Lithium battery with Emergency Start system

[tlaffourtit]

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

as long as you aren't charging the different types of batteries you will not have any problems, and in this case you aren't. i would reconnect the emergency switch.

 

[ducksface]

as long as you aren't charging the different types of batteries you will not have any problems, and in this case you aren't. i would reconnect the emergency switch.

I believe the lead and lithium mix problem may be holdover from days gone by.
Now lithiums regulate internally and I doubt you can readily buy one that doesn't internally regulate. Now When they've reached their limits, they stop at those limits of charge,volts, amps,heat,cold. Once the lithiums turn themselves off external regulation will still regulate the conventionals.
And
I believe it was originally all about getting 10 years of lithium service vs 8 years before they dropped off to 80% of rating.


I may be wrong about the why and it no longer matters, but I'm sure I'm right about internal regulators.

If I'm wrong, management can erase this post.


I THINK the
"Don't mix lithium with conventional batteries"
is old school advice like 3,000mile/3month oil changes

 

[16ACE27]

I believe the lead and lithium mix problem may be holdover from days gone by.
Now lithiums regulate internally and I doubt you can readily buy one that doesn't internally regulate. Now When they've reached their limits, they stop at those limits of charge,volts, amps,heat,cold.
And
I believe it was originally all about getting 10 years of lithium service vs 8 years before they dropped off to 80% of rating.


I may be wrong about the why and it no longer matters, but I'm sure I'm right about internal regulators.

If I'm wrong, management can erase this post.


I THINK the
"Don't mix lithium with conventional batteries"
is old school advice like 3,000mile/3month oil changes

You are right - all LiFePO4 batteries have ant internal Battery Management System (BMS).

The "Don't mix lithium with conventional batteries" axium applies to PERMANENT CONNECTIONS, not temporary connections for charging or emergency starting. if lithium and conventional batteries were tied together at rest, the lithium would always be trying to charge the LA batteries as the resting voltages are quire different.

And the oil change was 2000 miles/2 months

 

[ducksface]

Ford had 6,000 mile oil changes and 100,000 lube in their owners manuals in 1963.

'What dad said'
Dies hard.

 

[tlaffourtit]

what he wants to do is jump his mh engine. he isn't charging the batteries. it's the same thing as getting a jump from a friend.

 

[ducksface]

what he wants to do is jump his mh engine. he isn't charging the batteries. it's the same thing as getting a jump from a friend.

Yes, but the general lack of knowledge required some additional knowledge to get her on the right path.
These posts are read by sometimes 100,000 folks over time.

Comments aren't always directly for the op and are designed to fill in the blanks for questions reared, or questions that should have been reared.

Your
'as long as you aren't charging'
Wordage needed addressed so as to not confuse those who didn't expand the questions diameter, or like I, wasn't completely convinced but was moderately convinced that I had useful peripheral knowledge.

 

[Helimech-THOR]

Yep thats all. I have a Victron DC to DC charger for the charging issue. I removed the BIM 160 and installed a simple starter relay. Done, works great.

 

[jenniesdaddy]

Mark54, in your picture of the Trombetta solenoid on you Tellaro, the bottom terminal has a red wire and a black wire attached and both have doide holders attached. I took the diode out of the black wire and did not mark the direction of the arrow stamped on the diode. Does the arrow point toward the terminal or away from the terminal toward the orange wire with purple strip??? thank you

 

[Mark54]

Mark54, in your picture of the Trombetta solenoid on you Tellaro, the bottom terminal has a red wire and a black wire attached and both have doide holders attached. I took the diode out of the black wire and did not mark the direction of the arrow stamped on the diode. Does the arrow point toward the terminal or away from the terminal toward the orange wire with purple strip??? thank you

Diode arrow aimed/ pointed at Trombetta. I had to check at one point. So in other words flow of electrons towards Trombetta.