Starting Onan Generator with Lithium Batteries

[The Gabe]

2019 Minnie Winnie 22R, 4000W Onan Generator.

I'm scheduled to get some electrical systems work done to allow off grid camping. It includes 2 each 270 amp-hour Battle Born Lithium batteries to replace the 2 each 100 amp-hour wet cell batteries. I recently came across some comments on other Forums stating that lithium batteries don't have the cranking amps to start the generator. Thoughts?

Thank you!

 

[dkoldman]

2019 Minnie Winnie 22R, 4000W Onan Generator.

I'm scheduled to get some electrical systems work done to allow off grid camping. It includes 2 each 270 amp-hour Battle Born Lithium batteries to replace the 2 each 100 amp-hour wet cell batteries. I recently came across some comments on other Forums stating that lithium batteries don't have the cranking amps to start the generator. Thoughts?

Thank you!

Not true, I have one 300ah Lithium battery that starts my generator just as good if not better than the AGMs I retired. Further if my FLA Chassis was down, my Lithium would start my F53 Chassis on the AUX Start switch with no issues.

I would be more curious as to why one still buy Battle Born? When I bought my Lithium the Battle Born were more than twice the one that I bought and less capacity. i.e. $447 for $300ah and in the newest smallest mini footprint. I think my house battery is only 25 lbs. I was going to get two, but with the Victron DC2DC we rarely drop below a true 73 SOC.

 

[powercat_ras]

Most internal LiFe04 BMS (battery management systems) on 100 AH LiFe04 limit current to 100 amps output, even some bigger than 100 AH do too. With 2 or more LiFe04 there is enough amps output to crank a 4 KW Onan. I have had no issues and I have LiFe04s.

 

[Morich]

It's not the total amp hour rating that you want to look at on cranking engines but the CCA (cold cranking amps) is a factor to consider if it gets into a question as that is how much quick power you can get out of the design. I have not heard of problems with starting the generators on RV with the various type batteries as they are such small engines.
When CCA normally would be a question would be when starting something much bigger like The main RV engine on a cold day.
When really pressed and if it WAS ever a problem, you could first start the RV engine and then let that system tie to the new batteries and you would certainly have plenty for the short time needed to crank the generator.
A lot of people never do that but I've always wanted any starter to have as much, good full power as it needed, so I start the RV first, rather than letting lower voltage work to overheat the starter.
Most likely not a big problem but most any item works better with the right voltage available.

 

[creativepart]

I have not heard of problems with starting the generators on RV with the various type batteries as they are such small engines.

Richard, many Lithium Iron Phosphate batteries expressly state “not to be used to start internal combustion engines.”

And LFP batteries, as a general rule, do not publish CCA ratings.

There are exceptions to this and some used in boating applications are suitable for engine starting.

I have seen this discussed many times, but not seen many real world examples of actual problems starting RV generators.

Many motorhomes use chassis batteries to start the generator, I know mine does. But it seems to be a variable setup. Plenty of folks have reported that their RV uses the house batteries.

I’ve seen at least one poster say they were simply rewiring their RV to use the chassis battery. It’s not difficult to do, at least that seems to be the case.

 

[The Gabe]

Not true, I have one 300ah Lithium battery that starts my generator just as good if not better than the AGMs I retired. Further if my FLA Chassis was down, my Lithium would start my F53 Chassis on the AUX Start switch with no issues.

I would be more curious as to why one still buy Battle Born? When I bought my Lithium the Battle Born were more than twice the one that I bought and less capacity. i.e. $447 for $300ah and in the newest smallest mini footprint. I think my house battery is only 25 lbs. I was going to get two, but with the Victron DC2DC we rarely drop below a true 73 SOC.

Thanks dkoldman. That's encouraging. I'm using the Battle Born because I had them in my previous RV and have had a very good experience with them.

 

[The Gabe]

Most internal LiFe04 BMS (battery management systems) on 100 AH LiFe04 limit current to 100 amps output, even some bigger than 100 AH do too. With 2 or more LiFe04 there is enough amps output to crank a 4 KW Onan. I have had no issues and I have LiFe04s.

Thanks Randy.

 

[The Gabe]

It's not the total amp hour rating that you want to look at on cranking engines but the CCA (cold cranking amps) is a factor to consider if it gets into a question as that is how much quick power you can get out of the design. I have not heard of problems with starting the generators on RV with the various type batteries as they are such small engines.
When CCA normally would be a question would be when starting something much bigger like The main RV engine on a cold day.
When really pressed and if it WAS ever a problem, you could first start the RV engine and then let that system tie to the new batteries and you would certainly have plenty for the short time needed to crank the generator.
A lot of people never do that but I've always wanted any starter to have as much, good full power as it needed, so I start the RV first, rather than letting lower voltage work to overheat the starter.
Most likely not a big problem but most any item works better with the right voltage available.

Thank you Richard

 

[bigb56]

I have only one 100ah LiFeP04 battery and even though I measured the starter current draw of my QD3200 at close to 120 amps momentarily (peak) the single 100ah battery starts it just fine.

 

[The Gabe]

Most internal LiFe04 BMS (battery management systems) on 100 AH LiFe04 limit current to 100 amps output, even some bigger than 100 AH do too. With 2 or more LiFe04 there is enough amps output to crank a 4 KW Onan. I have had no issues and I have LiFe04s.

Good to know. Thanks powercat_ras.

 

[Morich]

When I see the recommendation to not use them for engine starting, I feel that may be a bit of not quite telling us what they have in mind. Engine starting is one I jump to thinking of starting the RV engine and that is a much bigger heavier load than the small generator engine.
So I go to a bit more thought and that is where I might recommend not using the lithium alone if the generator takes some time to get it started.
If it's cold and draggy or not been started in a while, that might be a good time to kick in the boost option and make sure by using both chassis and coach batteries! Good power is always better than trying too long with less than full power. That possible low voltage tends to make higher than normal current and given enough times and long enough, that high current can degrade the insulation on starter motors! Burnout!

So if we look at why we don't want the normal operation of the mode solenoid or BIM connecting the alternator to the lithium, that can be a problem as the lithium can draw so much current so quickly that we may tend to overheat the engine alternator as we drive!
That means each design has to have some thought to how you want to build your system to avoid overworking the alternator but also leave some option for tying them together when you want a boost start or in this case where you may want to use both chassis and coach to start the generator.

I'm not at all sure where you are on the planning, etc. but in the name of "never too much info" I might throw in some things about this battery area and it does seem to show the generator starts off the coach side. Ignore this if not needed!

As you go along, this area of the RV tends to be a bit more trouble than other points of the electrical as it does so much stuff and gets such heavy use.
There is a "mode solenoid" which has chassis battery on one big lug and coach battery on the other side. There are two small wires that operate this solenoid to connect both groups together. When we drive to charge the coach batteries off the engine alternator OR when we push a dash switch for jump starting a weak chassis battery!
So these contacts get a lot of abuse as they open/close often!
That is also one of the things to consider when changing to lithium as you don't want the alternator overworked as you drive if it is connected to lithium for too long!
Click this snip for best view or go direct to drawing here:
https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/2018/000038813.pdf

Left side is chassis battery fed from starter (stator?) and that makes sense as the other side has connections to wires J and KKF which feed the coach fuse panels!
We can decode those ID from this list:
https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/electrical_guide.pdf
The small wires are labeled near the ends!

Coach power from batteries comes in near lower left side, meets the chassis power through mode solenoid contacts and then also extends up to the coach battery disconnect relay. The small wires LR (bat) and FM (ground) work to operate/close the solenoid!
If that disconnect relay is closed, power goes out and down to the generator for starting!
Busy little spot and lots going on to be aware of for planning?
Good luck on the chase!

 

[guber]

Those little battery packs that are used to jump start cars etc. seem to work well. Is there a difference?

 

[bigb56]

Those little battery packs that are used to jump start cars etc. seem to work well. Is there a difference?

They probably don't have a BMS which can limit current

 

[The Gabe]

I spoke to Battle Born Tech Support this morning.

1. He gave a total thumbs up on starting the 4000W generator with 2 each 270 amp-hr Game Changer batteries.

2. I shared my concern regarding starting the generator to charge the batteries when the batteries run down due to low solar charge input. He said I will have no problem starting the generator when the batteries get down to 10% (12.2V).

I'm feeling very good.

Thank you for your input!

 

[dkoldman]

I spoke to Battle Born Tech Support this morning.

1. He gave a total thumbs up on starting the 4000W generator with 2 each 270 amp-hr Game Changer batteries.

2. I shared my concern regarding starting the generator to charge the batteries when the batteries run down due to low solar charge input. He said I will have no problem starting the generator when the batteries get down to 10% (12.2V).

I'm feeling very good.

Thank you for your input!

FWIW, my AGS is set at 12.5vdc which is effectively 12.7vdc in the lithium world. So if my House batteries hit 12.7vdc or about 15% SOC the genny will auto start for me.

I believe if my chassis battery, I could start using my Lithium House battery with no issue as well. Only exception would be if Chassis battery was completely dead like anything under 10vdc. If so, I would have to hold that AUX start button for a long time to help recharge the Chassis battery before actually trying to start it. I have never had a dead or low batteries so that is my plan if ever I had the need. My AGS will also start the genny if the Chassis battery get too low. I know I am in the minority, but I use my AGS a lot.

 

[The Gabe]

FWIW, my AGS is set at 12.5vdc which is effectively 12.7vdc in the lithium world. So if my House batteries hit 12.7vdc or about 15% SOC the genny will auto start for me.

I believe if my chassis battery, I could start using my Lithium House battery with no issue as well. Only exception would be if Chassis battery was completely dead like anything under 10vdc. If so, I would have to hold that AUX start button for a long time to help recharge the Chassis battery before actually trying to start it. I have never had a dead or low batteries so that is my plan if ever I had the need. My AGS will also start the genny if the Chassis battery get too low. I know I am in the minority, but I use my AGS a lot.

Thanks for that insight dkoldman.

 

[mdstrum]

We have an Onan 2600, and have started for the last 4 years with our Battle Born battery bank (4x100amp) no issues at all...I the draw on the starter is much smaller and shorter of a load then the Dog Blow dryer we run that tanks amps 120 through our inverter for 20-30 mins...again no issues with that load either. I think you are fine and Battle born support I believe will tell the same things

 

[The Gabe]

We have an Onan 2600, and have started for the last 4 years with our Battle Born battery bank (4x100amp) no issues at all...I the draw on the starter is much smaller and shorter of a load then the Dog Blow dryer we run that tanks amps 120 through our inverter for 20-30 mins...again no issues with that load either. I think you are fine and Battle born support I believe will tell the same things

Thanks mdstrum, they Battle Born support did.

 

[RV_Lee]

My generator starts just fine with lithium but when my rig sat for months this past summer the chassis battery died and the jumper switch did nothing. I figured the chassis battery was just really dead as it sat for 5~ months and was the original battery the RV came with when new.

 

[Morich]

My generator starts just fine with lithium but when my rig sat for months this past summer the chassis battery died and the jumper switch did nothing. I figured the chassis battery was just really dead as it sat for 5~ months and was the original battery the RV came with when new.

Part of the story that is not mentioned enough?
When we store and think we have done it all right by hitting the battery disconnect switch/switches, we need to keep in mind that DOES NOT remove all the loads on either battery if we don't do something special.
It's not a big load on either coach or chassis BUT if we give even that tiny load long enough, it does get the battery totally flat!
There are two groups of loads on both the coach and chassis batteries, one group after the cutoff relay and another for safety items which are BEFORE the relay and that last group stays connected even when the relay is open!
The only way to fully disconnect the loads from either battery group is to totally disconnect the battery.
Since I never like to get down and dirty with removing the battery cables, I set up some form of disconnect switch designed for that big heavy cable and put it in the negative cable.
Big reason I put it in the negative side is for safety when
I work on anything near the battery. If I happen to whack a wrench on something metal while it is on the positive connections, nothing happens if the negative is open!
If I do the same with the negative connected, I may burn up the wrench!

On your Aspect, I see no disconnect on the chassis side, so no convenient way to disconnect any of the chassis loads if one is not added. Radio presets, door locks, ignition are all light loads to kill the chassis battery slowly!

The price we may pay for the convenience of all the automatic stuff?