Merging house batteries with the alternator

luvrbus · February 04, 2023, 01:51:09 PM

Quote from: TomC on February 04, 2023, 01:31:14 PM
Check out this smart switch over through Battle Born. https://battlebornbatteries.com/product/lifepo4-battery-isolation-manager/

You see those on new RV's with the Lifepo4 so I take it those just work with Lifepo4 batteries? they all looked the same but had 4 or 5 different brand names Sure Power was the most common name

TomC · February 04, 2023, 05:37:02 PM

It works well with the 3 100amp Battle Born Lithium iron batteries. Good Luck, TomC

Glennman · February 06, 2023, 01:44:57 PM

This will probably not add value to the subject, but in my first bus, I had a typical deep cycle house lead acid battery bank. I had a battery checker above the driver's area where I could check the status of the house batteries from time to time while driving. I had a continuous solenoid (I don't recall the brand or type, but was for continuous duty vs. intermittent) that I would switch on when the house batteries would get low. I picked it up from a local automotive electrical outfit. It worked very well, as far as staying in the open position is concerned, but I only probably turned it on for an hour or two at a time, as needed. One problem though that I did have was that it did not account for balancing the system. I ended up ruining my bus starting batteries. It was explained to me later that I would have been better off with a system that balances the loads so that you don't fry one system while charging another. With gearing up for installing my system in my new bus "02 MCI, I will be designing this more carefully to make sure I don't have similar problems (especially when going with lithium-iron batteries). I'm definitely in a learning curve on this entire subject.

luvrbus · February 06, 2023, 02:54:55 PM

They have been using isolators for 50 years with just a solenoid to boost the batteries if needed. I still prefer the isolator system over the solenoids,they never give trouble unless it is human error.

buswarrior · February 06, 2023, 03:33:43 PM

Quote from: Glennman on February 06, 2023, 01:44:57 PM
With gearing up for installing my system in my new bus "02 MCI, I will be designing this more carefully to make sure I don't have similar problems (especially when going with lithium-iron batteries). I'm definitely in a learning curve on this entire subject.

Do NOT connect batteries of a different chemistry directly to the coach alternator.

A DC to DC charger, intended to charge that battery chemistry is a must.

The coach alternator regulator is commanding a charge profile that will be harmful to anything other than lead. And some battery chemistries will try to absorb all the power that the alternator is fooled into making, putting it at risk of burning out.

The DC to DC charger just becomes another normal load on the coach electrical system, no further work is needed on that side.

happy coaching!
buswarrior

luvrbus · February 06, 2023, 04:30:06 PM

Dual alternators 1 for house batteries and 1 for the chassis is fool proof.,when you get into merging the 2 banks is where you can get into trouble with different chemistry of batteries. I lost 6-8D AGM's batteries playing that game that was a very costly education.

Van · February 06, 2023, 07:44:05 PM

Quote from: luvrbus on February 06, 2023, 04:30:06 PM
Dual alternators 1 for house batteries and 1 for the chassis is fool proof.,when you get into merging the 2 banks is where you can get into trouble with different chemistry of batteries. I lost 6-8D AGM's batteries playing that game that was a very costly education.

buswarrior · February 07, 2023, 08:31:47 AM

Each alternator has to be regulated for the intended battery bank.

Using a "regular" automotive alternator for the lithium chemistries is going to get expensive fast.

An externally regulated alternator, with a regulator with matching charging profiles to the battery chemistry will make a sweet set-up.

Happy coaching!
Buswarrior

windtrader · February 07, 2023, 10:12:10 AM

Quote from: buswarrior on February 07, 2023, 08:31:47 AM
Using a "regular" automotive alternator for the lithium chemistries is going to get expensive fast.

Why? Seems like you would need a single system single alternator charging the lithium bank. That doesn't seem expensive, I must be missing something.

luvrbus · February 07, 2023, 11:00:08 AM

You cannot always depend on the BMS to control a spike from the bus alternator, a 24 volt will spike to 32 volts and a 12 volt system can spike to 19 volts old buses automotive style alternators never really completely charging.All the Prevost converters use 2 or 3 alternators now,lol you cannot buy a lifepo4 battery for a 100 bucks like you can a alternator.

buswarrior · February 07, 2023, 11:26:59 AM

Quote from: windtrader on February 07, 2023, 10:12:10 AM
Why? Seems like you would need a single system single alternator charging the lithium bank. That doesn't seem expensive, I must be missing something.
[/quote

Wrong voltage, so the lithium gets over or under charged, voltage sencing of traditional alternator will foul up the potential re-charge time, some lithiums will allow the alternator charging to go beyond its maximum and overheat it. Lithium does not withstand abuses outside their operating parameters.

Unfortunately, all we read is everyone is doing it, and the reporting is unblanced. Nobody gets on the internet to brag they fried their expensive toys, or burned down their bus.

There are way too many fooling with lithium, that do not know what they are doing, just blindly following what others have egged them on to do.

Happy coaching!
Buswarrior

Glennman · February 07, 2023, 01:23:30 PM

Quote from: buswarrior on February 06, 2023, 03:33:43 PM
Do NOT connect batteries of a different chemistry directly to the coach alternator.

A DC to DC charger, intended to charge that battery chemistry is a must.

The coach alternator regulator is commanding a charge profile that will be harmful to anything other than lead. And some battery chemistries will try to absorb all the power that the alternator is fooled into making, putting it at risk of burning out.

The DC to DC charger just becomes another normal load on the coach electrical system, no further work is needed on that side.

happy coaching!
buswarrior

I believe I'll have a DC to DC charger in the system. I'll have to check my materials list. I have yet to buy everything. I plan to do that next month (inverter, charge controllers, etc.).

luvrbus · February 07, 2023, 04:21:33 PM

The DC to DC isolates the batteries from alternator when you are charging from the inverter plugged in you need ECHO charger to maintain the starting and generator batteries or you end up with battery tenders.The ECHO charger when the house batteries are charging will pass a charge to the starting and generator battery.I love mine never a problem with the starting or generator batteries being low on charge when sitting for months if I am plugged in

windtrader · February 07, 2023, 08:25:26 PM

BW, Clifford,
Adding lithium into bus sytems does take quality research. I've not done any myself but seems highly probably that there is equipment to enable an alternator to charge lithium bank safely. Like selecting a BMS that is designed to accept power from an alternator which is very different that from solar panels etc.

luvrbus · February 08, 2023, 03:35:55 AM

By the time someone gets it figured out we will have new battery technology and it will start over again. I didn't go with Lithium ,the Lifeline 8-D's AGM were about the same in price as a Lithium 8-D size.Lifeline sells both and weighing the pros and cons.The only things I could come up with was the difference in weight and faster charging between the 2, since I don't have solar, I went with the AGM's