[cknuth]

Great perspective Richard. I haven't heard or found a guideline for how much continuous load one may safely power from my alternator. That total would include all running chassis 12V needs, including lights at night; starter battery charging; and house battery charging. What total amperage would you feel safe with?
Thanks again.

[Guy]

To be clear for my foggy brain, with our 1984 having a Leece Neville gear driven alternator, AGM Batteries are off the table and wet lead acid are our only option because of increased charging demands vs wet lead acid batteries ? I ask because our house batteries have passed away . We have spent a year being on various full hook ups, but now realize it's time to replace them. They are at least 5 years old.

[ron skeen]

Gray 
I think the AGM batteries will be fine not the Lithium’s to replace the lead acid.

[cknuth]

I’ve continue to measure loads on both 12V and 120V sides of the coach system. Starting to feel comfortable with the following direction.
- Replace existing golf cart batteries with 6 – 100Ah Battleborn lithiums.
- Adjust MagnaSine inverter charging parameters per BB specs.
- Replace the existing Echo Charger and battery isolator with a Sterling B2B 60A charger, also adjusted to BB charging parameters.

It was pointed out that running the air-cooled 270A alternator anywhere near its rating would lead to burn-out. Here are the 12V load numbers:
- Chassis driving requirements with all lights and and air conditioning on = 60A measured
- Chassis battery charging requirement nominally 10A measured
- House battery charging requirement= 60A (limited by Sterling B2B)
This total load of 130A whilst driving is less than 50% of the Leece Neville 270A rating, which seems safe.

The house battery charging rateof 60A works out well: eight hours of driving @ 60A is 480 Ah of charge. That’s exactly the capacity of the house lithium battery at 80% discharge. Subtracted from this, of course, are the 12V and 120V house loads that are on whilst driving – about 40Ah for that 8-hour period. And on shore power, the inverter will charge at 125A.

I’m inviting comment, questions and further input from any interested gurus. I’m about to pull the trigger and value your input as always.

Thanks!
Chuck

[Richard]

Sounds like a well thought out plan!

Do you know what the charging voltage will be during that 8 hour drive? And is that the charging voltage the BBs want? On second read, I see the BB is adjustable.

Is the 60 amp rating on the Sterling self limiting? In other words if the BB will take much more amperage will it put a strain on the Sterling. Just asking out of ignorance. I don’t know exactly which model of the Sterling you are looking at, so I couldn’t read the specific literature on their website.

I am commenting primarily out of two fundamentals. One, the lithium’s have a tremendous capacity to take and allow a high amperage input. Two, the charging voltage for a lead acid chassis batt and a lion bat are pretty different, and if you charge the lion like a lead acid, you have cooked it.

[folivier]

Richard the way I understand it is the alternator charges the chassis battery like it's designed to. Then the Sterling B-B only charges the house batteries and are adjustable to the parameters best for your house batteries. That allows them to be used for AGM, Gels, or different Lithium types. This may be the best option for Lithiums.

[cknuth]

Richard and Forest,
Thanks for your comments. Here's the B2B unit I'm planning to use:
https://www.sterling-power-usa.com/Sterl...arger.aspx

It appears to have all the features and programmability necessary to charge the house and chassis batteries independently regarding voltage and current limits.

Will share a wiring diagram soon.
Stay Healthy,

[Richard]

Chuck,
Thanks for posting this. I took the time to read the literature, and this looks like a really good solution to a vexing problem with the early adopters of LiPo batteries.

I think you will have a very good setup for boondocking.

But I would look carefully at the Echo charger, I did not see where you had any provision for the house batteries keeping the chassis batteries charged automatically.

[Latitude 28]

Chuck,
Checked out the Sterling B2B literature and really like the options one has with that unit. Where are you planning on installing the B2B unit?

A question; If the generator is running, while driving, the inverter/charger is an option for charging the house batteries. Which device has priority to charge the house batteries?

[cknuth]

Great observations on both points. I am trying to get on the phone with the Sterling folks to get a growing list of issues addressed, including:
- confirmation that the recommended Battleborn charging profile can be programmed
- what happens if the merge switch is used?
- what the heck is regenerative braking in this context?
- double check that the charger will not draw more than 60A from the alternator
- How do I keep the chassis battery charged when on shore power (explain current Echo setup?)
- If the generator is run while driving, is it OK for both devices to be charging the house battery or do I need to prevent the B2B charger from competing?

Thanks again!