Trojan 6v

[Overlord]

I am interested in buying 6 x T 145 trojan 6v batteries but am a bit concerned about the slow charge acceptance.Is this a concern ?
I have 3 x 235 watt solar panels and a xantrex 100amp charger for the generator to run.I just dont want to run it longer if they absorb charge much slower than agm or gell batteries
Any advice

[rebel heart]

I have four T-105's with 2x135 watt kyoceras. They provide ~12 amps of power during the morning hours when the batteries are somewhat depleted from the night, and by noon the charge controller is throttling back the current to ~5 amps or so despite plenty of available power from the panels.

It gets knocked back down to around 2-3 amps when they finally get the trickle charge mode.

Just my experience; don't know if that answers your question.

[S/V Illusion]

I'm assuming you have taken into consideration the actual charge rate capacity of your existing setup which has some inherent limitations making the advantage of AGMs over wet cells finite. Given the cost disparity between the two battery types, I think the real issues is cost vs. re-charge rate.

Since the acceptance rate curves are widely available, I won't reiterate here except to say the re-charge time difference shown is theoretical whereas your controller is likely a bigger limiting factor.

[btrayfors]

Six T-145's in series/parallel (about 780AH total capacity) will easily take 175-200 amps charging current. From what you said, you don't have anything aboard which can come anywhere near that.

All lead acid batteries (and gels and AGMs are lead-acid batteries, too) will taper off in their charge acceptance after about 85% of full charge.

With your panels, I'd probably go for flooded batteries like the T-105s or T-145's rather than AGMs. Much better cost/benefit, since -- aside from initial cost -- if you put 780AH of AGMs aboard you'd likely have to beef up your charging capacity as well, since they'd easily take 700-800A charging current!

Bill

[Overlord]

So i gather then that with my current charging set up , it wont really make that much of a difference as far as charging time is concerned.what type/ size of charger would be suitable for the amount of trojans i want to fit ? My xantrex inverter charger is pretty new and only charges at 100 amp per hour.I hope the solar will be able to put back enough so that my generator will not have to work to long.I have a fridge that draws say 5amp and then all led lighting

[S/V Illusion]

By way of example, we have 6 Trojan T125s and use an 80 amp charger which takes 3-4 hours to bring them up from 50 - 85% charge. Doubling my charger size would yield a 2-3 hour 85% charge. In both cases, the remaining charge to get to 100% takes a few more hours. In both cases, the total elapsed time to go from 50% to 100% charge is 4 to 5+ hours.

The morale of the story is batteries can only take so much charge and speeding up the process by playing with your controller serves only to shorten battery life.

AGMs have a capacity to recharge faster, as you know, but the total time difference to get a full charge of wet cells vs. AGMs isn't significant in most cases.
Therefore, as I implied, you may want to re-consider given the decrease you might attain in re-charge time vs. 1. whether you really need that increment of time, and 2. whether that time saving is worth the cost.

[Mark Johnson]

I concur that they will accept the charge more slowly, but only at the top 15% of their charge. Your solar panels should be fine for this. IF you can find a spot for them... two TALL Trojan L-14s or L-16s... (340 or 380 Ah) will work better for you. They last twice as many cycles as the shorter batteries, and if you top them up daily, (or often), they will last much longer for it as well. These are definitely the best bang for your buck, if that, and lifespan, matter.

BTW... If you can still get "Hydro Caps", they make watering an infrequent chore.

Mark

[cat man do]

Originally Posted by Mark Johnson

BTW... If you can still get "Hydro Caps", they make watering an infrequent chore.

Mark

Lead-Acid Battery Cap: Hydro Caps For T105 and L-16

[btrayfors]

Yeah, you can still get HydroCaps but they're outrageously priced @ $18 each.

A much better deal is the Water Miser cap manufactured by Flow Systems. I have 30 of them on my 10 T-105's. The standard height one is appropriate: Water Miser Battery Vent Caps

These DO reduce the need for water.

They DO make it much easier to check on electrolyte level and add distilled water when needed.

They DO NOT completely avoid the need for equalization.

They NEED NOT be removed when you equalize (HydroCaps need to be removed, to avoid damage).

Bill