PIP-5048MS shows no solar coming in and so won't start charging, until we flick the battery breakers. essentially power cycling the whole inverter. Anyone seen this? any ideas?
 
What is the input voltage of the solar panels?
 
Should be around 109v. I will check this next time I'm there. Do you think breaking and reconnecting the solar circuit spikes the voltage?
I'm thinking there must be enough voltage because when we flick the breaker it starts charging right? but there could be something else going on that I'm missing. Hoping it hasn't given up on me already.

BTW, your setup in your signature sounds godly, well done! =)
I might have to put mine up next to yours for a laugh ;P
 
You must log in or register to reply here.
Back
Top