External Smart Charger?

Davidw

If you were to go with an external smart charger for topping off batteries with a generator, what characteristics would it have?  While boondocking many days in shady conditions I have to resort to running the generator.  The WFCO convertor never achieves bulk mode for various reasons discussed in other posts and will only deliver 13.6v no matter the state of discharge of the battery.  I'm hoping to deliver up to 14.6v for deeper charging in less time with an external charger.  I currently have the WFCO8735, which delivers up to 35amp.  I am charging AGM's and am not interested in upgrading the converter at this time.

Dutch061

Even if you were to upgrade the converter, with it in the existing location and 8-gauge wiring it would still not ever enter the "bulk mode".

You don't say which model you have, but the best bet for the money would be to fix the resistance of the 8-gauge wiring by either using 6-gauge or add an additional 8-gauge circuit for both the positive and negative wires. By reducing the resistance, the charging properties will be much better.

I have a complete different set up than what was factory but can easily get 60 to 70 Amps to my batteries with the solar and converter.

Brad

Davidw

I'm curious what amp rating I would need to deliver the higher voltage?  The WFCO system states 35amps but doesn't give details about how many amps will deliver the bulk or absorption voltages.  If a smart charger will deliver higher voltages without the resistance issues inherent with the WFCO system, what amp rating do I need in a smart charger?  Any recommendations about a specific smart charger would be appreciated.

Dutch061

The actual amperage delivered depends entirely on the state of charge (SOC) of the battery bank. Even though I can charge at 60 plus Amps (including solar), if the batteries are nearly fully charged the amperage will drop way down to prevent damage and overcharging. 

All converters work in a similar fashion, determining the amperage rate based on the battery voltage (IE state of charge). The problem encountered with most all RV's is the gauge of wiring used between the Power Distribution Center (aka PDC) and the battery when combined with the distance it is run. On startup of the converter, SOC is determined by measuring voltage and how quickly it rises, if the voltage rises very quickly (such is caused by too small of wiring) it switches immediately to the Absorption Mode. Absorption Mode will take 24 to 36 hours to charge a small battery bank. 

If you are using AGM or Standard Lead Acid Batteries, the maximum charging rate is 15% to 20% of the total battery capacity depending on actual chemistry and Battery OEM Guidelines. IE, a 200 Amp Battery Bank could accept up to 40 Amps (again depending on actual battery chemistry and battery manufacturer guidelines), but I would probably stick with the 35 Amps you have.

Lithium batteries can take up to 50% of the total battery capacity. IE, in my case I have 400 Ah of Battleborn and could charge at up to 200 Amps. There are many reason that I don't use 200 Amps, which I will leave out of this discussion. 

In the case of Progressive Dynamics and their "Charge Wizard" technology for non-lithium batteries, the voltages are as follows:

Bulk (Boost) Mode 14.4 Volts
Absorption Mode 13.6 Volts
Storage Mode 13.2 Volts 

Storage is activated if there isn't any significant battery discharge in 30 hours. This prevents boiling of the electrolyte in the battery and ultimately damaging the battery bank. 

In my case, I removed the converter from the Power Distribution Center and installed a self-contained PD9160ALV within 12 inches of the battery junction block under the bed. I used 4-gauge battery cables to make the connection. My battery Bank is connected to this junction block with 2/0-gauge cables. This was a much easier to install solution since I needed to change the converter to a unit for Lithium Batteries anyway. It prevented me from having to run approximately 50 foot of additional wiring through some areas that are not easily accessible. I used very large cables to reduce this resistance along with the fact that 2/0-gauge is marginal if I were to pull the entre capability of the battery bank at once (800 Amps for 30 seconds). Since my highest draw is my inverter using a toaster at 90 Amps or less, 2/0 is more than enough.

Again, I am not sure exactly what you have, batteries, or year, other than it is a 320.

Bottom line becomes this, how much do you want to spend and are you able to do the work yourself? If you install a converter outside of the OEM, you will want to remove the original in the Power Distribution Center. It has 5 wires to disconnect and 2 screws to remove. 

Note: 14.6 is too high for non-lithium batteries to be charged at safely.

Brad

Denny16

Brad nice mod, I like what you have done.  When I upgrade my battery system to Lithium, and if I end up using the Victron 3K inverter/charger, I think I will just pull the WaCo Power Distribution Center out, and replace it with a Marie circuit breaker (AC/DC) panel and mount it where the OEM Power Distribution Center is, and use the Victron as the battery charger.  It has an auto shore power switch over feature that makes this seamless.  

I also plan to change the solid (household type AC wire with Marine 12/3 cable (and use 10/3 between Victron and distribution/breaker panel.  Then I will tidy up all the messy DC wire runs that are exposed (not buried in the cable runs), by harnessing them together, or use snap on cable covers. 

Cheers 

Maxcamp8

Great info. Wish we'd gone this route on our battery upgrade and converter replacement.  A tough job.

@Dutch061, what would be contraindicated  with using a 120v source smart charger clamped direct to battery terminals?  

We did this after five days boondocking in no services provincial park in the shade.
I was uncertain about charging the two parallel 100ah Battleborn LiPoFes together so pulled all the 30a inline fuses from interconnecting wires and charged one at a time using generator.  Did this during the day while we were out or not needing trailer systems. 
Made sure to balance charges at next park on shore power.
 Not something we'd want to do regularly but then we had not run down to 48 percent SOC ever before.

Dutch061

@Maxcamp8, the original question was the desire to deliver 14.6 VDC using an "external smart charger" to get the maximum amperage to the batteries; thereby reducing the charge time. As mentioned previously, the rate of charge (in amps) is related directly to the state of charge (measured in volts by the converter). I also mentioned that 14.6 VDC was too high of voltage for AGM or SLA batteries, you will toast them. In addition, it is imperative that you do not exceed the battery manufacturer's specification for "maximum rate of charge".

In my answer(s), I related what the problem is and how to correct it. I am fairly well versed in this, having gone through all of it already.

Yes, it is possible to carry an external charger with you, but the majority of those that are "consumer grade" and truly portable will only deliver 2 to 10 amps anyway. So, if that is the case, what did you actually gain? Why not fix the resistance problem and have 35 amps available in the "bulk mode"?

The batteries may be easily accessed on 320's but certainly not so much on 400's. I realize the OP has a 320 and the battery is likely still in the tub which would make connection simple.

Brad

rh5555

@Davidw: While I mostly agree with what Brad says, you could radically reduce your charge time by swapping out the converter section of your WFCO-8935 with a Progressive Dynamics PD4635.  This converter has a button that allows you to force it into Bulk charging mode irrespective of what it thinks your battery's state of charge is.

In Boost mode, the converter produces an output of 14.4V compared to the normal 13.6V.  This will charge your battery considerably faster, and probably as fast as any external battery charger.  True, you still have the wiring resistance to contend with which will drop some voltage and reduce your charge current, but you have to be better off.  If you wish to further enhance your charging ability, you could also replace the wires between the converter and your battery with the biggest wire that you can handle.

AldebaranJill

Had same issue with WFCO never getting above 13.6V - (I have 2013 T@B). I used Trojan battery which needed higher voltage to fully charge. My solution was a 15A Noco Genius charger. It worked better than WFCO and I used it for many years. Now I have a Victron 15A Smart Charger and am very happy - program it to match whatever battery you have.

grassgd

I am currently in the process of changing from an Interstate wet cell battery to an AGM or possibly a lithium and wanting to use a modern smart charger to handle battery charging when on 120 volt power in place of the WFCO in my 320s.

I would like to leave the WFCO as a 12 volt power supply and distribution center and have the smart charger handle the battery charging only.   The only confusing part of this for me is how to isolate the battery when charging but have the battery provide the 12 volt power to the WFCO when not on 120 volt power. 

Seems like the solution would be to have a 120 volt solenoid to isolate the battery from the WFCO when 120 volt power is applied but upon loss of 120 volt power connect the battery to the WFCO for 12 volt power distribution.  You could do this manually but a solenoid as I described would automate the switching.

Am I making this too complicated?

Denny16

What you are describing is a power transfer switch normally used for generator setups for auto transfer when shore power goes out, and a 30-amp or larger ones are pricey.  When you are on shore power, just switch off the battery disconnect switch and you have isolated the battery/batteries from the WFCO. 

Cheers 

AldebaranJill

I use a separate 15A Victron Smart Charger to charge my batteries and made no changes to WFCO. Victron is wired directly to battery and plugged into outlet. Before this I used Noco Genius charger. No issues. No need to isolate WFCO as it never goes above 13.6V anyway.

stepheng

If I remove the 30A "battery charger" fuse (#6) does this simply disconnect the charging when on shore power or disconnect the battery completely?  When on shore power is the battery charging circuit separate from the DC power supplied to the other DC circuits - 1-5?  If so, what circuitry in the WFCO isolates the battery when on shore power but connects it to DC circuits 1-5 when no shore power?

techietab

@stepheng Look at my other post in the thread detailing the shortcomings of the WFCO 8735-AD. Based on WFCO's wiring diagrams in the manual, I am fairly certain if you yank the F6 fuse it will entirely disconnect the battery from the DC side of the WFCO panel and render DC circuits unpowered if AC shore power is disconnected.

That said, if AC power is disconnected - I don't think there is any risk to yanking that fuse to see what happens.

The real question here is - what's going on with the wiring behind that fuse upstream on the AC side?

stepheng

@techietab Will pull and check out.  Trailer over in storage unit and battery dead so I have to charge and do some testing.  Will let you know.

ChanW

When parked at home, I normally pull that fuse and use the smart-charger on the battery to maintain it.

Then I'll keep the shore power plugged in to run anything as I need it. I'll keep the Tab powered up, keeping the tracker battery charged, etc. 

Thus the Tab is on shore power, and the battery is isolated on the smart-charger. I'd rather not confuse the smart-charger's algorithm by having two charging sources connected at once.

stepheng said:

If I remove the 30A "battery charger" fuse (#6) does this simply disconnect the charging when on shore power or disconnect the battery completely?  When on shore power is the battery charging circuit separate from the DC power supplied to the other DC circuits - 1-5?  If so, what circuitry in the WFCO isolates the battery when on shore power but connects it to DC circuits 1-5 when no shore power?

Denny16

If you have a battery cutoff switch, it will do the same thing as pulling the main battery fuse.  Turn the battery switch off, snd the battery is isolated, except for any rooftop mounted solar installs, which remain connected.  

Our local dealer technician recommend turning off the battery switch after the battery is charged up, whilst storing the camper or having the TaB connected to shore power during periods of non-use,b to prevent overcharging the battery with the WFCO converter/charger.
 Cheers 

MarkAl

I have found the WFCO charger to be much worse at charging than the Victron system. So I have a remote solar panel input that I plug a 100Watt 20V laptop supply into and it charges and floats the battery very successfully while stored.

AnOldUR

MarkAl said:

... I plug a 100Watt 20V laptop supply into and it charges and floats the battery very successfully while stored.

For emergencies, we use a small (900W) propane generator plugged into the shore power input to top off battery through the WFCO. We've only needed to use it a couple of times, but it works well for extended stays when solar charging conditions are poor.

Sounds like a power supply plugged into the generator and connected to our solar panel port would do a better/faster job? We have a MPPT 75/15 controller in our tub between the port and batteries.

Would you post a link to the power supply that you are using?

MarkAl

@AnOldUR I used an old laptop supply I had, I didn't buy one. See what you can find at Goodwill.  Also you are limited to the 100 watts (about one solar panel). I use it as the supply with my solar controller does a better job at keeping the battery topped off than the WFCO. Since you are running the generator you may be better off buying a dedicated high output charger @AldebaranJill suggested a good Victron one and connect it directly to the battery.

Dutch061

It is important to note that Victron MPPT Solar Charge Controllers, do not turn on until the PV voltage is 5 volts higher than the output voltage.

From the Victron MPPT Manual, (see attached PDF Page 7 at the top)

● The controller will operate only if the PV voltage exceeds battery voltage (Vbat).

● PV voltage must exceed Vbat + 5V for the controller to start. Thereafter minimum PV voltage is Vbat + 1V.

● Maximum open circuit PV voltage: 75V respectively 100V

Brad

GregChris

I have 2 external smart chargers, a 3amp and a 8 amp. They charge to 14.1v, then go into 13.6 maintenance mode. Supposedly it will not overcharge or boil the battery.

grassgd

I recently installed the Victron BMV-712 to monitor battery state of charge real time and just purchased a Victron IP67 Smart Charger.  I will hook the smart charger up to the battery and when on 120 volt "shore" power will disconnect the battery with the battery disconnect switch and let the WFCO provide 12 volt to the trailer while the battery is charged by the Victron IP67 charger.  The Victron phone app lets you see everything you need with the battery state of charge and the charger performance - really nice.  No more guessing on the battery state of charge and worry about the WFCO battery charging performance hurting life of the battery. 

I found a normally closed 120 volt relay that I may install to automatically disconnect the battery upon 120 volt so I don't have to manually disconnect the battery.  The relay is less than $20 but for now I will disconnect it manually.

AnOldUR

I touched on this in earlier threads, but can't get it right in my head. I want to charge my batteries with a NOCO smart charger. Is there any advantage to buying the Genius10 over the Genius5 or would the Genius10 overload the generator?

Also, the Genius5 say, "Battery Capacity: Up to 120Ah, Maintains All Battery Sizes". Does that mean it won't even work with two 125Ah batteries wired in parallel? Don't understand the difference between "capacity" and "maintains".

YanniLazarus

Good question, @AnOldUR... I have 2 6v agm batteries in my 320 and have long wondered if it was just dumb luck when I got a genius 10.  I noticed the "up to" specification only after purchase. Curious to know the answer. 

AnOldUR

@YanniLazarus Doing my best to research this, but not getting consistent answers to what I'm looking for, but did find this. If accurate, it indicates that the amp rating of the charger can be larger than the generator wattage output. Put a ticket in with NOCO yesterday. Waiting for their reply.

"How much muscle does your portable generator need to run a high-output battery charger? Simply speaking, a 300-watt generator can handle most 10-amp chargers; step up to a 600-watt generator to power a 30-amp charger. What about coupling a portable generator with your RV’s existing battery converter? Unless you’ve got one of the sophisticated converter-chargers mentioned earlier, the output from the converter is so low as to be almost useless."

techietab

AnOldUR said:

@YanniLazarus Doing my best to research this, but not getting consistent answers to what I'm looking for, but did find this. If accurate, it indicates that the amp rating of the charger can be larger than the generator wattage output. Put a ticket in with NOCO yesterday. Waiting for their reply.

This is correct. For instance, my Victron IP22 charger (30A model) runs just fine on my small Rainier 2200i generator (20A max, rated for 2200 peak/1800 sustained watts). This works because the IP22 wattage is relatively low - 30A at a theoretical max output of 14.6v is effectively only ~440w (Amps * volts = watts).

AnOldUR

YanniLazarus said:

... I have 2 6v agm batteries in my 320 and have long wondered if it was just dumb luck when I got a genius 10 ...

What is the total Ah rating of your two AGM's? Do you charge them in parallel?

YanniLazarus

My 2 6v batteries are wired in parallel for 12v- and I leave them that way when charging.  I do use the battery shut off when charging.  My noco genius recognizes them as 12v, and I select AGM.  I believe I have 220 or so amp hours, but, well, am painfully aware of how often I am wrong!  I did call NOCO to confirm this was okay to do. 

GregChris

I find this all very confusing. In stead of plugging my 320s into my gen/inv, I should plug my 8amp smart charger into it, and charge the battery directly. I am only running the standard 50 amp/hr lead acid it comes with. Excuse my typing, I one handed after surgery( left ) for 6 to 8 weeks.

techietab

GregChris said:

I find this all very confusing. In stead of plugging my 320s into my gen/inv, I should plug my 8amp smart charger into it, and charge the battery directly. I am only running the standard 50 amp/hr lead acid it comes with. Excuse my typing, I one handed after surgery( left ) for 6 to 8 weeks.

You shouldn't have any issues plugging your 320 S into your generator, then plugging your 8A charger into one of the AC outlets located inside/outside the cabin.