RV Genny starting with Lifepo04

[DonTom]

This 2022 Class A has two 6V Harris, HBDAGMG6-A 224ah six-volt batteries in series.

I am thinking about changing them to two of these in parallel. And adding a lith converter since the stock Xantrex Freedom X 1200 has no lith profile.

This RV uses the house batteries to start the Onan 5500 genny.

I would think the two Lifepo04 in parallel (400 AH) would be fine for RV genny starting. But when I ask Rufus on Amazon if I can do such I get this as the reply:

"No, two of the LiTime 12V 200Ah Mini LiFePO4 RV Battery batteries connected in parallel would still not be suitable for starting RV generators.

Here's why:
•
Peak current limitations: Each battery supports up to 1000A peak discharge, but generator starting requires sustained high current over several seconds. LiFePO4 batteries are designed to limit discharge to protect their chemistry—they're not optimized for engine cranking.
•
Cold cranking amps (CCA) specification: RV generators require 800-1,500 CCA ratings. The LiTime battery doesn't publish CCA specs because lithium batteries handle cold temperatures differently than lead-acid. Two of them together won't change this fundamental mismatch.
•
BMS protection: The battery's management system may shut down during extreme starting loads to protect the cells, leaving you stranded.
Best practice: Use a dedicated lead-acid or AGM starting battery (800+ CCA) for generator starts, and keep the LiTime batteries as your auxiliary/house power system"
Should I believe above or not?

-Don- Kingston Campground, NV

 

[RayIN]

Sounds like double-speak to me; I'd try it out anyway. If the genset starter is too much(which is doubtful), just switch the genset to the starting batteries.
Lithium starting batteries are sold today.

 

[Lou Schneider]

I call BS. When the starting battery died in my motorhome the two 100 a/h lithiums I installed had no trouble starting the main engine via the boost switch. The main engine needs several times as much starting power as the smaller generator.

If you ever drain the house batteries all the way down to where they won't crank the generator, the boost switch works the other way, too.

 

[DonTom]

I call BS.

That makes all three of us. I just wanted to be extra sure after I got that message on Amazon Rufus.

With the higher voltage, I would expect the genny starter to spin faster even if without any CCA spec. for such. I doubt it will load the battery voltage down below the voltage of stock LA batteries under the same high load. That is why I also call BS.

If you ever drain the house batteries all the way down to where they won't crank the generator, the boost switch works the other way, too.

If this Class A has a boost switch, I never noticed it.

FWIW, I never had the house batteries in this rig below 50% SOC yet. But I figure the stock LA batteries in this rig (including the engine battery) are all from year 2021, so I am probably close to when they should all be replaced.

Lithium starting batteries are sold today.

I heard of such years ago for ICE motorcycles.

But do you mean Marine Starting batteries like these?

-Don- Kingston Campground, NV

 

[Lou Schneider]

That makes all three of us. I just wanted to be extra sure after I got that message on Amazon Rufus.

With the higher voltage, I would expect the genny starter to spin faster even if without any CCA spec. for such. I doubt it will load the battery voltage down below the voltage of stock LA batteries under the same high load. That is why I also call BS.


If this Class A has a boost switch, I never noticed it.

FWIW, I never had the house batteries in this rig below 50% SOC yet. But I figure the stock LA batteries in this rig (including the engine battery) are all from year 2021, so I am probably close to when they should all be replaced.


I heard of such years ago for ICE motorcycles.

But do you mean Marine Starting batteries like these?

-Don- Kingston Campground, NV

Two years ago there was a company in Quartzsite's Big Tent selling 12 volt lithium automotive starting batteries. I don't remember any details though.

 

[triplethreat]

I've talked about this before, but to reiterate; I built a 302AH LFP battery back in early 2022. It was made up of 4 EVE brand 302AH cells and I have a 200A BMS for battery management. I don't have an inverter for the trailer, so I really didn't need a larger capacity BMS. My Toy Hauler is equipped with a factory installed 5500W Onan generator and the DIY battery starts it just fine. Amp draw for start up is +/- 100 amps for that particular generator, and it the battery spins it up quite nice with ZERO issues.

 

[John From Detroit]

It too would expect the higher voltage to spin the generator a bit faster.. Not enough to notice unless you use a tachometer to to measure it but a bit faster. Odds of damge.. well 0.lots of zeros one non zero%

 

[gwinger]

There are lifep04 batteries make for motorcycles. If it can start an 1000-1800cc bike motor, it will start a generator.
AI ain't perfect!

 

[ButchW1]

OK, then why not replace all of your battery's (chassis & coach) with lith batterys?... No more 12v... 14v... Will it hurt them, long term? ... I know the existing alternator would be a problem...
Butch

 

[DonTom]

AI ain't perfect!

Yeah, I noticed on a few other issues, but it is still helpful for many things. But we need to know when to question some of the info., as I did here.

OK, then why not replace all of your battery's (chassis & coach) with lith batterys?... No more 12v... 14v... Will it hurt them, long term? ... I know the existing alternator would be a problem...
Butch

Why do you think the existing alternator will be an issue? I wouldn't expect that with a lith battery that is designed for engine starting.

But I am not sure if a lith battery is a good idea for large engine starting--even if it does work. I would want to first see the cold weather specs, CCA spec and stuff like that.

But I will consider it if I see one that looks good and has some real true advantage and no disadvantages.

TBH, I am not sure why I want to change any of the batteries from the stock stuff as they all work well as is. And I have added a 2nd system for my toys (ham radio) and other high current stuff so the stock LA house batteries are only used for the stock stuff. I can now run my MW oven and other stuff without the genny--in either of my motorhomes. Often that is handy in places such as Organ Pipe where they have quiet hours.

My added system has a DC2DCC so it charges from the alternator too, all the way to full at around 30 amps.

Since it will soon be time to change all my batteries in this rig, I want to consider possible improvements & I want to replace them before they fail.

I had a house LA battery cell short out on me in my Y2K RV while boondocked at Sunset Camp in Death Valley. I had to take a trip to the Wal*Mart in Pahrump to get by for that trip. That was just before I purchased my first 300 AH lifepo4 battery (at twice today's price) when I got back home. And had to make a lot of modifications. I no longer have any battery in the stock location.

-Don- Kingston Campground, NV

 

[DonTom]

There are lifep04 batteries make for motorcycles.

Yes, and also for starting much larger engines, as show here.

They are still quite pricy.

But I could still consider one after I study the specs a bit more.

-Don- Kingston Campground, NV

 

[RayIN]

This jump-starter should remove all doubt of using Lithium batteries for starting batteries. I would've never thought it is re-charged with a USB cable.
I bought one about 5 yrs. ago and it's never failed me yet_ when used as directed.

 

[DonTom]

This jump-starter should remove all doubt of using Lithium batteries for starting batteries. I would've never thought it is re-charged with a USB cable.
I bought one about 5 yrs. ago and it's never failed me yet_ when used as directed.

I already own around a dozen of those (but different brands). I carry one or more in every vehicle for various reasons. I can even run this StarLink system with one of those.

BTW, the newer ones do not have a 12-volt output accessory socket. That problem is solved with one of these thingies.

-Don- Kingston Campground, NV

 

[RayIN]

I already own around a dozen of those (but different brands). I carry one or more in every vehicle for various reasons. I can even run this StarLink system with one of those.

BTW, the newer ones do not have a 12-volt output accessory socket. That problem is solved with one of these thingies.

-Don- Kingston Campground, NV

My pack might have one of those included, if not, it soon will. I just put in my cart. I'm going to try to power my 35G spot sprayer with the jump-start pack. It will be much easier than lugging a 12V LA battery around.

 

[DonTom]

I would've never thought it is re-charged with a USB cable.

Obviously, the newer C type of USB.

USB has changed greatly with the "C" type. The maximum output voltage for a standard USB-C port is 20V, which allows for up to 100W of power (20 VDC at 5 amps) when requested. It will also do 5VDC when not automatically requested by the equipment load.

There is now even a newer standard which will do even more than above.

So yeah, it has no trouble charging from that. My HFT Power Station (as I am now using for this portable StarLink) can also be charged via "C" USB, or one of my solar panels (if below 200 W & 30 VDC) or by 120 AC. My ham radio RF amp cable just happens to have the same type of connector on its cable so I usually charge it from that, which goes to my added 300 AH battery). The HFT Power Station will run my Starlink for more than 24 hours and will fully recharge as I sleep.

-Don- Kingston Campground, NV

 

[DonTom]

My pack might have one of those included,

None of the newer ones do, AFAIK:

Here is yours:

-Don- Kingston Campground, NV

 

[DonTom]

the boost switch works the other way, too.

I just now decided to look for a boost switch and . . .

I found it right up front!

-Don- Kingston Campground, NV

 

[gwinger]

My pack might have one of those included, if not, it soon will. I just put in my cart. I'm going to try to power my 35G spot sprayer with the jump-start pack. It will be much easier than lugging a 12V LA battery around.

I have started a Dodge Durango V8 with mine. No problem.
Problem with some of the boosters is they need to see a minimum voltage when connected. Without that voltage the booster will not supply the 12 volts.
Some also come with a manual override that lets the 12 volts to turn on.
My Antigravity brand does that.
Or, if you have a usb C connector on the booster, one of the will work for low current adapters.

Amazon.com

 

[DonTom]

Or, if you have a usb C connector on the booster, one of the will work for low current adapters.

Too low for much of anything useful. I own a few of those but with only 18 watts (~1.5 amps) available they are not good for much, unlike the ones I mentioned in post 13, which are good for ~60 watts (~15 amps).

-Don- Kingston Campground, NV

 

[DonTom]

I just put in my cart.

I should mention here that the car jumper batteries are not all designed the same way. With some, you need to press a button for engine start. This is NOT what you want to use the thingies in your cart. The problem with these is they automatically turn themselves off after a half minute or so, regardless of load (some other 12V thingies turn themselves off when they detect no load for so many seconds).

What you want for use with those 12V sockets is the type of that never turn themselves off and also do not need to be turned on.

Some of them are hot at all times and have all the safety BS in the charge cable instead of the battery booster thingy. You need to have the type that is hot at all times.

The type you want is the type that requires no buttons for engine start. That section is hot even when the unit is turn off.

It looks like the one you have, the ET03, is fine as I see no engine start buttons and I see the safety BS in the stock engine charge cable, which means that BS is NOT in the unit. So all looks fine for you.

I have several of each type here and I was just looking at them so I decided to post this message in case others find those socket do not work for more than a few seconds because of the type of jump starter they're using.

Don- Kingston Campground, NV