Battery Question

[kenkorona]

Hi,

I have a bunch of questions about batteries, invertors, charging, solar panels, etc. So I'll start off with batteries...

My TC came equipped with 2 Interstate Marine/RV Deep Cycle SRM-27 batteries. They are standard Flooded Lead Acid batteries with a cost of about $125 each. In the 10 weeks I've used my TC so far I never had an issue with adequate power, though to be fair I had little use for a microwave or A/C during that time. I also used the generator for a total of about 15 minutes during that 10 week period. And that was to run the A/C while I was stuck in the Walmart parking lot in Secaucus, NJ (please don't ask why I was there).

So I hear about people buying not just 2, but maybe 4 or more Lithium batteries at a cost of over $1000 each and I'm wondering why. I haven't done a thorough investigation, but from what I can tell the capacity of the Lithium batteries may be a bit better than a Lead Acid, but it seems hard to justify the wildly higher cost. Can someone explain?

Thanks
Ken

[ticki2]

Thanks for the explanation, interesting system . I will have some other questions when I have a chance to think a little more about it .

[pianotuna]

ticki2 wrote:

pianotuna wrote:


Take it out of storage at -37 and let me know how that works for you.

I sure would like to know your routine after you take your camper out of storage at -37 to warm the interior up to a reasonable temperature , with what heat source , and how long it takes .

Thanks for the question.

I have a decent size battery bank. The solar system maintains and charges the house, generator, and starter batteries. The charging is temperature controlled. This means the batteries are fully charged and kept at float.

Here is a step by step.

1. put magnetic heater on the bottom of the Yamaha generator.
2. turn on inverter to power the heater
3. wait 30 minutes
4. start the generator (sio2 equipped)
5. start electric heaters and plug in block heater for engine to the limits of the generator--which is also recharging the teleco batteries.
6. start furnace
7. furnace runs constantly for about 2 hours, as do the electric heaters.
8. start engine.

The various electric heat sources consist of heated electric carpets, oil filled heaters, 1 radiant heater (good for thawing compartment doors and the like), 2 fan based heaters. I protect the fridge with a 60 watt light bulb controlled by a themocube. I have fans in the fridge chimney and they restrict air flow somewhat in the winter time.

In the -30ties I'm able to heat 100% electrically, if there is sufficient shore power. The furnace set to cycle on should the power fail. The power needed is 4300 watts (continuous) with a peak load of 7100 watts. Total consumption for 24 hours is about 129 KWH.

To do this on a thirty amp RV I've added two auxiliary shore power cords, (15 amp and 20 amp). I have a "break out box" for 50 amp that has a 30 amp outlet on one leg and twin 20 amp outlets on the other leg. Each outlet has its own breaker.

Because power drops by the square of the voltage, I use an autoformer on the 30 amp service to provide sufficient voltage to keep the electric heaters working at peak output.

I have a hybrid inverter/charger which I operate in load support mode. I do limit the amperage on a 15 amp shore power to 13. On 30 amp the limit is 24 amps--or just about the same output as the Yamaha generator.

I've done some "back yard" experiments that document heating time and energy use both before and after modifications I've made. They exist somewhere on the boards. Try the winter camping thread on the full time forum?

I'd be delighted to answer any questions you or anyone else has.

[ticki2]

StirCrazy wrote:

ticki2 wrote:

pianotuna wrote:


Take it out of storage at -37 and let me know how that works for you.

I sure would like to know your routine after you take your camper out of storage at -37 to warm the interior up to a reasonable temperature , with what heat source , and how long it takes .

he has a motorhome, lots of room and payload capability for batteries, probably just starts the furnace while he drives. the weight and spae limitations of a camper mean nothing to him.


Steve

I am well aware of his rv , it is listed in his signature . I imagine he would heat the interior with the engine heater , at least at first . A truck camper does not have that ability , it would have to rely on the furnace or electric if shore power was available.. I also know from experience it takes a lot of heat to warm up the interior of a camper starting at -37C . That is why I was curios how the poster was accomplishing the above .

[StirCrazy]

Bradymydog wrote:

pianotuna wrote:

adamis wrote:
I don't understand these arguments at all...

If you have a LiFePo4 battery and camp in extreme cold weather, move the battery to inside the camper. Problem solved...

Take it out of storage at -37 and let me know how that works for you.

It is fine if one were full time.

I'm still waiting for FWC to describe the power system he uses.

If I were to take mine out of storage at -37, assuming the batteries had some % of charge remaining, I would:

1. Shut off/disconnect any charging devices - solar, shore power, DC-DC charger, no genny running.

2. Start the furnace. My 2 BB batteries are inside the conditioned space and have a heat duct discharge adjacent to the batteries. Let the furnace run for 24 hrs. while monitoring the battery temp via my Victron BM712 and an external digital thermostat next to the batts. My external digital thermo switch, serves a double duty as my Victron DC/DC charger generates considerable heat, so I installed 2 small 4" fans which are set to come on at 30C. My BB batts do not have built in heaters which are available.

3. Once I'm confident the internal battery temp is above 32F/0C, I'd start charging them.

Note: If attempting to charge cold batteries, according Tony discussions with BB, the BB internal battery monitor will disconnect at 25F to prevent damage to the batteries. To reset the internal BM, just disconnect/reconnect the negative battery cable.

On a side note, the coldest I've ever experienced was during an extended business trip to Prince Albert, SK. I'm not sure I'd personally want to camp in that weather but with adequate preparation, it should be possible.

if you bought quality LFP you wouldn't need to disconect the sources of power as the BMS would have already done that internaly. most have a internal reset, dont know for sure why battle born went with one that needs a total reset of the BMS... maybe when they started it was all there was..

the one I have ordered disconects at what ever I set it at so I could put it at -3C and set the reconect at 0C so when it hits -3 it will automaticly shut off charging ability and when it warms up to 0 it alows charging again.

there are newer ones you can buy that have heaters built into the battery case and the BMS will automaticly shut off charging of the battery but reroute the power supply to the heaters untill they hit a spicifc temp then start charging the batteries. so if you have solar, in the morning when the sun starts coming out and you have 0.5amps of power, this could be warming the battery for an hour then when the real Amps start flowing you charging. for a truck camer who boondocks in the winter I like this setup if you dont want to move the batteries inside the conditiond space. just do some nice foam insulation around the batteries to mak the warming more efficient and I dont think it would ever be to cold to camp.

Steve

[StirCrazy]

ticki2 wrote:

pianotuna wrote:


Take it out of storage at -37 and let me know how that works for you.

I sure would like to know your routine after you take your camper out of storage at -37 to warm the interior up to a reasonable temperature , with what heat source , and how long it takes .

he has a motorhome, lots of room and payload capability for batteries, probably just starts the furnace while he drives. the weight and spae limitations of a camper mean nothing to him.


Steve

[pianotuna]

Or Bradymydog you could simply buy SiO2 batteries and store them where ever you wish. No fussing about them. 1/2 the initial purchase price and equivalent cost per cycle as Li.

[ticki2]

pianotuna wrote:


Take it out of storage at -37 and let me know how that works for you.

I sure would like to know your routine after you take your camper out of storage at -37 to warm the interior up to a reasonable temperature , with what heat source , and how long it takes .

[Geterdone]

I decided against Lithiums due to non ability to charge in freezing temperatures. I got a good price on agms and my converter works on agm's but NOT Lithium, so check all the other stuff to be sure it is compatible with your choice or be prepared to upgrade.

[Bradymydog]

pianotuna wrote:

adamis wrote:
I don't understand these arguments at all...

If you have a LiFePo4 battery and camp in extreme cold weather, move the battery to inside the camper. Problem solved...

Take it out of storage at -37 and let me know how that works for you.

It is fine if one were full time.

I'm still waiting for FWC to describe the power system he uses.

If I were to take mine out of storage at -37, assuming the batteries had some % of charge remaining, I would:

1. Shut off/disconnect any charging devices - solar, shore power, DC-DC charger, no genny running.

2. Start the furnace. My 2 BB batteries are inside the conditioned space and have a heat duct discharge adjacent to the batteries. Let the furnace run for 24 hrs. while monitoring the battery temp via my Victron BM712 and an external digital thermostat next to the batts. My external digital thermo switch, serves a double duty as my Victron DC/DC charger generates considerable heat, so I installed 2 small 4" fans which are set to come on at 30C. My BB batts do not have built in heaters which are available.

3. Once I'm confident the internal battery temp is above 32F/0C, I'd start charging them.

Note: If attempting to charge cold batteries, according Tony discussions with BB, the BB internal battery monitor will disconnect at 25F to prevent damage to the batteries. To reset the internal BM, just disconnect/reconnect the negative battery cable.

On a side note, the coldest I've ever experienced was during an extended business trip to Prince Albert, SK. I'm not sure I'd personally want to camp in that weather but with adequate preparation, it should be possible.

[pianotuna]

adamis wrote:
I don't understand these arguments at all...

If you have a LiFePo4 battery and camp in extreme cold weather, move the battery to inside the camper. Problem solved...

Take it out of storage at -37 and let me know how that works for you.

It is fine if one were full time.

I'm still waiting for FWC to describe the power system he uses.

[Grit_dog]

Lol saying they charge in the cold is like saying I don’t wear a coat when it’s 20 below……if I’m not outside.

[StirCrazy]

Grit dog wrote:

Or to put it another way, they still don’t charge in the cold. Doesn’t matter if it’s -100 if you keep them warm. Then they’re not in the cold.

Thank you for finally using your words!

I hate it when people post statments like they dont charge in the cold. if you are camping and using your batteries you have obviously made it so the battery is kept warm, no matter what the weather is like outside. so they will act just like a normal battery and you can forget about them, which people seam to forget. the beauty about LiFePo4 is they are a zero off gass any position battery so you can tuck them anywhere. and if you make your own you can make them a wide viriaty of shape with out hurting preformance. this enables you to put them in places you couldnt put a normal battery.

I think part of the issue has been becuse they do have limit of cold charging, it was always asumed they have a hrd limit on cold dischare and if that was the case then yes Pianotuna would be right for extreem cold camping SIO2 were better, even though they are more expensive now.. but now that we have discovered that they will dischardw at much lower temps, the playing field has shifted back in favor of the LiFePO4. in fact at -30 they have less of a capacity restriction than SIO2 (60% capacity for SIO2 &0% capacity for LiFePO4. granted this will only be an issue for thr LFP when first starting a heating unit to warm up the batteries then they will be back at 100% capacity, the SIO2 sitting outside will still only have 60% capacity)

so as long as you can mount the LFP batteries where they will be kept warm for charging purposes, then at a lot less weight, and much smaller for the same usable AH, and cheeper. its a no brainer

Steve

[adamis]

I don't understand these arguments at all...

If you have a LiFePo4 battery and camp in extreme cold weather, move the battery to inside the camper. Problem solved... Unless you are sleeping with a camper below -20 deg, the battery will be plenty warm for it's expected use.

The rest of these arguments are just kind of pointless. Nobody is sleeping with a camper that cold so why are you expecting your battery to encounter that temp? Sure, maybe if you were loading your camper for first use and going out on a trip might the camper be that cold but be a little creative and figure out how to heat up the camper before you take off and to keep it warm as you travel. Both things that can be done without much effort.

Problem solved....

[ticki2]

mbloof wrote:

FWC wrote:
Again, this is all a distraction from the point I was actually making.

The point in the very unlikely circumstance that you need to use your LiFePO4 camper battery in temperatures below -20C, the battery will work just fine, you will be able to fire up the furnace or battery heater and warm up the camper. At that point you can charge your battery, fill your water tank, and do what every you need to do.

Every time there is a discussion of LiFePO4 batteries, there are always a few who say that they are no good if you camp in cold weather (some are now even claiming 'cool weather'). My experience is exactly the opposite, they have worked just fine for me in cold weather. Yes there are limitations on charging, but these are generally easy to overcome, and are not nearly as restrictive as the limitations on your water system.

While it has always appeared that rv.net has more then its share of trolls and internet experts who seemingly always want to argue why something won't work, the reality for me is that for where I live and camp I'd rarely if ever run into temperatures that make charging my LiFePO4 a issue.

Obviously for others their MMV.



- Mark0.

Are you guys trying to inject some reasoning into this subject ? Shame on you .