Basic generator charging question

[halibutcollier]

I am building a system that relies on a generator more than solar(please don't shoot me, I am in Alaska). My current generator is a Kohler 14kw model that is split phase and has 70 amp max output. I also just received my EG4 600xp which has(as I understand) a 125a charger. I am trying to calculate generator run time to charge my battery bank. My current plan is to have 48v 250ah bank of silica salt batteries that have an 80 percent DOD. There is no magic that is going to increase the amps coming from the generator...right? so all my calculations need to be off the 70a coming from the genny?
And with a 250ah bank at 80%DOD I am looking at 200ah of usable storage...right?
So, and here is the real question, if my batteries were sitting at 20 percent, almost dead, would my generator need to run full tilt for 2.85 hours to fully charge?
Sorry for the drawn out question, but I am new to this (solar/batteries and this forum). Thank you for any input and knowledge.

 

[sunshine_eggo]

You're on the right track, but it usually takes longer than a Ah/A calculation as most batteries need to be held at peak voltage as current tapers to full charge.

What is a silica salt battery?

 

[hwy17]

I believe charging amp figures are generally at battery voltage, so 125A x 48v = 5kW = 20A at 240v.

So your generator will need to run at low load for 2-3 hours. I don't know how quick those batteries will take the charge.

 

[sunshine_eggo]

I believe charging amp figures are generally at battery voltage, so 125A x 48v = 5kW = 20A at 240v.

So your generator will need to run at low load for 2-3 hours. I don't know how quick those batteries will take the charge.

LOL shit!!! That'll teach me to answer a question after waking up from a nap.

MY statement is only true if that's DC output of the generator, which doesn't happen.

What is actually charging the battery, and again, WTF is a silica salt battery?

 

[hwy17]

WTF is a silica salt battery?

I googled it and apparently it's AGM with special magic.

 

[seneysolar]

Special!12kWH Silicate Battery 12/24/48V Best Price per kWh -15 yrs -6000 Cycles at 30% 8yr3000cl at 60% – Temp -40F to 150F -NO BMS or Thermal Protection required, Non Corrosive explosive, A Count of 4 x 12v 250AH – Watts247 Wholesale

watts247.com

This???

 

[sunshine_eggo]

Ah... It's just a GEL battery.

@halibutcollier - refer to the maximum charge current specified by the battery manufacturer. You absolutely, positively do not want to exceed that unless it's an emergency, and only occasionally. Exceeding that value will dramatically. They tend to not be over 0.2C meaning it will take 5-7 hours of charging.

You also NEVER want to discharge them below 50% unless you plan to replace them every couple years.

 

[Bop]

Check the manufacturers specs for the maximum charging current- they really haven't taken off in Australia (their hot weather ability is good, on par with LYP lithiums, but their weight counts against them for transport costs here)

They can accept high charge currents for much of their charge cycle (up to 3C) but the last 10% float charge is recommended 0.6C or less
So for a 250Ah battery thats 750A max during boost, dropping to 150A max

 

[Bop]

Ah... It's just a GEL battery.

@halibutcollier - refer to the maximum charge current specified by the battery manufacturer. You absolutely, positively do not want to exceed that unless it's an emergency, and only occasionally. Exceeding that value will dramatically. They tend to not be over 0.2C meaning it will take 5-7 hours of charging.

You also NEVER want to discharge them below 50% unless you plan to replace them every couple years.

Not really- unlike 'normal' L/A batteries (including gels) they have a vastly better temperature range (-40C up to 70C for both charging and discharging) and can use practically all their rated Ah capacity without significant damage to the cells... (up to 90% DOD can be achieved and still not damage them, unlike gells which really shouldn't be taken past 60% at most- although any deep discharge shortens the service life of course)

 

[seneysolar]

Not really- unlike 'normal' L/A batteries (including gels) they have a vastly better temperature range (-40C up to 70C for both charging and discharging) and can use practically all their rated Ah capacity without significant damage to the cells... (up to 90% DOD can be achieved and still not damage them, unlike gells which really shouldn't be taken past 60% at most- although any deep discharge shortens the service life of course)

The advertised cycle life is impressive, if achieved. Ill be keeping an eye on these for sure.

 

[halibutcollier]

Special!12kWH Silicate Battery 12/24/48V Best Price per kWh -15 yrs -6000 Cycles at 30% 8yr3000cl at 60% – Temp -40F to 150F -NO BMS or Thermal Protection required, Non Corrosive explosive, A Count of 4 x 12v 250AH – Watts247 Wholesale

watts247.com

This???

Yes, exactly this. I'm not ready to commit to lithium, because I don't wanna run to my property in the middle of the night if the heat goes out. There seems to be a lot of benefits to these batteries at extreme conditions. To me they perform right in the middle of AGM and lithium. But I'm just starting this journey

 

[halibutcollier]

LOL shit!!! That'll teach me to answer a question after waking up from a nap.

MY statement is only true if that's DC output of the generator, which doesn't happen.

What is actually charging the battery, and again, WTF is a silica salt battery?

EG4 6000xp will be charging the batteries

 

[halibutcollier]

Check the manufacturers specs for the maximum charging current- they really haven't taken off in Australia (their hot weather ability is good, on par with LYP lithiums, but their weight counts against them for transport costs here)

They can accept high charge currents for much of their charge cycle (up to 3C) but the last 10% float charge is recommended 0.6C or less
So for a 250Ah battery thats 750A max during boost, dropping to 150A max

Check the manufacturers specs for the maximum charging current- they really haven't taken off in Australia (their hot weather ability is good, on par with LYP lithiums, but their weight counts against them for transport costs here)

They can accept high charge currents for much of their charge cycle (up to 3C) but the last 10% float charge is recommended 0.6C or less
So for a 250Ah battery thats 750A max during boost, dropping to 150A max

From the contact at watts247 max charge is 70 amps per string...

 

[Bop]

From the contact at watts247 max charge is 70 amps per string...

Like i said, always check the manufacturers specs, the ones I have seen used here had a 3C maximum charge rating (same as my own LYP lithiums which is how I remembered it) for bulk, and a 0.6C on float- which on a 250Ah battery is 750A on bulk and 150A on float...

 

[sunshine_eggo]

Don't care what Ian says. When it says 50A max starting current on a 250Ah battery, it's 0.2C. Absolutely, positively don't charge those at over 50A. Period.

Ensure no combination of AC and PV charging can exceed 50A.

Count on close to 7 hours of charge @ 50A.

Also worth noting that the 5 year warranty depends on restricting DoD to 50%.

Warranty: 5 years.

Warranty applies to systems which have a battery capacity of at least 2 x daily consumption.

example, if daily use is 12kwh, a minimum requirement of 24kwh capacity is expected