Lithium battery and generator start

[Rock-JAY]

I have been reading posts on other websites about this problem. Some folks have said that their lithium batteries will not start their generator. Have any of you who have replaced your lead acid with two group 24 lithium 100 amp hour had this problem? It seems to be a problem with the battery BMS limiting the amp draw of starting the gen. Some have said that one 200 amp lithium BMS is the problem. But two 100 amp will allow thru the BMS enough amps to start the generator. To add to this according to Jayco 2022 and later the coach alternator no longer charges the house batteries. I noticed on my Alaska trip driving pretty much daily my solar (I added a second panel for the 12 volt fridge) was putting out a ton of amp hours each day so now I know why. I was wondering why the coach was not keeping the batteries charged. We had a lot of rain and cold nights. I had to run the gen a bunch to keep the two wet batteries charged up dry camping after a days drive. I have a new AGM deep cycle and trying to decide should I get another AGM or two lithiums to replace the wet cells. I just want to ensure that the gen will start with the lithiums.

 

[craigav]

If the "chassis" engine alternator isn't connected to charge the coach (house, rv) battery(s) then I would install a DC2DC charger for sure. However and perhaps what you read, the coach charging system (the converter) is not (or rarely) setup to charge the chassis battery.

Regarding LifePo4 batteries, they are not all the same. Some 200ah batteries for example only have a 100A BMS which limits the total output at any moment where most 100AH batteries also have a 100A BMS therefore you should at minimum be able to pull 200A at any given moment when you have two of them which would be needed for example during the first second or two when starting the generator.

To add to this and back to my point, some LifePo4's (like the one I have) have a BMS that can output 500A for a second, 300A for 5 seconds, and 200A for 2 minutes similar to the specs of this one I found quickly on Amazon (not that I recommend or not this battery as I shared it just for example). I have never had any issues starting my Onan 4000 with a single 100AH LifePo4 battery. Having said that, I suspect that the Onan does pull more than 100AH during the first second or two of the startup therefore a single LifePo4 that has a BMS that can't exceed 100A's would be an issue. I would check the specs of any battery that you consider purchasing and if it doesn't say it can output 2~3x more current for short periods of time then I would suspect that it may be limited to 100A output (in which case you should have two of them minimum).

BTW, I am not sure of the peak starting amps my Onan 4000 pulls, but after a couple of seconds when my amp meter settled down the starter was pulling 70~75 amps. I wouldn't be surprised though if it didn't pull a lot more the first second (perhaps 150~200A) prior to getting a good reading. ~CA

https://www.amazon.com/Wattcycle-Li...7316042cee3deff35fb379&qid=1727840308&sr=8-18

 

[Rock-JAY]

Thanks for the link. Funny their new version with Bluetooth does not give a high output on the BMS. I tried finding a link to the company for info but could not. Bluetooth would be nice. You selected the correct battery with that high amp
Output BMS.

 

[Camper_bob]

This is a great question IMO.

I haven't installed mine yet, and this was one of the concerns I had for when I do. So this encouraged me to look closer at the specs on my battery. It says maximum cutoff discharge: 300A. But it doesn't say for how long. I think that's going to be enough to get my genny started, but something I'll want to test out right away...

 

[pconroy]

I have two 100Ah Li batteries. I start the generator from them all of the time. No issues. And my generator is a hard crank.

 

[Rock-JAY]

This is a great question IMO.

I haven't installed mine yet, and this was one of the concerns I had for when I do. So this encouraged me to look closer at the specs on my battery. It says maximum cutoff discharge: 300A. But it doesn't say for how long. I think that's going to be enough to get my genny started, but something I'll want to test out right away...

The 300 is like 2 sec but 200 amp it says 2 min (hope that is right). So two batteries would be 400 amp and 600 momentary. I just talked to Jayco and they confirmed no connection from alt to house batteries. Coach battery gets its charge from alt or thru solar only.

 

[Camper_bob]

The 300 is like 2 sec but 200 amp it says 2 min (hope that is right). So two batteries would be 400 amp and 600 momentary. I just talked to Jayco and they confirmed no connection from alt to house batteries. Coach battery gets its charge from alt or thru solar only.

Yeah, I'm 99% sure in my 2018 the house battery gets a charge from the alt. I know the chassis battery gets a charge from the converter because I put a Trik-L-Start in shortly after purchase. Now it's parked in covered storage with power, so the converter handles charging for both batteries.

That's the other tricky part of my install; I'm trying to charge 2 different types of batteries without installing a crap-ton of extra stuff to manage all of it.

Don't need solar, and have pretty moddest 12V needs when not plugged in at this point.

 

[dvspl]

I'm not sure what size generator is in your model so can only reference my 29MV that has an Onan 4 kw gas generator. The starter is wired with 2 AWG wire from the battery that goes through an 80 amp auto reset circuit breaker. I have 2 100 AH lithium batteries that each have 100 amp BMS, so should be able to provide up to 200 continuous amps for starting. I've started my generator at least monthly for the last four years in temps down to freezing. I don't start it below freezing since the batteries won't allow recharging. But I've never had an issue starting it. When it's cold, the starter sometimes hesitates right after engagement but then turns over and starts. I suspect this may be the circuit breaker opening then resetting. Bottom line; I don't think you'll have an issue if you look at the BMS specs for whatever batteries you select.

 

[Rock-JAY]

I am trying to get my ducks in a row for Amazon prime days. I talked with Jayco and Progressive industries tech. So I will be getting a pendant for the converter but still looking into the best Bluetooth lithium set up. Knowing you do not have a problem starting gen in cold temps is good news. Thanks for that info.

 

[Rock-JAY]

So I ordered two WATT CYCLE 100 amp
Group 24 batteries. Deep cycle with 120 amp BMS. Also called Progressive industries and confirmed all I needed was the pendant to get a full charge when needed. So this should be an easy swap since no DC to DC charger needs to be added. I have a battery jumper box but I need to find this out. Can you hook the booster to the lithium batteries if needed for starting the generator? I am waiting on an answer from Watt battery and Yasper jumper box?

 

[pconroy]

Can you hook the booster to the lithium batteries if needed for starting the generator?

Good question. I'll guess some of the answer will depend on the BMS and it's ability to accept high-current *input*.

But when I needed to start the generator, and my SLA battery was low, I'd just start the Ford engine. The alternator provided enough current to fire up the generator.

 

[GeekyGuy]

I have 2 LiFePo4 Power Queen Gr 24 batteries, under the stairs. GH 29MV 2022.

No issues whatsoever to start the Onan genny.

I also have installed a DC2DC 20A from Renogy. Works fantastic, recharges my batteries in no time.

I did buy the pendant Wizard to force my converter/charger to 14.4V, that works great too.

Finally I installed a Renogy Battery Monitor to see the status.

My solar panel still keeps the chassis and my new LiFePo4 batteries all topped off.

Could not be happier.

 

[Rock-JAY]

Good question. I'll guess some of the answer will depend on the BMS and it's ability to accept high-current *input*.

But when I needed to start the generator, and my SLA battery was low, I'd just start the Ford engine. The alternator provided enough current to fire up the generator.

Cannot do that on mine. Either 21 or 22 Jayco disconnected the engine alt from charging the coach batteries. My unit the gen, shore power or solar charge house batteries. They made the solar charge house batteries and when full the solar than charges the engine battery. The only connection is the button that lets house start the engine.

 

[Rock-JAY]

Just heard back from WATT batteries. They said do not jump unless your booster box is made for lithiums. If u use a lead acid booster box u can damage the lithium BMS. So now I wait on the booster company reply. I will probably just buy another just lithium booster since I dry camp for extended periods.

 

[craigav]

Just heard back from WATT batteries. They said do not jump unless your booster box is made for lithiums. If u use a lead acid booster box u can damage the lithium BMS. So now I wait on the booster company reply. I will probably just buy another just lithium booster since I dry camp for extended periods.

I am fairly sure that there are no such booster jump boxes that are made for lithium batteries, not to be confused with lithium battery booster boxes. Keep in mind that a booster jump box is designed to put out a lot of current, more so than the input of your LifePo4's BMS is designed for.

I would suggest now would be a great time to install a DC2DC charger in the 40~60A range such as what Renogy sells. That way if you did run down your LifePo4's you could use the engine alternator to jump\charge them... or speaking about jumping, some very long jumper cables would likely work as well and be easier to do overall. ~CA

 

[Rock-JAY]

I am fairly sure that there are no such booster jump boxes that are made for lithium batteries, not to be confused with lithium battery booster boxes. Keep in mind that a booster jump box is designed to put out a lot of current, more so than the input of your LifePo4's BMS is designed for.

I would suggest now would be a great time to install a DC2DC charger in the 40~60A range such as what Renogy sells. That way if you did run down your LifePo4's you could use the engine alternator to jump\charge them... or speaking about jumping, some very long jumper cables would likely work as well and be easier to do overall. ~CA

That would be an easy way. Long cables from Ford battery to Gen or the house lithiums. On mine the house and Ford battery are closer. The lithiums are Bluetooth so at least I can keep a close eye on them. At my mountain camp I have a portable gen so not a problem. I think what I will do when dry camping not at my camp I will just bring my little Honda gen with me as a last resort.

 

[pconroy]

Cannot do that on mine. Either 21 or 22 Jayco disconnected the engine alt from charging the coach batteries.

Well darn, I didn't know that.

 

[extrachrispy]

I have a pair of 100Ah BattleBorns in my 5'er, connected in parallel. I've been able to start the onboard Onan even with only 10.5V showing on the BattleBorns. I've also successfully jumpstarted the genny from my pickup on several occasions. When I do so, one cable is connected at one battery and the other is connected at the other, so that the entire inrush current is across them both instead of across just one. So far, so good.

 

[Rock-JAY]

Received my two WATT 100 amp bluetooth batteries yesterday. Removed the terrible lead acid ones and cleaned the wire terminal ends. I am surprised I did not have electrical issues since the terminals were coated both sides with the red anti corrosion spray. Batteries had about 40% charge. Charged overnight the stock converter put out 13.8 volts and 21-23 amps. Surprised this morning when they read 100% since I did not use the pendant. Posts have said the stock converter will only charge them to 85% I will hook up the pendant today so if needed can get a faster charge. So I gave the generator a try (mine since new either starts quickly or takes 4-5 tries) and after the fifth try started. I was now at 99% charge. I thought it would be much lower since I cranked 5 times. I did not get the new mini WATT 100 amp I went with the original one with bluetooth it has 120 amp BMS and is a proven battery. I reset the solar for 200 amps and lithium batteries. Cannot wait to see how the 400 watts of solar keep the batteries up with the 12 volt fridge.