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Old 12-16-2018, 09:13 AM   #1
packrat1969
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Better Battery Charger/Converter

Hello,

The 2017 Passport 2520RL I purchased second-hand in April came with a WFCO WF-8900 series power center. I don't have access to the trailer at the moment, but I'm pretty sure it is the WF-8955, a 55A converter/charger.

Anyway, long story short; I've upgraded the tiny Group 24 NAPA deep-cycle battery to a pair of Trojan T105s, and I do not believe the WF-8955 is bringing the charging voltage up to Trojan's specs.

From the T105 spec sheet:
Bulk Charge 14.82
Float Charge 13.50
Equalize Charge 16.20

For some reason Trojan does not list a voltage for the absorption phase of the charge cycle. I will call them next week. From WFCO's documentation, their converter/chargers appear to use a time-based charging methodology rather than measuring the battery's status and are completely lacking an equalization charge phase.

Does anyone know of a reputable manufacturer of programmable charger/converters? I'm looking for one that will allow me to set the voltages for the 4 stages of charging (bulk, absorption, float, equalize) manually. I know this is a common feature on higher-end solar charge controllers, but I have yet to see the feature included in 120VAC converter chargers.


Any relevant info appreciated..

packrat
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TT: 2017 2520RL, Twin Trojan T105s, BM-1 Compact, Xantrex SW1000, Curt Roundbar WDH

TV: Mostly stock 2016 Bluejeans F-150 XLT FX4 SCrew 5.0, 6.5' bed...
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Old 12-16-2018, 09:37 AM   #2
JRTJH
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There are as many "battery charge technologies" as there are manufacturers of batteries and chargers. So, depending on which manufacturer you choose, "their system is best".... Honestly, they're probably all correct and they're all incorrect at the same time. More a "marketing strategy" than an "electrical/battery charging strategy".

You're probably looking for a charger/converter similar to the Progressive Dynamics 4 stage charger. Keep in mind that their "fourth stage" is really the 3rd stage times to "desulfate the battery bank" every 21 hours for a 15 minute time period.

You can read about the differences and similarities between Progressive and WFCO at these two "factory links"... Remember that they are the manufacturer's links, so like GM, Ford, RAM, Toyota, Nissan.... Their product is best and the "website mission" is to convince you of that....

https://www.progressivedyn.com/rv/po...#charge-wizard
http://wfcoelectronics.com/wp-conten...6_8900_MBA.pdf

I will note that WFCO does monitor battery voltage and switch between the three phases as required based on output voltage of the battery. That is explained in the WFCO FAQ section located here: https://wfcoelectronics.com/faq/

And further note that the 4 stages in the PI converter are the same 3 voltage levels as the 3 voltage levels in the WFCO output (both use 14.4, 13.6 and 13.2 VDC). The difference, a 15 minute "spurt of 14.4 VDC" every 21 hours. Some battery manufacturers recommend that "spurt" some recommend against it (or state that it is not needed) and some don't address it.

ADDED: Thinking about your question after I wrote my response, I remembered a service caution in the Atwood Furnace Troubleshooting Guide.

1. Never use a battery charger to power or test an electronic ignition furnace as they sometimes provide more than 14.5 DC Volts that could damage the module board.

Your statement concerning the "maximum charge voltages for the Trojan 105 battery indicate a maximum charge voltage of 16.2 VDC. If you set up a charging system to 'maximize the battery capacity" you may inadvertently damage your 12 VDC trailer system which has limits of "around 12.2 - 14.4 VDC with nominal operating voltages between 13.2-13.6 VDC. There are "12 VDC" circuits in almost every appliance in the trailer, many are sensitive to voltages greater than 14 VDC and some may be damaged by "pushing 16.2 VDC through the system to "supercharge" the batteries beyond the voltage design of the trailer system.
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Old 12-16-2018, 03:57 PM   #3
packrat1969
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JRTJH,

Thanks for the reply and information.

Why does it seem there is such a disconnect between the battery manufacturers and the battery charger manufacturers? There are even some significant differences in recommended charging voltages depending on the brand of batteries used. I've found these bulk-rate levels so far:

Trojan: 14.82V
US Batteries: 14.7V
Crown: 14.5V
Rolls: 14.7v
Interstate Batteries: Specs not readily available online
Deka: Specs not readily available online

Since the RV charger manufacturers never know what brand of battery will be attached to their hardware it seems prudent to allow for application-specific adjustments (the WF-8955 in my TT will never reach any of the recommended voltages above). Maybe they're just not concerned with the issue in regard to deep cycle lead-acid batteries. Things will change though, as more of the market begins to look at lithium ion technology. I would love to have a battery bank that I can discharge to <20% and weigh less than half the same capacity lead-acid bank. Right now it's just not cost-effective.

As for your recommendation to about maintaining the voltage levels in the camper to something below 14.4v, I would tend to agree with you. I do not want to wreck anything. I can envision a couple of scenarios though with an external adjustable charger and cut-out/switch-over relays or some kind of regulation circuit. This is getting far too complicated....


packrat
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TT: 2017 2520RL, Twin Trojan T105s, BM-1 Compact, Xantrex SW1000, Curt Roundbar WDH

TV: Mostly stock 2016 Bluejeans F-150 XLT FX4 SCrew 5.0, 6.5' bed...
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Old 12-16-2018, 05:02 PM   #4
JRTJH
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You are correct, it is getting far too complicated.

If you look at it from the aspect of any product, it all boils down to "engineering philosophy" at the company... One could ask, WHY DON'T ALL WATER PUMPS FIT ALL ENGINES???? Why does GM build 8 or 10 different water pumps for their vehicles? Why are there 3 rear end ratio choices? Why do RV manufacturers offer 13.5K BTU A/C's as standard and then offer 15K units on some trailers? Why do they almost always install a 15K as the main A/C and a 13.5K as the bedroom unit? Wouldn't heat pumps be better?

Then we get to "hybrid" systems like using "GOLF CART BATTERIES" in an RV... The reason the voltage requirements for "full charge" are somewhat different from 12 volt "marine cycle" batteries is the plate construction, cell construction, engineering design and designated purpose. Golf cart batteries aren't "designed to be used in RV's"... We adapted them because they work better in "deep discharge situations" but we can't use them as designed by the manufacturer because the rest of our system (thermostat, refrigerator and furnace control boards, control system for the A/C, etc) are designed to operate on a maximum of 14.5 VDC (in most situations) and trying to operate them on 16.2 volts from "GOLF CART" batteries would likely overpower the systems if used for prolonged periods, not to mention the 12 VDC LED fixtures that won't even operate properly at 13.6 VDC without flickering and smoking within a few hours.

So, to answer your question, at least my opinion, is that hybridizing an RV system by installing "GOLF CART" batteries is a modification that wasn't intended or forseen by WFCO or Progressive Industries when they designed the converter/charger systems for RV's. Our systems are designed to operate on one or two 12 VDC deep cycle "marine" batteries. That's what the converter/charger is designed to support. But in both situations, using PI or WFCO converter chargers to support golf cart batteries "works well enough that no modifications are necessary" Is it "plug and play" Not really, but it is "install and make do and most people never know the difference"....

When we modify our battery bank with "non-standard batteries" we can't expect the converter charger to "automatically reset itself" to the new requirements just like when we go to NAPA and ask for a water pump for our Ford and get home to find the DW's Buick water pump just went out, we can't expect that one we bought to "adapt to pump antifreeze through her engine"....

As for why Trojan, Excide, Interstate and most other battery manufacturers have different plate thickness, different max charging recommendations, different plastic case thickness, different carrying handles is the same as why Fords don't look like Chevys and why one has a 302 engine while the other has a 305 engine. Design engineering "freedom" to adapt for a better product to fit their design criteria.

As for maximum voltage to "de-sulfate" battery plates (14.2, 14.5, 14.7), that voltage changes based on the thickness of the plates, the separation distance between plates, the depth of the plates, clearance between the bottom of the plate and the bottom of the case, the amount of liquid in the cell (cooling capacity) the vent caps and how they help to "recover moisture emitted during charging" and a host of other factors that I have no capacity to understand nor desire to try.... I just know that you can't treat two different design batteries the same and expect similar results in both situations. That IMHO is why the recommended charge voltages are different in batteries that are "built slightly different by the competition"....

Another question: Why do some people like chocolate ice cream and others refuse to eat anything but Fudge Royale???? More or less, the same concept with why do some people install GOLF CART batteries in an RV?

Answer: Because we can...... YMMV
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