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Old 26-10-2018, 07:03   #31
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Re: Battery voltage with Inverter on.

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Originally Posted by coopec43 View Post
According to my research each T-145 weighs 28kg so you have app 250kg of batteries?

WOW!

Clive
At that he gets well over half again the amp hours my 4xL16HAC (@125# each, 435AH each, 870AH nominal @ 12VDC) provide with not much more weight.

Space limitation is why there are only that many, but our daily load is more like 300AH, so we have more headroom, percentage wise. As in most sailboats, the biggest draw is the food cooling (reefer/freezer on spillover) - in our case, averaging about 10A, which is about double what our prior Frigoboat system (failure documented thoroughly here on CF a couple of years ago) pulled, which is not a happy event for us. However, our solar upgrade has largely eliminated our need to run the Honda 2000 for charging...

That said, I think that we've seen those voltages, particularly first thing in the morning, when our system is down from overnight without wind to help, and it's not alarming to me.

I'd do a temperature compensated specific gravity reading, and if it's not up to snuff at the indicated C100, then worry. Also if the cells aren't essentially (say, 0.05 difference) the same, equalize until they are...
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Old 26-10-2018, 08:32   #32
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Re: Battery voltage with Inverter on.

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Originally Posted by spudsdailey View Post
I have a battery bank with approximately 1300 amp hours. Charger keeps them at 100% SOC. When I go out on the boat and have the inverter on, the voltage drops in a few hours to 12.4 or so. I am drawing about 40 amps 12 volt.
Is this OK, normal?

When you off of shore power, no engines are running and the inverter is ON, the inverter consumes quiet a lot of power while only in stand-by mode.


As for the figures you mentioned I cannot comment on them. Too little knowledge about the stand-by consumption of various inverters.


I switch off my inverter as soon as I am off of shore power and the engines are not running and save a lot of energy. That would also be my recommendation. Additionally watch how much energy you can save.
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Old 26-10-2018, 09:09   #33
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Re: Battery voltage with Inverter on.

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Originally Posted by skipgundlach View Post
At that he gets well over half again the amp hours my 4xL16HAC (@125# each, 435AH each, 870AH nominal @ 12VDC) provide with not much more weight.
If that's true, something's wrong there, as the "20-hour rated AH per pound-of-lead" ratio should hold pretty closely.

Especially since AFAIK both models there are true deep cycling, and they're both from Trojan, right?

If not, the lighter weight one is IMO the lower quality one, wrt deep-cycle longevity anyway.
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Old 26-10-2018, 09:41   #34
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Re: Battery voltage with Inverter on.

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Originally Posted by john61ct View Post
If that's true, something's wrong there, as the "20-hour rated AH per pound-of-lead" ratio should hold pretty closely.

Especially since AFAIK both models there are true deep cycling, and they're both from Trojan, right?

If not, the lighter weight one is IMO the lower quality one, wrt deep-cycle longevity anyway.
Hoping this shows up right under yours, so mine appears nearby as well...

I know of no L16 class battery which isn't in the 400AH range. Some lower, and some higher, like mine (Rolls is even higher but they wouldn't fit my box), and all weigh in north of 100 pounds each.

However, it appears that 72x8 (not the earlier 28kg mentioned, from which I based my comment) is still only 576#, about 15% more than our bank total, whereas the AH is in the +50% range.

I believe that our amperage is more common, but this appears to be a massive improvement in the weight-to-AH measurement.
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Old 26-10-2018, 09:48   #35
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Re: Battery voltage with Inverter on.

Hm. Looking at Trojan website. (https://www.trojanbattery.com/product/t-145_plus/)

Each t-145 Plus = 260AH

Each pair therefore = 12V with 260AH/20hour rate
4 pairs = 1040, not 1300 AH.


Thus the weight of the bank vs the AH of the bank is consistent.

It also explains some of his concerns about his voltage level, as a constant drain at his rate is severe for that level, possibly?
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Old 26-10-2018, 11:14   #36
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Re: Battery voltage with Inverter on.

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Originally Posted by spudsdailey View Post
...Trojan, L16-AC. 435 Ah each @ 6volts. There are 6 of them, hence, 1305 Ah bank... close to 12 volts. Back on shore power, it re-charges quickly to 100% SOC within an hour or so...
We can call the connected batteries a 'bank', but your appliances and charger see it as one battery.

Red flag!

At 12v, your battery is all tuckered out. Pumping that much juice, going zero-to-full, in one hour could melt the plates from heat generated by internal resistance.

Good grief! This sounds like a recipe for catastrophic failure. More than your battery might be in the path...

PS:
Three refrigerators?

Over on the RV forum, folks are all in a rush to buy the newest BillionBuxBus conversion. Forty-five feet and 50,000# and 600hp. I don't judge.
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Old 26-10-2018, 12:44   #37
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Re: Battery voltage with Inverter on.

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Originally Posted by skipgundlach View Post
Each pair therefore = 12V with 260AH/20hour rate
4 pairs = 1040, not 1300 AH.

Thus the weight of the bank vs the AH of the bank is consistent.
Yes losing a third of capacity is significant.

And I'm glad the weight issue turned out to be consistent.

The better the battery, the more lead per AH rating.

A lighter weight per AH is a red flag that it's not actually built for deep cycling longevity.
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Old 26-10-2018, 12:52   #38
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Re: Battery voltage with Inverter on.

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Originally Posted by spudsdailey View Post
The 40 amps are due to 3 refers, and the Nav equipment, stereo, etc
Forget cranking the big stereo, and you can definitely improve the energy efficiency of the fridges.

Get a coulomb-counting meter and determine the AH per 24hrs usage of your big consumers individually, circuit-groupings for the small stuff.

> Voltage has gone down under this load close to 12 volts. Back on shore power, it re-charges quickly to 100% SOC within an hour or so.

Impossible. Faulty charging gear, or at least not adjusted properly. Should not drop to FloatV until trailing current has tapered to say 5-10A.

Or drops less than .1A over an hour.

Should take at least 6 hours, likely much longer.

It is very likely your bank needs replacing, but first focus on reducing consumption, and on running loads from sources active while away from shore power.
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Old 26-10-2018, 12:54   #39
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Re: Battery voltage with Inverter on.

You mention daysailing.

Are you ever away from shorepower overnight?
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