Converter issue or wiring?

[garyb1st]

Purchased a WFCO AD (auto detect) converter last September. Despite its auto detect feature it's never gone into the Lithium mode. WFCO has explained how to make that happen but I don't have a way to separate the house from chassis battery so it's still charging on the Lead Acid basis.

For the past month, I've had the Pace parked on my property and plugged into the homes 120v power. Initially it charges my two lithium batteries and kept them at 100%. Then after a day or two, the batteries begin discharging. Initially at more than 1 amp an hour and then when the batteries are at about 65% the discharge fluctuates between .5 and .05 amps per hour. At least according to my Chinese knock off battery monitor.

Does this sound like a converter issue or do I have a wiring issue?

 

[OldWEB]

Purchased a WFCO AD (auto detect) converter last September. Despite its auto detect feature it's never gone into the Lithium mode. WFCO has explained how to make that happen but I don't have a way to separate the house from chassis battery so it's still charging on the Lead Acid basis.

For the past month, I've had the Pace parked on my property and plugged into the homes 120v power. Initially it charges my two lithium batteries and kept them at 100%. Then after a day or two, the batteries begin discharging. Initially at more than 1 amp an hour and then when the batteries are at about 65% the discharge fluctuates between .5 and .05 amps per hour. At least according to my Chinese knock off battery monitor.

Does this sound like a converter issue or do I have a wiring issue?

Why can you not disconnect the two battery systems? It should only be one wire to remove.

While you watch the discharge, go and disconnect various fuses, wires and disconnects, looking for the offending electron kidnapper.

 

[garyb1st]

Why can you not disconnect the two battery systems? It should only be one wire to remove.

I wouldn't know which wire or where to disconnect. Even if I did, wouldn't I have two new issues. First the start battery would only be charged by the alternator. Second that would defeat the ability to use the house batteries to start the engine.

While you watch the discharge, go and disconnect various fuses, wires and disconnects, looking for the offending electron kidnapper.

Sounds like you're suggesting the wiring associated with one fuse could disrupt the power supply from the converter? If that's possible and I find the offending fuse, what's the next step.

The only disconnects are the battery control center. It has two. One for the chassis and one for the house. It's been a problem in the past and was replaced at least once before I purchased the Pace. Is there is a way to determine if it has failed or is failing?

 

[Mark_K5LXP]

Gotta wonder how the converter senses what chemistry is connected. But separate from that you've got two different chemistries connected so solving that disparity is probably the path to take, since one or the other will never be optimally charged that way. Do you need to charge the chassis battery or just maintain it? Seems one of the trickle chargers available for that purpose might be a better way to manage that, as it appears as a load rather than a battery. The boost function is then done through the conventional method of a solenoid.

Mark B.
Albuquerque, NM

 

[OldWEB]

Ahhh.... a BCC, do you know which model?

I misunderstood, it discharges while still plugged into sp? What are the voltages then?

 

[dktool]

You should not have lithiums connected to LA batteries.

 

[garyb1st]

Gotta wonder how the converter senses what chemistry is connected.

The mystery of the WFCO AD converter. According to WFCO, if I fully discharge the lithium batteries and then turn on the converter it is supposed to charge via the lithium profile. From what I've read, that doesn't always work. WFCO has updated the converters firmware and I might try that.

But separate from that you've got two different chemistries connected so solving that disparity is probably the path to take, since one or the other will never be optimally charged that way. Do you need to charge the chassis battery or just maintain it? Seems one of the trickle chargers available for that purpose might be a better way to manage that, as it appears as a load rather than a battery. The boost function is then done through the conventional method of a solenoid.

Agree. I think as OldWEB suggested, the simple solution is to disconnect the house from chassis batteries.

Mark B.
Albuquerque, NM

 

[John From Detroit]

Gotta wonder how the converter senses what chemistry is connected.

Resting voltages are different

 

[garyb1st]

According to WFCO tech support, the converter will output 14.4v for the first 30 seconds, but needs to see a 22 amp draw to maintain it, otherwise the voltage will be reduced to 13.6v. I've never seen 14.4v except when the alternator is running.

My battery monitor system has never seen more than 10 to 15 amps when the batteries are connected to shore power. If I start the engine, the alternator will put out 50 - 60+ amps initially and then taper off to maybe 30 -40. The batteries will be fully charged by the time we get to a campsite.

Yesterday I unplugged the shore power and immediately plugged it back in. The BMS was indicating a charge of less than .1 Ah before unplugging the cord and about 14 Ahs after. The BMS is now indicating the batteries are fully charged. This has happened before and I suspect will happen again. I'll check the batteries every day to see if/when they begin discharging.

Based on this, it sounds like the issue might be related to the Pace's electrical system. I also mentioned this to the WFCO tech and he suggested the converter is working as is should.

 

[Mark_K5LXP]

the converter will output 14.4v for the first 30 seconds, but needs to see a 22 amp draw to maintain it

My battery monitor system has never seen more than 10 to 15 amps

That's a question mark right there. Even my vintage parallax can pump a solid 35+ into a flat battery. Could be explained by a long cable but until that's resolved you have little more than a single stage maintainer and not a multistage charger.

Mark B.
Albuquerque, NM

 

[Gary RV_Wizard]

You should not have lithiums connected to LA batteries.

Well, it's not the ideal situation, but it's pretty much a given in most motorhomes unless both house & chassis batteries are changed to lithium at the same time. The house and chassis batteries get connected in parallel while on shore power, so that the chassis batteries get "maintained" as the house batteries go thru their normal discharge/charge cycles. With a lithium profile in use, a lead-acid chassis battery can get somewhat overcharged. Further, with the engine running, the house & chassis get paralleled. Won't hurt either battery, but there may be some risk of the lithium batteries overloading the engine alternator by suck high amps.

There are various ways around it, but the simple (brute force) method is to disconnect the relay that links the house & chassis banks. If you like, add a 120v-powered trickle-charger on the house circuit to maintain the chassis battery when shore power is present. However, you lose the ability for a manual emergency start via the dashboard Aux Start button, which uses the same relay.

 

[Kirk]

I don't have a way to separate the house from chassis battery

I wouldn't know which wire or where to disconnect.

The easy way to do this while you are testing is to just lift the negative cable from the chassis battery. That won't work long term but could help you to figure things out.

 

[John From Detroit]

Where are you measuring voltage.. Pick one
At the converter's output terminals
At some point inside the RV (A voltage monitor panel)
At the batteries.
All 3 will give different readings the 14.4 is at the converter's terminals.

 

[garyb1st]

That's a question mark right there. Even my vintage parallax can pump a solid 35+ into a flat battery. Could be explained by a long cable but until that's resolved you have little more than a single stage maintainer and not a multistage charger.

Mark B.
Albuquerque, NM

It's been a while but my old WFCO converter had charged at a higher rate from time to time. Don't recall what the amps going in were but they were considerably more than 10 - 15v. It had likely gone into bulk mode. The problem with the WFCO converter is, as best I know, you can't force it into bulk mode. The lithium batteries voltage is 13v even when 70% discharged. That looks like a full battery to a standard lead acid charger.