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Charging Question
I have eight group 4D lead acid batteries on my coach. They are all about six months old and were installed as a new set. On Saturday I topped off all of them with distilled water using a battery filler that stops at the correct level. I then performed an equalization charge on the them for eight hours. Everything went well and the battery bank read about 14 volts at the end of the equalization charge and the inverter/charger remote panel read that in was in “float” stage. I returned on Monday to find the remote panel in “charge” stage and the bank voltage read 12 volts. Thinking maybe something was simply drawing on the batteries that caused them to discharge and kick the charger in (which never happens when I am plugged into 50AMP service) I left and returned again today to find it yet again in “charge” state and about 12 volts of voltage reading.
Any thoughts on what I may have done or possibly disconnected when sliding the batteries out to top them off? They had plenty of cable to pull them out of the rack two at a time and check/fill the electrolyte and slide them back in. Everything seems to be in order, but it would seem my charger will not shut off as the bank will not come up to “float” voltage.
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26 Replies
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Chris,
I am assuming lead acid batteries since you topped them off with water. My first thought is why you felt the need for an equalization charge. How were the batteries acting prior to doing that? Did they go into float?
The voltage in equalization is pretty high compared to bulk charge so have you checked the electrolyte level in the batteries after the charge? Is it possible a cable came loose?
I realize getting back to basics may seem obvious, but have you had any interruptions in shore power so the batteries have been discharged through the inverter? Assuming you have eliminated all loads are you showing no loads on all your coach meters? You will have some loads from items like clocks, thermometers, alarm system etc. but those loads are relatively small and your inverters should easily go into float unless you have the inverter charge rate set excessively low. Have you checked that? If you have the inverter set for a high rate of charge it should overcome all but the heaviest loads. You should be reading 14.25 volts with the chargers on unless the loads on the batteries are very high.
Is there any chance a battery has failed such as an internal short? That will suck the life out of batteries.
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Thanks Jon. All of the obvious stuff is pretty much in check. The batteries were acting and performing just fine. Our coach is always plugged in and we have not lost shore power since Saturday. The batteries remain in “float” at all times as other than the phantom loads, nothing has been used on the 12v side.
Wondering if my charger(s) are not turning on or functioning as my voltage continues to read between 11.5V and 12V on the remote meters while the remote panel reads it is in “charge” mode.
I checked the bank with a multimeter and each battery reads 12.19 volts. They are not showing any signs of overcharge (boiling, gurgling, heat or overflow of electrolyte).
Both chargers are set to full amperage for charging.
Any thoughts on a wire that might keep the panel from actually kicking in the chargers? They both read “charge” but they are not reading voltage that the chargers are functioning.
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OK I think I have this solved. I unplugged from shore power and noticed that the inverters did not kick in even though the remote panel showed that they were “on”. I subsequently turned each inverter off at the unit itself for about 15 seconds and turned them both back on. Walla, the inverters kicked in. I then reconnected to shore power and waited for the transfer switch and walla, the chargers kicked in and the panel voltage now reads 13.7 volts and they have dropped down to “Accept” stage. Apparently, neither unit was either charging or inverting although both were switched “on”. Turning them off and then back on seems to have solved the issue. Not sure of the cause, maybe just a funky Xantrex thing. They are Freedom 25’s waiting to be replaced but so far have not had any issues.
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I have limited knowledge of the various inverters and their remotes since the variations are nearly endless. But all inverter / chargers if functioning should be sensing that voltage and responding by going into bulk charge rate.
The inverters I have the most knowledge of did not have any “sense” wires, but only the heavy cable connections to the battery bank. If those connections are tight and clean the inverters should recognize how low the voltage is and start charging. You have two inverters? I question that because unless both have failed one or the other should be able to handle the charging. Have you tried shutting down the coach and giving the inverters a chance to reboot?
I have even less knowledge about CC than I do about inverters so I would also look to see if there is something CC did that might affect charging.
What happens if you shut down the inverters and isolate the batteries? Isolating the batteries by turning off the master switch(es) should leave the batteries at their current voltage and it should remain veirtually unchanged for at least a day or two.
Is it possible one of the chargers had failed unknown to you, and now the second has failed and you are seeing the impact. On a previous coach one of my inverters almost 100% of the time showed charging while the other did not show any. However, if I turned off the one that seemed to be working, it was only a few seconds before the second one started to assume the responsibility for charging. I checked that often just to avoid a surprise such as finding them both failed.
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Thanks Jon. Just checked the bus again tonight and everything seems to be good and back to normal. Remote panel reads 13 Volts and charger status reads “float”.
It would appear that the remote panel will operate independent of the actual inverter/charger. By this I mean the remote panel will show the actual voltage of the battery bank along with the state that the inverter/charger “should” be in. In my case the red “charge” light was illuminated but neither inverter/charger was operating. Not sure why they stopped, but simply toggling the on/off switch on the face of each unit seemed to fire them back up.
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Chris,
Did someone change to 4D’s instead of 8D’s at some point? My 2000 CC had 8’s and were AGM, unusual to see wet batteries anymore for the house.
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Tom, yes someone did. The previous owner had the bus stored with the broker we purchased it from. When informed that he needed new house batteries he elected to save money on a bus he never used and put eight cheap NAPA lead acid 4D’s in as replacements. Eight 8D AGM’s would have been nice. The real crazy part are the racks are made for 8D’s which even from NAPA are only about $30 per battery more than the 4D’s. We will let them run for a while as they were new and I am used to checking and topping off wet lead acid batteries in my various electric carts and such although it is a real PITA pulling them from the racks.
We pretty much go from pole to pole with little or no dry camping. If we ever had a situation arise where we needed to dry camp, I would have no issues running the generator for an extended period of time. We run a refrigerator, wine cooler, basement ice maker, and occationally the microwave while on the road. We have CC OTR air so our roof A/C’s are not on the inverter circuits. With our described battery load and needs, how many 8D AGM’s do you think we should go with?
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If you go from power pole to power pole, or run your generator a lot one battery will work. If you want to do away with that battery just get a 120V converter (120 VAC to 12 or 24 VDC) and run the generator all the time and throw away your inverters. That will save you about 1000 lbs, improve your front axle load, and eliminate the need to screw with house batteries. Use your chassis batteries for generator start.
I am only half kidding when I say the above. The reality is our motorhome conversions are all a compromise intended to meet the needs of folks who spend a lot of time in Quartzite dry camping, as well as the folks who are always plugged in when not in motion, and everyone in between.
Since a lot of conversion owners will overnight in a Walmart or a rest area the batteries allow power for lights, TV, to make coffee, etc without running the generator so you have to decide how you use the coach, and then set it up for your needs. But departing from what is the norm for a conversion may make resale a little difficult.
Those lead acid batteries, especially when being equalized or getting a bulk charge are outgassing to an extent. If your battery compartment does not have a lot of venting, and I mean a lot, be very much aware of the fact corrosion can begin on all steel parts and electronic devices.
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Good advice Jon. I left the cover off my battery rack enclosure for the entire eight hour equalization. Not a single cell pushed electrolyte past the cap/vents.
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Chris it is not the liquid electrolyte that will eventually screw up electronic items and start corrosion on exposed steel parts but the vapors you cannot see. That is why the lead acid batteries are vented. That allows the release of those minute vapors that can do damage far beyond their slight amount.
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Chris,
That explains it, he took the cheap way out as you explained. I would stick with 8 AGM’s when it’s time to make the change, that’s how the coach was setup from the factory. Eight 8D’s on a 12v coach without AC’s on the inverter circuit is a great setup for just about any dry camping situation that comes along. You nver know, you might want to be in the boonies one day.
The 4D’s are 2″ less in width than 8D’s, so you may have some battery movement in the bay.
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Chris,
As you know our coaches are very similar. Although our battery compartment will house 8 8Ds, I replaced my 6 wet cells with 6 8D Lifelines. I went with 6 at the recommendation of some on this board. If I was doing it again I would go with 4 8Ds. Even dry camping at the ballon feista for 5 days my power needs could have been satisified with 4 batteries and the generator. For me, 12-20 hours of battery use is all I need. If I need AIr Conditioning, like you, we need AC power.
What I did do and highly recommend is run each battery to a buss bar. This improves charging effectiveness and allows for simply battery isolation.
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Thanks Gil. This is exactly what I was looking for. Some “real world” experience with a similar coach and similar Amp Hour needs. Other than maybe a couple hours of TV/Satellite and a few quick bursts with the microwave my primary inverted power needs come from running the three cooling appliances (Refrigerator, Ice Maker and Wine Cooler). These three appliances are tough to estimate their total Amp Hour comsumption as they cycle at different times and durations and at different wattages. Add to this the relative uncertainty as to the efficiency of the old Freedom 25’s.
I am thinking an easy and free test for me would be to drop my current system to just four of my 4D flooded lead acid batteries (about 800Ah) and test the duration I get with “real world” scenario’s. If I get the performance I need then four 8D AGM’s would give me a little extra head room with 1000Ah.
Refrigerator draws about 550 watts and runs about 63% of the time or about 350 Wh.
Wine cooler draws about 200 watts and runs about 63% of the time or about 130 Wh
Ice maker draws less than 100 Wh
TV/Satillite about 200 watts for say four hours = 800 Wh consumed
Microwave 1200 watts for say 5 minutes or 100 Wh consumed
Then you have the 12v needs. I like Gil have converted just about all 12v lighting to LED.
Let’s say we can get things down to 200 Wh for the direct 12v draw outside the inverters (This is a wildcard)
800Ah to start with less approximately 90 Ah consumed by TV/Satellite and Microwave
710Ah remaining drawing down at approximately 76Ah per hour (780Wh = 65Ah / .85 efficiency = 76Ah)
710Ah/76Ah = approximately 9.3 hours of run time on a 800Ah battery bank.
Gil, I think the four 8D AGM’s just might be perfect as you have suggested. Is my math close or fuzzy in any way?
This would save me about 500lbs. as well.
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Chris,
I recall you having Link 2000 remotes. They can display actual current consumed. Why not do a 24hr or longer test with actual use? You can do this without using coach. You can simply add microwave, TV and other loads that would typically be used. Also, add some added load for refrigerator door opening and ice maker cycling that will be more often if the coach is actually in use.
I recall 8Ds being in the 160 pound range. If so, going from 8 to 4 batteries would save almost 650 pounds! That leaves a lot of capacity for your favorite beverages.
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For real world requirements don’t forget phantom loads which range from inverter inefficiency, to small loads such as all the various hidden devices such as clocks, alarms, tank level sensors, etc.
Then factor in the loss of battery capacity as the batteries age.
While I fully agree with striving to get rid of excess weight and battery cost, I also think it is equally silly to drag around a big diesel generator and then plan on ways to not use it. Keep in mind it is OK to crank up the generator even if you are just stopping for lunch and you want to crank up a couple of Cruise Airs, or you are stopping at Walmart for the night and you want to relax before bed with all the lights on, the TV, and any other energy hogging devices. We are driving luxury coaches. I want to live luxuriously. You can reduce weight considerably if you choose to make generator operation a part of the equation.
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