DC - DC Charger for Chassis battery?

[aippolito184]

It is a Xantrax Freedom 458 30A, not designed for lithium. The main fuse I speak of is the 300a, it feeds a panel with a plethora of other fuses. So if the battery can handle 560A continuous and the fuse is 300A it sounds ok with the BMS.

In regards to the alternator scenario, I plan to remove the solenoid and install and Amp-L-Start to charge the chassis battery from the house when it is charging (solar, shore, generator) and then a DC - DC charger that will be controlled by the ignition to charge the house from the alternator while the coach engine is on. Solid plan? Anything you would add?

 

[John Frum]

It is a Xantrax Freedom 458 30A, not designed for lithium. The main fuse I speak of is the 300a, it feeds a panel with a plethora of other fuses. So if the battery can handle 560A continuous and the fuse is 300A it sounds ok with the BMS.

If you want to talk about the overall system that is fine.
Please include a topology diagram.
The system fuses primarily protect the wires.
So a 300amp fuse need a wire that can handle > 300 amps fault current.

In regards to the alternator scenario, I plan to remove the solenoid and install and Amp-L-Start to charge the chassis battery from the house when it is charging (solar, shore, generator) and then a DC - DC charger that will be controlled by the ignition to charge the house from the alternator while the coach engine is on. Solid plan? Anything you would add?

I would like to see the topo drawing.
It sounds like you will have parralel paths one for charge and one for discharge which may not work as expected.

 

[BobR]

@BobR your uri points to a file on your computer.

Thanks fixed it

 

[MisterSandals]

I plan to remove the solenoid and install and Amp-L-Start to charge the chassis battery from the house when it is charging (solar, shore, generator)

How do you intend for this mechanism to know when the house battery is charging?
I have mine setup to always charge the engine battery but my RV sits in the sun so solar always available (i do disconnect solar most of the time and only charge periodically to keep house battery in low storage voltage (12.9V - 13.2V). It takes a little attentiveness but only every other week.

 

[aippolito184]

How do you intend for this mechanism to know when the house battery is charging?
I have mine setup to always charge the engine battery but my RV sits in the sun so solar always available (i do disconnect solar most of the time and only charge periodically to keep house battery in low storage voltage (12.9V - 13.2V). It takes a little attentiveness but only every other week.

It says in the documentation it only engages when the battery is being charged. I think that is why the Trick L Start is not intended for LiFePO4 since the charge voltage is different.

 

[MisterSandals]

It says in the documentation it only engages when the battery is being charged.

Ok, i did not know if was a smart voltage sensing charger (like the Victron Orion). I would check to see what the start voltage is and make sure that your 3 charging sources produce a voltage that meets that.

 

[aippolito184]

That is the issue with using a Tric L with lithium, they say the fact it doesn't float and the discharge curve confuses it because it was made for lead-acid. The Amp L has selectors that change the input sensing, although I don't think it can charge lithium, which is why I am looking at a DC-DC controlled by the ignition.

 

[aippolito184]

From support:

"As mentioned on our TRIK-L-START web page, TRIK-L-START is NOT recommended for use with Lithium house batteries, for several reasons:

1. TRIK-L-START does not have any provision for adjusting the charging turn-on and turn-off voltages supplied to your starting battery - and the fixed turn-off voltage is too low to prevent substantial house battery discharge before turn-off finally occurs.

2. Some Lithium house battery chargers maintain the Lithium batteries at a voltage considerably higher (14.5+ volts) than the ideal "float" voltage for your lead-acid starting battery (13.5 volts). TRIK-L-START doesn't have any ability to reduce the house battery voltage to the ideal 13.5 volts, and thus overcharging of your starting battery is possible.

For lithium house batteries, we recommend using AMP-L-START instead, which has several user-adjustable turn-on and turn-off voltage settings - one of which is specifically tailored to lithium batteries."