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Startling behavior of a RAM 1500 HEMI 5.7 with e-Torque - TV parasitic draw from RV


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2 hours ago, Overland said:

modern electrical systems only provide the voltage that the truck needs at any given time

And, the premiss behind smart alternator systems is that a vehicle's battery does not unnecessarily need to be maintained at 100% SOC, 100% of the time.  A more practical SOC level reduces demand on the charging system, which save energy to drive it, which.......

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17 hours ago, Overland said:

Exactly. Here’s a chart from a 30 minute trip I just made. This is from the battery monitor on an AGM house battery that I have under the back seat of my truck. It’s connected to the starter battery with 2 awg cables and a Victron Cyrix smart relay.  I have a 12 volt fridge attached to the house battery, which is the amperage load that you see on the chart.  I had auto start/stop disengaged.

In this case, I had just made another short highway trip that had already fully charged my start battery, so you don’t see a prolonged period at 14.6+ volts are the start. The house battery was at about 85%.  You can see that the voltage goes into the 14’s for just a brief period before settling in at 12.8 or so. The spikes at the beginning of the drive are in stop-go traffic. (The truck has electric assist on the brakes so those are the spikes.) You’ll see that it evens out for a bit once I get in the highway, but then jumps suddenly to around 13.4 volts. That’s when I turned on my headlights. (BTW, that’s been a GM owners trick for a while to get their voltage up to a charging level.)

So you can see that modern electrical systems only provide the voltage that the truck needs at any given time. They do this regardless of what other load you add to the system.  Unfortunately, while I may be able to trick the system into providing 13.4 volts, that isn’t enough to charge lithiums, since I’d probably only see 13.2 or less at the battery. So yes, a B2B charger is absolutely needed. 
 

 

I believe I see the flaw in your test. An AGM battery at 85% SoC will draw low current. The  #2 wire may also have high voltage drop thus reducing current output. A great test will be to apply a 100A continuous load on the house battery and drive again. I could be wrong here but the higher load should trigger the DC voltage to rise as it attempts to deliver demand current.

The E-Torque 48V battery can not be maintained at 100% SoC as it is used for engine braking also. With low loads it must stop charging or reduce charge current to maintain the proper SoC. Their must always be "room" in the battery for the regenerative braking. This reduction may also affect the DC converter output but only momentarily as the controller regulates the 48V SoC.

This is my understanding but I'm no expert on that system.

Larry Crutcher, GM
LiFeBlue Battery

sales@lifebluebattery.com

(920) LiFePO4
(920) 543-3764

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18 minutes ago, Overland said:

2 gauge cable, less than 10' long?  How many amps do you think I'm pushing through this?

That's a very short run from alternator to house battery.  Are you measuring the entire wire length? At 10' and 100A charge current, you are loosing 2.23% through the wire plus connector and isolator losses. That's probably over 0.5 Volts. If your alternator is at  14.0V then the battery end will only be 13.5V.

We recommend designing for 0.2V drop maximum if you want to charge with high current from an alternator. The important part to understand is the lower the voltage drop in he circuit, the higher current that will be delivered to your house battery.

Larry Crutcher, GM
LiFeBlue Battery

sales@lifebluebattery.com

(920) LiFePO4
(920) 543-3764

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So if you think that a 2 awg cable is undersized for a 10' run, then what size cable do you recommend for the 25' to the trailer battery?  My calculator says you'd need 4/0 to give a 0.2 amp drop at 100 amps.  That's a very safe recommendation, since no one would do it.  Just like adding a constant 100 amp load to my battery is a safe suggestion, since I'm not going to do that either.  

Edited by Overland
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LOL, I cannot imagine running two 4/0 cables all the way from engine to trailer batteries, the logistics are horrible and the cable cost would be outrageous at $5 to $8 per foot.... and those huge copper terminals are pricey too. 

How hard would it be to install a separate small "dumb" alternator on the truck dedicated to just trailer charging, run 00 AWG cables, and use a big DC to DC charger in the trailer to bump up the voltage and control the charge rate? This Redarc dual input unit has 50 amp input and output, combined with a MPPT solar controller for a portable panel. They make smaller ones too.

https://redarcelectronics.com/products/dual-input-50a-in-vehicle-dc-battery-charger

John Davies

Spokane WA

 

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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I think the question is how much of a charge do you really need?  It seems to me that 15-20 amps from your vehicle would be plenty for even those of us who want to optimize everything, for which 6 awg would probably suffice, 4 to be safe.  Then add a B2B charger and you don't have to worry at all what voltage your vehicle is providing.  

I say 15-20 because if your vehicle is producing 12.8 v minimum, say you see 12.5 v at the trailer, 12.5 x 15 amps ÷ 14.4 v charge x 6 hour drive = 78 Ah, which is about a day's usage.  Plus what you get from your solar.

Sure there's always the possibility of snow for four days and you desperately need 300Ah of charge in a 2 hour drive, but I don't know if that's a practical thing to plan around.  

But then sure, more is more - 50 amps would be awesome.  

Edited by Overland
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On 12/8/2020 at 5:44 PM, Overland said:

 

So you can see that modern electrical systems only provide the voltage that the truck needs at any given time. They do this regardless of what other load you add to the system.  Unfortunately, while I may be able to trick the system into providing 13.4 volts, that isn’t enough to charge lithiums, since I’d probably only see 13.2 or less at the battery. So yes, a B2B charger is absolutely needed. 
 

 

Yep. It only keeps the vehicle charged to design - less draw - better efficiency. Need an isolation - and appropriate charge system. Your examples are spot on. TKS.

Cindy,  Russell and  "Harley dog" . Home is our little farm near Winchester TN

2018 Oliver Legacy Elite II - 2018 GMC 2500 Duramax 

"Die young - As late as possible"
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On 12/8/2020 at 10:33 AM, John E Davies said:

Their Zamp PWM solar charge controller will not even charge to 100%, it needs to be changed to a better MPPT unit that will, and Zamp does not even make one that is suitable. Expecting owners to run their generator or plug into shore power is just stupid.

My 30Amp Zamp controller charges my Lithiums up fully.  I ran the test yesterday and today since it was sunny out.  I made sure that solar was the only thing charging.  No problem at all.  Well, technically I only saw 99% before I cut it off, so maybe not 100% - you are sort of correct JD.  🙂

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5 minutes ago, NCeagle said:

My 30Amp Zamp controller charges my Lithiums up fully.  I ran the test yesterday and today since it was sunny out.  I made sure that solar was the only thing charging.  No problem at all.  Well, technically I only saw 99% before I cut it off, so maybe not 100% - you are sort of correct JD.  🙂

Thanks for the info, I was commenting based on reports from another member here. It just goes to show, don’t believe anything you read on the Internet. And don’t repeat other peoples’ comments 😀 I will try to do better.

What battery management system do you have, are you using the battery manufacturer’s app? Does it seem pretty decent?

John Davies

Spokane WA

Edited by John E Davies

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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John,

You likely quoted my previous comment since I have only been seeing 13.3V at the ZAMP display until recently when I checked the controller before towing and saw it at 13.8V.  Note that after 25 minutes of towing the voltage had dropped to 13.3V at the ZAMP (could be parasitic drain to the TV or loss when lifting trailer to hitch).

After being plugged in to shore power I typically see 14.5V, which I consider full.

NCeagle,

What voltage are you seeing when the ZAMP is "full"?

Mike

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1 hour ago, John E Davies said:

Thanks for the info, I was commenting based on reports from another member here. It just goes to show, don’t believe anything you read on the Internet. And don’t repeat other peoples’ comments 😀 I will try to do better.

What battery management system do you have, are you using the battery manufacturer’s app? Does it seem pretty decent?

John Davies

Spokane WA

The other member could be using an older Zamp controller that does not support Lithium.  

I'm using the BMS on the LifeBlue's - along with the 30 Amp Zamp controller on board.  Not sure how they interact, but I assume not all that well since there's a solar cutoff provided to protect against overcharging or keeping the Lithiums "topped off" - up to the owner to keep an eye on the batteries and cut off when necessary.  The app is OK at best - bare bones - it tells the level of charge, the status (charging, standby or discharging), the total capacity of whichever battery you are linked to, the temperature, the discharge / charge rate (amps) along with the battery voltage.  I think it would be a lot better if it would have data collection and trending along with monitoring/notifications.  It's also a pretty weak bluetooth signal - I lose it regularly and can only sporadically get it while in my truck.

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1 hour ago, mjrendon said:

NCeagle,

What voltage are you seeing when the ZAMP is "full"?

Mike, I'm seeing 13.3 when 100% full from multiple sources  - the LifeBlue BMS, the SeeLevel Battery monitor and the Zamp Solar charger.  I can't remember ever seeing anything higher than that but I'll have to double check when it's charging.

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Is this table from LifeBlue?  I've seen 13.4 on the BMS, which is 99% but never on the other monitors.  They are going to vary based on the accuracy of the electronics as well as the length and gauge of the wire, etc., so I trust the BMS the most.  I'll check again tomorrow with some 30 Amp shore power tests since my batteries are close to full now.

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Thanks for posting that chart.  I've seen another that had identical figures, but I was actually going to ask Battleborn next time I spoke with them if they had one of their own.  

When I've spoken with them on the phone they've always said "13.4 or so" as what their batteries should settle into when full.  That's the voltage I see now, but when they were brand new I'm pretty sure it was 13.6.

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According to the LifeBlue data sheet, 13.32 Volts is the full charge resting voltage, so that's what I'm seeing at rest.  When charging, I'm seeing 3.7V when the battery is at 99% - that's in the float range.  I'll check next time I'm low to see what absorb voltage is.

http://www.lifebluebattery.com/ewExternalFiles/LB12200-HC Data Sheet-2.pdf

Edited by NCeagle

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47 minutes ago, NCeagle said:

According to the LifeBlue data sheet, 13.32 Volts is the full charge resting voltage, so not the same as Battleborn, which according to the chart would only be 92% or so with 13.32 Volts

ZAMP specifies lithium charging absorption at 14.4V and a float of 13.6V.

 

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13 hours ago, mjrendon said:

The table was sourced from Battleborn, but was published on this website.

LithChartBattleBorn.jpg

@LiFeBlueBattery, two quick questions.

1. Is there a similar chart for the LifeBlue batteries that we can use as a reference?  This one is specific to the BattleBorn batteries.

2. Does LifeBlue have a recommendation for a solar charger / controller?  Zamp seems to be basic and probably not the most efficient?

Thanks!  

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I do not believe that the ZAMP controller is inappropriate for LifeBlue or Battleborn batteries (as it is spec'ed).  Both batteries have BMS to prevent over/under charging and excessive charge/discharge rates. Some BMS also provide cell balancing capabilities.

Advantages of the ZAMP controller is that it is relatively simple to setup and use and it is effective.  Its disadvantages are that it is both less efficient and customizable than other options.

Edited by mjrendon
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My SoC is now 100% and reads 14.0 Volts.  Interestingly, I was not able to get the batteries to 100% with the Xantrex inverter/charger - it stayed at 99% and the BMS continued to go into "standby" while the voltage would bounce between 3.7 and 3.6.  I turned on the solar and it ran the voltage up to 14.0 and the BMS is reporting 100% and kicking into into standby.  The amps coming in through the solar are still available - I turned on a bunch of things and the solar was powering rather than the battery.  Pretty good!!

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2020 Elite II, Hull 688 --- 2021 Silverado 2500HD, 6.6L Duramax Diesel

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You might try disconnecting the solar for a bit just to see what the batteries settle in at.  Otherwise, I'm glad to see that the Zamp controller is indeed providing a decent voltage.

Back to the previous discussion, I found this video today that gives a nice primer on battery to battery chargers, and also a good look at the Victron Orion B2B unit.  You guys know that I'm a sucker for Victron gear.  $220 is the best price I can find for the 30 amp version.  They also make an 18 amp model for $165.

 

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