Lithium batteries

PawPaw_n_Gram wrote:
Weight is a huge issue with batteries and trailers. A great many folks simply don't have the weight capacity to add a good bank of lead-acid batteries. And the battery weight is almost always mostly increased tongue weight.

That is not the case with many Class A motorhomes and some Class B/C motorhomes.

In our situation, we intentionally bought a Class C motorhome on an over-kill chassis that can handle 14,050 total lbs. while at the same time our usual fully loaded total camping weight is only around 11,800 pounds. We can carry plenty more weight but I don't want to give up gear storage volume to add more batteries.

Hence, a couple of Group 31 size 12 volt lithium batteries with a capacity of say, 400 amp hours mounted right in our present battery cabinet - instead of our current two AGM lead acid batteries with only 200 amp hours - would be just the ticket. We don't need a huge battery bank, as our motorhome is equipped with three ways of charging our battery bank as frequently as needed when drycamping without solar ... and we can always add some solar should we want to.

Perhaps someday lithium batteries will be available two ways: Weight Efficient - standard group sizes with around the same lead-acid capacities but very light, and Capacity Efficient - standard group sizes with higher than lead-acid capacities but very heavy.

PawPaw - as I noted above, we would have to have approximately 1000# in lead acid to have the same usable energy storage as our 250# of LFP. that extra 750 would put us over pickup rear axle weight.

We are pretty much weight police and always check weight on CAT scales before we start a new segment of travel. We weigh with 80 gallons of fuel (transfer-flo), 81 gallons of freshwater, 6 full 20# propane canisters and, if really in desert boondocking, another 30 gallons of freshwater in Jerrycans.

Our capacity is 8500# on rear axle (dualie with Michellins rated at 3200# each = 12800# total) and we are at 7500#, 10,200# on trailer axles (2) and the Michellins on trailer wind up at 12,800# and rear axle weight on scale is about 9,400#.

The front bay of our Open Range 337RLS is designed to carry an Onan 6.5 kW (290# or 131 kg). I asked about this and was told by manufacturer that the steel plate floor is designed to handle over 400#. We could conceivably install 50% more LFP but see no reason to. 1000# of lead acid would probably wind upon the ground with some of the roads we have been on in Yucatan (particularly after hitting an unforeseen topay/speed bump).

pnichols wrote:
I don't care about them being much lighter weight in the standard group sizes as compared to good old lead acid batteries - that's not important.

I disagree.

Weight is a huge issue with batteries and trailers. A great many folks simply don't have the weight capacity to add a good bank of lead-acid batteries. And the battery weight is almost always mostly increased tongue weight.

Modern Lithium batteries would mean that rather than two 12-volt batteries - I could have the equivalent of four 12-volt hours - more than double the usable amp/hours - and still end up with lighter weight.

(I, and many trailer owners, have the physical space to have four 6V or 12V batteries - just not the weight capacity.)

Have been using LFP for two years (9.6 kW-hrs worth) and have had zero problems. Advantages are:

A lot of energy storage for much less weight (9.6 kW-hrs at 250 lbs, of which 8 kW-hrs are usable for several thousand cycles). We would need about 1000# of lead acid to get the same usable storage.

Really do charge up almost linearly without the Peukert disadvantaes of lead acid.

Do not have to use generator (we do have a 1 kW Honda which has only been turned on to make sure it still works) which makes for quietude in boondocking and the resultant non-disturbance of wildlife. We hooked up once last year when we were in Spokane, it was over 100 F,and we were parked in shade at a trailer park.

They do not self-detonate. LiCo systems have caught fire, the Boeing problem.I have been following every LFP fora I can find and no one has had a detonation or fire. Some of set things up incorrectly and ruined their battery suites. You can easily do the same with lead acid.

The down sides are:
They are more expensive but the costs are going down

There can be problems if charging is attempted below freezing with certain LFP configurations. We left our rig at son's place a year ago and it got down to -20 F and there was no loss in battery capacity. Of course it was doing very little charging since the inverter was not turned on.

We do use an expensive battery management system (BMS). The only arguments amongst LFP users are whether to use BMS or set system at 3.4 V (approximately) per cell. The Aussies and sailboaters seem to like this later methodology.

We do have four batteries (each of 4 Chinese Aviation cells) set in series for a 48 V nominal battery suite.

One has the choice of using or not using.

I think these upcoming LiFePO4 technology 12 volt batteries in standard group sizes with built-in charge control so that they're direct drop-ins for lead acid batteries could be the perfect next generation of RV batteries - except for one aspect: I don't care about them being much lighter weight in the standard group sizes as compared to good old lead acid batteries - that's not important. What WOULD BE GREAT is - if they were way up in amp-hour ratings in the standard group sizes as compared to lead acid batteries.

Wouldn't it be fantastic to have an RV battery available with characteristics just like LiFeO4 that was, say, 200 amp hours in Group 31 size? What us RV'ers need, IMHO, is higher energly density per cubic inch in our batteries - not necessarily lighter weight! I'd love to have 400 amp hours of 12V deep cycle battery capacity in my RV mounted right in the same spot and taking up the same volume as my current 200 amp hours worth of deep cycle capacity as is contained in my two current 12V AGM RV batteries. Where in the world is the real high tech battery chemistry when you need it!! :h

..... Or alternatively ..... when are propane powererd fuel cells going to be ready for anywhere anytime noiseless battery charging in the RV world?

I've had my eye on these Lithium Ion deep cycle batteries from Starkpower. They have dropped below the $1000 mark for 100Ah from around $1299 since I first looked. They also recommend a battery converter that cuts off and does not trickle charge the battery once it is fully charged. Progressive Dynamics carries the PD9100L series that handles that.

The one holdups I see is only a 1 year warranty, and have 2 AGMs that are still in good shape.

Search for lithionics battery.

They say:
"Lithium-Ion batteries specifically designed for the needs of the Recreational Vehicle customer!"

They are getting cheaper, but still expensive. Newer lithium based technologies behave better than earlier chemistries. Getting good enough to use on more premium priced hybrid and electric vehicles, replacing nickel metal hydride.

They are used in RVs, for applications where weight is important but price is not. That second part is not most of the RV marketplace where buyers accept major quality downgrades to get marginally lower prices.

They are being used in this persons new Class B. So far they appear to be working great.
Davydd's new Class B built by Advance RV.

Call (425) 342-2121 and ask them about these batteries and safety issues. Chris