DC DC Converter Wiring Questions

[Carolina Quards]

I'm considering converting to Lithium. I've see a lot of good comments and advice about Batteries and I would like any feedback on my plan.

1) Remove existing house batteries and add 300aH Lithium
2) Keep existing PD9100 Converter, B.I.R.D and Emergency Start Relay. (I wouldn't inted to use the Emergerency Start with Lithium, so I may want to disconnect it).
3) Add a DC to DC charger just before the house batteries (see diagram).

Specific Concerns:
I seems like the DC/DC charger would be able to fully charge the battery even with the old converter. It doesn't seem like I'd need both a DC/DC charger and AC/DC Lithium converter. Is this correct?

I am uncomfortable deleting or modifying the B.I.R.D. and Soloniod. What's the harm in leaving it in place?

Thank you in advance for your advice.

 

[Just two]

Nice print. Thanks,
What model camper do you have?
I answered your questions on the Kiwi step thread.
I have already started the Lithium conversion and have been running with Lithium batteries for 2 years.
We have a 2021 BT 5210. I replaced the charger/converter under the fuse panel for one that supports lithium 4 stage charging. I have also replaced the alternator with a 400 amp model. I am currently using the original relay system to do the B2B charging for the 210 AH of Lithium. There is also 200 watts of solar on the roof charging the 12 volt.

Also we added 400 AH of 24 volts Lithium batteries. This supports a 3000 watt hybrid inverter to power the microwave, coffee maker, toaster, water heater and other 110 volt AC devices. I also added a 24 volt DC Air conditioning 12000 BTU unit for off grid cooling. I added 4 - 200 watt Rich solar panels through 2 Victron MPPT charge controllers. I have 3 B2Bs that charge 24 volts off the 400 amp alternator. 2 Victron 12 to 24v 15 amp. And a new Renogy 12 to 24 volt 50 amp B2B with a built in MPPT controller. I use this controller for some portable solar suit cases.

 

[THenne1713]

I'm considering converting to Lithium. I've see a lot of good comments and advice about Batteries and I would like any feedback on my plan.

1) Remove existing house batteries and add 300aH Lithium
2) Keep existing PD9100 Converter, B.I.R.D and Emergency Start Relay. (I wouldn't inted to use the Emergerency Start with Lithium, so I may want to disconnect it).
3) Add a DC to DC charger just before the house batteries (see diagram).

Specific Concerns:
I seems like the DC/DC charger would be able to fully charge the battery even with the old converter. It doesn't seem like I'd need both a DC/DC charger and AC/DC Lithium converter. Is this correct?

I am uncomfortable deleting or modifying the B.I.R.D. and Soloniod. What's the harm in leaving it in place?

Thank you in advance for your advice.

Three issues I think of: 1) Lithium requires higher voltage to charge fully/ properly, but also read that 85% charge extends life?; 2) Lithium charge controller required to prevent overheat burnout of alternator, and it shuts down coach charge for timed OFF/ ON for alternator cooling; Does not affect chassis charge. 3) Lithium fine for emergency boost, that is what is used in portable boost packs.

 

[Just two]

Three issues I think of: 1) Lithium requires higher voltage to charge fully/ properly, but also read that 85% charge extends life?; 2) Lithium charge controller required to prevent overheat burnout of alternator, and it shuts down coach charge for timed OFF/ ON for alternator cooling; Does not affect chassis charge. 3) Lithium fine for emergency boost, that is what is used in portable boost packs.

Good stuff, thanks.

I finished replacing the smaller lithium batteries with the big 300 amp hour one. I found it easier to remove all the relays, fuses and components, then replace them. Took a bit to check and label all the circuits and wires.
Added the new B2B. The one thing left to do is reinstalled the engine start assist relay system. Also the new Renogy B2B has a built in Solar MPPT charge, I need to test that function.

So my take away from this is that the original BT Cruiser Engine Charge System doesn’t work correctly with lithium batteries. You lose a lot of capacity.

 

[Just two]

I'm considering converting to Lithium. I've see a lot of good comments and advice about Batteries and I would like any feedback on my plan.

1) Remove existing house batteries and add 300aH Lithium
2) Keep existing PD9100 Converter, B.I.R.D and Emergency Start Relay. (I wouldn't inted to use the Emergerency Start with Lithium, so I may want to disconnect it).
3) Add a DC to DC charger just before the house batteries (see diagram).

Specific Concerns:
I seems like the DC/DC charger would be able to fully charge the battery even with the old converter. It doesn't seem like I'd need both a DC/DC charger and AC/DC Lithium converter. Is this correct?

I am uncomfortable deleting or modifying the B.I.R.D. and Soloniod. What's the harm in leaving it in place?

Thank you in advance for your advice.

Specific Concerns:
I seems like the DC/DC charger would be able to fully charge the battery even with the old converter. It doesn't seem like I'd need both a DC/DC charger and AC/DC Lithium converter. Is this correct?

That is true, as long as you plan on doing most of your charging by driving. If you plan on plugging into shore power then replace the AC/DC charger also.

I am uncomfortable deleting or modifying the B.I.R.D. and Soloniod. What's the harm in leaving it in place?

Yes the Bidirectional means that when the lithium gets over the voltage threshold power flows to the chassis battery. So if you have solar or have a fully charged lithium battery the B.I.R.D will try to move that charge to the engine battery.
I’ve seen this happen. That is why I removed those components.

 

[Carolina Quards]

Good stuff, thanks.

I finished replacing the smaller lithium batteries with the big 300 amp hour one. I found it easier to remove all the relays, fuses and components, then replace them. Took a bit to check and label all the circuits and wires.
Added the new B2B. The one thing left to do is reinstalled the engine start assist relay system. Also the new Renogy B2B has a built in Solar MPPT charge, I need to test that function.

So my take away from this is that the original BT Cruiser Engine Charge System doesn’t work correctly with lithium batteries. You lose a lot of capacity.

Great job. Well done. I'm curious, my battery is in the compartment just rear of the wheel well. Is that the original location of yours? I like the box and use of bus bar - nice touch. I'm inspired.

 

[Just two]

I’m working on a 2021 BT 5210 Ford E350 chassis.
What do you have?
The battery box is on driver side just in front of the rear tire. Very tight location for the relay components, batteries and connections.
Picture shows the door open on the battery compartment. Just to the front is the generator. Behind the rear wheel is a compartment I added for extra storage and to the rear of that is the waste tank dump area.

 

[Just two]

Did some testing this morning. Ran the Ford and got about 50 amps of power to the 12 volt system from the alternator. Looks like the 24 volt batteries were charging at 24 + amps.