Bad batteries affecting inverter operation

[Tom]

Over the weekend a friend was having problems with the inverter on his boat continuously shutting off. He'd aparently been having this problem for some time. The inverter is a 4000W Xantrex/Trace supplied by 8 L16 batteries connected to provide 24V. The L16 battery has a similar footprint to a golf cart battery, but is very much taller and has a much higher capacity. The same bank of batteries also starts one engine and he complained that he hasn't been able to start that engine without using the emergency start switch to jumper over to the pair of 8D batteries that start the other engine.

Making some voltage measurements, I was guessing that he had a couple of bad cells, coupled with the possibility that his batteries needed equalizing (he's never equalized them). He followed us home and, when I finally dug out a hydrometer from the garage, all 3 cells in each of three batteries and 1 cell in one battery were dead. Three of the batteries were in one bank and the fourth battery was in a second bank, although both banks were connected in parallel. Disconnecting all 4 "bad" batteries and connecting the 4 good batteries into a single bank resulted in things working just fine, although he obviously has half the original battery capacity.

Prior to this experience, I wouldn't have expected to see 4 batteries go bad, and all within approx 2 years of purchase. BTW they were Trojans, which was even more surprising.

 

[Ron]

This could very well be caused by discharging the batteries to levels much lower than 50% or by just poor maintenance.  Not adding water when necessary.

 

[Tom]

Ron, you're right on. I should have mentioned that, by asking questions, I discovered he had unintentionally let the batteries run all the way down when there was a power outage (maybe more than once) and recently found four of the batteries "dry". Strangely enough, only three of the bad batteries had run dry, while one dry battery was the "good" one we merged into the new bank of four. He's bracing himself for the purchase of 4 or maybe 8 new batteries and those L16's don't come cheap.

 

[Ron]

If any of  the 8 batteries were interconnected with the bad batteries your friend should replace all 8 batteries. He will probably save money in the long run.  No way to tell if the remaining four batteries were also damaged to some extent.  If only the batteries that are known bad are replaced the remaining batteries, if they were damaged, can shorten the life of the new batteries.

 

[Tom]

That was my advice to him Ron, but 8 L16's is a big chunk of change.

FWIW I believe that the bad bank was dragging everything else down and nothing was getting properly charged.

 

[Ron]

It will cost him more when the old batteries that are not replaced dag down the new batteries and possibly damage them too.

 

[Tom]

That may be Ron, but for some folks short-term cash flow might be an issue and I don't pretend to know other folks' financial situation. I think he's going to try getting at least some allowance from Trojan since their batteries should have lasted a lot longer than that.

Meanwhile, I suggested he run on the smaller bank of 4 batteries for a while - to give them a workout.

 

[Ron]

I can't imagine Trojan giving him a break for something he caused by allowing them to discharge more than 50% and poor maintenance.  He may just end up buying 12 batteries in the end.  the first 4 then 8 more when he finds out replacing just 4 wasn't a good idea.  Then you can tell him I told you so. ;D

 

[Marsha/CA]

Tom,

You mentioned equalizing the batteries.  Is this something that needs to be done on a regular basis?  We've had our coach for 3 years now and plan on getting new batteries before the QZ trip.  But I'd still like to know about equalizing.

BTW, will you and Chris be at QZ?

Marsha~

 

[Tom]

Ron

FWIW I'm not convinced there wasn't a contribution from the inverter/charger. It doesn't appear to me to be putting out much of a charge, as measured by the Link 2000, but it's hard to tell when half the batteries are nearly fully charged and the other half are dead. We also couldn't get the inverter to go into equalize mode, so a call will also be made to Xantrex.

This model of inverter has a weird method of setting the charge current; You have to set the maximum AC current and mentally multiply by 4 to figure out the max DC charge current. So, a "max charge current" setting of 35A translates to 140A max charging current.

 

[Tom]

Is this something that needs to be done on a regular basis?

Marsha, the short answer is it depends. You can easily tell if it needs doing by the fact that the batteries don't hold as much charge. For a better explanation click the Library button above, select Maintenance items, then click Equalizing deep cycle batteries.

will you and Chris be at QZ?

Since we retired, we don't plan that far ahead 

 

[Ron]

We equalize the batteries usually a few weeks before the QZ rally. ?Our batteries are the original ones installed by American Coach in August of 98. ?In our coach we depress two buttons at the same time to start the equalizing process which lasts for about 8 hours. ?When equalizing we do not use anything that required 12 DC since the charge voltage is brought up to about 16VDC during this process. ?There should be some instructions on how to accomplish battery equalization.

 

[Tom]

Correct Ron and explained in the article I referenced.

However, be advised that some inverter/chargers have the capability of automatically initiating an equalization cycle under programmable conditions. e.g. much more frequently and for shorter periods of time. One such inverter/charger I saw recently can be programmed for an equalization cycle duration from 10 minutes to 10 hours.

My Heart inveter/charger can't doesn't have the same programmable capabilities so, like you, I initiate it manually and let it run for 8 hours.

 

[BernieD]

Marsha, the short answer is it depends. You can easily tell if it needs doing by the fact that the batteries don't hold as much charge. For a better explanation click the Library button above, select Maintenance items, then click Equalizing deep cycle batteries.

Tom

FYI

My Lifeline AGM batteries have been "acting up" for a while now and I hadn't been able to get a good reading on them via my Trace Meter. Talking to Lifeline, they recommended that I equalize them. The Lifeline spec sheet calls for equalization once a year or every 30 cycles. However, the recommended equalization period is 1-3 hours vs the 8 hour automatic procedure that my Xantrex controller provides, so I do have to manually shut down.

 

[Ron]

My Heart inveter/charger can't doesn't have the same programmable capabilities so, like you, I initiate it manually and let it run for 8 hours.

We have a Heart Inverter/charger with a link 1000 controller. ?I have to initiate the equalize cycle manually but it returns to normal after 8 hrs automatically.

 

[Tom]

Pretty much the same with my Link 2000 Ron.

 

[Tom]

Interesting Bernie. My recomendation is for folks is to follow the battery manufacturer's instructions, but it must be confusing for folks when the inverter/charger manufacturer says something different from the battery manufacturer. In reality, I doubt that the absolute time is critical, just whatever time it takes to agitate the electrolyte long enough for the sulphates to be removed from the plates.

When battery efficiency falls off it's a good clue that equalization is due.

 

[Tom]

All this talk about batteries made me go check electrolyte levels in the batteries on the old tub. They were fine of course, since I normally keep on top of them.

 

[Karl]

Just a note: Make sure your batteries are full, not overfilled, before you start an equalization; then check and top them off after it's done. They will lose some water during the process.

 

[Ron]

All this talk about batteries made me go check electrolyte levels in the batteries on the old tub. They were fine of course, since I normally keep on top of them.

Now how are the batteries in the coach? ?You want to have them in top shap for QZ.