Lithium battery drain to TV

[Dream]

Recently, I queried Battle Born lithium battery regarding disconnecting the 7 pin while parked. Their answer was yes it should be done since the tow vehicle would rest at a lower voltage and drain the lithium batteries. The #4 pin is energized while the truck is turned off. Couple of thoughts: How large of a drain on the lithium will occur? Significant for a day or two or large drain quickly to where the truck won't start. What if plugged into shore power? Does that still drain the truck batteries via the lithium? Does the drain actually hurt either batteries, the truck or the lithium? How can I measure the drain on the truck's battery while stationary without the engine running? Not very electrically minded so I need advice. Thanks

[tdf-texas]

Originally Posted by Dream

Recently, I queried Battle Born lithium battery regarding disconnecting the 7 pin while parked. Their answer was yes it should be done since the tow vehicle would rest at a lower voltage and drain the lithium batteries. The #4 pin is energized while the truck is turned off. Couple of thoughts: How large of a drain on the lithium will occur? Significant for a day or two or large drain quickly to where the truck won't start. What if plugged into shore power? Does that still drain the truck batteries via the lithium? Does the drain actually hurt either batteries, the truck or the lithium? How can I measure the drain on the truck's battery while stationary without the engine running? Not very electrically minded so I need advice. Thanks

The more important question is - does you TV have a relay that disconnects the 7-pin when the TV is turned off.

If the answer is yes (most TVs do), then don't worry about it - the TV and the Battleborn are not connected when the TV is off and there isn't any drain path.

If the answer is no, you might want to consider adding one.

[Vermilye]

My solution to this problem (and to get a higher voltage from the tow vehicle to the lithium batteries) was to install an inexpensive DC to DC converter in the trailer's tow vehicle charge line. The DC to DC converter is a one way device, preventing the tow vehicle from discharging the trailer batteries. If you do this you must also provide a different wire for the trailer's breakaway switch since it is powered by the trailer charge line & won't be connected to the trailer batteries after the addition of the converter.

This also prevents overloading the tow vehicle charging system. Lithium batteries draw as much current as possible until near full. In some cases this has overloaded the tow vehicle alternator. Usually the less than adequate wire sizes & length limits charging current, but in a properly sized system this can be a problem.

[tdf-texas]

Originally Posted by Vermilye

My solution to this problem (and to get a higher voltage from the tow vehicle to the lithium batteries) was to install an inexpensive DC to DC converter in the trailer's tow vehicle charge line. The DC to DC converter is a one way device, preventing the tow vehicle from discharging the trailer batteries. If you do this you must also provide a different wire for the trailer's breakaway switch since it is powered by the trailer charge line & won't be connected to the trailer batteries after the addition of the converter.

This also prevents overloading the tow vehicle charging system. Lithium batteries draw as much current as possible until near full. In some cases this has overloaded the tow vehicle alternator. Usually the less than adequate wire sizes & length limits charging current, but in a properly sized system this can be a problem.

Jon, it's amazing how often tunnel vision kicks in. A parked vehicle should have the disconnect relay that would take care of this but it doesn't do anything for when the TV is running. The DC to DC converter seems to be really needed when lithium batteries are installed.

Lithium batteries really requires some thought about how a proper installation should look like!

[tdf-texas]

Oh, here is a example diagram of trailer wiring with separate emergency brake wiring.

[Dream]

Thanks Vermilye and tdf Texas. I did have ETI replace the WFCO in the trailer with the WF8955. Yes the #4 pin of the 7 pin is hot when my GMC Sierra is turned off. I had thought of just placing a disconnect in the #4 pin line to the trailer to use when parked rather than unplugging.

[Brian B-P]

Originally Posted by tdf-texas

A parked vehicle should have the disconnect relay that would take care of this but it doesn't do anything for when the TV is running.

And it doesn't need to do anything. With the tow vehicle running its electrical system will be at a high enough voltage that even a fully-charged lithium (4-cell LiFePO4) battery would discharge very little if at all.

Still, I agree that a suitable DC-to-DC charger is desirable.

[Vermilye]

Originally Posted by Brian B-P

And it doesn't need to do anything. With the tow vehicle running its electrical system will be at a high enough voltage that even a fully-charged lithium (4-cell LiFePO4) battery would discharge very little if at all.

Still, I agree that a suitable DC-to-DC charger is desirable.

Depends on your tow vehicle. Most trucks that have a tow/haul switch will keep the voltage to pin 4 high enough, but lots of modern SUVs will drop the charging voltage as soon as possible after starting the vehicle in order to save fuel.

Assuming you have solar, when the alternator voltage drops below the typical 14.4 charging voltage of the trailer's solar system, it will be charging both the lithium batteries & the tow vehicle battery through the charge line. A DC to DC converter prevents this. A diode would do the same, but produce a .7V drop, something you generally want to avoid.

[rubicon327]

Originally Posted by Dream

I did have ETI replace the WFCO in the trailer with the WF8955.

I’m confused by this comment. The stock WFCO power center is the WF-8955. A lithium compatible version appears to be the WF-8950L2PEC. What did Escape do and why?

[alanmalk]

Originally Posted by Vermilye

...

Assuming you have solar, when the alternator voltage drops below the typical 14.4 charging voltage of the trailer's solar system, it will be charging both the lithium batteries & the tow vehicle battery through the charge line. A DC to DC converter prevents this. A diode would do the same, but produce a .7V drop, something you generally want to avoid.

For someone who wants to experiment, here is a link to an ideal (0V drop, 50 amp) diode.
https://www.amazon.com/dp/B084GNR7M4...xpY2s9dHJ1ZQ==

I have seen others for sale outside North America with ratings as high as 600 amps.
--
Alan

[TTMartin]

Originally Posted by Dream

Recently, I queried Battle Born lithium battery regarding disconnecting the 7 pin while parked. Their answer was yes it should be done since the tow vehicle would rest at a lower voltage and drain the lithium batteries. The #4 pin is energized while the truck is turned off. Couple of thoughts:

The resting voltage of a fully charged Battle Born Battery is 13.5 to 13.6 volts.

The resting voltage of a fully charged flooded lead acid battery is 12.6 to 12.7 volts.

Originally Posted by Dream

How large of a drain on the lithium will occur? Significant for a day or two or large drain quickly to where the truck won't start.

Power from the lithium battery will be moving toward the nonlithium battery, so there is no reason the truck wouldn't start.

Originally Posted by Dream

What if plugged into shore power? Does that still drain the truck batteries via the lithium?

It doesn't drain the truck battery it drains the lithium battery. When plugged into shore power you will be over charging your truck battery, assuming you have a converter with the proper lithium charge profile

Originally Posted by Dream

Does the drain actually hurt either batteries, the truck or the lithium?

Yes, it can over charge the truck batteries. This can reduce its life

Originally Posted by Dream

How can I measure the drain on the truck's battery while stationary without the engine running? Not very electrically minded so I need advice. Thanks

Again, power will move toward the truck battery from the lithium battery.

[TTMartin]

Originally Posted by vermilye

my solution to this problem (and to get a higher voltage from the tow vehicle to the lithium batteries) was to install an inexpensive dc to dc converter in the trailer's tow vehicle charge line. The dc to dc converter is a one way device, preventing the tow vehicle from discharging the trailer batteries. If you do this you must also provide a different wire for the trailer's breakaway switch since it is powered by the trailer charge line & won't be connected to the trailer batteries after the addition of the converter.

This also prevents overloading the tow vehicle charging system. Lithium batteries draw as much current as possible until near full. In some cases this has overloaded the tow vehicle alternator. Usually the less than adequate wire sizes & length limits charging current, but in a properly sized system this can be a problem.

^^^ t h i s ^^^

[Dream]

rubicon327 My understanding was the wf8955 was an upgrade from the standard and according to WFCO "Use any existing WFCO power center or converter to safely charge your lithium batteries. Our standard products will charge your lithium-ion battery, without damage or excessive heat so you will not have to worry about where your power supply will be coming from. The following products are lithium-ion compatible:" the WF8900 series was listed as lithium compatible, including the 8955.

[rubicon327]

Originally Posted by Dream

rubicon327 My understanding was the wf8955 was an upgrade from the standard and according to WFCO "Use any existing WFCO power center or converter to safely charge your lithium batteries. Our standard products will charge your lithium-ion battery, without damage or excessive heat so you will not have to worry about where your power supply will be coming from. The following products are lithium-ion compatible:" the WF8900 series was listed as lithium compatible, including the 8955.

Ok thanks. I know for certain the standard WFCO used by Escape has been the WF-8955. Maybe the upgrade for use with lithium is the WF-8955LiS? Has a switch that changes the charge profile.
https://wfcoelectronics.com/product/wf-8955lis/

[Vermilye]

Originally Posted by Dream

rubicon327 My understanding was the wf8955 was an upgrade from the standard and according to WFCO "Use any existing WFCO power center or converter to safely charge your lithium batteries. Our standard products will charge your lithium-ion battery, without damage or excessive heat so you will not have to worry about where your power supply will be coming from. The following products are lithium-ion compatible:" the WF8900 series was listed as lithium compatible, including the 8955.

While on paper, the specifications of the WF8955 indicates that it will fully charge a lithium battery if is goes into the bulk mode (specified at 14.4V). I've seen 14.2V - 14.6V specified for bulk charging the various brands of lithium batteries. The problem is the WF8955 is incredibly difficult to get into the bulk, or even the absorption mode (specified at 13.6V). It likes to cruise along at float (specified as 13.2V), too low to fully charge a lithium battery.

When I used it to charge my lead acid batteries, I never saw it go into bulk and rarely into absorption. I changed the bottom of my converter to a Progressive Dynamics PD 4635LIV when I added my lithium batteries, so I don't know how well the WF8955 would have worked.

While it is possible that the high demand of lithium batteries would push the WF8955 into the bulk stage, I'd like to see some examples. Although I don't have a great deal of comfort in WFCO products, if I was going to stick with the WFCO line, I'd request the WF-8950L2PEC power center, which WFCO says is designed for lithium batteries.

[Greg A]

Jon’s DC to DC is the way most of the lithium solutions on the web are installed for the reasons listed above. I just got the one he uses thru Wal mart for $60 so not a huge expense to set things up well.
My buddy that was at Q last year just didn’t bother hooking up the charge line from the tow since he has about 900w of solar on the roof, he didn’t need it.

[Dream]

Ok, Can't say I didn't warn you all about my being electrical handicaped and apparently can't read either. I just re-read my build sheet. The one installed in my trailer is the WF8955Lis and not the WF8955. Now just what product by name and number and exactly where do I need to install the DC to DC. (to make an excuse for myself, my last trailer was a long time ago and much simpler)

[TTMartin]

Originally Posted by Dream

Ok, Can't say I didn't warn you all about my being electrical handicaped and apparently can't read either. I just re-read my build sheet. The one installed in my trailer is the WF8955Lis and not the WF8955. Now just what product by name and number and exactly where do I need to install the DC to DC. (to make an excuse for myself, my last trailer was a long time ago and much simpler)

Related post in another thread: DC-DC Charger Update from ETI

Have you taken delivery of your trailer?

[Dream]

TTMartin, trailer is completed and leaves Chilliwack December 16/17. I hope the Lithium changes in the referenced post applied to my trailer. I had two Battle Born batteries delivered to ETI in late November for install. The trailer was started in early November and the Lithium decision was made several of months ago with ETI approval. To continue the flooring discussion. We elected to use the Armstrong Stratamax Good x4475 Parchment and ordered it from Olsen Flooring. Maria was very helpful. We visited suppliers here in Texas to pick it out and while I'm sure it is not as robust as some it was quite better than the ETI samples. If I can figure out how to post a picture I will.

[TTMartin]

Originally Posted by Dream

TTMartin, trailer is completed and leaves Chilliwack December 16/17. I hope the Lithium changes in the referenced post applied to my trailer. I had two Battle Born batteries delivered to ETI in late November for install. The trailer was started in early November and the Lithium decision was made several of months ago with ETI approval. To continue the flooring discussion. We elected to use the Armstrong Stratamax Good x4475 Parchment and ordered it from Olsen Flooring. Maria was very helpful. We visited suppliers here in Texas to pick it out and while I'm sure it is not as robust as some it was quite better than the ETI samples. If I can figure out how to post a picture I will.

You might want to contact ETI and ask them if the DC to DC charger was installed (I doubt it since you supplied the batteries) and if not, could they do a last minute install of one prior to shipping it out. I'm guessing they won't be able to, but, it never hurts to ask.