Bad battery or inverter?

[Max Simmons]

First off, Electrical issues are my least favorite problem to deal with on the boat.
Over last weekend, on the hook for 3 days I ran into an issue with the inverter. When not on shore power, we use the inverter intermittently to run the refer and charge electrical devices.
Friday, all was good. inverter worked fine, no issues. Saturday, ran the genset in the morning to charge the house batteries (2-8D's), panel showd them fully charged after about an hour, which is normal. Later, switched on inverter and nothing. The battery switch at the panel can be turned to 1, 2, both or off.
I normally leave it in the both position. I switched to battery 1, meter shows a little over 12 volts, switch to #2 and meter shows 0. Since the #2 battery is around 7 years old, I figure that it is shot, so pulled it out (fun!) planning to replace it. Just stopped by the battery store, they check it and say it's fine. It's at about 85% charge and cells all look good.
I checked corrosion on all the terminals and connection points and all look good.
Suggestions on what to check next? Was planning on getting out this weekend and this has put a crimp in our plans.
The inverter/charger is a Xantrex Freedom 20 and never a hick-up.

 

[High Wire]

Assuming the battery is back in place and the problem still exists, then you need a dvm to check the battery switches and fuses. Even a simple test light will work. You are looking for where the voltage goes to zero.

 

[caltexflanc]

Plus it sounds like it is on the "meter" (whatever that is) side of the circuit, not the inverter. A good multimeter is an invaluable tool, would have saved you the strain and pain. Might as well get one now to track this down. A real battery monitor (as much discussed here at TF) would be another very useful investment.

 

[DavidM]

Further to High Wire's suggestion, a first test would be to make sure the inverter is off and then check the voltage going to the inverter. Should be about 12.5 with charged batteries. If low check for the cause.


If ok then turn the inverter on and again check the voltage. If the voltage drops to zero when you turn the inverter on, then you have a bad connection somewhere.


If the voltage is still high and the inverter is on then you have a problem with the inverter.


David

 

[FF]

"Saturday, ran the genset in the morning to charge the house batteries (2-8D's), panel showd them fully charged after about an hour, which is normal."

I think its time for an SOC meter.

8D are about 200A each, so at 50% discharged 200AH would need to be pumped into the batts (100 AH each). Hard to do in an hour , even if you had a 300Amp alt.

I think you are monitoring voltage , which is almost useless in monitoring a house set SOC.

The batts probably received some charge , but not enough for the inverter to produce some 120V with out hitting the low volts setting.

 

[ranger58sb]

Saturday, ran the genset in the morning to charge the house batteries (2-8D's), panel showd them fully charged after about an hour, which is normal.

I normally leave it in the both position. I switched to battery 1, meter shows a little over 12 volts, switch to #2 and meter shows 0. Since the #2 battery is around 7 years old, I figure that it is shot, so pulled it out (fun!) planning to replace it. Just stopped by the battery store, they check it and say it's fine. It's at about 85% charge and cells all look good.

I'd guess NOT fully charged, after only an hour. AND/OR... older batteries no longer capable of holding a full charge. "A little over 12 volts" could mean dead. Fully charged, should be 12.7 or 12.8V. If they said it was 85% charged right after you thought it was fully charged... it's probably old, on it's way out.

You might just have a closer look at battery voltage -- with a multi-meter, at the batteries, after "resting" for 4-6 hours or so (off the charger, with no loads).

Or it could be that your charger is switching to float prematurely.

-Chris

 

[caltexflanc]

The original post is worded so it concerns the battery that read 0 at the meter. And we are not sure what measurement the "85%" is derived from that the shop got from that battery.

 

[kchace]

I've been reluctant to add my .02 but here goes.


If the Xantrex Freedom 20 is your house charger its WAY undersized for 2 8D's. Its not that it won't charge the 8D's, it will just take much longer than if it was a more appropriate size.



You say "panel" showed the batteries to be fully charged after an hour, but WHAT panel is this? One connected to the charger? And what voltage or other indication DURING charge are you considering to be "fully charged"? (If during charge, one should see a voltage of at least 14.5 and even then, after only an hour the batteries would at best be done with bulk charge which is no more than 80%)


The inverter would not work when the batt switch was set to "both". You switched to battery 1 and the "meter" showed a little over 12V. Where is this meter? You then switched to battery 2 and the meter showed 0, but when you pulled that battery the shop said it was 85% charged - so obviously not 0. (unless you pulled the wrong battery?)


The first thing to do is shut the battery switch off and physically measure AT the battery terminals with a hand held meter. These readings will tell a lot. Telling us more info about the "meter" that you had indicating 12 and then 0 will also help with diagnosis.


Just an FYI - if one battery is really at zero and then other is at 12 or so and you put the battery switch to both - its very likely the NET battery voltage will be too low for your inverter - but what's really going on is a total guess without more info as I mentioned above.


Manually measure both batteries and give so more info about the setup and we can help a lot more.


Ken

 

[Baker]

I'd say you did good, Ken!!!!

I will echo everyone else. No batteries will charge in an hour....especially batteries that have been supporting a load for the last 24 hours. It is also why one of your battery are dead. With this type of treatment I am surprised it lasted 7 years. Magnum sells a batery monitoring kit(BMK) that is reasonably priced and fairly easy to install. It simply meaures the amps going in and going out and gives you the net and puts it on a nice easy to read display. It will pay for itself many times over by knowing the health of your batteries and knowing what is going on with your electrical system. Only partially charging your batteries(85%) over and over and over is very hard on them and will drastically shorten their life....usually in the 4 year range. Like I said, surprised you got 7.

 

[DDW]

A battery monitoring device is a good idea - I don't like the Magnum, there are many other choices. The Balmar is probably the most idiot proof while giving you the least information. Blue Sea, Xantrex, Victron, Mastervolt, and many others make them.

I'll echo others than you cannot properly charge a lead acid battery in an hour. Perhaps 3 or 4 if not too discharged. LA batteries reduce their charge acceptance as they get above 70 or 80% state of charge no matter what charge source is hooked to them. The last 20% takes a long time to get in (2 hours or more), no way to rush it and if left at 80% for any period of time they batteries will die early.

 

[Baker]

The last 20% takes a long time to get in (2 hours or more), no way to rush it and if left at 80% for any period of time they batteries will die early.

And this is the reason solar panels make sense on a cruising boat. Not to charge the batteries. But to charge them that last 15-20% instead of having to run the generator until noon just to put that last trickle charge into them.

 

[kchace]

And this is the reason solar panels make sense on a cruising boat. Not to charge the batteries. But to charge them that last 15-20% instead of having to run the generator until noon just to put that last trickle charge into them.

This use for solar has saved me a lot of generator hours and made my batteries a lot happier. (more regularly fully charged)

 

[Max Simmons]

Wow, thanks for the responses and for further convincing me that electrical issues are a royal PIA! I'd get a pro, and may end up there, but their weeks out, so will continue to diagnose as able.
To clarify:
Meter is the volt meter at the electrical DC panel. The battery switch is there as well.
The Xantrex remote shows the state the batteries are in, granted it just has dummy lights, but it's what I've been referring to over the last 12 years and seems to work.

Current plan is to further check connections to the inverter/charge and voltage at the inverter. Also will check other house battery. The boxes are labeled 1 and 2, but I have never traced them to confirm.

Thanks

 

[kchace]

Unfortunately that doesn't have much data regarding the state of charge. Empty, half and full are pretty coarse measurements. It looks like it may show battery voltage during charge but unless you also know the amps going in you can't really tell the state of charge.

Ken

 

[Max Simmons]

So, pulled the other 8-D and had it checked. Results were poor as well so replaced both with new,, plus as noted, they were both 7+ years old so were on borrowed time. Not to mention I had a strong helper to assist in pulling and installing.
Got everything back in place, same situation!
Frustrated, started checking all connections again. Found the negative connection to the inverter was bad. The cable had pulled loose from the lug, but the amount of electrical tape wrapped around the connection made it appear that it was good.
2.95 for a new lug and all is good.

 

[sdowney717]

So, pulled the other 8-D and had it checked. Results were poor as well so replaced both with new,, plus as noted, they were both 7+ years old so were on borrowed time. Not to mention I had a strong helper to assist in pulling and installing.
Got everything back in place, same situation!
Frustrated, started checking all connections again. Found the negative connection to the inverter was bad. The cable had pulled loose from the lug, but the amount of electrical tape wrapped around the connection made it appear that it was good.
2.95 for a new lug and all is good.

Old batteries can completely fail at any time so you did good. Just about all my batteries eventually fail with a shorted cell, sometimes 2.

I like to run them till they start having problems. I just bought new house batteries, they failed and were from 2012. One day they just shorted the cell, so volts dropped to 10. And the charger was pumping in 15vdc to compensate, and they were bubbling a lot. Prior to this they had lost capacity due to sulphation.

 

[Wxx3]

Sounds like I'm late to the party.

Yes, 1 hour won't fully charge anything, except a motorcycle battery.

I ended up ruining my 4 8D's by not having them fully charged over the winter. They were being charged, but not fully, all the time.

 

[FF]

"They were being charged, but not fully, all the time."

Depending on age and use batts will internally loose 1% to 3% per day.

Old well used house batts can need help every 2 weeks .

 

[TG]

I have the Xantrex Freedom 20 inverter charger as well. The primary charging circuit can deliver 100 amps DC charge so you have a pretty robust charge capacity. I find that 1 8D AGM at 250 AH will still take about ~ 3hrs to charge when the battery is at 11.4 vdc. I typically recharge at 11.4 vdc.

From the manual:
Freedom battery chargers with temperature
sensitive charging (TSC) are electronically
controlled. The primary charge output current
is rated at 12 volts:
Freedom 10 50 amps DC
Freedom 15 75 amps DC
Freedom 20 100 amps DC
Freedom 25 130 amps DC
Freedom 30 140 amps DC

I run two refrigerator/freezers and a ULINE Ice Maker along with all the cellphone chargers and an occasional Keurig Brew and I typically get about 8 hrs between charges on 1 8D AGM. I always run generator for big loads like microwave, oven, water heater, house charger etc...