LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[DotDun]

Originally Posted by campr

What would interest me more, is if there were 12V DC induction cookers. Why waste efficiency going to 110V or 220V

12v would require cables bigger than your windlass does .....

[Cotemar]

campr,

Good article, but it sounds like they were using lead batteries not LifePO4

[deckofficer]

Originally Posted by campr

The Nuwave2 uses 1300W according to their FAQ (Induction Cooktop | Buy Cooktops | FAQ - NuWavePIC.com) at maximum setting. Using around 90% conversion efficiency from your 12V->110V inverters, this would render you needing ~ 2860W or around 220A at 13V. Since the 400Ah cells support 3C current, (1200A), this should certainly be possible. Expect ~ 1.5 hours of cooking time with topped-up batteries.

1.5 hours of cooking on a 400 a-hr LiFePO4 bank? On the medium setting that would be used for most cooking, would be 600 watts @ 50% duty cycle. More like 6 hours of cooking to 80% DOD.

There is no reason cruisers who have switched to LiFePO4 cells couldn't go to a fully electric galley with induction cook tops and get rid of the propane.

[T1 Terry]

We have a member of our motorhome group who have gone all electric, he does a lot of my on road testing as he 100% free camps and only recharges via solar and alternator charging. He has an all 240vac set up that runs the inverter 24/7 as his fridge/freezer is 240vac. He can also run his split system air con, induction cook top, hot water heater, bread maker, coffee machine etc etc, just like a house on mains power. He often does it at free camps just to stir up the nay sayers :lol: His bus is not a big rig, around 7 mtrs (21ft) with a weight restriction of 5.5tonne all up, so battery weight was very important. Propane has become rather expensive and getting hard to find when travelling in the outback, so a move away from propane use is becoming a necessity.
I have been using an induction cook top, as have many other members of the group, for quite some time, it takes a while to get the hang of turning it right down low so stuff cooks through, not just brown on the outside.

T1 Terry

[T1 Terry]

Originally Posted by deckofficer

T1 Terry, we share some of the same interests.

I'll research your suggestions, thanks. Do they have better specs than my link? I plan to go with the threaded ends for using buss bars to make a 32S3P pack. That would be 96 volt (102.4 volt) 45 a-hr bank. Total 96 cells at 480 grams, 101 lbs and good for 10 C discharge (450 amp), for a cost of $2283 for 4.7 kwhr bank.

The other choice is use the cells they use, 5.6 kwhr for $8500. This pack is 23 lbs lighter. But it only has a 700 cycle life.

Here is one link to electric aircraft, Randall has a electric trike, and single seat electric Moni electric glider and a SLA two place electric.
ElectraFlyer.com - The World Famous ElectraFlyer-C

This company uses, as all the others do, 2 stroke engines in their ultralight offerings but I feel their Aerolite 103 is a perfect candidate for electric propulsion.
Aerolite103

The Headway cells have a serious problem with the treaded end caps coming off, they are not well secured to the actual cell. The cells may be able to discharge at 10C but the screw caps won't transmit that from the cel to the bus bar without a high number of casualties, meaning a regular pack strip down the repair/replace dead cells.

T1 Terry
EDIT: Maybe these posts should be moved to another section away from house battery stuff as the subject is completely different, very high discharge rates is not something that is required or desired in a house battery bank.

[deckofficer]

Originally Posted by T1 Terry

The Headway cells have a serious problem with the treaded end caps coming off, they are not well secured to the actual cell. The cells may be able to discharge at 10C but the screw caps won't transmit that from the cel to the bus bar without a high number of casualties, meaning a regular pack strip down the repair/replace dead cells.

T1 Terry
EDIT: Maybe these posts should be moved to another section away from house battery stuff as the subject is completely different, very high discharge rates is not something that is required or desired in a house battery bank.

Your right Terry, it should be moved, but thanks for the heads up on the Headway cells. I guess for safety's sake since it is aviation, I'll have to bite the financial bullet and pony up for Kokams.

[transmitterdan]

Originally Posted by campr

What would interest me more, is if there were 12V DC induction cookers. Why waste efficiency going to 110V or 220V

Induction heating requires AC else there would be no heating of the cooking vessel. DC current cannot induce the opposing current in the bottom of the cooking pot that heats the food.

Also, 12V wiring for a cook top would be massively large and heavy thus negating the advantage of LiFePo.

[s/v Holiday]

Originally Posted by roetter

Our new LiFePo system

I use a LightObjects programmable voltmeter set to:
HVC 14.2 off/ 13.4 back on
LVC 12.0 off / 12.5 back on
With it I drive two BlueSea solenoids for LVC and HVC.
All loads are on the LVC busbar and all charges are on the HVC busbar.
.

Hi Roetter,

Could you please tell me how you drive the two BlueSea solenoids with the Lightobjects voltmeter? I was thinking of installing the same system but I haven't figured out how to set it up yet. Do I need a device between the 2 units?

Any info would be greatly appreciated.

CJ

[boatpoker]

I'm a bit behind the curve and have been following this thread closely trying to learn. I'd like to hear more about what to look for in marine chargers for these batteries. All input appreciated.

[roetter]

Originally Posted by s/v Holiday

Hi Roetter, Could you please tell me how you drive the two BlueSea solenoids with the Lightobjects voltmeter? I was thinking of installing the same system but I haven't figured out how to set it up yet. Do I need a device between the 2 units? Any info would be greatly appreciated. CJ

The LightObject programable volt meter has two relays that can each drive. Up to 220V/3A AC. The Blue Sea solenoid runs at 12V and takes 3.8A during switching, otherwise 0.13A.

I connected 12V from the battery through a 5A fuse to the common connection of each relay and from there went to the solenoids and then to ground.

[roetter]

Originally Posted by boatpoker

I'm a bit behind the curve and have been following this thread closely trying to learn. I'd like to hear more about what to look for in marine chargers for these batteries. All input appreciated.

You want one that lets you program the maximum voltage (absorption) to 13.8-14.2V. Then the float needs to be programmable to 13.2 or so.

On my mono (different installation). It had a Quick 30A charger with next to no choice for programming (just LA and Gel). I just use the Light Object programmable volt meter and use a relay to cut the AC power to the charger when it hits 13.8V. So now the charger off. I set the low point on the Light Object to 13.2V, so the charger comes back on.

Make sure to calibrate the volt meter on the Light Object. Both of mine were off by over 0.15V.

[sv.antea]

I am planning to go put four 260Ah cells on Antea and wonder if any of the little panel meters from Light Objects or similar could be used to monitor each cell individually. Make a stack of four displays. That way I could see the balance at a glance. My question is, can these units be powered together from a small switching power supply? I am guessing the measured voltage input is independent of the supply power?

[yamez4u]

Originally Posted by boatpoker

I'm a bit behind the curve and have been following this thread closely trying to learn. I'd like to hear more about what to look for in marine chargers for these batteries. All input appreciated.

I love my Victron Quattro 5000 Inverter/Charger It has built in LiFePo charge profiles. I highly recommend Victron chargers.

[transmitterdan]

Originally Posted by sv.antea

I am guessing the measured voltage input is independent of the supply power?

Your fist guess should be no until confirmed against the specifications. It costs money to have this feature so you often don't see it. The cell logger volt meters that many R/C hobbyists use can measure stacks of cells but the lowest cell has to be ground. But a single channel cheap voltmeter may or may not be able to do it. Check the specs carefully before assuming otherwise.

[roetter]

Originally Posted by sv.antea

I am planning to go put four 260Ah cells on Antea and wonder if any of the little panel meters from Light Objects or similar could be used to monitor each cell individually. Make a stack of four displays. That way I could see the balance at a glance. My question is, can these units be powered together from a small switching power supply? I am guessing the measured voltage input is independent of the supply power?

Some more info on individual cell voltage monitoring.

Best solution is the Junsi Celllog. Can be ordered at Hobby King for less than $30. It not only shows you each voltage but it can also log them for display on you Windows machine. You can record several days worth of voltages and then download them with USB and show detailed graphs.

You can also hook up a small buzzer to alarm you on these conditions.
- cell voltage low or high
- battery voltage low or high
- difference between highest and lowest cell

All these values are adjustable.