Alternator charging question.

[Artie]

Any reason my aux battery voltages are much higher in the morning versus a few hours later into a drive?

Battery 1 is aux battery, AGM.
Battery 2 is the factory start battery and anderson plug to be mentioned further down is connected to this battery as instructed by Redarc for charging a RedVision and manager 30 for my camper. I realize this isn’t the battery in question but there are some charging issues i’m having with my camper and I’m curious if there is a charging behavior from the alternator that could be contributing to it.

Batteries on camper are lithium.

This is 9am outside Uravan, CO

This is 3 hours later in the same area, just on the Rimrocker trail:

The main issue this is causing is when I pull my camper the voltage to the anderson plug drops so low that my camper Redarc RedVision won’t charge from the vehicle. This lower voltage does not show at the battery gauge pictured but shows on a volt meter at the plug on the manager 30. In fact, when connected to the vehicle, the voltage on that anderson plug is reading 11 volts at the Redarc manager 30 connection that is fed from the LC bumper which is connected to the start battery. When the camper is unplugged the voltage goes back up to 13.5. This voltage drop happens as soon as the manager 30 sees the vehicle charging source and initiates charging.

It could be the cable on the camper, it’s one single run and has been trouble free for 3 years. These issues are completely new to this trip so I haven’t ruled this out, I just can’t really test in the field and since I’m seeing voltage variations I’m curious about the charging behavior of the alternator. I should add that we are experiencing far hotter temps on this trip than we have in the past when using this setup.

One of the redarc customer service guys says the LC alternator is not a smart variable voltage alternator but will vary output based on temperature. The shop that installed the dual battery setup and has done many LC installs says it is smart alternator.

I’m kinda at a loss and came to the Mud brain trust to explain How the charging works and if there is a better option to supply a constant voltage to my anderson plug.

 

[Sandroad]

I'm not sure about the connection to the camper from the vehicle, but you mentioned the LC bumper. If that's the 7-pin connector, bad connections there with the trailer power supply pin can cause the voltage drop when plugged in. In the RV world, those 7 pin connectors are the cause of a lot of problems from corrosion/dirt/wear. Solution is a complete cleaning and lube and/or replacement.

 

[04UZJ100]

Any reason my aux battery voltages are much higher in the morning versus a few hours later into a drive?

Battery 1 is aux battery, AGM.
Battery 2 is the factory start battery and anderson plug to be mentioned further down is connected to this battery as instructed by Redarc for charging a RedVision and manager 30 for my camper. I realize this isn’t the battery in question but there are some charging issues i’m having with my camper and I’m curious if there is a charging behavior from the alternator that could be contributing to it.

Batteries on camper are lithium.

This is 9am outside Uravan, CO
View attachment 3073114

This is 3 hours later in the same area, just on the Rimrocker trail:
View attachment 3073118


The main issue this is causing is when I pull my camper the voltage to the anderson plug drops so low that my camper Redarc RedVision won’t charge from the vehicle. This lower voltage does not show at the battery gauge pictured but shows on a volt meter at the plug on the manager 30. In fact, when connected to the vehicle, the voltage on that anderson plug is reading 11 volts at the Redarc manager 30 connection that is fed from the LC bumper which is connected to the start battery. When the camper is unplugged the voltage goes back up to 13.5. This voltage drop happens as soon as the manager 30 sees the vehicle charging source and initiates charging.

It could be the cable on the camper, it’s one single run and has been trouble free for 3 years. These issues are completely new to this trip so I haven’t ruled this out, I just can’t really test in the field and since I’m seeing voltage variations I’m curious about the charging behavior of the alternator. I should add that we are experiencing far hotter temps on this trip than we have in the past when using this setup.

One of the redarc customer service guys says the LC alternator is not a smart variable voltage alternator but will vary output based on temperature. The shop that installed the dual battery setup and has done many LC installs says it is smart alternator.

I’m kinda at a loss and came to the Mud brain trust to explain How the charging works and if there is a better option to supply a constant voltage to my anderson plug.

How did the ambient temperature change? Do you have battery temperature monitors?

As things warm, alternator output and battery output will decrease.

 

[TeCKis300]

To answer your question - it's a temperature compensating alternator. Even if it's a smart alternator, the charging architecture would be similar to manage charging.

Reason the alternator output voltage drops is due to temperature compensation. Batteries require different charge profiles and compensation for temp, which is why you see the voltage high at startup, versus warm. This is expected and normal.

Did you mix up the batts in the description?
- Battery 1 looks to be the starting battery. Seeing a high of 14.7V at startup and 13.5V when warm as fed directly from the alternator
- Battery 2 is the AGM, looks charged and stable at 13.7V?
Both things look healthy and normal there.

Regarding your bumper mounted Anderson. I would expect some degree of voltage drop when charging as the Manager 30 would pull upwards of 30amps to charge the lithium and power various electronics. Probably closer to 50 amps at full tilt. That's okay in and of itself.

11V does seem problematic and suggests there's too much resistance in the wiring somewhere. What gauge wire did they run to supply the bumper mounted Anderson? How is the ground wire from that Anderson run and where does it terminate? I would agree with you that it's where I would look first. Another complexity could be the ground on the 7-pin. Is the Anderson ground and 7-pin ground tied together? That would be another area I would look closely at.

It's possible and likely some wire segment or connector has been compromised.

 

[Artie]

How did the ambient temperature change? Do you have battery temperature monitors?

As things warm, alternator output and battery output will decrease.

Ambient temp went from 70° to 85°.

There is a battery temp sensor on the RedVision and they are at 90-95°.

 

[Artie]

To answer your question - it's a temperature compensating alternator. Even if it's a smart alternator, the charging architecture would be similar to manage charging.

Reason the alternator output voltage drops is due to temperature compensation. Batteries require different charge profiles and compensation for temp, which is why you see the voltage high at startup, versus warm. This is expected and normal.

Did you mix up the batts in the description?
- Battery 1 looks to be the starting battery. Seeing a high of 14.7V at startup and 13.5V when warm as fed directly from the alternator
- Battery 2 is the AGM, looks charged and stable at 13.7V?
Both things look healthy and normal there.

Regarding your bumper mounted Anderson. I would expect some degree of voltage drop when charging as the Manager 30 would pull upwards of 30amps to charge the lithium and power various electronics. Probably closer to 50 amps at full tilt. That's okay in and of itself.

11V does seem problematic and suggests there's too much resistance in the wiring somewhere. What gauge wire did they run to supply the bumper mounted Anderson? How is the ground wire from that Anderson run and where does it terminate? I would agree with you that it's where I would look first. Another complexity could be the ground on the 7-pin. Is the Anderson ground and 7-pin ground tied together? That would be another area I would look closely at.

It's possible and likely some wire segment or connector has been compromised.

Popped hood to confirM. Bat1 is group 35 AGM aux battery, I’m sure it’s battery one as it’s the one that dips when the compressor runs.

Bat2 factory Toyota lead acid.

On LC cable for anderson is 6awg. Ground is to the outside of the frame about 12 inches from plug, redarc recommended ground to chassis versus a run back to the battery.

On Camper anderson cable is 6 awg and grounded to redarc ground shunt.

I am not sure where the 7 pin is ground but I will look. I’ve checked the anderson and they both look fine. I just pulled my panels in the camper and went through those connections as well… that was a treat while at camp in Moab, talk about a toxin release sweat lodge.

 

[TeCKis300]

Popped hood to confirM. Bat1 is group 35 AGM aux battery, I’m sure it’s battery one as it’s the one that dips when the compressor runs.

Bat2 factory Toyota lead acid.

On LC cable for anderson is 6awg. Ground is to the outside of the frame about 12 inches from plug, redarc recommended ground to chassis versus a run back to the battery.

On Camper anderson cable is 6 awg and grounded to redarc ground shunt.

I am not sure where the 7 pin is ground but I will look. I’ve checked the anderson and they both look fine. I just pulled my panels in the camper and went through those connections as well… that was a treat while at camp in Moab, talk about a toxin release sweat lodge.

Would you have a system diagram?

Maybe inconsequential to your issue at the trailer, but what is charging your AGM battery? The higher voltage would be whatever DC-DC charger that is tendering your AGM. That's normal as it would be a smart charger with temp and charge profile compensation. Basically the AGM is almost charged and the DC-DC charger is reducing its output.

Back to trailer charging, key symptom is 11V as you suspect. When you see that, what's the voltage at the starter battery? I assume it's 13.7V that is indicated by the pictures earlier? That would suggest the issue is not the supply (alternator), but the wiring to the Anderson. Something inline with that is failing with high resistance - wire, connector, etc.

Best way to debug that is to use a voltmeter when the trailer draw (charging) is active. Check voltages down the line, starting with the terminals at the starting battery. It very well could be the chassis grounds as well, make sure they are bolted down tightly. Terminations are on clean metal, free of paint and corrosion. Check the ground pigtail that goes between the starting battery and inner fender.

 

[Artie]

Would you have a system diagram?

Maybe inconsequential to your issue at the trailer, but what is charging your AGM battery? The higher voltage would be whatever DC-DC charger that is tendering your AGM. That's normal as it would be a smart charger with temp and charge profile compensation. Basically the AGM is almost charged and the DC-DC charger is reducing its output.

Back to trailer charging, key symptom is 11V as you suspect. When you see that, what's the voltage at the starter battery? I assume it's 13.7V that is indicated by the pictures earlier? That would suggest the issue is not the supply (alternator), but the wiring to the Anderson. Something inline with that has high resistance - wire, connector, etc.

Best way to debug that is to use a voltmeter when the trailer draw (charging) is active. Check voltages down the line, starting with the terminals at the starting battery. It very well could be the chassis grounds as well, make sure they are bolted down tightly. Terminations are on clean metal, free of paint and corrosion. Check the ground pigtail that goes between the starting battery and inner fender.

I do not have a system diagram, one regret I have from this build. However, I am in frequent contact with the electrician and I’ve checked the grounds as you mentioned on the vehicle side and they are all as they should be.

I’m using a redarc dc-dc charger.

Voltage is 13.7 at battery when connected to manager 30. At this point in time I’ve only checked in line is at the manager 30. I need to find a good place to get underneath the camper to check there.

I wonder if the 6 awg is enough.

This has not happened on previous trips. One thing I should mention is I have moved my 1000w inverter ground from the camper battery to the manager 30 ground shunt. I did this for 2 reasons, the redarc contact said this is how they recommend it and now I get accurate state of charge when using inverter. I used the recommended wire size of 1/0… it’s the largest ground cable in the system and shared the shunt with 3 other 6 awg cables. I wonder if I should just remove this from the equation and see what happens.

 

[TeCKis300]

This stuff can get complex fast on the trailer side. I'm not familiar with the Manager 30 but I do have a large lithium system in my own Airstream with shunt and larger inverter.

Would be worthwhile to understand if your trailer battery system is fully isolated from the tow vehicle properly. That is the DC-DC charger (Manager 30), is the single go between of the tow vehicle/Anderson side, to the trailer battery/electrical side. There shouldn't be any bridging/bonding of grounds, and I'm partially wondering if they bridged the Anderson/TV ground to the 7-pin ground/trailer grounding bus.

Did your trailer come originally with lithiums? Or did you upgrade?

4AWG would be better, but 6AWG should be okay to feed a manager 30 that should draw something like 40 amps to feed its 30amp battery charging capability.

 

[Artie]

This stuff can get complex fast on the trailer side. I'm not familiar with the Manager 30 but I do have a large lithium system in my own Airstream with shunt and larger inverter.

Would be worthwhile to understand if your trailer battery system is fully isolated from the tow vehicle properly. That is the DC-DC charger (Manager 30), is the single go between of the tow vehicle/Anderson side, to the trailer battery/electrical side. There shouldn't be any bridging/bonding of grounds, and I'm partially wondering if they bridged the Anderson/TV ground to the 7-pin ground/trailer grounding bus.

Did your trailer come originally with lithiums? Or did you upgrade?

4AWG would be better, but 6AWG should be okay to feed a manager 30 that should draw something like 40 amps to feed its 30amp battery charging capability.

To the best of my knowledge, the Manager 30 is completely separate from the TV wiring. The all the 7 pin wiring grounds to the 7 pin junction box and there is no chassis grounds for any wiring, it all comes back to the manager 30 for the 12 colt system or back to the 7 pin junction box for that wiring. The only other ground is for the 110v shore power and I’m not sure where that goes. I left every bit of that alone when. I made the switch to the manager 30.

It originally came with Lithiums

The Redarc kit is not then”factory” set up, it came with its own stuff that was originally built for the South African market but modified for the US to run on 110v. Long story short I had an issue with that South African system and switched to the redarc setup, which I installed myself. I’m likely to blame for these issues but it’s been flawless until yesterday and I installed it last October.

 

[Artie]

@TeCKis300

You might find this interesting.

I connected tonight when it was cooler and camper batteries were charged more… it’s taking amps from the vehicle now. Battery temp 84° Outside temp 80° now, before when it charging battery 91° outside 91°

That doesn’t seem like a big different in temps but I’m not sure what the thresholds for the lithiums or alternator are.

 

[TeCKis300]

@TeCKis300

You might find this interesting.

I connected tonight when it was cooler and camper batteries were charged more… it’s taking amps from the vehicle now. Battery temp 84° Outside temp 80° now, before when it charging battery 91° outside 91°

That doesn’t seem like a big different in temps but I’m not sure what the thresholds for the lithiums or alternator are.

Hrmm...those temps should be well within battery operational envelopes. What type of lithium batt do you have in the trailer? Lithium or LiFePO4?

That must be something translating South African, Australian, US wiring standards!

How is the positive wire sources hooked into the trailer? Where does the 7-pin positive go to? Does that tie into the positive (+) bus bar that is tied into the trailer battery?

 

[Artie]

Hrmm...those temps should be well within battery operational envelopes. What type of lithium batt do you have in the trailer? Lithium or LiFePO4?

That must be something translating South African, Australian, US wiring standards!

How is the positive wire sources hooked into the trailer? Where does the 7-pin positive go to? Does that tie into the positive (+) bus bar that is tied into the trailer battery?

Batteries are LiFePO4

The wiring was interesting… the 7 pin uses a totally different color designation but the same colors. Some are the same, blue for brakes… but the others are not and the distribution box is wired all crazy. I had to use a volt meter to determine what was what. The positive on the 7 pin went to the box and no further. I ended up running it to the manager 30 for the ignition trigger.

The other positives are all on one batter post. So it’s a 2 battery setup, one batter wired to the other so that’s one positive and one negative ran to the kitchen side battery, than that battery has the positive for the inverter and the positive for the redarc all on the one post. It’s tight in there and getting a bus bar would be tough. It was set up with it wired to the posts like that so I didn’t change it. All the grounds go to the ground shunt for the manager 39. Pictured below.

On that shunt you will find inverter negative, solar, bumper anderson, and redarc on the “GND” side and the other goes to the camper battery.

It’s all pretty straight forward but it looks like a mess because inside that panel is wiring for the manager 30 along with everything in this lower panel… this is just before I made the swap so the top is completely different now. Manager 30 in the bottom, RedVision is in the top.

All this to say that if those temps aren’t anything to cause concern over then there’s still something afoot with the wiring. Sounds like I need to get under there with my meter and do some probing.

 

[Sandroad]

The sequence of events may offer a clue. If this is the first trip you’ve had the problem, what changes were made prior to the trip?

For both this issue, future troubleshooting, and future changes, would be hugely helpful (essential really) to have a system diagram. Even if you just use a big sheet of paper and colored pencils, I strongly suggest you get your setup diagrammed.

 

[Artie]

The sequence of events may offer a clue. If this is the first trip you’ve had the problem, what changes were made prior to the trip?

For both this issue, future troubleshooting, and future changes, would be hugely helpful (essential really) to have a system diagram. Even if you just use a big sheet of paper and colored pencils, I strongly suggest you get your setup diagrammed.

100% agree on the diagram, this will be done once we return home in a couple weeks.

There are two things that are I would consider ‘changes’:
1. On camper: moved ground for inverter from batter camper battery to manager 30 ground shunt. This allows for battery manager to see inverter use and calculate state of charge.
2. Trip duration and temps. This is far hotter than we’ve ever experienced. It should be noted that charging was fine for a week and 1800 miles, issues started as we left Colorado and entered Utah while running Rimrocker trail.

I can easily eliminate the ground and and see if that makes a difference.

 

[Artie]

Update for this morning is that charging is working. Temps are lower, 67 outside and battery 75. Not pulling max amps of 32 as I’ve seen in the past but this may keep me from running the generator at our next stop.

I’m going to take advantage of this parking lot and cooler temps to crawl around and probe with my meter and visually inspect anderson wire from LC battery back as far as I can.

We have two weeks left on this trip… this is our second time to Moab and both have been plagued with bizarre travel oddities. Maybe just some bad juju around these parts, idk…. we’re headed south to Bears Ears today just to be safe.

 

[mep1811]

What year 200 series?

Have you changed the alternator fuse for an alternator voltage booster? I replaced my fuse with the HKB booster and that eliminated my charging issues. I have AGM dual batteries and charge my trailer through a separate circuit.

HKB Electronics

The Alternator Voltage Booster was the first of its type on the market and is the only unit available that was has been purpose built for alternator voltage boosting.

www.hkbelect.com

Dirty Parts

dirtyparts.com

 

[Artie]

What year 200 series?

Have you changed the alternator fuse for an alternator voltage booster? I replaced my fuse with the HKB booster and that eliminated my charging issues. I have AGM dual batteries and charge my trailer through a separate circuit.

HKB Electronics

The Alternator Voltage Booster was the first of its type on the market and is the only unit available that was has been purpose built for alternator voltage boosting.

www.hkbelect.com

Dirty Parts

dirtyparts.com

It’s a 2021.

I have not changed any of that stuff but will be looking to now. What exactly does this task entail?

 

[Artie]

So probing under the car shows:
Battery 13.35
Bumper behind anderson plug:12.95
3 feet into trailer past anderson plug : 11.36
Manager 30: 11.07

Issue must be with plug at bumper.

Editing to add that when bumper plug is unplugged the voltage is same as at battery….

Maybe too much resistance and need larger cable?

 

[TeCKis300]

So probing under the car shows:
Battery 13.35
Bumper behind anderson plug:12.95
3 feet into trailer past anderson plug : 11.36
Manager 30: 11.07

Issue must be with plug at bumper.

Editing to add that when bumper plug is unplugged the voltage is same as at battery….

Maybe too much resistance and need larger cable?

Good sleuthing.

What size Anderson plug and what size wire on the trailer side? Does look like potentially some resistance there? Does anything feel warm/hot to the touch? Plug or wire? That's where most of the resistance will be. Anderson pins are usually self cleaning and pretty robust unless tweaked. I would possibly suspect the wire behind that - either termination on the anderson pins or on the trailer panel side.

In regards to the inverter ground change, that doesn't sound like a problem as that's how they're typically hooked up, including in my own setup.