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Old 08-12-2018, 07:41 PM   #18
Seevee
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City: st pete
Vessel Model: 430 Mainship
Join Date: Sep 2016
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Quote:
Originally Posted by djmarchand View Post
Well, I see several problems with your current set up and operation:

You say the engine alternator was over charging the batteries in the past? With an internally regulated alternator that is unlikely.

You now recharge the batteries at anchor by starting your genset at less than 11 volts on the batteries. I suspect that voltage is measured with significant load on it which really makes it worthless for diagnosis. But that is too low in any case and you are slowly killing them by doing that. BTW all of the voltages I talk about here and below are measured after killing ALL loads for at least an hour, except for the voltage measured while charging.

How does your genset recharge the batteries? I assume with a shore powered three step charger. You say you shut it off whn it reaches about 12.5 volts. That is way, way too low. A genset powering a large (50+A) charger should go to 14+ volts to get even close to fully charged. I suspect that your current batteries have gone bad and that is what is limiting charging voltage. When it gets up to 12.5 it expends all of its current on heating the batteries- feel them next time. But you may just be operating them badly- too much current draw and not enough genset running time, or not a big enough charger.

So what to do about it?

First do a load test on your current batteries. You need to put a constant load of 1/20 * 380 for ten hours, then let the batteries sit for a couple of hours and measure the voltage. Anything below 12.0 volts indicates you don't have the original capacity. Or if you are ready to scrap them and try something else, skip this step and do the following:

We don't really know what the cumulative load is between the time you shut off the genset in the morning and when you turn it on in the morning. If it is more than 190 AHs (or your current batteries have much less than 390 AHs of capacity) then you need to reduce load, improve your recharging capability or add more battery capacity.

I can't really comment on the first two without more information, but there might be an easy, if not cheap way to add capacity. First of all Lifeline batteries while good are terribly expensive. I believe that plain old FLA batteries, either golf carts or the higher capacity L16s (used in floor polishers) give more bang for the buck.

L16s will almost double your capacity. They have more or less the same footprint as your current batteries but are much taller. But you say you have space. So replace all of your current 6V AGMs with L16s. You might not even need to do any rewiring.

Then make sure you recharge to above 14V on the genset powered shorepower charger and don't draw them down below 12.0 volts (measured after you turn off the load and let them sit for an hour).

I presume you are not a full time anchored out boater. If so then you need to consider a way to fully and I mean fully at 14.5 volts or greater, recharge the batteries at least once or twice a week. Otherwise the new ones won't last long either.

David

David,

Good info and thx......

Re overcharging the AGM with an unregulated alternator (internal)..... I've been told by too many electricians that this will kill AGMs. It's either on or off, 100% charge at ~14.6 or nothing, so no float mode.

Both the alternator (with a Balmar regulator) and the genset or shore power (with the Magnum regulator) will charge up to ~14.6v but will regulate for float charge when necessary. I never turn of the charger is on shore or genset.... it's regulated to do the right job for the AGMs.

Agreed, on the "reduce load" or "add capacity" and that's the gest of this thread. Looking for a better battery capacity to fit where the West Marines will come out, but also looking for other options if they are there.

Solar is out....no space, period.

Reducing power is an option. Can turn off the portable freezer and it will stay frozen for at least 12 hours if not opened. Can put all chargers on 12v instead of the inverter, except my computer which I really don't need charged overnight. But coffee maker is a must in the morning and the 950 watt unit should not be an issue..... I think....


I'm not a full time anchor out, but doing the loop, so out perhaps 5 to 7 days at times.

Still looking for the L16s, a search shows many but at the same price as the Lifelines....
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