WFCO 8955 LIS upgrade/Lithium battery issue

[DVeePee]

The trailer is a 2013 E19.

In switching to Lithium batteries (2 100a/h Renogy Smart batteries) I installed the Lithium/LA switched circuit board and converter in the existing WFCO 8955 panel. The batteries are wired with 4 gauge wire, ran through a 60a circuit breaker, and mounted right behind the panel in the driver's side dinette bench. The wire runs are hence very short.

The 12v system works fine. The 110v system works fine. However, the charging system shuts down after moments of operation. It will reset itself after a bit, only to shut down again. After three or so cycles, the 60a breaker will disconnect. Reading the EMS, and an inline ammeter, the system is trying to push 58-59amps into the batteries. The specs for the batteries say that max charging is 55 amps.

When the original batteries are hooked back up (they weren't removed, only disconnected) and the Li/LA switch turned back to LA, the system works fine. Charging is 3-4 amps, with spurts to 14 to boost the charge when needed.

Thus, I can't get the system to operate so as to charge the lithium batteries.

Anyone out there have any suggestions for troubleshooting this? I've got phone and email messages into WFCO tech support, and am awaiting a response. I'm just hoping someone here has some useful advice.

Thank you in advance for any help you can provide.

[Brian B-P]

In "lithium" mode, the charger presumably tries to maintain a fixed voltage output at all times, and that voltage is very high compared to those used with lead-acid batteries. If the lithium-ion batteries are at a low state of charge, that high voltage causes high charging current, which trips the WFCO's protective logic and eventually the breaker. It seems that the charger capacity, wiring, and corresponding protective device (breaker) are just marginal for the size of the batteries when using this primitive charging control method.

My guess is that if you charge the batteries by some other method (solar? external charger?) then try again, much less current will flow and everything will be fine. That's not a solution, only a troubleshooting step.

If all of the wire between the charger-converter and the batteries is 4 gauge you don't need the breaker to have such a low rating (60 A), but even if you change the breaker to something higher (but still safe for the wire), the converter-charger output is still going to exceed 55 amps and apparently this causes problems for the converter-charger.

[Vermilye]

A properly designed converter should not exceed its rated output current, even into a dead short. Current limiting should be built into any design. A lithium battery will draw the full output of a converter until it reaches around 98% of full charge.

I purposely undersized the 35 amp (Progressive Dynamics PD 4635LIV) converter I switched to when I went to lithium batteries because I use a 700/900 watt propane only generator as a method of charging the batteries when I don't have sun for a string of days. A larger converter would draw more input current at 120V than the generator can supply.

While so far I have not needed the generator, when the batteries are down and the only load is the 1 to 2 amp basic load of the appliances, etc on standby, my battery monitor shows between 33 & 34 amps going into the batteries. This is feeding 3 100 amp hour Battleborn batteries, which, when below full, are capable of drawing far more than 35 amps. Again, the Progressive converter is limiting its output current to 35 amps.

[DVeePee]

Thanks for the responses.

FWIW the batteries check out fine, w/no error codes. They were delivered partially charged, at 33 & 41% respectively. So, the controller was working pretty hard to deliver the current that both the batteries would take.

I didn't try separating the batteries and to charge just one, and wonder if doing them one at a time would pull less draw (seems only logical) and allow the system to function.

In that case I could replace the switch with a battery selector and use them one at a time, (I've done that on another trailer and liked that actually).

Right now, I'm charging them with a small portable charger that has lithium mode, but a low rate of charge - this will take a day or two but that's OK. I expect that once they are brought up to 90%+ the charging rate will be quite a bit less.

That still doesn't solve the problem if I want to keep them connected in a bank, but narrows things down and makes it usable until it's corrected.


I agree that the converter should self limit at its rated capacity, and so I'm pretty sure the WFCO board is faulty. I've yet to hear back from them.



Isolating the batteries, increasing the size of the breaker, are easily enough done. Replacing the circuit board is only a small chore, too.



As for charging in the field, I've put in a jack for a portable solar panel, and have a Victron solar charge controller.

And, our tow rig has a 7.4 kw generator, and at idle you can barely hear it, so charging in a campground won't be bugging the neighbors. It brings the golf cart batteries up from 50% in a pretty short time.

I still will need the converter to work right, but I'm on the right track.



Thanks again for your replies.

[Vermilye]

Isolating the batteries will not make a difference. A single lithium battery will draw the full output of your converter until close to 98% full.

Battleborn, as well as some other lithium battery suppliers recommend charging individual batteries to full prior to paralleling them. That won't solve the converter charging problem, but will provide better balancing between batteries.

[Shon414]

Not sure this applies but I wanted to see my behavior
Converter behavior when charging. Same converter,2 Lithium 100 amp, 2021 Escape 19 Eti Setup.
Numbers from a battery monitor.

7:25PM 37% 720W 52A 13.58V
7:53PM 49% 652W 48A 13.59V
8:38PM 67% 613W 45A 13.67V
9:01PM 75% 596W 43A 13.71V
930PM 85% 568W 41A 13.76V

[DVeePee]

Thanks, Vermiyle - You saved me the time and expense of installing a selector, at least at this point.

And thanks Shon414, your setup is virtually the same as mine, and works. This is proof of concept.
I've got some more investigation and head-scratching to do.

[Shon414]

Thanks, please let me know the results. I had not taken my battery's close to zero. I would not be surprised that they may exceed their max 55 Amp for short periods of time. ETI now supplies a Victron 18 amp DCDC charger and I was kind of surprised when Victron exceeded their AMP rating for small periods of time. Victron stated it was normal behavior so the devil is buried in the details. Not sure it matters but ETI provided Lithium batteries are Sun Cycle

[DVeePee]

I'll let you know how this turns out.

Both Renogy and WFCO have replied, with questions that I've answered and I'm waiting to see what they have to say.

I'd think a 55a charger would only produce 55a, no matter how much current to battery could take if supplied. Am I right?

I do have a DC/DC charger that I was going to use with a different tow vehicle. I wonder if it could be used to limit the charge output to 50a?. Obviously I'm easily stumped.

[alanmalk]

Originally Posted by DVeePee

...

Reading the EMS, and an inline ammeter, the system is trying to push 58-59amps into the batteries. The specs for the batteries say that max charging is 55 amps.
...

Here is a quick, dirty and cheap possible solution - if you:
1 Feel comfortable doing some basic wiring changes and installations,
2 Don't mind turning a switch when you arrive at your campsite.

Basically, you are adding some resistance intentionally when charging in order to reduce the current. The switch lets you remove the resistance when boondocking and running of the batteries. The resistance I wrote down is just a guess - I would start with a single 1 ohm, high wattage resistor and add another if necessary. Get second hand resistors off Ebay since they have no moving parts and don't wear out. Mount them somewhere where heat won't cause problems. Spend the real money on a high quality switch from a boating supply company. The "high drain load" in the diagram is your battery.

[DVeePee]

Thanks, that's an approach I hadn't thought of. I'll try it if I don't find some other solution. I'm still wondering why the 55a charger wants to push more power than it's rated for. I know the battery will take just about all you can give it (though it's rated at 50a charging rate) but the charger should go to it's capacity and stop there, should it not? The trickle charger I'm using is happily producing its rated power, and not trying to produce more.

I'm thinking the problem is either with the WFCO control board, or the battery BMS.

But I'm easily confounded on many subjects, and this is one of them.

[Perry Butler]

On my phone and might have missed something, but is your solar running? 55 amps from the charger and additional amps from the solar could explain the extra amps.

Food for thought,

Perry

[DVeePee]

Thanks, but the solar panel isn't hooked up. Right now I'm just using a portable, and it's not deployed.

I appreciate the suggestion, though.
DVP

[Brian B-P]

The difference between DVeePee's system exceeding the converter-charger's rated output and Shon414's system maxing out at slightly under is probably the resistance in the wiring between converter-charger and battery. The undersized stuff installed by ETI is probably throttling the charging current just enough to avoid exceeding the 55 A rating. Perhaps two wrongs (inadequate charger and marginal wiring) can make a right in this case.

Originally Posted by DVeePee

I'd think a 55a charger would only produce 55a, no matter how much current to battery could take if supplied.

Yes, probably, but to the degree of accuracy in this sort of hardware 55 A and 59 A are essentially the same thing.

[DVeePee]

Thanks, Brian.

RE: downsizing the wire to create more resistance: see alanmalk's suggestion a few posts back. Wherein he suggests creating a switchable loop with resistors on one side to bring the current down when charging. The switch permits removal of the resistance whilst consuming battery power, and yet puts it in play whilst charging ; allowing its removal when using battery power.

Thus one can keep the safety and efficiency of the lower resistance wire, but lower the current when charging.

That makes sense, and is much easier/cheaper than rewiring the setup.

The original EFI battery wiring was #10, which seemed way too small, but then it did work for 9 years with the LA batteries....


If resistance the solution, it is quite ironic - the choice of big wire was accommodate the higher current demands of charging the LiPo batteries.



I still think the WFCO charger should self limit at a level that doesn't trip any built-in safety shutdown measure. So far, it's Crickets from them about discussing this situation.


Shon414 - if you're still reading this, I'm curious what size wire EFI used to connect your LiPo batteries.

[Shon414]

Not sure on the ETI Guage used, it's label is some kind of boat wiring. Looked like 8 AWG so could be to small. I don't think there's a fuse after the converter so I could get away with higher amps.
If others read this let me know if there is a fuse I am missing.

[gbaglo]

8 AWG is heavier than 10, is heavier than 12, 14, 16.

[Effie]

Originally Posted by DVeePee

If resistance the solution, it is quite ironic - the choice of big wire was accommodate the higher current demands of charging the LiPo batteries.

I still think the WFCO charger should self limit at a level that doesn't trip any built-in safety shutdown measure. So far, it's Crickets from them about discussing this situation.

Yes it is quit ironic, and I will keep the wires sized to accommodate system demand as you stated.
As other noted a well behaved charger will limit the current depending on the batteries voltage and it's own capacity. As long as the voltage is under the absorption voltage programed it will supply the maximum current it was designed for, lowering the current as the voltage get close to the above absorption level to keep from creating over-voltage in the battery (of course with Lithium the BMS will protect from a misbehaved charger).

I have six Renogy Smart Lithium batteries (not installed in "production") and I'm using a relatively weak Victron 15a charger. Charging individually or all together with 1/0 wires and as expected it always supply 15a until the batteries are around 98%. Obviously charging six batteries takes awhile if they are depleted.

[DVeePee]

Well, I separated the batteries and charged them individually, and things worked fine. They only took about 15-20a charging rate each, so even combined that's a lot less than was being produced to charge them in parallel simultaneously, causing the overcurrent protection to activate. The charger worked quickly even at that rate, and quietly, and never had a hiccup. They are now both at 99%.

I am very relieved I don't have a warranty/replacement issue with either battery or the controller.



The issue was related to the parallel hookup somehow. I had checked my work, and I rechecked the quality of the connections, and all seemed ok. As for the cause, it's got me stumped.



I'm going to go ahead and install a "1-2-both" battery selector switch, wiring each one to the switch instead of in parallel. That way I can charge them individually and draw on either or both - I had that arrangement on another trailer and I liked it.


Someone once said "anything that's not a mystery is pure guesswork" - in this case it applies to me.



Thanks to all who offered their thoughts on the subject.

[Shon414]

Glad you have a solution.
FYI I checked the SunCycle battery spec on ETI provided and it allows100 amp charging.

When I get a chance I will take my batteries down to 10% to see what that batteries pull to get a better profile. See if I burst into flames etc. To cold here to do it now.