12v charging loss from shore power

[tonyz]

So it seems every time I charge the batteries by simply plugging in the sore power and using the inboard system supplied by the factory, I do not get a solid full charge. Why is that?

I decided to add a little trickle charger to the battery box that stays in the box and plugs in separate from the shore power and I noticed the batteries hold a stronger charge for a lot longer. Note: I only charge with one or the other, never both plugged in at the same time, I know the consequences of that.

Is there really that much loss from the shore power, or is the inverter in the tt poor quality and/or bad? Suggestions?

[LadyWindrider]

Only a voltmeter will answer your question. Get one, and read the battery. Then connect to shore power, and check again. See what your converter is putting out. Also check the specs on your converter, amperage, how many stages of charge, etc. And how old are the batteries, (yes plural, as that is what you wrote), and how are they wired?

[Mountainmanbob]

Originally Posted by windrider

Only a voltmeter

Only a voltmeter
will make this all so easy to figure out
takes the guess out of the game
I take it on all trips out
plus
I check the battery from time to time
while unit is parked at home

batteries last longer
if kept with close to full charge

10 dollars well spent
seen them for 1.99
I like the 10 dollars model
Christmas time Sears
had a nice one for 9 bucks on sale
can probably be had now for 15

MM

[Herk7769]

The "charger" in your TT is not an "inverter," it is a "converter."
That may seem like semantics, but there is a big difference.

An inverter takes 12 volt DC from your battery and MAKES 120 volt AC for things like your TV and coffee maker when NOT plugged in to shore power.

A converter takes 120 volt AC from shore power and MAKES 12 volt DC for your battery powered camper items like lights and your furnace. It also charges the battery based on its (the battery's) level of charge at the time.

The "dead'er" the battery; the lower the charging voltage and higher the charging current.
The "full'er" the battery the higher the charging voltage and lower the charging current.

This is done in "stages" of charge in order to avoid destroying your battery. Thus a single stage charger (like a car battery charger) has just ONE (or a manual switch) setting.

The converter in your TT can be a dual stage; three stage; or some of the newer ones are FOUR stage chargers. This allows the battery to remain plugged in without damage because as the battery fills, the charging current drops off to a trickle to just replace the charge lost due to internal resistance. Trickle charging starts at a certain percentage of "Full" depending on the number of converter stages and the manufacturer.

For example,

A very low (an actually DEAD battery WILL NOT CHARGE due to circuitry in the converter designed to protect the converter) battery in stage "one" might be charging at 14 volts and 30 amps.

At "say" 50% capacity; the converter will switch to stage TWO and drop the charging voltage to 13.5 volts and 10 amps.

At say 80% capacity; the converter go to stage THREE will drop the voltage to 13 volts and the charging current to 1 amp OR LESS.

A four stage converter will drop the current to a couple of hundred MILLI-amps at 98% capacity and will remain so for "days" to completely top off a battery.

These stages are designed to PROTECT your battery from overcharging; electrolyte loss; and ultimately destruction due to too much current too quickly for the state of charge.

If you charge your Deep Discharge "house" (trailer) battery with a 50 amp two stage car charger and gas generator like I do (to speed up the process) you MUST watch the battery and monitor the water level constantly. You can not simply hook it up and walk off. At the least, electrolyte can bubble and splash out of the vent cap holes (YOU DID REMEMBER to remove them when doing this right?) and corrode the metal under the plastic battery box.

Trickle chargers and "battery minders" only use the "third or fourth stage" setting and are GREAT for "tending" the battery; keeping it warm in winter; and topping it off (not so good for quick charging).

[tonyz]

Thanks all, what I a getting is what I suspected. There is a fair amount of loss due to resistance and may never let the batteries, 2 6v Trojans in series, fully top off charging off the converter. I will keep them on the trickle charger over the winter and when docked at home.

[Herk7769]

Originally Posted by tonyz

Thanks all, what I a getting is what I suspected. There is a fair amount of loss due to resistance and may never let the batteries, 2 6v Trojans in series, fully top off charging off the converter. I will keep them on the trickle charger over the winter and when docked at home.

Tony,

You do realize that you CAN use a 12 volt battery tender with your twin 6 volt Trojans, right? You just hook the red wire from the battery tender to the positive terminal on one battery and the black wire from the tender to the ground terminal of the other. You will need to keep the jumper that connects the batteries in place when doing it. The tender will "keep" both batteries (a 12 volt "bank") topped off at the same time.

[tonyz]

yes, thank you

[Mountainmanbob]

Originally Posted by tonyz

I will keep them on the trickle charger over the winter and when docked at home.

you may wish to try one of these
I bought one a while back
just went out to my trailer
and the battery reading was 12.52
plugged in my Sunforce 5 Watt
in two hours it read 12.57
after waiting a while for a true reading
Mountainman

Sunforce 50022 5-Watt Solar Battery Trickle Charger






List Price:$69.99Price:$47.80

[tonyz]

Oh yes, I have been thinking of getting one for a while, I thinks it time to get one, would be good to add a bit of a charge while boon docking too I would guess.

Originally Posted by Mountainmanbob

you may wish to try one of these
I bought one a while back
just went out to my trailer
and the battery reading was 12.52
plugged in my Sunforce 5 Watt
in two hours it read 12.57
after waiting a while for a true reading
Mountainman

Sunforce 50022 5-Watt Solar Battery Trickle Charger






List Price:$69.99Price:$47.80

[Mountainmanbob]

Originally Posted by tonyz

would be good to add a bit of a charge
while boon docking too I would guess.

yes those were my thoughts
when I bought this THING
but it seems it is only good
for a (very little) topping off juice
it seems the 15 Watt is the minimum required
to make up a little for day and night
lights, pump, TV etc use

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• Kit includes: one 15 Watt amorphous solar panel, a 7 Amp solar charge controller, 12 ft. of wire, CLA adapter and battery clamps for easy installation

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