A way To Save Charging Time

[Kenomac]

I meant to write Ah in my calculations to keep Stu happy.

[Paul L]

Originally Posted by Kenomac

Voltage reads 26.62v

The meter is now set to a maximum capacity of 380 and the percentage now reads 100%. Up from the previous setting of 370.

If I increase the capacity figure to 390 the percentage drops to 97.5%, so I think 380 is where it needs to be. It only adjusts by increments of 10.

So if I understand everything correctly, I have an availability of 190Amps to use daily. 380 divided by 2 = 190. With the addition of 450w of solar coming onboard in two weeks and my daily consumption being somewhere between 110-140Amps, it looks like everything is OK.

Am I understanding this correctly?

You will still need to supplement with the genset. 450 watt solar is not going to provide 140ah x 24v = 3.3kwh per day.

[Kenomac]

When I return from Venice on Tuesday evening, we're moving on to battery equalization. The literature I read on equalization indicates that wet cell batteries are 90% efficient. Does that mean that out of the rated max value of 450ah capacity for my house back, the usable amount is 405ah? Or does the rating on the housing indicate the 90% capacity?

[a64pilot]

I would force the charger into absorption voltage, one way is to simply set float voltage to absorption.
I would then do nothing for 20 min or so and after that time if the bank really is fully charged, then the current will be down really low, like less than 5 amps if there is no house loads. If it's not down to real low current, then the bank is not fully charged and you need to leave it at absorption until it's at low current. Or measure specific gravity of the cells.
It is very, very common for chargers to trip into float prematurely, and very little if any charging is done at float voltages.

Telling your monitor your at 100% if your not, it will tell you your fully charged when you are not and lead to chronic undercharging.

Or just install the smart gauge and just use your monitor as an amp counter, which is what I am going to do, but first I have to finish a Buss bar to gang all my grounds together

[StuM]

Originally Posted by Kenomac

When I return from Venice on Tuesday evening, we're moving on to battery equalization. The literature I read on equalization indicates that wet cell batteries are 90% efficient. Does that mean that out of the rated max value of 450ah capacity for my house back, the usable amount is 405ah? Or does the rating on the housing indicate the 90% capacity?

Different meaning of "efficiency".

If the rated capacity is 450Ah, then that is what you should have available when the batteries are new. (but of course, you should never use all of that - the old 50% minimum SOC is still a good rule of thumb).

As the batteries age, their capacity will decrease ( as will the 50% which you can comfortably draw), but there is no fixed "efficiency" in that sense.

What that literature probably meant was that wet cell batteries are roughly 90% efficient at converting the Ah pushed into them to stored energy. So if you have used 100 Ah, you need to push 110 Ah back into them to replace the used energy. (This is again an approximation - the efficiency depends to a degree on what SOC they get down to and the rate at which you re-charge them. Peukert Exponent comes into play again. The faster you charge them, the less efficient the charging is, same as the faster you discharge them, the less Ah you can get out of them).

[StuM]

Originally Posted by Kenomac

Why would the battery monitor be reading 380Ah at 84.4% When I changed the capacity number to 450Ah?

The electrical guy in Spain had the max capacity set to 370Ah, I changed it up to 450.

The chargers are both registering float.

Because the BM thinks that you have 380Ah there ( 380Ah capacity at 100% - that's what you told it).
380 is 84.4% of 450. When you change the capacity to 450Ah, all it knows is that it has that 380Ah stored. You need to find out how to reset it to 100% when you change the capacity setting. (Assuming that the batteries ARE fully charged.)

[StuM]

Originally Posted by Kenomac

Voltage reads 26.62v

The meter is now set to a maximum capacity of 380 and the percentage now reads 100%. Up from the previous setting of 370.

If I increase the capacity figure to 390 the percentage drops to 97.5%, so I think 380 is where it needs to be. It only adjusts by increments of 10.

Again, 380 is 97.4% of 390. That's what the battery thinks it had stored.

If your capacity setting was changed from 370 to 380 and the charge went back up to 100%, that means that another 10Ah have gone into the bank since you changed the capacity figure - so your bank proabably was undercharged.

Try resetting it to 450Ah. The SOC should drop back to 86.7%. Then monitor it for 24 hours. Hopefully the SOC% will creep back towards 100%.

But if you've been on shorepower for some time and are sure that the batteries are fully charged, then find out from the manual how to "manually synchronize" the BM i.e. set it to 100% with the new capacity setting.

[mitiempo]

Originally Posted by Kenomac

When I return from Venice on Tuesday evening, we're moving on to battery equalization. The literature I read on equalization indicates that wet cell batteries are 90% efficient. Does that mean that out of the rated max value of 450ah capacity for my house back, the usable amount is 405ah? Or does the rating on the housing indicate the 90% capacity?

How old is your battery bank? As batteries age they have less capacity. If you set the monitor to 450 AH and the batteries have lost capacity - very likely - when the monitor states that you are at 50% you could well be at a lot lower than 50%. This will hasten their demise.

[Kenomac]

Will equalization bring back some of the lost capacity? These batteries are five years old, and we spend nearly all our time at anchorages.

[Sailmonkey]

Originally Posted by Kenomac

Will equalization bring back some of the lost capacity? These batteries are five years old, and we spend nearly all our time at anchorages.

Sometimes yes. But you'll need the hygrometer to accurately determine when the equalization is complete.

[poiu]

You've probably got the shunt set correctly as if it was wrong the meter would give gibberish information. You can measure it with your meter too if it is a very good one, or put a known load on it and see if it reads correctly.

Your batteries will have lost some capacity depending on abuse. Maybe if you nurtured them perfectly for 12 years they might lose 20%, so after 5 years of only mild neglect maybe 12%. So 400Ah is OK as capacity in parameter 2 or something else if you think it appropriate. You could do a full discharge test with a known load and time it if you wanted to really know.

After charging to a level you think is near 100% such as after a long period of float charging you can reset the counter to 100% : Press mode and the top set button at the same time for a second or so, then press mode six times until you get to 'Set Counter'. Use the arrow to change the display to 1. Press mode again and you are out of the settings menu. Job done.

To determine the 100% level I found it is always more than a day until volts have stopped rising and have arrived at the maker's spec voltage, which indicates you have got there, but this also depends on your float voltage and battery condition and battery type.

[Bleemus]

Originally Posted by Kenomac

I've had some sucess setting up the battery monitor, but I need some help coming up with a couple of numbers to plug in. I need to determine the total Ah capacity of the bank according to the original Trojan battery specs.

Here's a description of the bank:

8 Trojan 6v batteries set up for 24v
Each one is rated for 225Ah @ 20hrs. And 185 @ 5hr

Can someone please calculate the original capacity of the bank? Presently the meter is set at 370Ah which then indicates a 100% charge. The charger has been registering "float status" for over 24hrs having been plugged into shore power.

One more question: Regarding The very first question in the setup manual "shunt". My monitor is presently set on type #3 (see pic of directions on prior post) How would I check to see if this is the correct setting?

Thanks

This is where typical battery monitors fail most mortals. You can enter the number of Ah as if the batteries are new and it will always be wrong. Without doing a long 20 hr test you never really know your Ah capacity and the minute you do it still changes as soon as you finish. Good luck getting that test done while living on the boat.

[mitiempo]

Originally Posted by Bleemus

This is where typical battery monitors fail most mortals. You can enter the number of Ah as if the batteries are new and it will always be wrong. Without doing a long 20 hr test you never really know your Ah capacity and the minute you do it still changes as soon as you finish. Good luck getting that test done while living on the boat.

Or just set it for 85 - 90% of their new capacity.

[Bleemus]

Originally Posted by mitiempo

Or just set it for 85 - 90% of their new capacity.

True, unless of course they are four years old and have been abused by someone who didn't realize how to maintain batteries so the number could be anything. Without a proper test you are still just guessing. Tough to do a proper test with the microwave and induction cooktop running. [emoji12]

[mitiempo]

Originally Posted by Bleemus

True, unless of course they are four years old and have been abused by someone who didn't realize how to maintain batteries so the number could be anything. Without a proper test you are still just guessing. Tough to do a proper test with the microwave and induction cooktop running. [emoji12]

Best bet is the op is unlikely to do a proper test.