Have I been charging my batteries wrong

[smac999]

Originally Posted by motion30

Keith. It is unless I run my 8 KW westerbeke generator, what should I do not often do but when the sun is not shining it becomes necessary

with an 8kw gen I would add a 2nd battery charger. with 1200ah battery you should be / can be charging in the 200a range. you could add another 100a charger and cut your gen time (and fuel) in half.

[john61ct]

Originally Posted by motion30

I have 12 215 amp 6 volt batteries.

That's a good size bank.

Nit pick, but you mean AH.

So OP you know this, but for those following along,

@12V that's 215x6 = 1290AH capacity

@24V would be 215x3 = 645AH.

Halve that for normal "usable AH", and the real number drops as they age.

[john61ct]

You could use a bigger charger, but with FLA just means a slower early stage, not a longevity issue.

If regularly discharging 50% not nearly enough panels to rely only on solar, even on ideal sunny days.

[james247]

Originally Posted by smac999

with an 8kw gen I would add a 2nd battery charger. with 1200ah battery you should be / can be charging in the 200a range. you could add another 100a charger and cut your gen time (and fuel) in half.

I just wanted to add this thought. With new electric cars - battery's have been reinvented. I have researched and am in the process of installing a 50kw charger in a condo building this will 94percent charge the battery in 20 min. We could have installed a 100 kW charge which could charge it in 7 min.
Imagine using the full 8 kW of your generator to charge your batteries huge savings in fuel and not having to listen to that motor at anchor for long at all.
In the design of new boats electric car batteries should be considered for their efficiency and their benefit as ballast

[hellosailor]

Be careful of rapid charging. Every manufacturer has limits as to how fast a battery can be recharged (i.e. 1/5th C for wet lead acid, 1/4C for AGM) and the car chargers often are specific to lithium technologies with active cooling. Just feeding conventional batteries everything they can take, can damage them or make them explode. (Supposedly some 10,000 people go to ERs in the US every year, after trying to charge dead car batteries.)

[john61ct]

Originally Posted by james247

With new electric cars - battery's have been reinvented.

Nothing to do with cars.

LFP has all that benefit without the fire danger of recycling EV packs.

And less use as ballast, half the weight per usable AH.

[rom]

Too bad motion30 (OP) 's last message was deleted, it was funny. Same for Stu, not very funny this one, but useful, IMO.

Anyway, motion30, CF is obviously willing to help you but you do not provide enough information. Anything new ? Did you change your charging parameters (bulk or "boost" voltage especially ?) What were they initially ?

I am very surprised some are suggesting to increase charging capacity where you are complaining about having to add water more often than expected.

[Bleemus]

The tough part is finding a place for the 100Kw generator. 🤣🤣🤣

[mitiempo]

Originally Posted by hellosailor

Be careful of rapid charging. Every manufacturer has limits as to how fast a battery can be recharged (i.e. 1/5th C for wet lead acid, 1/4C for AGM) and the car chargers often are specific to lithium technologies with active cooling. Just feeding conventional batteries everything they can take, can damage them or make them explode. (Supposedly some 10,000 people go to ERs in the US every year, after trying to charge dead car batteries.)

With lead/acid technologies the battery determines the current it will accept. As long as the charging voltage is correct it matters not if the charger is 50 amps or 500 amps.

Of course, at a certain level it is not economical to go too large.

Lithium technologies not included in the above.

[StuM]

Originally Posted by mitiempo

With lead/acid technologies the battery determines the current it will accept. As long as the charging voltage is correct it matters not if the charger is 50 amps or 500 amps.

Of course, at a certain level it is not economical to go too large.

Lithium technologies not included in the above.

A bit of an oversimplification there?
You need to add "at a given voltage". If you put a high Amp dumb charger fixed at say 14.7V on a heavily discharged battery, you could well damage the battery. (As implied by your second sentence.)

That's the whole point of the "Constant Current" stage of a smart charger. Current is limited initially in effect by controlling the input voltage to a certain level above the battery's internal voltage..

[mitiempo]

Originally Posted by StuM

A bit of an oversimplification there?
You need to add "at a given voltage". If you put a high Amp dumb charger fixed at say 14.7V on a heavily discharged battery, you could well damage the battery. (As implied by your second sentence.)

That's the whole point of the "Constant Current" stage of a smart charger. Current is limited initially in effect by controlling the input voltage to a certain level above the battery's internal voltage..

Reread what I posted. I stated "...as long as the charging voltage is correct...

[john61ct]

Charge sources should have temp sensing wires.

If so then a 500A "available" voltage regulated source will not harm even a small lead batt.

[rom]

Originally Posted by StuM

A bit of an oversimplification there?
You need to add "at a given voltage". If you put a high Amp dumb charger fixed at say 14.7V on a heavily discharged battery, you could well damage the battery. (As implied by your second sentence.)

That's the whole point of the "Constant Current" stage of a smart charger. Current is limited initially in effect by controlling the input voltage to a certain level above the battery's internal voltage..

I am not sure what you meant in your first sentence, but the second one doesn't seem right. There is no (not yet) voltage regulation in the "constant current" phase. Current is typically limited by how much current the source can provide (e.g. 110A charging a 1290Ah battery in the case of the OP). If charging current was unlimited, then it is the battery that would limit current, as it just cannot accept infinite current. Once battery voltage reaches "say 14.7V" we enter the "constant voltage" phase where current is limited.

Also I disagree with the idea that it would not hurt to have an "unlimited" current source. Victron says: "The charge current should preferably not exceed 0,2 C (20A for a 100Ah battery).The temperature of a battery will increase by more than 10°C if the charge current exceeds 0,2C. Therefore temperature compensation is required if the charge current exceeds 0,2C."

Victron also recommends short (if any at all) absorption phase for batteries than are not "deep cycled" (as in a golf cart, say 80% DoD). Most cruisers are probably cycling within 20 to 40% DoD anyway, so bulk phase doesn't last long anyway and current is quickly limited in absorption.

[john61ct]

Each manufacturer sets their own charge profile specs.

.2C and .4C are often **minimum** charge rates to ensure longevity for top mainstream AGM vendors like Odyssey and Lifeline.

Others are more conservative, but the consensus is that is for legal liability rather than battery health.

Originally Posted by rom

most cruisers are probably cycling within 20 to 40% DoD anyway, so bulk phase doesn't last long anyway and current is quickly limited in absorption.

Just to clarify, "deep cycling" as a term includes low DoD usage patterns, just a general category as opposed to Starting use cases.

With a large bank and lower range currents, CC/Bulk can take a good hour or two. Obviously then no heat issues, just saying.

Yes, current starts falling in CV/Absorb stage, but it can easily be 4-5 more hours until 100% Full endAmps level is reached.


In any case, as I said in general, lead batts don't accept more than what's good for them, vendor max current ratings can be ignored:

as long as

voltage is well regulated once CV/Absorb stage is reached,

temp compensation sensing is in place, and

you check or ensure there aren't other temperature issues, your wiring/CP infrastructure is robust for high currents.

When the above is all true, there is no harm offering a lead bank as high currents as you like.