[Jon]

Why rewrite a good plan? Put 3 new Lifeline’s in there and you are good for 10 years and still have a bunch of money in your pocket.

[Jon]

Here’s the good news. you likey will save 300 or more pounds of weight. If you never let then go below 50% SOC you can measure their life in decades. You will have more power available so 2 may be equal in available capacity to your 3 AGM. If you use 3 Li you will have an incredible gain in useable capacity. You can use the charts and your own experience to decide what works best for your application.

Here’s the bad news. Your autostart will not work. You can see from the Li curves the voltage drop off is so steep if you need autostart you will need to install a system that tracks battery usage (like a fue gauge for amp hours) and trigger autostart from usage, not voltage. Here’s worse news. They are not justified economically.

I replaced mine with Li and it was one of the best things I ever did to my coach but it wasn’t cheap. It cost me about 3 1/2 times what AGM would have cost but at least I never have to replace my batteries. I removed my AGMs on a 5 year schedule because there is no way I was going to nurse my batteries as they started to wear down so my payback on the purchase only applies to how I maintain my coach. You have to use your own numbers for your situation.

[Jerry]

If you do go with LI, you have a much easier go of it since your 12v. Your present battery capacity is 765 amp hrs, 383 amp hr usable at 50% discharge. 2 Relion 200 amp 8D’s would almost meet your present usable amp hrs at 90% DOD or 360 amp hrs. Better choice would be 2 Relion 300 amp hr. Keep in mind you have to protect them from cold charging temps or go with the Relion 300LT (low temperature). In the 8D size, Relion makes 100, 200 and 300 amp batteries.

Jon was meticulous on his research and had a complete understanding of what was involved with his 24v Liberty conversion to LI. So do your homework and if I can help you with LI or AGM, let me know.

[Jon]

Look at the articles I wrote for Bus Conversion magazine on doing exactly what you want to do since my CC is set up very much like yours. Simple conversion if you split the house batteries into two banks – your existing AGMs for the 12vdc loads and new lithium’s for the 120vac loads powered through your two Magnum 2800 inverters. btoB charger handles charging the Li batteries from your existing house alternator and the 2800s can easily be set to a Li charging profile to charge Li batteries while on shore or gen power. Works like a charm and allows you to fine tune the systems to your specific needs over time. There are now a number of high quality 12vdc lithium options at very attractive prices, some nearly dollar for dollar the same price as new AGMs.

Jerry

[DON]

In a Liberty like Don’s dealing with the cold is an easy process. Add a wall between the batteries and the Cruisairs and aux compressor. Insulate it a little. In the rear of the rear wall of the entertainment center mount a small 200 watt heater in the battery area, use the 120V outlet in the entertainment center rear wall for power to the heaters. Add a thermostat control for the heater (mine is on at 40 degrees, off at 50) and problem solved. The power to maintain the heat comes from the Li batteries via the inverters so you may want to consider the small current draw in doing you evaluations. Simple, automatic and never exposes the Li batteries to any risk of charging in cold temps.

[Unknown Member]

I’ve never used the Liberty auto start so I won’t miss it.

We don’t use our Liberty in the winter. It stays home in central TX where it rarely gets below freezing. Like Jon said, it would be easy to isolate, insulate, and heat the area where the batteries live in case there is ever another cold spell like the one we/TX had last Feb, or never say never, we may take it somewhere cold in the winter.

I’ve been reading what Jon and dtjoint/Jerry have done. I have a 12v group 29 wet cell gen battery that is connected to the house bank via a battery isolator. Gen battery get its charge from the house bank only. So I could go with 2 or 3 8DL 200ah or 300ah Lithiums for the house, and when the Lithium BMS disconnects from the 12v alternator it won’t freakout because it’s still hooked up to the gen battery, CORRECT???.

[DON]

No. The gen battery is separated via an isolator so it can get charged via the house batteries, but a set of house batteries will not get current from the gen battery.

If the house Li batteries go into shut down you will need to start the bus to get current flowing into the house batteries, and then gen or shore power can recharge them. I know this because I did a lot of testing on my systems to determine actual length of time I had from fully charged to shut down.

[DON]

The gen battery is connected to the current house 12vdc AGM batteries via either a combiner (voltage controlled relay) or an isolator (diode block) so it gets charged via the alternator while driving or via the house AGM charger while on shore or gen power. The combiner or isolator will prevent current from flowing from the gen battery to the house agms.

if you split the house battery bank so the remaining AGMs power only the 12vdc loads and the new Li bank powers only the 120vac loads through the inverter/charger the gen battery will still get charged as it always has been. You will add a BtoB charger to charge the new Li bank from the alternator while driving and you will add a conventional RV converter/charger to charge the remaining house AGMs and that gen battery while on shore or gen power.

On most Webasto hydronic heating systems there is a setting for automatically keeping your water and holding tanks from freezing in low temps. That will also keep your new Li batteries warm during cold spells. Or, you can mount your new Li batteries in the living area (as I did).

Either way, having Li batteries that only power the high current draw 120vac loads through your inverter(s) and leaving some AGMs to handle only the 12vdc loads will allow the AGMs to live far longer than they will being hammered by those high draw inverter loads which are ideal to be handled by the Li batteries.

Splitting the house bank like this is easy, fast, very reliable and requires little in the way of new components or re-engineering. Another Bus Conversion magazine article is coming out soon that shows how you can even add a second Li bank tsp a separate Li bank powers each of the existing 2800 inverter/chargers. I now have 300 available amp hours of Li capacity to handle the 120vac loads on the passenger side where my residential refer and basement refer are located and 400 available amp hours to handle the 120vac loads on the drivers side where my kitchen and AV appliances are located. I kept 200 available amp hours of AGMs to handle the very light 12vdc loads which for me are just LED lights and a few fans and pumps. Any time I wish I can move any of those over to either Li bank if I ever want to shed even more AGM weight. So far, no need.

Everything is automatic and all three banks stay fully charged while driving, or while parked on shore/gen power, with no need for intervention on my part.

‘Jerry

[Bob]

OK

How about a 200 amp battery isolator between the gen battery and the Lithium house batteries, getting its input from the 12v alternator?? The battery isolator 2 outputs would feed 1) the gen battery, 2) the Lithium House batteries?? This protects the 12v alternator and charges both banks when the Detroit is running.

When on genny or on shore power and the Magnum inverter/chargers are on, the house Lithiums will get charged from the Magnum inverter/chargers. The gen battery with get charged through the existing small 1 input/1 output battery isolator that Liberty has between the the house and gen batteries.

What do you think ???

[rafael]

Why reinvent the wheel?

Your system has withstood the tests of time, works, is reliable, and relatively simple. I cannot think of a bigger pain in the ass than making a complex coach even more complex.

[Jon]

Why reinvent the wheel?

Because there is an improvement to be had (better wheel), lithium batteries.

The lithiums are physically the same size as the Lifelines. Existing cables will work. I will only need to add the 2 cables, 1 each from the isolator to each bank. The two banks are near each other. Easy peasy. Enclosing the area where the batteries live should be done either way because there is a CruiseAir condenser underneath the battery rack that creates a lot of heat in the area.

My coach/bus is relatively simple, no multiplex, no antiquated software, no circuit boards, etc. It has good ole fashion switches, circuit breakers, fuses, wires, etc. Adding lithium batteries as stated in my last post will only add a battery isolator and 2 cables to the bus. That’s not really adding complexity if you ask me, and I can easily do it.

Kind of like the Matthew Valentine LED headlight setup I’m fixin to install. And the Pure sine wave Magnum inverter/chargers I installed 5 yrs ago in place of the ole Heart 2500 modified sine wave units. Or synthetic fluids in place of conventional, all LED internal and external bulbs/lights, etc.

[Archived]

Not questioning the switch to Li, but having a house with two types of batteries each with different charging schedules.

[DON]

Don,

The SOB’s use this BIM.

[Marshall]

Yep..that is what I have. Renegade did have to replace it as it failed almost right away after delivery, but it is working fine now.

[Archived]

BtoB chargers handle the different charge profiles for Li and LA batteries so both get fully charged without changing anything in your existing setup if you currently have 12vdc house batteries. The BtoB charger also acts like an isolator or combiner to prevent the Li and LA batteries from ever coming together. It is all gain and no pain, particularly if your existing house LA batteries are nearing the end of their useful life. They will last much longer if you release them from the strain of powering 120vac loads through an inverter. Li batteries are well suited to that task, LA batteries are not.

jerry