Lithium battery with Emergency Start system

[Helimech-THOR]

I bought a class A (2018 Vegas 25.4) that has 5 LiFePo4 batteries for the house bank and a standard Lead Acid battery for the Chassis. The RV comes standard with an Emergency Start system like a lot RV’s have. You push Emergency Start switch, it activates a relay that connects the house bank to the chassis battery and you hold the switch down while you crank the engine. The previous owner disconnected this by removing the cables going to the systems relay because he said the Lithium and Lead Acid have different chemistry and can’t ever be joined. I understand that I can’t connect these different type batteries together permanently but I’m wanting to reconnect this emergency system. Do any of you guys have this battery setup and also have the Emergency Start system still enabled? Thanks for any help.

Site Team Edit:
Added Year/Make/Model RV info

 

[DavidEM]

With 5 Li batteries, presumably 100 Ah each, you have enough current capability- probably 500 amps, to start your chassis engine using the emergency start switch.

Try it.

David

 

[ducksface]

It's mythical except in laboratory or nerd-need situations.

The not-mixing has to do with squeezing the last smallest portion of availability from a battery.
Under normal use where absolute maximum of listed battery chemistry is NOT A HOBBY... it's all fine.
Honest.

However,
Lithiums usually have electronic circuits to measure flow.
That might stop you...but it'll stop it from working without doing any damage.

I don't have the asked of system yet, but I should be done with it by the end of the day. I'm in the middle of setting one up.

If you have concerns there is a manual way to make emergency start easier.
https://www.amazon.com/gp/aw/d/B004HGTXUQ?psc=1&ref=ppx_pop_mob_b_asin_image
https://www.amazon.com/gp/aw/d/B09W5SFK6L?psc=1&ref=ppx_pop_mob_b_asin_image
https://www.amazon.com/dp/B07LGCY3R...94ZP8U2L&psc=1&ref_=list_c_wl_lv_ov_lig_dp_ii

I use the above along with my emergency start system.
(One is none)

 

[16ACE27]

Depends on what battery isolation system you have and what was actually disconnected and if anything was removed.

I suspect you have a BIM160 which would be located under the hood in front of the driver as I recall. Take a look to verify that it's there and we can go forward or make a turn if not there or if you have a BIRD/IRD system.

 

[Helimech-THOR]

Yes 500AH. So you don't think there would be an issue combining the Lithium and Lead Acid banks together for the short time it would take to start the engine? I agree but wanted to make sure I wasn't missing something

 

[16ACE27]

With 5 Li batteries, presumably 100 Ah each, you have enough current capability- probably 500 amps, to start your chassis engine using the emergency start switch.

Try it.

David

It's disconnected - hence, the point of his post.

 

[Chateau_Nomad]

I have exactly that... LiFePO4 house batteries and a lead-acid chassis battery. When I installed the lithium batteries I also installed a Li-BIM225.

Without explaining it's exact function here (please search it), it allows charging of BOTH battery systems AND emergency start. The Li-BIM is designed exactly for those functions.

Mine has worked perfectly in keeping batteries charged from solar, alternator, generator and shore power... and I've used the E-start function a couple times... both were due to operator error!

P.S. I also carry a jump pack... and have Coach-Net. Redundancy is a good thing when you camp in the middle of nowhere.

 

[Helimech-THOR]

I have the BIM 160. The chassis battery cable is disconnected from this and stowed. I also have a Victron DC to DC charger installed.

 

[ducksface]

So
Since this the OP has been settled and alternative offered;

I'm about to install a DC to DC charger and I have the lithium BIM mentioned above and my inverter charges at 150a.
Did I go overly redundant? Will the DC to DC have value?

400 or 800a lithium is the set up and each have 200a controllers on 200a batteries.(I have the batteries for 800, but have little need for such until I buy the 12v air conditioner)

 

[Mark54]

I have the BIM 160. The chassis battery cable is disconnected from this and stowed. I also have a Victron DC to DC charger installed.

Already answered but in short (pardon the pun)- temporary use of LFP to start engine is not an issue. They are only used for a few seconds.
Then go have chassis battery tested by auto parts place, like Advance (who checked mine and alternator in my Rialta) and found my chassis battery was indeed shot.
I had 414Ah of lithium in that RV as well. No problems with the e-start.
As long as it is a momentary switch that cannot be left 'on', your fine. Most are.

 

[16ACE27]

I have the BIM 160. The chassis battery cable is disconnected from this and stowed. I also have a Victron DC to DC charger installed.

So if you have a DC-DC charger installed, you probably do NOT want to connect the BIM 160 as originally wired in parallel with it. In this case I would replace the BIM160 with a simple heavy duty "Ford" starter relay where the emergency start switch activates the syarter relay to tie the battery banks together.

 

[ducksface]

My dc-dc charger can be turned off remotely with an app.
I don't think I like a bim because of the on off cycle times doubling charge time, though my generator and inverter's charger cancels this by NOT being
Regulated as the bim is.

In regard;
I might use the relay you showed(I have a few sitting around here) to disconnect/connect the bim remotely.
Then I'd have a backup system depending on what was on or off.

Is this an idea?

 

[Helimech-THOR]

Thanks for all the info. I'm new to this RV and have to do some more investigating into this Emergency Start system. I thought the clicking noise I hear when I push the emergency start button was coming from the BIM160 but now I think that’s wrong. I need to get someone to push the button while I’m up front to see where the noise is coming from. My Battery Compartment Layout schematic from Thor shows an E-Start Sol that I need to find. Thank and sorry for the confusion.

 

[16ACE27]

Thanks for all the info. I'm new to this RV and have to do some more investigating into this Emergency Start system. I thought the clicking noise I hear when I push the emergency start button was coming from the BIM160 but now I think that’s wrong. I need to get someone to push the button while I’m up front to see where the noise is coming from. My Battery Compartment Layout schematic from Thor shows an E-Start Sol that I need to find. Thank and sorry for the confusion.

The "E-Start Sol" is a function of the BIM or the BIRD/IRD system, it is not a discrete component. You may be hearing the BIM160 clicking but if the chassis battery cable is disconnected it won't tie the battery banks together.

 

[Chateau_Nomad]

So if you have a DC-DC charger installed, you probably do NOT want to connect the BIM 160 as originally wired in parallel with it. In this case I would replace the BIM160 with a simple heavy duty "Ford" starter relay where the emergency start switch activates the syarter relay to tie the battery banks together.

This.

The reason the BIM160 is disconnected is because the BIM160 is NOT compatible with lithium batteries. Lithium batteries have MUCH lower resistance when charging and will potentially fry your alternator if left connected for any length of time. Thus the Li-BIM225 was developed which uses a timed connection period... not perfect, but at least lets the alternator cool.

In your situation I would do exactly what ACE suggested.

 

[ducksface]

LiBim installed,
dc-dc charger, biggest shunt I could find(1,000), monitors,
on the bench, sorted, and starts tomorrow.

I'll add the selonoid and wireless switch to cut out the LiBIM to the coach.

 

[Mark54]

Thanks for all the info. I'm new to this RV and have to do some more investigating into this Emergency Start system. I thought the clicking noise I hear when I push the emergency start button was coming from the BIM160 but now I think that’s wrong. I need to get someone to push the button while I’m up front to see where the noise is coming from. My Battery Compartment Layout schematic from Thor shows an E-Start Sol that I need to find. Thank and sorry for the confusion.

This is the e-start Trombetta solenoid TMC uses in the Tellaro/ Sequence RVs
Mine was underneath, now up inside... It's a lot cleaner now.
No BIM or BIRD in my 2022 20L.

 

[16ACE27]

No BIM or BIRD in my 2022 20L.

Probably due to your UHG configuration in your Class B van. OP just has a standard Class A Axis/Vegas.

 

[Helimech-THOR]

Yep I also agree with ACE. Out with the BIM and in with the Starter relay. Thanks all.

 

[BASSMAN-THOR]

I have a 2017 Axis 25.4, I got rid of the original lead acid for the coach and bought 4, 100 amp hour Gel Cells, I by passed the BIM and installed a DC to DC battery charger, I put a Cat Master switch between the coach batteries and the engine battery, if emergency start is needed I just switch on the Master switch and then used the emergency start switch, once started I just disconnect the Master switch, The DC to DC charger has dip switches to set it for what ever kind of battery you are using.