Move to Lithium with a Generator

[Tik]

Did some reading but didn't find what I was looking for.

Has anyone made the transition from lead acid batteries to lithium with a generator.
My understanding is that the Lithium doesn't have the CCA's to turn over a generator. So I'm thinking of maintaining a single lead acid and 2 100 ah lithium batteries.
Currently have 400 watts of solar on the roof from Renogy with their charge controller. Eventually will put in a small inverter to power TV's in the Toy Hauler.
2020 Keystone Raptor 354 with a 5500 watt Onan generator.

I'm looking to go middle of the road on new lithium batteries.

Any input is appreciated.

 

[NH_Bulldog]

You are correct in that lithium is not appropriate as a cranking battery (yet). They are working towards one that can do it efficiently, but lead acid still owns that space. A lithium battery has a battery management system (BMS) that regulates how many amps you can draw in order to prevent damaging the batteries (typically 100a max draw).

In an RV, the generator (even an onboard unit) does not directly charge the house batteries. The generator replaces the shore power connection (just like plugging the RV into a portable generator). So the house batteries (your lithium) are charged by the converter/charger. On a 2020 model, it is not likely that your converter has a setting or capability to select battery chemistry, but looking up the model number of the converter will tell you for certain.

My Cougar came with an auto detect converter, but the onboard solar conflicts with the ability of the converter to function correctly, so I ditched the WFCO unit and replaced it with a Progressive Dynamics unit that lets me set it to lithium and it will stay on lithium. I also just added a Progressive Dynamics 2000w inverter while I was at it.

 

[Hblick48]

I have an onboard Onan in my rig. When I installed my LiFePO4 280 AH battery, I also installed a LiFePO4 Motorcycle Battery and a Xantrex Echo Charger. The charger maintains the motorcycle battery from the 280 AH as it charges. I also have 600 Watts of solar. The Echo Charger requires both batteries to be the same type.

I don't have to worry about keeping enough "juice" in the big battery to start the generator.

https://www.amazon.com/gp/aw/d/B099DZGNQW?psc=1&ref=ppx_pop_mob_b_asin_title

https://www.amazon.com/gp/aw/d/B0016G8RT8?psc=1&ref=ppx_pop_mob_b_asin_title

 

[chuckster57]

We just put a pair of LiPo4 100aH batteries in a toy hauler with an onboard gen. The batteries we used had documentation that they were generator starting compatible. Let me look and see what we used.

 

[Stircrazy]

Did some reading but didn't find what I was looking for.

Has anyone made the transition from lead acid batteries to lithium with a generator.
My understanding is that the Lithium doesn't have the CCA's to turn over a generator. So I'm thinking of maintaining a single lead acid and 2 100 ah lithium batteries.
Currently have 400 watts of solar on the roof from Renogy with their charge controller. Eventually will put in a small inverter to power TV's in the Toy Hauler.
2020 Keystone Raptor 354 with a 5500 watt Onan generator.

I'm looking to go middle of the road on new lithium batteries.

Any input is appreciated.

there are lithium starting batteries, but they are over priced. all you need to do is figure out the maximum cranking amp draw of your generator and make sure you have at least 50% more available. so if your cranking amps of your genny is 400 amps I would make it so you have enough capability to handle 600 amp draw.

now this takes some research in selecting your batteries so if you find a battery that has a 200 amp continuous output for the BMS I would get three of them and you will be good. if your batteries are only 100 amp continious output then I would go for 6 of them. there are some batteries comming out with 250 and 300amp continious output BMSs but they are usaly in the 300AH or higher range.

and the issue isn't that lithium doesn't have the cranking capacity, the issue is that the BMS are limiting as it cost more to make a more robust higher output board. a good prismatic cell its self will handle a 5C discharge for a period of time, longer if you can keep it cooled but the BMS would be many times more expensive to handle that kind of output.

the problem comes in when people are trying to crank a 400amp genny over and they only have a 200amp continious reserve so they are going in to the max output area where you only have 0.3 to 2 seconds before the BMS shut off the battery for over current (may be longer than that, its getting better haha)

if you want to spend the little bit extra, it would probably be around 500 US

https://harbourchandler.ca/alberta-lithium-13.2v-100ah-1000cca-starter/deep-cycle-lifepo4-heated-battery/?srsltid=AfmBOorf3L2v96mQBfjgTJXoH6OghgTvB4WbjRr3N87ZWKsQ8zXrLgO0

 

[JRTJH]

Something to remember about "Hybrid battery systems" (FLA coupled with Lithium batteries on the same charging system) is that the charge profiles and voltages are significantly different. You risk damage by overcharging the FLA while the lithium set is charged or you risk undercharging the lithium set by "protecting the FLA" using that profile for all the batteries.

If you do install an FLA battery as a generator starting battery, remember that you should not connect it to the same charger that you use to charge the lithium battery bank.

Onan generators in fifth wheels typically do not have a battery charging capability, so the generator won't keep its starting battery charged. What I've seen most people do is install a "stand alone AUTOMATIC charger" for that starter battery and plug it into a shore power outlet. That way, when the generator is running and/or when the trailer is plugged into shore power the starter battery will be maintained.

That way, the "house batteries" can be isolated from the "generator battery" and the two profiles don't interfere with each other.

 

[Raptor Dave]

Onan generators in fifth wheels typically do not have a battery charging capability, so the generator won't keep its starting battery charged.

Maybe they changed this in some later models? We've always used the gen to boost the battery if we used it longer than normal in the eve after the sun went down.

 

[triplethreat]

I have a DIY built LiFePO battery in my camper. It is 302AH and I have a 200A DALY BMS installed for the battery. I also have an onboard Onan 5500W generator and the battery system I built easily cranks/starts the generator. The cranking amp draw for that generator is in the 110 -115 amp range during startup. So the takeaway from that info is this....

1. If your LFP battery can provide enough cranking amps for the generator starting motor, you'll be fine.
2. If the battery is limited somehow by output current availability (usually a smaller batter and/or a BMS that limits the current to something less than what you need), you may not be able to start the genny.
3. Many of BMS controlled LFP batteries will have a "surge" current time built in that will allow for short bursts of higher than setpoint current draw. Let's say the BMS "normal" current cutoff will shut down anything over 100A current draw, but the surge current may be something like 50% greater for a short time...think maybe 3 seconds...maybe 5...it will all depend on the manufacturer and what and how they built the battery.

So my advice to you would be to carefully look at the data specs BEFORE you buy any LFP battery. Certainly a larger one would have a much better chance of being able to provide the current for the generator startup, as long as the built in BMS does NOT limit it to say 100 amps output. And if it does, see if there is any mention of "surge current" operation from the battery and what percentage MORE that it would allow and for how long it will allow the surge.....a couple of seconds, maybe 5, maybe not allow surge current at all. You'll have to do the research on that to make sure you don't get something that will not work.

 

[JRTJH]

Maybe they changed this in some later models? We've always used the gen to boost the battery if we used it longer than normal in the eve after the sun went down.

I can't remember any "newer or older" Onan generator in any trailer that has a "starter battery charging system"... The starter battery is always connected to the "house charging system" (converter/charger) and recharged from shore power or from the generator when it's running (providing shore power)...

I'd SWAG that your procedure to recharge the batteries using the generator to boost the battery has occurred "before the batteries were drained too low to provide enough power to start the generator"...

Try doing that when you wake up in a cold trailer from "the furnace ran down the batteries" and you'll be jumping the house battery bank with the tow vehicle to get the generator started so it can power the converter/charger to recharge the "generator starting battery"....

ADDED: Here's an old thread (2013 revived in 2021) that addresses Onan 5500 starter battery charging. Nothing has changed in at least the last 15 years...
https://www.keystoneforums.com/forums/showthread.php?t=15017

 

[Raptor Dave]

I'd SWAG that your procedure to recharge the batteries using the generator to boost the battery has occurred "before the batteries were drained too low to provide enough power to start the generator"...

Exactly....Why would you wait till the batteries are all sucked out to try and start the gen?
I probably missed something in the course of the conversation but wouldn't it be counter productive to try and start a gen with dead/low batteries?
I'm pretty anal about keeping an eye on the juice but if you don't it's not going to produce a happy camper situation but instead another adventure.

 

[JRTJH]

Exactly....Why would you wait till the batteries are all sucked out to try and start the gen?
I probably missed something in the course of the conversation but wouldn't it be counter productive to try and start a gen with dead/low batteries?
I'm pretty anal about keeping an eye on the juice but if you don't it's not going to produce a happy camper situation but instead another adventure.

Yes, you "missed something"...

The OP was asking about converting from FLA to Lithium batteries. The post was to verify that if he does that conversion, he needs to assure the lithium battery BMS is strong enough to allow for generator starting. If his generator starter draws more amperage than the lithium battery can provide, he can't start his generator AND: If he stays with a FLA starter battery, then he can't rely on the lithium battery charger to recharge the FLA battery because the charge profiles aren't the same....

And, you'd be surprised how many threads on this (and every other forum) start with, "My generator wouldn't start when I woke up to a cold trailer".....

 

[flybouy]

To add to the last sentence in John's post, when it's very cold outside the starter on the generator will draw higher amps than it "normally" does. If you camp in very cold climates regularly then you'll need a battery that's capacity is well above the generators "notmal" stated starting amps.

 

[Raptor Dave]

Yes, you "missed something"...

The OP was asking about converting from FLA to Lithium batteries. The post was to verify that if he does that conversion, he needs to assure the lithium battery BMS is strong enough to allow for generator starting. If his generator starter draws more amperage than the lithium battery can provide, he can't start his generator AND: If he stays with a FLA starter battery, then he can't rely on the lithium battery charger to recharge the FLA battery because the charge profiles aren't the same....

And, you'd be surprised how many threads on this (and every other forum) start with, "My generator wouldn't start when I woke up to a cold trailer".....

Thanks for pointing out my inability to comprehend.
We're not cold weather campers so I don't worry about it.
If it's going to be that uncomfortable all night I break out an extra blanket and pack up in the morning.

 

[JRTJH]

I don't know why Onan hasn't included a 12 VDC charger system in the 5500 watt RV generator series, but it is what it is. I'd guess they "designed out that capability" based on having the generator connected to house batteries (already wired into the 12VDC system) so no need for an additional starter battery, but not everyone wants to use it that way....

That "designed out" feature certainly limits the ability for owners to set up an independent battery system for the generator without buying a separate charger to keep the starter battery charged.

I've got a 10KW Champion "battery start" construction generator and even it has a battery charger circuit off the generator output.... But Onan??? Nope...

 

[Rhino-KEY]

I use this to charge my generator starting battery from the lithium batteries. I also have a connection from the charger to my truck, so everything stays topped up in storage.

 

[Tik]

Thanks all for the responses. I'm sure I'm not the only one with this type of problem so hearing from some more seasoned folks really helps.

I like the idea that Hblick-48 suggested and will do some more research along those lines vs a separate lead acid battery just for the generator. Keeping that charged up could be a challenge or another problem to solve.

We do a combination of boon docking and hook up camping. We bought our Raptor 2yrs ago new to us but not our first RV with a Generator. The dealer put 2 cheap 88 amp hour batteries in it which are fine but may be getting a bit long in the tooth or have another year in them. I pull them every winter and put in the garage on a trickle charger. I'm pretty OCD about running the generator to charge up the batteries for the evening currently. Adding the solar has somewhat eliminated this need. We live in Idaho so it does get cool in the evenings at elevation and the furnace will kick on or we will have an extra blanket. Not a big deal.

Just trying to come up with a better mouse trap than what we have currently and part of that was my thought to transition to Lithium vs lead acid.

Appreciate the responses and it gives me a rough plan or direction I want to pursue after more research. You don't know what you don't know right?

 

[Hblick48]

I like the idea that Hblick-48 suggested and will do some more research along those lines vs a separate lead acid battery just for the generator. Keeping that charged up could be a challenge or another problem to solve.

The Xantrex Echo Charger requires that both batteries be the same type. It duplicates the charge profile for the secondary battery from the charge profile of the primary battery. That's why I used LiFePO4 Motorcycle Battery for my generator.

 

[Tik]

Batteries being the same meaning lithium batteries correct? Would they also need to be the same size meaning 100ah or 250ah for example?

If I mirrored your set up of 8ah battery you referenced for the generator and 2 100ah lithium batteries for the RV I should be ok still correct.

Apologies but an electrician I am not. I understand the basics and wiring etc.

 

[Hblick48]

Batteries being the same meaning lithium batteries correct? Would they also need to be the same size meaning 100ah or 250ah for example?

If I mirrored your set up of 8ah battery you referenced for the generator and 2 100ah lithium batteries for the RV I should be ok still correct.

Apologies but an electrician I am not. I understand the basics and wiring etc.

Both batteries need to be same type (lithium or lead acid). Capacity has nothing to do with it. Since main battery is lithium, starter battery needs to be lithium. Motorcycle lithium battery works great.

 

[Tik]

Thank you, makes sense to me.