battery choice

Hi,

They are worse because you can't equalize them--they would vent and soon be out of electrolyte. You can "condition" them, but that is an equalization on wimpy pills.

One company is saying only 500 cycles for 50% discharge on L-16.

AGM do recharge faster so generator charging should be more affordable.

I'm sure some of you want to know why I want so many amp-hours. It is because I cold weather RV and at 0 C (32 f) capacity is down to 65%. I do see -40 every year. That is why Li chemistry is not on the table for me.

I'm 67 and will most probably no longer use my rv when I'm 75. The Surrette's are total replacement for 2 years, and prorated for 5 additional years.

brulaz wrote:
And maybe separate issue: are AGMs better or worse at surviving partial charge regimes? For example, first day can only recharge to 90%, second day to 80%, ... , fifth day to 50% and then break camp to find a 120VAC plug. Would AGMs or FLAs survive this better over the long run?

Hi,

No, they don't prefer a high amp rate recharge. They REQUIRE it.

brulaz wrote:
So if all you have is solar, sounds like a higher ratio of Panel wattage to battery Ah is called for with AGM. Are the data sheets saying that not only can AGMs take the high charging amperage, but they prefer it?

pianotuna wrote:
Hi,

They are worse because you can't equalize them--they would vent and soon be out of electrolyte. You can "condition" them, but that is an equalization on wimpy pills.

One company is saying only 500 cycles for 50% discharge on L-16.

AGM do recharge faster so generator charging should be more affordable.

I'm sure some of you want to know why I want so many amp-hours. It is because I cold weather RV and at 0 C (32 f) capacity is down to 65%. I do see -40 every year. That is why Li chemistry is not on the table for me.

I'm 67 and will most probably no longer use my rv when I'm 75. The Surrette's are total replacement for 2 years, and prorated for 5 additional years.

brulaz wrote:
And maybe separate issue: are AGMs better or worse at surviving partial charge regimes? For example, first day can only recharge to 90%, second day to 80%, ... , fifth day to 50% and then break camp to find a 120VAC plug. Would AGMs or FLAs survive this better over the long run?

ISTR the Surrettes have a 10 yr warranty. Check that wegosolar link to confirm (I am back camping and low on internet data/ time again to go posting links etc, sorry)

There are guys camping here with 5ers who show no sign of slowing down age 76 plus. It's all about what kind of shape you are in!

PT, can't you put Lithium batts in a heated cabinet? That's my plan, eventually... replace the vent grill with an insulated panel, in winter, and heat either electrically or hydronically.

275A of solar plus Magnum's 125A will get you up to 25% charge ratio.

HTH;
John

Hi,

I snowbird--but not in my RV. Therefore the RV has to endure -40 and 120 days of being in storage.

Heating from -40 to 0 C (32f) would consume a lot of energy.

jrnymn7 wrote:
PT, can't you put Lithium batts in a heated cabinet? That's my plan, eventually... replace the vent grill with an insulated panel, in winter, and heat either electrically or hydronically.

hi John,

I'll be keeping my two bank configuration--so the Magnum will offer 125 amps @ 12 volts (nominal) into 400 amp-hours. I expect to not use 200 amp-hours very often.

I do know my flooded banks tied together last fall would draw 125 amps from the Magnum when it was being powered by the Yamaha sIEB 3000, while powering a pair of 1/2 size oil filled heaters.

full_mosey wrote:
275A of solar plus Magnum's 125A will get you up to 25% charge ratio.

HTH;
John

I think lots of AGMs are tickled to death with low bulk current. If one is not gong to take advantage of their ability to accept huge currents, well there goes one of their major benefits.

I have a Northstar AGM group27 at 91 AH. It responds well to 40 amps from my MeanWell power supply. It does not really seem to like 200 watts of low and slow solar. Voltages under load after a solar only recharge sag noticeably in comparison to a MW 40 amp blast, and the rather impressive ability to crank my engine extremely swiftly fades with each solar only low and slow

Now, I never discharge it unless I can plug in the meanwell or have a good enough highway drive so the alternator can quench the thirsty devil.

I personally would not get AGMS for a solar only recharge application.

This guy knows his feces:
http://forums.sbo.sailboatowners.com/showthread.php?t=124973

Hi Land,

Thanks for the links.

Unless I misread the Lifeline technical manual, high current charging is recommended when DOD exceeds 50%. Is that not correct?

IOW is it needed if doing 70-90 for instance.