A way To Save Charging Time

[Kenomac]

Here's the semi final house battery numbers 435Ah and 96.7%. I'm going to leave it in float status overnight, then hit it once again tomorrow with absorption. The batteries are still accepting more charge.

What's your take on this? Have my batteries been rejuvenated? It looks like their going all the way up to 450Ah. Who knew?

By doing what I've done, is it the same as equalization? I checked the water levels today, not much if any change over the past week.

Or should I hit it again this evening with a final absorption charge while I'm on a roll?

[barnakiel]

I am not sure. I think to equalize you drive them really high for a time. Not all batteries can get equalized though. Lead acid open ones do. About gel and agm read from the specific manufacturer. Some batts die on overvoltage.

How far off the top you are you can tell by simple reading of the Amps accepted. If you are below 1% batt bank Ah in Amps, this means the bank is virtually full.

This must be measured where the juice goes to the battery so depending on where your shunt is placed within the system, you will be able to measure like this or not.

b.

[Kenomac]

Originally Posted by barnakiel

I am not sure. I think to equalize you drive them really high for a time. Not all batteries can get equalized though. Lead acid open ones do. About gel and agm read from the specific manufacturer. Some batts die on overvoltage.

How far off the top you are you can tell by simple reading of the Amps accepted. If you are below 1% batt bank Ah in Amps, this means the bank is virtually full.

This must be measured where the juice goes to the battery so depending on where your shunt is placed within the system, you will be able to measure like this or not.

b.

The batteries were still accepting 2-3Ah per hour before the voltage dropped to float 26.65V. When I ran the microwave for several minutes, the charge indicator stayed positive. Right now the indicator is showing positive and a 0.3-0.4 increase during float status.

The published max for these Trojans is 450Ah for the entire bank at 24V. Charge is being measured at the shunt.

[barnakiel]

Originally Posted by Kenomac

The batteries were still accepting 2-3Ah per hour before the voltage dropped to float 26.65V. When I ran the microwave for several minutes, the charge indicator stayed positive. Right now the indicator is showing positive and a 0.3-0.4 increase during float status.

The published max for these Trojans is 450Ah for the entire bank at 24V. Charge is being measured at the shunt.

IMHO:

Battery 450Ah, when at absorption voltage (I assume for 24V the absorption is about 28.8-29.4V) accepts less than 4A, you are within 1% off full charge. GREAT.

If I read your post right, your charger fell back on float when your batt accepted 2-3A. This implies your charger assumed (I believe correctly) you bank is 'full'. Keeping the bank at float now will take care of the remaining 1%.

The reasoning is laid out in plain English here:
24 Volt Charger Tutorial | ChargingChargers.com

As for your 'at the shunt' I do not know where your shunt is. To use the above method effectively the shunt must be the first thing from the battery. (Examples when it is not: the shunt just next to, or built into the charger).

I bet Calder's book shows where to place the shunt for the general meter.

Some chargers have built-in meters, these show what goes out of the charger, not what goes into the battery. The same applies to some solar chargers. They all make sense but they do not meet the criteria for a/m simplified battery management.

b.

[a64pilot]

How long you going to be on shorepower? If more than a few days, I'd cycle the batteries to close to 50%, then do a full recharge like you have, you may as you have seen already have to cycle the power on the charger, then let them rest overnight and I'd follow the manufacturers direction for an equalization.
Note equalization voltage may be so high that you do want want anything sensitive and or expensive powered during equalization.
I would follow Trojans directions to the letter, they are a very respected manufacturer and likely know more about their batteries than most of us do.
Your bank may not be in as bad a shape as you thought, but may well have been chronically undercharged. I believe however you are in very good company, I think that is more common than not.

[Symphony]

This is all fun, and I enjoy learning more about these Ah counters - but I don't think in the long run it will make a lot of difference to your life if the Ah meter says you have 450Ah or 400Ah or whatever. When you draw Ah's out it won't be a linear situation, so the information is only relatively useful.

I think the voltage of the bank, and even individual cells, is instantly more useful. I know if my counter said I had 450Ah but 23V I would be in trouble - or if it shows 200Ah and 25.75V I know I'm good to go. Voltage info trumps Ah info. right?

Once you feel you are fully charged you let the batteries sit unloaded at least a day. then see how the voltage changes. you'll know some useful info without buying more stuff.
I love buying "stuff," and I love tracking liter/ hour and SOG and set and drift, etc etc - but don't let the meters and "stuff" start running your schedule. Kenomac, you are already living the dream with a dream boat.

carry on!

[a64pilot]

You can tell a lot with a voltmeter, in my opinion.
However you have to understand what your looking at, if you have a decently large load on the bank or have recently had, then your voltage will be lower than the corresponding SOC, however you will always be conservative if going just by a voltmeter and the SOC chart for your battery. However you will be short changing yourself and carrying around a lot of extra battery that you are not getting full use of, balance that against life is proportional to depth of discharge, and it's maybe not a bad thing though.

A danger with an AH counter type of battery monitor is it doesn't know your bank is losing capacity, unless you tell it, so if you have 400 AH capacity but you tell it you have 500, then when it says your at 50% SOC your really much less and are killing the bank by discharging too deeply.
Perhaps that is why Kens electrician intentionally set his low, so it would protect the bank?

Smart Gauge though is just too easy, completely maintenance free and somehow it knows your banks true capacity as it loses it, so that its stated percent of SOC is always accurate.

[Paul L]

Originally Posted by a64pilot

You can tell a lot with a voltmeter, in my opinion.
However you have to understand what your looking at, if you have a decently large load on the bank or have recently had, then your voltage will be lower than the corresponding SOC, however you will always be conservative if going just by a voltmeter and the SOC chart for your battery. However you will be short changing yourself and carrying around a lot of extra battery that you are not getting full use of, balance that against life is proportional to depth of discharge, and it's maybe not a bad thing though.

A danger with an AH counter type of battery monitor is it doesn't know your bank is losing capacity, unless you tell it, so if you have 400 AH capacity but you tell it you have 500, then when it says your at 50% SOC your really much less and are killing the bank by discharging too deeply.
Perhaps that is why Kens electrician intentionally set his low, so it would protect the bank?

Smart Gauge though is just too easy, completely maintenance free and somehow it knows your banks true capacity as it loses it, so that its stated percent of SOC is always accurate.

On a full time cruising boat you have the opposite issue also of having unreliable voltage readings because of charge currents from solar - which might be for a long portion of the day.

[Kenomac]

Status this morning: 450Ah at 100% Then unplugged from shore power, waited an hour and checked voltage 25.08V. Now letting the bank discharge for the day and will recharge using the generator to see what happens.

[Kenomac]

Originally Posted by noelex 77

By "topping off" the batteries, I think Ken is referring to achieving 100% SOC or at least close to that.

The biggest factor in determining the life of a lead acid battery is depth of discharge, both the lowest SOC and the time spent at low states of charge. However, there are many other factors that influence lead acid battery life. Periodically getting the batteries to 100% full helps. This is especially important for AGM batteries.

It is difficult for a boat without wind, solar or regular access to shore power to reach 100% SOC. Charging via a generator is usually stopped around 80%. Solar can fill this gap allowing the batteries to get close to 100%. As well, the slower all day charging produced by solar means the batteries lowest SOC will not be as severe. Combined with reduced run time for the generator, there are lots of positive benefits.

However, the real beauty of solar is when the noise, heat, and unreliability of generator can be dispensed with entirely. This is not possible on Ken's boat with his requirements. He needs to be careful that he does not fit a token amount of solar that has little practical impact. On the other hand even a large solar array will not allow him to dispense with the generator, so I think this would also be a mistake in his case.

The 100AHrs @ 24v is realistic in summer in Ken's location for 450W, but much of this power will be taken up using running his fridge/freezers and the other electronics. Will the remainder be enough to raise the SOC from 80% to 100% following a generator run. Without more information It is only a guess, but I think probably yes, although it definitely won't do this year around. A 250w array would still have some practical benefits, but I don't think it will fulfil Ken's aim of regularly achieving 100% SOC.

Originally Posted by weavis

If I recall correctly, Noelex77 had his (now sold vessel) almost running solely on Solar. His soon to be completed boat will again have a large amount of solar panels.

I learned a lot from him by reading the associated threads. His approach is straightforward and useful. I have no idea if he is an electrician but his knowledge base is solid.

Sorry weavis, I re-read his post, and it appears noelex is recommending the use of solar. I'd originally interpreted his post as a don't bother with it unless you go all the way. I thing with my plans to go with 450w, my needs will be met according to his post.

[Kenomac]

Originally Posted by Symphony

This is all fun, and I enjoy learning more about these Ah counters - but I don't think in the long run it will make a lot of difference to your life if the Ah meter says you have 450Ah or 400Ah or whatever. When you draw Ah's out it won't be a linear situation, so the information is only relatively useful.

I think the voltage of the bank, and even individual cells, is instantly more useful. I know if my counter said I had 450Ah but 23V I would be in trouble - or if it shows 200Ah and 25.75V I know I'm good to go. Voltage info trumps Ah info. right?

Once you feel you are fully charged you let the batteries sit unloaded at least a day. then see how the voltage changes. you'll know some useful info without buying more stuff.
I love buying "stuff," and I love tracking liter/ hour and SOG and set and drift, etc etc - but don't let the meters and "stuff" start running your schedule. Kenomac, you are already living the dream with a dream boat.

carry on!

Symphony,

What kind of harpsichord is that? We have a 7ft French double manual by Frank Hubbard in our living room. I built it myself 20 years ago.

Ken

[barnakiel]

The discharge/measure voltage method is to be used with caution: the books give voltages past discharge and at rest. If you measure right after discharge the meter is down a bit. Wait about one hour and it gives you a more adequate view of things.

This is similar to charge / wait / measure.

The voltages / percentages are one thing. And how sound the bank is you can judge easily with a load meter. Each car garage has one. I used to carry one when I worked on the biggie boats too.

Slow (20hr rate) discharge to any given % is also a good test. Some manufacturers quote different rates too - I have had 10hr and 5hr rates on our NECs. If you apply a different rate, you must adjust the Ah rating of the bat accordingly - lower Ah rating goes with higher discharge rate.

b.

[Kenomac]

I'm going to check everything today after a 10hr long slow discharge of approximately 70Ah, then see how long it takes to fully charge up again. Kind of a typical day with temps in the 80's refrigeration running frequently.

Voltage right now is 24.84v after 7 hrs and 42Ah.

[Stu Jackson]

https://forums.sailboatowners.com/in...pacity.185414/

Maine Sail has said repeatedly that full is when the charge rate is <2% at absorption voltage. So, yes, kick it back to absorption when you think it's full and see what the charge rate is, simple as turning off the charger and on again.

[Kenomac]

Originally Posted by Stu Jackson

https://forums.sailboatowners.com/in...pacity.185414/

Maine Sail has said repeatedly that full is when the charge rate is <2% at absorption voltage. So, yes, kick it back to absorption when you think it's full and see what the charge rate is, simple as turning off the charger and on again.

It didn't decrease to <2 until the house bank reached 100% at 450Ah, then it goes into float @ .2-.3 or so. During absorption near the 435-450 the readings were 3-4Ah going in.