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Topic: Check your batteries! (Read 2660 times) previous topic - next topic

Check your batteries!

We have the 3 8D Gel batteries.  I just realized that my bank has been broken since I purchased the motorhome.  I've never seen the voltage climb very high before the current goes down.  After some research I realized that things aren't right.  We've been boondocking lately and we've been having more and more trouble with the batteries.  So I took the negative terminal off of the batteries to separate them out.  2 of them were 13v, one of them was 11.9!  So we have a shorted cell in the one battery.  Now that I took the battery out of the loop, it has been pulling in massive current all day long (on the generator).  We're up to 14v.  I'm not entirely sure the bulk charge stage is even finished yet.  We'll probably get a lot better life out of the 2 left than we did with the 3 including a bad one. 

So yeah, split your battery bank out into the individual batteries now and again to make sure you don't have a bad one!

Anyone have a mid life 8D GEL battery they want to part with?  I'd hate to put a new battery in but I don't want to throw away the existing reasonably well working ones.

Also our water pump started leaking.  It never ends ;)

Re: Check your batteries!

Reply #1 –
Engine water pump or fresh water pump??  If it's the engines water pump, try a can of Barrs leak in it and run it for a while.  Good stuff, does a lot which includes water pump seal leakage if it's not too bad.  Have a great day  ----  Fritz

Re: Check your batteries!

Reply #2 –

Two batteries may work just fine. We boondock with two gel 8D.

One way to find bad batteries is to put a simple shunt on each battery and use an inexpensive millivolt meter to see how many amps each battery is discharging & charging. No other way to know if a parallel connected battery is carrying its share.

$16 buys this meter & shunt.
Amazon.com: Volt Meter/DC Digital LED Amp Volt Meter + Shunt /200V 200A /Blue:

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Check your batteries!

Reply #3 –
The most important lesson I learned the hard way was to have a max capacity set of perfect quality batteries in any dry camp coach. 

Put new batteries in every single coach I used from inventory before leaving town.

And a new house water pump and new wiper blades.  Dozens.

Much less drama camping.  Less gen run time.

Re: Check your batteries!

Reply #4 –
It's the house water pump.  We have two water pumps (and fresh water tanks) but even if we use the other pump the primary still leaked due to the pressure.  I took it apart and put it back together and it stopped leaking.  I ordered the later model flojet replacement from ppl motorhomes.  Our accumulator looks and seems fine so I will continue to use it. 

Thanks for the links to the meters and shunts.  That is the cheapest I've ever seen that setup, even on ebay.  I might buy 3 of those.

Re: Check your batteries!

Reply #5 –
"Also our water pump started leaking.  It never ends." And the more you fix the longer the list seems to get, you just gotta love it.

Re: Check your batteries!

Reply #6 –
My coach has two ordinary lead acid 8D batteries and I do just fine boondocking. I normally run my genset an hour or so a day but I don't really need to. I don't use the inverter and I really don't use much DC power either, mostly just my laptop computer from a 12 volt DC power supply. Unless you use more power than I do you should be okay with two gel cells. You should try it and see. It's not like you'd be ruining a set of new batteries or anything. Now is the perfect time to experiment, when you have little to lose... You might be able to sell your matching pair of used gel cells and put the money toward a new set of three batteries if that's what you think you need... Be aware that as you connect more batteries in parallel you increase the likelihood that one bad cell in any of the batteries will ruin the other batteries, which is almost what happened to you. It actually did happen to me a year ago and I only have two batteries in parallel. Three batteries in parallel is even more risky. Cells can go bad from vibration or hitting a big bump in the road, or from drastic temperature changes. I suspect it was the drastic temperature change that shorted out a cell in my 8D last year. I've had several motorcycle batteries short out from vibration over the years.

Re: Check your batteries!

Reply #7 –
We are pretty heavy users.  We would run the generator until the batteries are fully charged around 8pm.  Then the wife usually watches tv for at least 2 hours.  This is 50" samsung LCD, Dish DVR, a mini ITX server that holds all of our movies, an apple tv and a router. 

Then there are both of our laptops, mine is a big old 17" model.  But I work at night every night.

Lately the aquahot has been running for heat at night because it was in the 30's as well.

We are very efficient with lighting, we don't use the halogens, just the one smalll desk lamp.

Once we go to bed around midnight, we shut down all loads we can find and run two fans, one for us, and one for my son.  The 2 8D's are right at 12.0 volts in the morning.  We have one 12v fan and I plan to install a 12v outlet in the bedroom and get another 12v fan so that we can shut down the inverter at night.  I'm operating on the assumption that that should put us in much better shape.

But yeah, we're pretty bad and could easily benefit from all 3 batteries.  ;)

Oh and we actually did better overall with 2 batteries than we did with the 3 and one being broken.  So the 3rd battery was bringing the other two down.

Re: Check your batteries!

Reply #8 –
Quote from: piku –
We are pretty heavy users.  We would run the generator until the batteries are fully charged around 8pm.  Then the wife usually watches tv for at least 2 hours.  This is 50" samsung LCD, Dish DVR, a mini ITX server that holds all of our movies, an apple tv and a router. 

Then there are both of our laptops, mine is a big old 17" model.  But I work at night every night.

Lately the aquahot has been running for heat at night because it was in the 30's as well.

We are very efficient with lighting, we don't use the halogens, just the one smalll desk lamp.

Once we go to bed around midnight, we shut down all loads we can find and run two fans, one for us, and one for my son.  The 2 8D's are right at 12.0 volts in the morning.  We have one 12v fan and I plan to install a 12v outlet in the bedroom and get another 12v fan so that we can shut down the inverter at night.  I'm operating on the assumption that that should put us in much better shape.

But yeah, we're pretty bad and could easily benefit from all 3 batteries.  ;)

Oh and we actually did better overall with 2 batteries than we did with the 3 and one being broken.  So the 3rd battery was bringing the other two down.

My link 2000 gauge says 13.65 fully charged and at 12 volts would be 100% discharged as far as I understand.

Left a bunch of stuff on by mistake in storage. When I went to the coach the link showed -434 amp hours and 12.65 volts.  That's out of 660 amp hours.

At 13 volts mine would be roughly 50% discharged and that's the recommended limit of use.  My -434 was 70% down.  Not good. 

If you measure at the batteries it might show different from your inside gauge.

If not you are going from 50% discharge to almost 100%.  If true the batteries are dead in my understanding. 

Or the charger is not set correctly as they should be charging at almost 14.15 volts until full. 

Then drop back to 13.65 with no load.

Takes a long time to get from 90 to 100 percent as the charger reduces the amps automatically.

My lead acid were higher than what you are posting and were more than 1\2 worn out. 

I fear your two left are also dead. 

Three new 8d gels would be an eye opener as it was for us..

Like I said fully charged is 13.65. 

Something is still wrong. Which you already mentioned.  Just mentioning my results

Re: Check your batteries!

Reply #9 –
I doubt there's much wrong with your remaining two batteries if they can run all that load the entire night. They definitely need charging by morning though. If they're really at 12.0 volts measured at the batteries with no load then you discharged them too far and you're shortening their life a lot. In the morning turn off everything and wait a while before you check the voltage at the batteries, not on your voltage monitor inside the coach. You can reduce power consumption a lot. Watch TV on your laptop with a 12 volt DC power supply instead of the big screen TV. Turn off your inverter and only run 12 volt DC equipment when you're on batteries. Do all your 120 volt AC stuff while the genset is running. If you can't rearrange your power usage to fit a pair of 8D batteries I'll be very surprised. If I can do it anyone can.

Re: Check your batteries!

Reply #10 –
I've always read that 12.1v open circuit is fine and getting into the 11's is where the problem is.  Now I am seeing alternative information here.  When it is charging I rarely see it go above 14v.  In fact, 90% of the time it sits at around 13.8v.  I wonder if the thermal control is holding back on the voltage and current.  When I touch the negative lead during heavy charge it is warm but not hot.  The charger does feed 100 amps to the batteries though for hours but no more.  We've been plugged in for a few days and the batteries have had a thorough soak.  I'll turn off the charger, drain off the surface charge and see what the voltage is on the two remaining batteries. 

But when it comes down to it I have no doubt that they are in barely acceptable condition.  The dealer we bought the rig from did not plug it in and ignored a faulty intellitec porch touch light which kept the porch light on permanently, as well as bin lights being on and more.  When we discovered the condition the coach and chassis batteries were completely flat.  The boost switch was left on as well.  I priced around $1800 in coach batteries into my negotiations and made them put a new chassis battery in.  After I worked on the batteries a bit, even then my load tests showed around 100 amp hours of useful capacity.  That's the only reason I didn't make them put new ones in right then.

The thing is we don't dry camp that often so I'd rather nurse along with what I have.  When we are with friends and family a 15 amp cord is always available which is more than enough.  If I am going to try to avoid going under 12.5v however then we're only talking like 30 amp hours of drain on these batteries.  Even with brand new batteries my winnebago only had 100amp hours useful capacity so it actually feels nice still.  The only problem was when we started using the aquahot.  That is a bit of a pig, and worse it smokes at any voltage under 13v (probably needs a new nozzle).

Re: Check your batteries!

Reply #11 –
Doesn't your auto-start kick in the generator at 12.2v?

Re: Check your batteries!

Reply #12 –
Update your charger.  If you have not updated the charger, check with your battery manufacturer and note the spec's for your battery.  Get a "smart" charger. 14.2V is not fully charged.
 
Older un-programable inverters will not properly charge a battery.  Plug in your new "smart" charger along with the old inverter. 

I have 8D's that are 7 years old and saturated @ 14.7V till the "smart" charger cuts back.

Please take the time to read "HandyBob's" website.  pc

Re: Check your batteries!

Reply #13 –
The label on my new deka gel 8g8d's says to charge them at 14.2 volts max.

Resting voltage should be 13.65 according to my guru. 

Re: Check your batteries!

Reply #14 –
Quote from: Caflashbob –
The label on my new deka gel 8g8d's says to charge them at 14.2 volts max.

Resting voltage should be 13.65 according to my guru.


We are not reading from the same manual.
 
14.6V until the battery gets to temp will fully charge a gel 8D.
This is why getting a smart charger is necessary.
 
Most older battery chargers will not attain the voltage necessary to fully charge a battery.  The moment the charger gets to 14.2V, it cuts back to float which is not fully charging the battery.

A (big) percentage of battery's rarely (if ever) get fully charged.  pc



Re: Check your batteries!

Reply #15 –
Per Deka, East Penn, taking a Gell to 14.6 sure is not recommended, they indicate 14.2 VDC as max.
Why all the opinions need research due to bad info being told as gospel :o

Re: Check your batteries!

Reply #16 –
Quote from: Dave M –
Per Deka, East Penn, taking a Gell to 14.6 sure is not recommended, they indicate 14.2 VDC as max.
Why all the opinions need research due to bad info being told as gospel :o

Tag on the battery from DEKA said 14.2.  Used to be less. No idea on anything other than the east penn/deka gels as that is all my buddy will install.  Nine years in a 24volt bus with four is pretty good.  Two tested ok.  Normally should be moved every year to equalize wear according to him.

Re: Check your batteries!

Reply #17 –
I have a Prosine 2.5 which for sure is not a dumb charger.  I do know for sure as well that 14.2~14.3 is the max voltage for these gels so the charger is setup properly even if it's not functioning properly (it may be a few tenths too low).  The generator auto start will kick on at 12.2 but we disabled it while we were sleeping due to it kicking on about half hour to an hour before we wake up.  We may be able to reenable it as the batteries are functioning far better without the bad battery in the loop.

Regarding the charge rate, even if it never does hit 14.2 the batteries will eventually come to a full charge at 13.65 which is where they float at.  And certainly at 13.9v as well.  There is a point in time where if I disable all of my 12v accessories, the display shows 0 amps, meaning the batteries will not accept anything, even at a slow rate that 13.65v would supply.  So certainly at least when we set out after a long multi-day soak the batteries are fully charged.

I could be wrong here, and perhaps I am, but my understanding is: A primary concern is the length of time they sit dead.  It takes time for the lead sulfate to crystalize.  As such my understanding is that draining them below the acceptable limit but only for an hour or two is far less harmful than draining them to say 12.3v and leaving them sit a week where the lead sulfate has ample time to crystalize.  When we drain the batteries we always charge them immediately upon waking up.  And of course if we get new batteries they will never get that low, even with our crazy usage.  3 8D gel's is quite a bit of power. 

With a pair of 200 watt solar panels, we'd probably be able to go quite a while without running the generator aside from when making meals and using high drain electrical appliances.
 

Re: Check your batteries!

Reply #18 –
Looks like 13.8 is correct as when it is hot outside that is the charge voltage.  Only when it is warm or cold does it go higher per the manual.  We're in Arizona right now.  I would say that if the charge voltage doesn't increase when it is much cooler out, there is probably a problem with the temperature compensation thermistor.