It is time. My two 3+ year old 100AH AGM house batteries are toast (I found a date on the sides after I pulled them out). Using the shore power and the converter/charger, they haven't got up above 11.1 volts. On the off chance that there is something wrong with the charger, I attached a regular charger and got same thing. They won't charge so they are dead. Time to replace them. This may well be the cause of my refrigerator failure last summer (It wasn't). I can't test that out until I replace them.
Ever since Technomadia put in their LiFePO4 battery bank 2.5 years ago, I've lusted after those batteries. They have a terrific explanation of the batteries and comparison to the regular lead acid so I refer any questions to their pages found at the link. My lust is based on the following things:
1. The 100 usable amp hours in my current house batteries has been marginal for me. I don't do things like run the radio or watch a DVD because of the marginal juice available. Having 12V refrigerators adds to that problem, altho for the bits that the old 3 way refrigerator ran, it used quite a bit of battery.
2. I really prefer boondocking whenever feasible and camping in primitive campgrounds where there is room between campers. I'd like to be able to comfortably boondock for a few days at a time.
3. The LiFePO4 batteries allow use of 80-90% of their amp hours. It is almost like getting 2 batteries out of one.
4. The LiFePO4 gives a very even voltage when in use. This stays steady until they are done. You get full power out of them then they shut off. This makes all the 12V things perform better.
5. They have a life span of 10 years. At least we hope so and indications are good for this to be true. They rate them for 3000 discharge cycles at full power. After that, you still have a battery that has 80% of its original capacity.
6. The LiFePO4 chemistry is not flammable, unlike the LiPoly batteries that Boeing is using in their airliners (for reasons I just cannot understand - bad engineering?) That makes these batteries less hazardous than lead acid batteries.
The problems I face in this decision are:
1. Space. I have two subfloor battery boxes that hold my Group 31 batteries. If I don't get batteries of the same size, then I would have do some major surgery to find a good place for them.
2. Many of the LiFePO4 batteries' form factor just would not fit into the boxes.
3. Many of the LiFePO4 batteries require cell balancing, a good battery management system to guard against under and over charging, and special chargers. This can get a little tricky as the info on the Technomadia site describes. They say it is not yet ready for mass use but people like them are willing to experiment with them. I read it and think I understand but I am afraid that I don't quite understand it all.
4. Space again for the needed electronics (item 3). A class B doesn't have nice big bays to stash stuff.
5. Cost. Altho these are quite expensive, the long run costs could be comparable or possibly less than AGM replacements. I have always been good at living below my means so if I want to, I can afford to invest in these. The DYI systems do cost significantly less than the "drop-in" replacements but there are quite a few things that have to be done right. Also, the cells for them don't fit my space very well.
6. Do these batteries require a different charging technology than the lead acid? Lead acid batteries like a 3 stage charging and like to be topped off with a low amp float charge. LiFePO4 batteries don't. You charge the lithium batteries and then you stop. No floating needed. You don't keep it plugged in to top it off.
7. They don't like being charged in freezing temperatures but are fine being used in freezing temps. For winter storage, it is best to draw them down to about 50% charge and leave them. Apparently, they store best like that.
Now for what I am leaning towards doing:
There are a few manufacturers that have made LiFePO4 batteries in the same form factor as standard lead acid batteries. They also include battery management systems in the same box and say that they are drop-in replacements for the old lead acids. You have to pay more for this but it would really solve the space issue (Items 1 - 4).
Technomadia says that whatever LiFePO4 battery you buy in the USA, has to be tested to meet certain standards whether they are the individual cells or the fully integrated drop in replacement. You can save money by doing all the configuring yourself but then you assume the responsibility that you did it right. An engineered product takes a lot of that responsibility away from me. Technomadia also says they don't think their set up is for Joe and Susie Average RV'er yet. While I don't pretend to have the expertise they have, I do think my technical skills are a few notches above the average RV owner. (Can you tell I'm a big fan of Technomadia?)
These are starting be used in the boating community. I found this huge
thread where some have put them into boats with good results: http://www.cruisersforum.com/forums/...65069-230.html There are several discussions where they use the lead acid chargers on the LiFePO4 battery with very good results.
From what I can gather, they are a really good solution and the drop-in
variety don't need special charging. They will work with the regular
lead acid chargers because they each have their own battery management
systems that keep from dropping too low and keep from getting over
charged - the two killers of these batteries. Special chargers are only
needed if you want really fast charging with high amps as the lithium
batteries can take in whatever you give them - no trickle float needed. (Item 6)
From what I can find, Group 27 form drop-in batteries with 100AH cost:
$900 - http://www.starkpower.com with 1 year warranty
$952.49 - Bioenno Power with 2 year warranty (backordered currently)
$1300 - http://www.lithiumion-batteries.com with 5 year warranty
It seems to me that the quality of the battery management system is
really important. The cells are all made in China anyway. All these companies talk the good talk about how long
lasting they are and how great the BMS is, but only Lithiumion actually
gives a solid warranty backing up their talk. They also have a better
web site with more solid info. The other two don't supply good consistent spec sheets on their batteries, they don't give pictures of each individual battery, and I am left feeling very uncertain of whether they produce a quality product. And with such short warranties, they don't seem very certain either.
It is a big price difference but with
being on the cutting edge, I'm nervous about track records which are
hard to find.
So I keep thinking maybe spending a few hundred more and getting a 5 year warranty means I get a better quality battery. Several commentators on the threads cite the same concerns and seem to feel better about Lithiumion for that reason. Lithiumion also says that their batteries work just fine with existing chargers and alternators made for lead acid batteries. In asking questions, they are very responsive. They say that their battery management system allows you to do the same things you do with the AGMs including keeping it plugged in and using the same charging system, and even charging below freezing. It almost sounds too good to be true.
It appears that my charger will only charge the LiFePO4 batteries to about 80% because it maxes out at 13.9V. So I would either have to supplement the charge with a plug in charger or get a better charger.
Lithionics batteries is used by some and gets very good reports but they don't seem to have a Group 27 form factor unless you go to only 60AH. Since I really want to add a lot more amp hours to my power setup, they are not attractive to me.
Getting nearly double the amp hours is the number one driver on spending all this money.
I know many people do not think it worth spending the high cost over the cost of the AGMs (which would easily be in the neighborhood of $800 for good ones), but I really want more power available in the van.