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Solar/AGM Charger-Converter/ Victron Li Charger....All together????


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I have a travel trailer with 420w solar on the roof. Two 100ah Renogy 12v Lithium batteries.....MPPT solar charge controller. Currently the Progressive Dynamics charger/converter does not have a lithium setting but it does have the "Charge Wizard Boost" dongle that can increase charging to 14.6 with the push of a button. I also have a Victron Blue Smart IP22 / 12v / 30amp charger available.

 

Question.... Can I leave the factory installed AGM charger/converter in place connected to the batteries and also connect the Victron charger and solar....and use them all at the same time? Or can I only use one of the chargers at a time?

 

The plan would be to use the PD charger/converter when on RV park power.....Use the Victron from my generator when needed off grid.....And solar when conditions favor it. Any danger in "back feeding" the PD or the Victron from each other?

 

Thanks in advance

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BTW...This is the charger/converter I have:

A concern might be the "equalization" phase with Li batteries???

The Progressive Dynamics 4600 Series replacement RV converters feature their 4-Stage smart Charge Wizard that greatly increases battery life. The Inteli-Power PD4655 can recharge a battery pack to 90% in approximately 3-6 hrs using their patented Charge Wizard Technology.

The Charge Wizard Technology features:

  • BOOST Mode 14.4 Volts – Rapidly brings RV battery up to 90% of full charge.
  • NORMAL Mode 13.6 Volts – Safely completes the charge.
  • STORAGE Mode 13.2 Volts – Maintains charge with minimal gassing or water loss.
  • EQUALIZATION Mode 14.4 Volts – Every 21 hours for a period of 15 minutes prevents battery stratification
    & sulfation – the leading cause of battery failure.
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rb, great questions. Im NOT any solar expert but will offer my opinions until such time the true experts arrive and see if they agree or not ???????? 

3 hours ago, rbertalotto said:

Two 100ah Renogy 12v Lithium batteries.....MPPT solar charge controller. Currently the Progressive Dynamics charger/converter does not have a lithium setting but it does have the "Charge Wizard Boost" dongle that can increase charging to 14.6 with the push of a button. I also have a Victron Blue Smart IP22 / 12v / 30amp charger available.

 My LiFePo4 batteries recommend a charge voltage of 14.6 (yours is ??) HOWEVER BOTH my Lithium specific charger as well as my battery EMS shut down or trickle once my batteries are full charged, does your BMS and PD charger do that orrrrrrrrrrrrrr would your PD keep pumping 14.6 charging volts constantly ?? Not having your specs I would guess your BMS wont let the PD overcharge and keep charging 14.6 and/or the PD will shut down once your batteries are charged. READ THE BATTERY AND PD MANUALS  don't rely on my guesses 

 My bottom line opinion absent any specs are while your PD can indeed supply a degree of charge to your LiFePo4s ITS NOT THE SAME QUALITY AS A LITHIUM SPECIFIC CHARGER MIGHT OFFER. My preference given the huge battery investment would be a Lithium specific (or setting) charger even though sure your PD can still provide charging amps.

 My bottom line opinion is iffffffffffffff your Victron is a Lithium specific ???????????????? (or has settings ) I would use it instead of the PD to be on the safe side or at the minimum use BOTH for a short time to get near full charge quickly then shut off the PD and use Victron..   NOTE also do  not exceed the max charging amps your batteries are rated for !! IE dont use both if it exceeds the max charge amp rate    

 

3 hours ago, rbertalotto said:

Question.... Can I leave the factory installed AGM charger/converter in place connected to the batteries and also connect the Victron charger and solar....and use them all at the same time? Or can I only use one of the chargers at a time?

YES you can use BOTH provided you don't exceed the max charging amps and the two don't conflict with or fight each other but once more ifffffff the Victron is Lithium specific (or has settings) and you're in no hurry to achieve 100% SOC I would trust/use the Victron ONLY to provide a better quality more specific tailored for lithium charge versus the PD. If in a hurry to get 100% SOC use BOTH for a limited time then switch to the Victron ONLY (If its lithium approved) 

 

3 hours ago, rbertalotto said:

The plan would be to use the PD charger/converter when on RV park power.....Use the Victron from my generator when needed off grid.....And solar when conditions favor it. Any danger in "back feeding" the PD or the Victron from each other?

 My NON EXPERT opinion:

Iffffffff theres no hurry and ifffffffff the Victron is Lithium approved I would use it alone when on shore power. Why mess with the PD if the Victron is for specific charging Lithium ??? (is it ??) while the PD is questionable??

SURE use the solar and lithium matched MPPT (is your MPPT okay for your lithiums???) anytime you can

Quote

 

 FINAL NOTE I know people who use an older PD to charge Lithium (newer PD have a Lithium specific charger like I use)  and sure it works. SURE you could use both. However MY PERSONAL PREFERENCE would be at the high cost of Lithium batteries prefer a Lith specific charger versus an older PD set for boost. I would NOT use any so called equalize charge (for lead acid) on my Lithiums.   

This is ONLY HOW I WOULD DO IT so see what the experts have to say. Even if the PD works (set on 14.6 volts) I prefer a Lithium specific charger but that's just me. Again my batteries say on the label use 14.6 charging volts and if your PD does that ?? sounds okay provided it doesn't overcharge and doesnt equalize and your battery EMS provides protection against overcharge. Unless there's an urgent need to get full charged quickly I dont see you need BOTH PD and Victron but hey its your choice and your battery investment none of ours

 GO WITH THE BATTERY AND CHARGER SPECS OR THE EXPERTS NOT MEEEEEEEE yet this is still how I'd do it lol Looking forward to expert opinions ....

PS I dont know the exact voltage of the PD in boost mode or how long it lasts nor your battery recommendations concerning charging voltage so its hard to say how it does other than again sure it can provide a degree of charging and provided your BMS protects the batteries AND YOU DONT EXCEED MAX CHARGING AMPS OF YOUR BATTERIS (mine are max charge rated at 50 amps) it alone or BOTH PD and Victron can work even if I still prefer a Lithium Specific charger on my expensive batteries YOUR MONEY YOUR BATTERIES YOUR CHOICE NOT OURS 

 John T

     

Edited by oldjohnt
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You can connect multiple DC charging sources together without any issues.  They won't backfeed into each other, all that will happen is the one with the highest voltage will supply the majority of the charging current and those with lower voltages will back off.

You can't supply too much charging current, as long as the charging voltage is within acceptable levels the batteries will only draw as much current as they want.  For lithium batteries this is 14.6 volts or lower.  Lead acid batteries lose water if the charging voltage is left at this level after the battery is fully charged, which is why multi-stage chargers reduce voltage when the battery stops accepting charging current.  Lithium batteries don't care, and lithium specific chargers just stay at this voltage all the time.

You didn't say what the voltage setpoint is for your solar system, but all of the output modes of the Charge Wizard are safe for lithium batteries.  It's just the converter won't contribute much to increasing the charge level of the batteries when it's not in Boost or Equalization modes.  But it will contribute power to keep the loads from discharging the batteries in all modes except Storage. 

To address oldjohnt's concern about the Equalizing voltage, note on the Charge Wizard it's the same as the Boost mode voltage.  Other converters may push a higher voltage in Equalizing mode, which would be a problem.

In practical terms this means your solar system will charge the batteries when sun is shining on the panels and the Charge Wizard converter will power the loads whenever the solar system isn't producing enough power (at night or when the panels are shaded).

Lithium batteries charge at 14.4-14.6 volts and produce that voltage when they're fully charged, which reduces the charging rate to zero (you need to apply more voltage than a battery is producing to push charging current into it).  But their voltage quickly drops to 13.8 volts at 90% charge and stays almost perfectly flat until it reaches 13.6 volts at the 20% charge level.  So a Charge Wizard controlled converter will help the solar system charge the batteries in Boost or Equalizing modes if they want more charging current than the solar can supply and will keep the batteries from discharging below 90% charge in it's Normal mode. Close enough in my opinion.

Edited by Lou Schneider
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Thank you both...Great info!  I thought "Equalization" did some kind of pulsed reverse polarity? Or am I thinking Desulfasion (sp?)?

I just found out that my PD charger has a jumper to put it into Lithium mode. Then it outputs 14.4v constantly......Some are not a fan of this constant voltage output. Other say Li batteries simply stop receiving the charge once the BMS sees the battery is fully charged......

I think I might just bite the bullet and buy a true Li charger/converter.........It's only money!

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I have multiple charge controllers to charge my lithium, LFP batteries.  3 solar charge controllers, inverter charger and the original converter.  While you can charge LFP batteries at 14.6v the chargers I have are purposely not set to that high of voltage.  When LFP batteries are fully charged and then rested the voltage will settle around 13.3 or 13.4v.  Given enough time these batteries will charge at a much lower voltage.  The old converter in our RV maintains 13.8v and that will easily fully charge the LFP batteries.  I set the solar charge controllers to charge at 14v and the inverter is also set to 14v.  The float voltages are set at 13.4v as it is not recommended to keep the batteries at much higher voltages for long periods.  Most LFP batteries can accept charge rates of .5c or more, which means a 100ah battery can easily accept 50 amps.  I have a large LFP bank and when I run the generator I like to plug in every charger I have.  For whatever reason my converter runs at a higher voltage than most and so I don't leave it connected constantly as 13.8v is to high keep the batteries at.  I set the inverter charger to float at 13.4v so I use that for when we are plugged in.  For long term storage these batteries don't self discharge like lead acid and maintain the charge for weeks or even months.  These batteries are best stored at around 50% SOC.

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58 minutes ago, rbertalotto said:

I just found out that my PD charger has a jumper to put it into Lithium mode. Then it outputs 14.4v constantly......Some are not a fan of this constant voltage output. Other say Li batteries simply stop receiving the charge once the BMS sees the battery is fully charged......

1) Since we now know it actually has a setting for Lithium and its 14.4 volts (although my batteries state charge at 14.6 yet my charger is often around 14.4 or a tad above ?? but the accuracy is ??)   THAT SOUNDS MUCH MORE REASONABLE   and I'm more inclined to favor their use then I was above. I highly suspect your batteries BMS will shut down charging to protect the batteries, and if so ??? that's even more reason not to fear using your existing PD.

 

58 minutes ago, rbertalotto said:

I think I might just bite the bullet and buy a true Li charger/converter.........It's only money!

2) It's your money and your choice but I do not regret purchasing a Lithium specific charger versus my old PD even if it would have worked.  

3) Like the others I can use BOTH my MPPT Solar Charge Controller as well as my Lithium Charger AT THE SAME TIME especially since I know my BMS will protect my batteries, not overcharge them, and allow only a float maintenance charge level (13+ Volts) once 100% SOC is achieved.

4) One final warning regarding the use of too many multiple charge sources IS NOT TO EXCEED THE BATTERIES MAX CHARGING AMPS (which multiple sources could well achieve subject to if the BMS will prevent it???) as they are expensive and you don't want to risk damage or voiding the warranty.

 ITS YOUR CHOICE  I broke down and bought a Lithium specific charger even if my old PD would work, and I have NO regrets..

 Again see what the experts have to say, regardless this is how I chose to proceed.

 John T

Edited by oldjohnt
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10 minutes ago, rbertalotto said:

Thank you!......If I have two 100aH batteries in parallel (200ah), is my .5c charge rate 100 amps or does it stay at 50 amps......

With TWO batteries in parallel the total max charging amps (subject to proper balance) would double (what each is) as only 1/2 in theory goes to each battery. IE if they each have 50 max charging amps the two in parallel can accept 100 Amps from all your charge sources.. I would NOT exceed the max charge rating but that's likely only possible if you have too many high enough current charging sources and the BMS may prevent it regardless READ THE LITERATURE don't take my word for it.

Hope this helps and answers your question, as always see what the experts AND YOUR MANUALS have to say

John T

Edited by oldjohnt
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Voltage is the critical charging parameter, it doesn't matter if the charger(s) can deliver 100,000 amps, if it's at the correct voltage the batteries will only draw what they want to accept.  Anywhere from 50 amps each over most of the charging curve to 0 amps when the battery is full.

If the charging source can't deliver all of the current the battery needs it will draw down the voltage, reducing the current the battery can absorb until it matches what the charger can deliver.

If you increase the voltage beyond the recommended limit the battery can draw more current and overcharge.  But it won't if the voltage stays within spec.

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14 hours ago, Lou Schneider said:

Voltage is the critical charging parameter, it doesn't matter if the charger(s) can deliver 100,000 amps, if it's at the correct voltage the batteries will only draw what they want to accept. 

This is not an entirely correct statement.  It depends on the charger.  Some chargers send out constant voltage and constant amperage.  If your charger is an 80 amp charger (at the proper voltage) for example and it sends a constant 80 amp stream of power to your battery that is only rated to take a 50 amp charge, then you will eventually damage the battery.  

Victron programmable chargers will send out a constant amperage based on how they are programmed.  If I had a 100 amp Victron charger charging a battery that could only accept a 50 amp charge rate, I would program the charger to only charge at 50 amps.  If I programmed the charger to charge at its max 100 amp rate, it would damage the battery in this example.

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9 hours ago, Chad Heiser said:

Victron programmable chargers will send out a constant amperage based on how they are programmed.  If I had a 100 amp Victron charger charging a battery that could only accept a 50 amp charge rate, I would program the charger to only charge at 50 amps.  If I programmed the charger to charge at its max 100 amp rate, it would damage the battery in this example.

Usually what happens when you select a constant amperage, the output voltage is allowed to DROP when the current reaches that value because the load's impedence is too low to support full voltage at that current. 

Conversely, as iong as the maximum voltage doesn't exceed the battery's maximum charging voltage, the current won't exceed what the battery can accept.

The only way a charger can pump more current into a battery than it can accept is if the voltage rises above the battery's rated maximum charging voltage.  If the Victron allows this it's a bad design.

Or are you saying Ohm's Law doesn't apply to lithium batteries?

Edited by Lou Schneider
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26 minutes ago, Randyretired said:

The internal resistance on LFP batteries is so small it is easy to drive more than recommended.

Only if the charging voltage is allowed to rise above the battery's maximum charging voltage, no?  Are you saying something like a Progressive Dynamics PD 9180ALV converter can overcharge a single lithium battery since it can deliver up to 80 amps at a constant 14.6 volts?  Or will the battery only absorb as much current at that voltage as it can safely handle?

Edited by Lou Schneider
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Lou,  The lithium batteries are different.   The last cells that just arrived have an internal resistance of .25 milli ohms.  These are a matched set that I ordered and yes it is easy to drive them beyond specs.  Most inverter/chargers have the option to regulate the amps.  For most people though it isn't a problem because it is rare that LFP can't accept at least .5c and most are 1c Some are 2c or more.  The lithium batteries are crazy different.  From about 20% state of charge to about 90% the voltage only changes about .1v.  When charging these the charge will not change the voltage that much either.  Most of the time the battery will just take whatever you throw at it.  Then as long as the voltage is within parameters the current just stops when the battery is full.

Edited by Randyretired
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Posted (edited)

A quick search..."The appliance will draw only as much current as it needs. The only factor that determines current draw is the load (another term for resistance) the device places on the charger."

I'm confused.......How do we make a charger deliver more current than the batteries are requesting?

Edited by rbertalotto
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Most LFP batteries have a BMS that will disconnect the battery cells if the charge current is to high.  That saves the battery cells but the voltage spikes when this happens is significant and can cause series problems. I have seen voltage spikes above 21v on a 12v system.  Another thing that is interesting is if you connect a fully charged LFP to a discharged battery the current can be really high.  100's of amps.

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21 minutes ago, rbertalotto said:

Anything I should know about putting them in parallel for 200aH that is diofferent than my two AGMs? 

Until Randy arrives check out this link that will tell you more then you need to know about how best to connect multiple batteries in order to achieve balance so each receives or delivers equal charging and load current. Most aren't aware of the subtle differences and of course its best if EACH battery gets charged the same and delivers the same current into the load. NOTE sure it still works and there are a gazillion wired in parallel in simple straight ladder that work fine, but its good if EACH worked the same WELL DUH..  

 Of course, + to + and - to - and AGM or Lithium or Wet Flooded Lead Acid would still be the same as far as how to connect multiple batteries 

 See if the experts agree or differ from the Smart Gauge approach as how to achieve the best balance, I tend to agree with their approach but that's just me and others may disagree which is to be expected. Of course, subject to how wired and the size,, length,, and resistance of the connecting cables matters and the differences in connection methods may be small or insignificant  BUT THIS IS INFORMATION to take or leave as one pleases even if there's little difference I would prefer that EACH battery in parallel works the same. Thats my story n Ima stickin to it regardless lol . 

http://www.smartgauge.co.uk/batt_con.html

John T

 

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33 minutes ago, rbertalotto said:

Randy...On your last post about connecting batteries together. I have two Renogy 100aH Lithium batteries on their way to me.....Anything I should know about putting them in parallel for 200aH that is diofferent than my two AGMs? 

 

As long as the battery voltages are close I have never had or seen a problem.  The problems arise when there is significant differences in SOC.  Some manufacturers go so far as to suggest the voltages should be within .05v for balance.  In my fooling around parallel batteries that are pretty close will balance themselves.  Certainly the first time they are fully charged.

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56 minutes ago, Randyretired said:

Most LFP batteries have a BMS that will disconnect the battery cells if the charge current is to high.  That saves the battery cells but the voltage spikes when this happens is significant and can cause series problems. I have seen voltage spikes above 21v on a 12v system.  Another thing that is interesting is if you connect a fully charged LFP to a discharged battery the current can be really high.  100's of amps.

Randy my experience and (old engineers) understanding of Li is similar. My Lith battery BMS will prevent overcharging, disconnect before the SOC becomes excessively low, and prevent low temp charging in case my Smart Lith charger fails to do parts of its job and charging algorithm. Also the resistance of Lith is such that they can accept high charging current in order to achieve 100% SOC faster then Lead Acid. For example, one reason I ordered a smart Lithium DC to DC charger to allow my engines alternator to deliver a certain degree of charging to my Li house batteries (Low resistance) is that if I connected my engines alternator direct to them they could draw excess current and over tax the alternator unless its has protection. 

As always fun sparky chatting with you

John T Too long retired n rusty EE but still enjoy the topic

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