Lithium Iron Phosphate (LiFePO4) Batteries

[GregOConnor]

A good real time test on this would be two harbor freight trickle chargers one for each 12 volt start battery plugged into a tell - a - watt for two months. Then you can calculate impact these chargers would have if tied thru the lithium powered inverter . I use the harbor freight $5.00 trickle chargers on tractors that sit and have had good luck with the auto feature but blame one of them for cooking a lead acid dry. I am not sure a cheap one or failed auto stop charge prompt can screw up agm's. F OLIVER has a good idea and that doesn't complicate the need to find a way for one charger to send two different charge cycles. Redundancy is also a good thing

one thing to keep in mind with two banks side by side is to maintain directional isolation charge only and a back up line protection fuse. I once installed a genset start battery and simply charged it with a 10 gauge wire to a 0 gauge run off of the house bank. Once when the new start battery failed to maintain a Sufficient charge the Un fused 10 ga wire got cooked as it became the path for start power. Folie idea requires no extra fuse or fear.

[davidbrady]

Greg,

My coach uses a Guest 16102 to keep the 24V chassis bank charged. Works great! (You can see it on my previous schematic at the lower right hand corner). It plugs into a house receptacle that's keyed to the ignition switch; i.e., the receptacle is powered only when the ignition switch is off. The 16102 is a twin 12V output which can be wired to charge 24V banks. Newer buses use true 24V chargers. Iota provides the DLS-27-40 which looks like a good choice. This upgrade is on my TODO list.

[davidbrady]

Out of the attached study comes the suggestion to keep our LiFePO4's at or around 68 deg F, discharge them moderately, and keep the discharge rate down at fractional C levels. Also, there are exciting anode and cathode technologies on the way. One of them is Lithium Titanate (Li2TiO3) which may take us to the next level. In any case, all of these technologies will likely have similar concerns for us; namely, cell balance and voltage reversal when put into series strings, strict low and high cutoff voltages, and special constant current and constant voltage charging regimens with limitations on float current. It's an exciting time to be an electrochemist, a battery material scientist, or a motorhome owner!

  LiFePO4 Cycling Degradation Battery.pdf (Size: 1.38 MB / Downloads: 1587)

[GregOConnor]

Now that I'm in the market for a vintage tow'ed vehicle I stumbled on to an article about a GM project in '66 with a fully electric Corvair . The article said batteries were the holdback. At 160,000. For each car.

[davidbrady]

(12-21-2014 16:00)GregOConnor Wrote:  Now that I'm in the market for a vintage tow'ed vehicle I stumbled on to an article about a GM project in '66 with a fully electric Corvair . The article said batteries were the holdback. At 160,000. For each car.

Wow! $160,000 in 1966 dollars? In fifty years, for a given energy capacity and power delivery, we brought the cost down to Tesla's $16,000, - very good. We'll likely lick this problem within the next 25 years! Whether it's an electrochemical battery or a fuel cell remains to be seen.

An EFOY hydrogen fuel cell you can buy today for your motorhome. Only $7000 for a 2.5KWhr unit. Gasp!

[GregOConnor]

(12-22-2014 20:24)davidbrady Wrote:  Wow! $160,000 in 1966 dollars? In fifty years, for a given energy capacity and power delivery, we brought the cost down to Tesla's $16,000, - very good. We'll likely lick this problem within the next 25 years! Whether it's an electrochemical battery or a fuel cell remains to be seen.

An EFOY hydrogen fuel cell you can buy today for your motorhome. Only $7000 for a 2.5KWhr unit. Gasp!

I know we are getting away from the topic a bit but here is a video on the Fuel Cell concept way back also. in this same series you can find a vid on the corvair Electro-Vair II
https://www.gmheritagecenter.com/videos/...rovan.html
I am surprised how slow all electric cars are catching on. I have a hard time finding charging stations for my Fiat so I don't use it unless I can return home on the 90 mile range. We put 10,000 miles on it this year but most consumers don't have a backup long range car available. I have several cars and can even visit a customer with a M923. I think green Diesel will pass the all electrics before the hydrogen cell advances and takes off. For my 77 GMC project I am kinda set on using a Yamaha EF4500iSE.This Generator is called an Inverter. I always understood an inverter to be the device that changed 12 volt battery energy to AC 120 volt electric but here it is a device that replaces the batteries with a gas engine and an alternator. Here is how HONDA describe their inverter/generator

[[Honda 's inverter technology takes the raw power produced by the generator and uses a special microprocessor to condition it through a multi-step process.
First, the generator's alternator produces high voltage multiphase AC power. The AC power is then converted to DC. Finally the DC power is converted back to AC by the inverter. The inverter also smooths and cleans the power to make it high quality. A special microprocessor controls the entire process, as well as the speed of the engine.]]

I wonder if the process of using a Inverter/Generator and an Inverter Battery charger to charge a storage bank of DC Batteries can be improved by the engineers at Honda? I believe there is some caloric loss some place that can be recovered? As it is now, my Yamaha will be Making AC then DC then AC then my Xantrex inverter/charger will be taking the AC to make DC to charge the batteries. AC-DC-AC:AC-DC. the last conversion of AC to DC is in the Inverter Charger when they detect incoming AC from the Yamaha Genset. I think Honda has a small 12 volt charger on their i1000.
I do think this discussion should be part of the new power storage technologies because any power you store originated at the genset and one of the issues has been the lost power produced and not captured when the diesel genset runs with a lite load.

[davidbrady]

Hi Greg,

The Yamaha is phenomenal technology and it seems ideal for your application, but I can't help thinking that it's really meant to be used without an external inverter or battery bank. Also, these smaller gasoline systems rarely beat Powertech at fuel consumption. I do see benefit at very low rpm use at almost zero load, sound levels, weight and form factor; you're not likely to find space for a 15KW Powertech in a GMC. Yikes! Nonetheless, it's interesting to compare efficiency.

Here's some Powertech fuel consumption figures I gathered:


From the Yamaha manuals I've gathered a fuel tank of 4.5 gallons and a run-time at full load of 7.4 hours at rated output of 4KW and 15.2 hours at 50%:

7.4 hours at 4KW: 0.61 GPH
15.2 hours at 2KW: 0.30 GPH

Without doing a bunch of extrapolation, from the 15KW Powertech numbers we see that 0.33 GPH gives 3.75KW and 0.67 GPH gives 7.5KW. I think that it's safe to assume that at outputs of 2KW and 4KW the Powertech fuel consumption numbers would be even better.

[davidbrady]

These look promising: Power Stream DC/DC converter, or Newmar Power, or Vanner 90-50A. I'd need two of them to handle my 100A of 12V DC load. I'd like to test one to see how well they voltage regulate at full output power. I haven't yet found an off-the-shelf converter capable of 100A continuous output - surprising.

[davidbrady]

Greg,

Here's the ticket for your GMC. Check out the Video.

[GregOConnor]

(01-04-2015 01:50)davidbrady Wrote:  Greg,

Here's the ticket for your GMC. Check out the Video.

A bit of a marketing issue with the name. cool little unit. Amazing how engineers develop these things. I use 4 of the Armasafe batteries they sell in my Wanderlodge and just pulled 2 more out of a truck to set up in the GMC. I found a GMC specialty repair facility close by and sourced some oem cab chairs. he had 20 or so units on his lot with every power management hack you could dream up. One unit had what looked like a bank of capacitors for starting the a/c unit. he might deserve the name also RIP GMC