System upgrade for Lithium coach batteries issue

[SFVdave]

Looking at upgrading my system to Lithium coach batteries. My system currently has a PD4560 converter charger and a Precision Circuits BIM allowing bi-directional charging to both coach and engine batteries, all batteries are flooded acid cell.
Under new upgrades with Lithium coach batteries, the PD4560 would have to be changed to PD4560Li which no longer has the charge wizard and equalization mode and provides the 14.4v constant. This will cause an issue with the Precision Circuits BIM which allows bi-directional charging and engine battery boost function. The PD4560Li converter charger manual states "DO NOT USE WITH FLOODED ACID CELL BATTERIES" for obvious reasons of charging parameters.
There is an expensive upgrade for the Precision Circuits BIM costing $500. Wouldn't just disconnecting engine battery from the BIM and isolating it work? Battery cable from engine battery goes to a fuse box first before running back to the BIM and is easily disconnected. This would provide engine battery charging, but no charging to the coach batteries while driving. However, I have 300 watts of roof top solar which would be charging the coach batteries. I'm not sure what's tied to the engine battery to draw it down. The dash radio with CD, DVD and navigation is wired to the coach battery and No power steps.
Has anyone encountered this situation and if so what was your solution?

[pianotuna]

Hi Mex,

Thanks for the information!

[MEXICOWANDERER]

It is possible to charge divide any power source easily as long as the charging source is higher voltage than what is needed.

Don up there in Canada 🙂

vf voltage drop is related to amperage .7 volts is only a standard ambiguous number. A thirty amp rectifier may drop voltage .395 volts at 1 amp, and .900 at 25 amps. It is not a regulator. The massive Schottky in the Borg drops .502 at 100 amps. But a mere tenth at trickle amperage.

[MrWizard]

I don't have lithium, but i dont think there will be any problem

the avg generator can be started with a motor cycle battery

they just happen to be connected to larger batteries in an RV

your (2) battle born, should have no problem starting your generator

when i had a low 6v house batteries
i started the onan with a little portable lithium jump starter
i even started this Ford 460 with it, then went to the store and bought a new chassis battery

lithium has tremendous surge current capabilities, despite the conservative rating they have speced it at

most starters most of the time, do not draw near the CCA rating of the batteries or starter

i doubt the generator starter draws more than 80amps

look on the web, at all the 'go carts' kids toys, made use a car starter and one battery and the hours of run time they get before recharge

ratings are for worst case scenario, cold very tight engine

if you ever have a problem, start the drive engine, then hold the emg start button while starting the genny

[SFVdave]

Here is another question. Will the 2 Lithium batteries provide enough starting amps for the Onan 4K generator? Reading it needs 350-450 amps and the Lithiums provide 200amps each for 30 seconds.

[BFL13]

bestconverters says

New models with "VL" and "L" incorporate the latest technology and new surface mount technology (SMT) as well as a Lithium-Ion jumper to switch between standard flooded, AGM, Gel or Lithium. You can now charge ANY RV battery with one unit.

They have a 4655 amper but no 60 amper.

[2oldman]

SFVdave wrote:
Just 2, no room for any more.

You'll love 'em.

[SFVdave]

2oldman wrote:

SFVdave wrote:
Battle Born 12v Lithium 100ah

Nice. How many?

Just 2, no room for any more.

[2oldman]

SFVdave wrote:
Battle Born 12v Lithium 100ah

Nice. How many?

[time2roll]

As long as you have the solar I think it will be fine as is.
Give it a go. Monitor the chassis battery voltage in the early afternoon.

[SFVdave]

2oldman wrote:

SFVdave wrote:
Wouldn't just disconnecting engine battery from the BIM and isolating it work?

Yeah.. that's what I'd do. I'm sure the alternator will handle your engine battery like it's supposed to.

What Li batteries are you considering?

Battle Born 12v Lithium 100ah

[2oldman]

SFVdave wrote:
Wouldn't just disconnecting engine battery from the BIM and isolating it work?

Yeah.. that's what I'd do. I'm sure the alternator will handle your engine battery like it's supposed to.

What Li batteries are you considering?

[LittleBill]

im pretty sure the replacement is meant for both engine and house battery's to be LI, not separate chemistry.

i would not even remotely consider combining the battery's their charge profile are vastly too different if using a 18650 based lithium cell, over voltage on a LI pack is a death sentence, both to the battery and potentially you

[SFVdave]

camperdave wrote:
Does the Progressive Dynamics charger continue to supply 14.4v even after the Li battery is charged? That seems odd to me, I thought Li's don't like being trickled like that. If it just charges at 14.4 then shuts off, I think you'd be fine with the lead chassis battery.

No, it shuts off when lithium batteries are charged. No trickle charging.

[camperdave]

Does the Progressive Dynamics charger continue to supply 14.4v even after the Li battery is charged? That seems odd to me, I thought Li's don't like being trickled like that. If it just charges at 14.4 then shuts off, I think you'd be fine with the lead chassis battery.