Lithium Iron Phosphate (LiFePO4) Batteries

[davidbrady]

Here's an outfit offering an LFP battery conversion for the Prevost crowd: Volta Power Systems. I think they have a connection with Pantera Coach. Their solution is a complete swap out of the alternator, voltage regulator, inverters, battery bank, and battery equalizer, with the addition of a 48V to 12V DC-to-DC converter. To me it looks like a bunch of off-the-shelf parts. My guess is the DC-to-DC converter pushed them into the 48VDC world. I have yet to find a 24V to 12V DC converter able to supply a continuous 100 amps of current, and apparently they couldn't either. The 48V solution is okay for new builds, but it's a tough $30K sale for the poor M450 owner who simply wants an LFP "upgrade"!

[davidbrady]

Here's an instructive article from Maxim Integrated on the inherent challenges involved in building a DC to DC Converter.

[GregOConnor]

(01-09-2015 13:50)davidbrady Wrote:  Here's an instructive article from Maxim Integrated on the inherent challenges involved in building a DC to DC Converter.

I understood one of the issues with different dc voltage was the chassis banks were 24v and the house bank was 12 volt. would it not be better to use all 24volt inverter chargers and banks then step down the house dc output to 12volt appliance demand (mostly audio and lights). the house would power the inverters with 24volt but power the other 12 volt demand with 1/2 of a set of batteries in series. there is not much of a 12 volt demand anymore anyway.

the construction equipment chassis that run 24volt often have a bunch of 12volt demand. On Bus chassis that are 24volt, is it just the Detroit starter motor that require 24volt?. seems too simple to work , so I must be missing the entire need or advantage to go 24 volt.

[davidbrady]

(01-10-2015 02:38)GregOConnor Wrote:  I understood one of the issues with different dc voltage was the chassis banks were 24v and the house bank was 12 volt. would it not be better to use all 24volt inverter chargers and banks then step down the house dc output to 12volt appliance demand (mostly audio and lights). the house would power the inverters with 24volt but power the other 12 volt demand with 1/2 of a set of batteries in series. there is not much of a 12 volt demand anymore anyway.

the construction equipment chassis that run 24volt often have a bunch of 12volt demand. On Bus chassis that are 24volt, is it just the Detroit starter motor that require 24volt?. seems too simple to work , so I must be missing the entire need or advantage to go 24 volt.

Hi Greg,

Maybe an M450 owner can chime in, but I think the house on a 450 is 24V with 24V Vanner inverters and one or two Vanner Equalizers to supply the 12V loads. I think the chassis uses this same battery bank for it's 24 and 12V loads. I believe the generator has it's own 12V start battery. (IOW's, one center-tapped 24V battery bank for the house and chassis).

Maybe Dan can help us out with some requirements of what he'd like to see.

I'm not an M450 owner but if I were I'd want:
1) the fewest number of battery banks possible,
2) only one deep cycle battery bank, in this case Li-ion,
3) all other banks charged by 120VAC house trickle chargers,
4) good separation between chassis and house systems,
5) a house system capable of 12VDC and 24VDC,

Any more?

There are other ways, but my preference to solve these would be a dedicated lead acid bank for the chassis, a dedicated generator start battery, and a Li-ion 24V house bank with a 100A 24/12V DC-to-DC (buck) converter for 12V house loads. The genny and chassis batteries would be trickle charged off the 120VAC house system.