Chinook RV

chin_k wrote: August 10th, 2023, 6:49 am .. but all analog (and most digital) SOC meter is just use the voltage as an indicator of the SOC.

For LFP? Do you have one that you can recommend?

chin_k wrote: August 10th, 2023, 6:49 am I think the shunt in Camaro rig is for his current meter (ammeter, which is actually a voltmeter that measure the voltage drop across the shunt).

Correct its a 50MV Deltec shunt for the TriMetric Battery Monitor.

Scott wrote: August 10th, 2023, 9:39 am For LFP? Do you have one that you can recommend?

I don't really have any recommendation, since you either get one that is simple to use (two wires, bar graph), or one that you have to program (digital, with shunt). It really depends on how much you want to play around. For most people, the simple SOC meter will be fine as long as the voltage profile matches the battery type. That is what we have in the original Chinook (bar graph type with LEDs).

chin_k wrote: August 10th, 2023, 7:39 pm

Scott wrote: August 10th, 2023, 9:39 am For LFP? Do you have one that you can recommend?

I don't really have any recommendation, since you either get one that is simple to use (two wires, bar graph), or one that you have to program (digital, with shunt). It really depends on how much you want to play around. For most people, the simple SOC meter will be fine as long as the voltage profile matches the battery type. That is what we have in the original Chinook (bar graph type with LEDs).

Can you hook up the original Chinook bar graph meter to an LFP bank and get a reliable state of charge value? Can you share how you would do this?

The Specialty Concepts Mark 15 on the Chinook is meant for lead acid chemistry, and won't work too well for Lithium. It probably give you "fully charged" status until the BMS on the lithium shut down the power, since the voltage vs SOC curve for lithium is very different from lead acid. Lithium pretty much maintains a constant voltage and it drops very quickly. Let me know if you can see the graphic here:



It will be very difficult to modify the Mark 15 to get it to work with lithium. You would need something that is programmable.

If you’re looking for good shunts, Victron is a pretty solid choice. It has BT and an app that you can monitor various metrics remotely. LiFePO batteries are significantly cheaper than a couple of years ago, so it’s economically a smart choice to upgrade battery storage bank and even starter battery to lithium.

I think you need to have a different type of starter to be able to use lithium battery for your chassis starter. Lithium does not have the cranking power for regular starter on a long term basis.

chin_k wrote: September 5th, 2023, 12:33 pm I think you need to have a different type of starter to be able to use lithium battery for your chassis starter. Lithium does not have the cranking power for regular starter on a long term basis.

In video below Ross at past half-way through talks about using a Victron Multiplex Inverter Charger to trickle charge your engine battery from lithium batteries. Also at 27:49, he discusses and shows how to jump start from lithium batteries. You need a bigger DC/DC charger than I have and he gives example and picture using the Sterling 60amp. This probably won't start dead battery, but would help with weak battery.

https://www.rosslukeman.com/van-power-w ... ing-2-q323

chin_k wrote: September 5th, 2023, 12:33 pm I think you need to have a different type of starter to be able to use lithium battery for your chassis starter. Lithium does not have the cranking power for regular starter on a long term basis.

What type of starter would be needed?

I should not have suggested that there are different type of starters, since those that are available are not compatible with lithium. For hybrid vehicle, their engine is much smaller, and their generator/starter motor is usually much bigger than typical alternator or starter in gas engines. It is very difficult to made a starter that is strong enough to crank engine with only 12V lithium battery the size of a lead acid battery.