6volts- did I trash my new batteries?

[Bdold]

I bought two 6v Trojan batteries about 2 years ago. They no longer hold a charge per the 4 light gauge on my grandby. I have an 80 watt panel on the roof. During the day the lights a show a full charge. After dark only 3 lights shine. I always plug it in when I return from a trip. Did I trash the batteries by leaving it plugged in for weeks?

I have a 2010 Grandby and I did buy an I Q4 smart charger.

 

[Wandering Sagebrush]

The charge status lights are notoriously inaccurate. I suspect your batteries are fine. After charging, use a digital voltmeter and measure no load, resting voltage across the two. It should read around 12.6 volts. Across one battery, it should be around 6.4 volts. Check the Trojan site for better info on those specific batteries.

Your solar should keep them topped off if outside. When you’re plugged in, is your battery switch pulled out so the batteries can charge?

 

[Bdold]

Sage I'm not exactly sure what battery switch you mean.

 

[Bdold]

When I go home this evening I'll take some measurements. Thank you

 

[Wandering Sagebrush]

Sage I'm not exactly sure what battery switch you mean.

The pull out toggle that turns your DC system on when you’re not on Shore Power. Unless I’m wrong (often), when you’re on SP, the battery does charge unless the toggle is pulled out. You’ll have DC on your internal circuits, but not to the battery if the toggle is pushed in. That’s the way my Grandby was configured.

 

[Bdold]

I see. Yes I have that switch. I never disengage it or turn it off. I leave it engaged when I plug it in as well as when I'm on the road.

 

[Old Crow]

If the Trojans are the flooded variety (as opposed to AGM), I'd also want to the check the water level in the cells and check them periodically from now on (if it's not already being done).

Concerning the monitor panel....

As I mentioned in this post, I contacted the panel manufacturer for the KIB Electronics M1106 monitor panel (I'm assuming that's what this one is) and the tech support guy told me the voltage ranges are:

C (Charge) is 12.5 to 13+ v
G (Good) is 11.7 to 12.5v
F (Fair) is 11.2 to 11.7v
L (Low) is 10.0 to 11.2v

The voltage at the panel is probably about a tenth of a volt less than voltage at the battery bank so that has to be taken into account when thinking about it. In practice, though, that doesn't matter much as the panel only provides a very general idea of battery voltage.

For example, Trojan's battery maintenance page says their 50% state of charge level is 12.1 volts (6.02 when measured at each 6v battery). But the monitor panel would be showing Good well below that.... down to 11.7 volts. And the Trojan charts says that would be around a 20% state of charge.

On measuring battery voltage in general...

The other thing to think about here is what exactly is going on at the instant the voltage is being read with a meter or digital readout. While charging systems are charging a battery, its voltage reads a lot higher. A battery that reads 12.6(ish) at rest will appear to have "more than 14 volts in it" if voltage is measured while the charger is in its bulk-charging mode (and mid-13s when it's in float mode). That's not 14 or 13 volts available in the battery after the charger is removed, it's the voltage the charger is applying to it at the time.

Batteries also have an artificially-high voltage reading for several hours after the charger's removed. Trojan recommends waiting six hours (preferably 24) if you want the reading to give you a good indication of the battery's current state of charge. My point is this phenomenon can give us a false impression when taking a voltage reading.

The other thing that complicates this is the fact that voltage does not equal capacity. A battery can show good voltage but die very quickly in use. (I'm already posting a wall of text so will leave it at that).

 

[Bdold]

Thank you old crow. I will start digging around a little bit more. And read those other links you sent. I'm at work now so it's a little hard to screw around. I am aware that that monitor with the four lights is not a very good way to understand your power and consumption. I looked at a monitor a while back but was a little confused on how to connect it. My batteries are AGM.

 

[klahanie]

dbold, maybe pick up a voltage meter/multi tester, even an inexpensive $10 one is a useful tool worth carrying in your rig tool kit. And read up on how to check state of charge (SOC) using voltage.

FWIW I didn't see anything in the IQ4 manual about NOT leaving the charger hooked up for long term. I'd check to see if the battery mfr has recommendations for long term storage.

As for trashed, may I suggest you test them with the appliances you have in the camper. Perhaps you have a fridge and can measure how long the batteries - after charging with the Iota - will power it without any shore or solar input, then compare to your expectation/experience. I think if the batts are toast you'll know from their current ability.

Good luck with it.

 

[Vic Harder]

If the Trojans are the flooded variety (as opposed to AGM), I'd also want to the check the water level in the cells and check them periodically from now on (if it's not already being done).

Concerning the monitor panel....

As I mentioned in this post, I contacted the panel manufacturer for the KIB Electronics M1106 monitor panel (I'm assuming that's what this one is) and the tech support guy told me the voltage ranges are:

C (Charge) is 12.5 to 13+ v
G (Good) is 11.7 to 12.5v
F (Fair) is 11.2 to 11.7v
L (Low) is 10.0 to 11.2v

The voltage at the panel is probably about a tenth of a volt less than voltage at the battery bank so that has to be taken into account when thinking about it. In practice, though, that doesn't matter much as the panel only provides a very general idea of battery voltage.

For example, Trojan's battery maintenance page says their 50% state of charge level is 12.1 volts (6.02 when measured at each 6v battery). But the monitor panel would be showing Good well below that.... down to 11.7 volts. And the Trojan charts says that would be around a 20% state of charge.

On measuring battery voltage in general...

The other thing to think about here is what exactly is going on at the instant the voltage is being read with a meter or digital readout. While charging systems are charging a battery, its voltage reads a lot higher. A battery that reads 12.6(ish) at rest will appear to have "more than 14 volts in it" if voltage is measured while the charger is in its bulk-charging mode (and mid-13s when it's in float mode). That's not 14 or 13 volts available in the battery after the charger is removed, it's the voltage the charger is applying to it at the time.

Batteries also have an artificially-high voltage reading for several hours after the charger's removed. Trojan recommends waiting six hours (preferably 24) if you want the reading to give you a good indication of the battery's current state of charge. My point is this phenomenon can give us a false impression when taking a voltage reading.

The other thing that complicates this is the fact that voltage does not equal capacity. A battery can show good voltage but die very quickly in use. (I'm already posting a wall of text so will leave it at that).

This is a great reminder that the 4 light panel is really very poor at telling you your State of Charge. Thanks for reposting!

 

[Ruck_and_Roll]

I concur. That is the what the manual says and I just confirmed that with my batter monitor. Toggle "In" the battery monitor shows '0' as far as amperage. "Out" shows +15 amperage.

The pull out toggle that turns your DC system on when you’re not on Shore Power. Unless I’m wrong (often), when you’re on SP, the battery does charge unless the toggle is pulled out. You’ll have DC on your internal circuits, but not to the battery if the toggle is pushed in. That’s the way my Grandby was configured.