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Old 01-18-2022, 02:40 PM   #1
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Switching to LiFePO4 in TT, do I need to protect alternator in TV?

I'm planning to replace the two lead acid batteries in my TT with two LiFePO4 (100AH each) and I've been reading the forums and anything else I can find for info. I know I have to replace the original converter (WFCO 8955) with one capable for lithium, probably a PD4655L and I'll add a battery monitor, probably a Victron BMV-712. I'm wondering if I need to do something to protect the alternator in my TV (a 2013 Honda Pilot) while towing. I'm concerned the current draw for charging 2 LiFePO4 100A batteries might draw too much current and damage it. Any thoughts or advice would be welcome.
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Old 01-18-2022, 02:55 PM   #2
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I'm planning to replace the two lead acid batteries in my TT with two LiFePO4 (100AH each) and I've been reading the forums and anything else I can find for info. I know I have to replace the original converter (WFCO 8955) with one capable for lithium, probably a PD4655L and I'll add a battery monitor, probably a Victron BMV-712. I'm wondering if I need to do something to protect the alternator in my TV (a 2013 Honda Pilot) while towing. I'm concerned the current draw for charging 2 LiFePO4 100A batteries might draw too much current and damage it. Any thoughts or advice would be welcome.

The tiny wires from the alternator to the 7 pin connector will limit the charge to something the alternator can handle easily. Protecting the alternator is more important in motor homes.


Where are you putting the LiFePO4 batteries? They don't like cold.
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Old 01-18-2022, 03:05 PM   #3
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Thanks for the reply. It's a fairly small TT and the only place to put the batteries is on the tongue. I don't plan to camp when it's too cold.
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Old 01-18-2022, 03:39 PM   #4
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If you also use solar I would make sure your controller is an MPPT unit.
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Old 01-18-2022, 03:44 PM   #5
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Especially if you are getting that controller W5CRE mentioned (or any that has Li ability), you don't NEED a new converter. The old converter will work fine, just won't top it all the way up. But your solar will take over and top it up all the way to 100%.
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Old 01-18-2022, 03:44 PM   #6
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I have a portable Zamp solar panel and I seem to recall it can be configured to charge lithium batteries as well. I intend to verify that as soon as I can get back into the TT where it's stored. Too much snow right now.
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Old 01-18-2022, 03:45 PM   #7
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Thanks for the reply. It's a fairly small TT and the only place to put the batteries is on the tongue. I don't plan to camp when it's too cold.
your trailer is bigger than mine! I could easily fit a couple Li batts under sofa.
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Old 01-18-2022, 03:46 PM   #8
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You could also pull the tow vehicle fuse for the charging pin if you are really worried.
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Old 01-18-2022, 03:47 PM   #9
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Thanks. I hadn't thought of letting solar finish the charging.
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Old 01-18-2022, 03:50 PM   #10
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Is mounting the batteries on the tongue in place of the original ones a bad idea? They will be in battery boxes.
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Old 01-18-2022, 03:51 PM   #11
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they are so expensive and light weight, I'd hate to leave them there in such a theft accessible location. And for me, low temps would be a factor.
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Old 01-18-2022, 04:04 PM   #12
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Is mounting the batteries on the tongue in place of the original ones a bad idea? They will be in battery boxes.
If theft is a concern, and not cold. Then you can use one of these options.

https://www.amazon.com/RV-Battery-Lo...g=hmtownrv2-20

https://www.amazon.com/Batteryshackl...0LE06LRG&psc=1
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Old 01-18-2022, 04:15 PM   #13
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Camper Lucy,
I like that second option, less weight on the tongue. That's a big reason I'm considering lithium. Thanks for that!

corn18, you said LiFePO4 don't like the cold. I've read they won't charge below 32 degrees. Is there something else about the cold I'm not aware of?
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Old 01-18-2022, 04:24 PM   #14
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Is mounting the batteries on the tongue in place of the original ones a bad idea? They will be in battery boxes.
LiFePo4 batteries generally like to be in conditioned space, and don't want to be charged when they are below 32°. Some BMS systems have a low temp cutoff to prevent this, other batteries include a heater function. I'd be REAL tempted to pull them inside the coach body, and find a spot for them under the murphy bed or potentially under one of the two booth benches. Letting them ride in the coach lets you take weight off the tongue, and place it more over the axles for a better tow experience. Also adds some theft protection.

Likewise, you'll want to make sure you have a true battery disconnect such that the LiFePo doesn't get depleted or charged when the temps are low (considering life in Virginia).

You can separate your trailer system from the Pilot's alternator with a DC-to-DC charger (Renology has a 20A DC-to-DC for $100). I don't think there's a real danger, but if you're trying to spec a proper system, some isolation is good idea.

As others have commented, your existing converter will charge the LiFePo up to a certain point, and you can get there the rest of the way with solar. For 150 or so, I'd be tempted to swap the charger portion of the converter to something that was designed to get LiFePo all the way there (rather than the solar topoff).

Good luck, I'm loving LiFePo life!
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Old 01-18-2022, 04:27 PM   #15
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Camper Lucy,
I like that second option, less weight on the tongue. That's a big reason I'm considering lithium. Thanks for that!

corn18, you said LiFePO4 don't like the cold. I've read they won't charge below 32 degrees. Is there something else about the cold I'm not aware of?

That's the big one. Do not charge them below 32 deg F. Some have a built in cutoff that will not allow them to charge below 32 deg F. Most do not. If they don't protect themselves and you charge them below 32 deg F, they might be ruined. You can discharge them down to about 10-20 deg F depending on the manufacturer's specs.



Other than that, they don't mind the cold. They just sit there and don't really self discharge.
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Old 01-18-2022, 04:31 PM   #16
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I'm seriously considering the Lion Energy Safari UT1300 batteries. They do have thermal protection built in. And the PD4655L Wildcat is a direct replacement for the WF8955 converter portion of the power panel. I'll seriously look for a place inside the TT for the batteries. But then I'll have some major re-wiring to do.
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Old 01-19-2022, 04:21 PM   #17
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I just talked to Lion Energy about their LiFePO4 battery and they recommend using a DC-DC charger when charging from the alternator while traveling due to the higher voltages required. I've seen installation diagrams for MH but not for a TT. Where would it be installed, on the TV or the TT?
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Old 01-19-2022, 04:31 PM   #18
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I just talked to Lion Energy about their LiFePO4 battery and they recommend using a DC-DC charger when charging from the alternator while traveling due to the higher voltages required. I've seen installation diagrams for MH but not for a TT. Where would it be installed, on the TV or the TT?

Either works. Just need to check wire sizes to see what size DC-DC charger to get. What is the wire size going into your 7 pin connector for the DC charge line? What size fuse does it have in the TV?
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Old 01-19-2022, 05:16 PM   #19
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Typically charging from tow vehicle is negligible, and I'm guessing more so on a nearly 10 year old Honda. Just like the converter in the RV, the voltage will not be high enough to top off the battery completely, but should be enough to at least keep batteries from discharging in transit, running any small loads like running a propane powered fridge.
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Old 01-19-2022, 05:21 PM   #20
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With the battery change your making what are your priorities, weight, amp hours, cost or size. The Ampere Time batteries have been getting decent reviews in the teardown post. If it’s weight you’ll be cutting it in half with the LionEnergy’s. Two lead acids will likely be around 80lbs. Size wise a single Ampere time 200ah will be smaller and significantly less expensive with a bms does the same things. Ampere Time has a 300ah battery that has a 200 amp discharge rate, has a smaller footprint that the two Lion Energy’s and will be SIGNIFICANTLY less costly than the 2 LionEnergy’s your considering. Just my opinion and remember YouTube is your friend.
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