I replaced the start batteries on my coach today. Removing them was more difficult than I expected. I did have to remove the stock muffler to get enough clearance to get the Group 31 Duracells out of the rack. I could have removed from the rear, but a bundle of pipe and wiring passed over the top of all three batteries. This prohibited lifting up enough to clear lip of angle iron that the bracket was built from. After removal of the muffler I was able to lift and slide the center battery out then each of the front and rear batteries I could slide to center space and remove them one at a time. New batteries went back in uneventfully. I ordered a resonator and some fittings to replace the stock muffler. I was able to install the resonator and a large El pointing down near the tail pipe. All bracketed snugly and will take it to a muffler shop to fabricate a connection to the stock tail pipe.
I used the boost switch to top off the charge on the new batteries and closely monitored the voltage drop after turning the boost switch off. The resting voltage of start batteries with just the 4 am trickle charge from the Victron Multiplus I installed earlier is now at 12.77-78 and appears to be holding. I expected a bit more, but the old batteries would not hold a charge at all. I think I will be putting a B to B charger in the engine compartment from under the bed , replacing the old stock battery isolator.
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My question is: Does 12.76 or so volts sound about right for resting voltage on my start batteries? I imagine there are some current draws on them even though I have shutdown what I could find.
Should be a much cooler environment for your start batteries with the big muffler can gone...allowing more room for air to circulate in that area. :thumbsup:
Sounds like your new batteries are fine. Quote below from the Optima battery web site:
"Fully-charged, most 12-volt lead-acid batteries (including AGM products like OPTIMA batteries), should measure at least 12.6 volts. We indicate our REDTOP batteries are fully-charged at about 12.6-12.8 volts..."
For the longest life, 13.2 volts is recommended for the float/maintenance voltage. Our Progressive Dynamics converte/charger keeps it within three or four hundreths of the 13.2 they advertise. I tie both banks together with the cord I've previously posted photos of. Our house AGMs are still working like new since we installed them in '08. 31 series maint free engine batteries are about 3 or 4 years old now.
Pierce
The Victron keeps the house batteries floating at 13.22 or so. I think when I leave the coach for a week or so, I will turn the boost on and keep the new start batteries the same. I know that running them down below about 12.1 is not good. Below that irreversible damage occurs.
Yes. That number varies slightly depending on the exact lead alloy used, but what you have there is a fully charged lead acid battery.
After I killed yet another battery by allowing it to be drained of all its electrons, I purchased and installed a Progressive Dynamics PD-9260 dedicated to the engine start battery aka the chassis battery. I figure that if the engine driven charging system ever goes south on the road all I need do is fire up the generator and drive on the electricity from the PD-9260.
If you have the boost switch on for a week and you lose 120 then all of the house and chassis batteries will be dead. You should put some type of battery maintainer on the chassis battery.
While 12.7V represents a fully charged battery, 13.2V is the recommended float voltage when the coach is at home or in storage. Conventional solenoids will use 1 to 2 amps to stay in the boost position. This is why it's a poor idea to keep the boost solenoid on all the time to keep both battery banks charged. If you lose power, the constant loss of the solenoid will flatten both banks and may ruin them.
If the batteries are disconnected, they will go through the entire winter and retain their voltage. But the terminals have to be pulled.
Pierce
Herb, float means a charger is on in float mode, your readings are "still" readings with no charger. You will be fine with your still readings.
At the coldest of this cold snap coming in a few days, I will be monitoring from about 1.5 hours away. If the power goes out, I get a text from the Co-op with a time frame for restoration of power. I have wifi here at the coach and can monitor my Victron and the Victron buss installed in the coach. If I can be sure that the 4 Amp trickle charge is working properly, I should be ok to leave it without the boost on. I will be able to see the house and start (Chassis) batteries remotely. Of course if I leave the boost switch on, I can still monitor remotely, but the two voltages will be nearly the same within a couple of hundredths. My internet works off of my house batteries, so I will not lose it with a power outage. Yea Elon! I do have another charger to put on the start batteries. It is a small Battery Tender. Would there be an issue with adding this directly to the start batteries from the Isolator under the bed? It would be in parallel with the 4 Amp trickle from the Victron Multiplus although not at the same physical location, but nearly the same electrically. I am just not sure the trickle is working as this morning the Start batteries are reading 12.65 and have been steady for the last couple of hours. We will see how they make the morning. That will determine whether I connect the Battery Tender or not. I would like to leave the boost off if I can.
The resting battery voltage goes down with the temperature.
While you can't charge a LI-ion battery fast at temps below 32, storage should be no problem. Conventional and AGM batteries can't be frozen and won't be damaged at 12.65V no matter how cold it gets at your house. Remember the DieHard battery frozen all winter in a block of ice? Chipped the ice away and it had full juice.
If you leave the batteries connected in winter (or anytime) in storage, coach parasitic loads will flatten the batteries so the cables must be disconnected.
Pierce
The last two winters we were in Riverton, WY, and the coach just sat in the storage lot all winter. I disconnected all batteries when I parked it. When I got ready to use the coach I connected the batteries and away we went.
Best money I've spent is for battery disconnects on house and chassi batteries. Disconnect them when storing and you don't have to worry about them.
Tommy
Do you have pics of your battery disconnects?
Thinking that would be a good thing to do
Not sure who suggested these on the forum but they have worked great for me
Amazon.com : Blue Sea Systems 3000 HD-Series Heavy Duty On-Off Battery... (https://smile.amazon.com/gp/product/B000MMDLB6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
Used this for house batteries
Amazon.com: Blue Sea Systems 9003E e-Series Battery Switch, On/Off, Red :... (https://smile.amazon.com/gp/product/B000MMC914/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
Used this for chassi/start batteries
Well, it seems I have my start batteries being charged along with my house batteries. Why? I do not know. To find out I will have to see just what is going on with my system. I have a direct line from the trickle charge outlet that when connected, my start batteries show about 12.66 volts. When I disconnect this wire from the trickle charge output, the start batteries jump up to 13.2 or so. As I have watched it for last 12 hours, the house batteries lead the start batteries by one tenth of a volt. After daylight today, I will take my meter directly to the house batteries and make sure they are reading the float voltage I am seeing from the Victron displays. I still have the original battery Isolator in the system, I wonder if it is connecting the start batteries to the house batteries.
I am pretty sure the displays are reading correctly because when I first disconnected the direct wire from the trickle output, I watched the start battery slowly increase over a couple of hours to finally reach within a tenth of the house battery voltage.
OK, the Victron Displays do not read the start battery unless the trickle charge wire is connected to the start battery. Somehow without the trickle charge connection, the displays are reading the house batteries from another point in the system. My start batteries were 12.69 volts at the Isolator which is a direct connection down to the start batteries. I connected the wire from the trickle charge output to the start batteries. Last night I ran a direct wire to the batteries, previously I had picked a point under the white panel for the start battery connection. So now I am sure the connection from the Victron Multiplus trickle charger is direct. I do not seem to be getting a trickle charge though as the voltage is dropping very slowly. However I have a Battery Tender that only has a 1.25 Amp output and with it connected directly to start battery, the voltage starts upward again. At least now I can be sure that my start batteries are keeping a charge through this cold snap. Yes I could disconnect the batteries and let them stay at charge. However I want to keep heat on as the aqua hot keeps the bays warm. I leave both thermostats at 40d F and I the wet bay thermostat the same approximately. I also leave the bathroom manual thermostat at its lowest point on. It is just what I do. Raining here now and warming up a bit. But we expect low teens before Christmas and two or three nights in a row below 20. Water disconnected and off at meter. This is a second home for us so we really never put it in storage. Just the way we have operated since 2005.
OK here is the I hope final data on the trickle charge from the Victron Charger Inverter. Over the cold spell we just experienced, I watched the start battery level online through the Victron App. and Starlink. It slowly dropped from about 12.9 to around 12.51 or so after a week to 10 days. I was prepared to run back ahead of time if necessary to recharge the start batteries. Upon assessing my installation I decided to run a new 12 ga stranded wire direct to the start batteries. I had previously pick up terminal under the white panel. I finally ended up with about 30' of 12 ga wire to connect the start batteries directly to the Victron trickle terminal. Still no joy as when hooked up to fully charged batteries, I had over a 3 volt drop at the trickle terminal, I then disconnected the trickle charger and the voltage jumped up to 13.1 or so. So I calculated the minimum gauge wire for a 60 foot run. 30 out and 30 back. and it said use 10 gauge wire. So down to Lowe's and back with small spool of 10 gauge stranded copper. I think the 12 gauge I had was copper clad aluminum. Bingo. Used a more difficult but shorter run distance from the trickle charger to the start battery positive terminal. For over 24 hours now we are holding the start batteries on trickle at float about .70 volts less than the House Batteries. During this time we had a 4.5 hour power outage. The start batteries maintained without a charger working around 12.75 volts. This morning we are back up to float as you can see by the picture.
The picture above shows the shunt measurements. The House Battery voltage is directly at the batteries. The start battery voltage is showing the voltage drop to the batteries of the 10 ga run which is probably 20 foot one way now.
My isolater had a heavy part time draw and did not like one side being charged to 13.6 volt.
Disconnect it and everything works swell .
Herb, might I make a suggestion re the "choke" point on your battery tray. Why not weld or bolt a piece of angle iron under the "choke" angle lip, then cut out the "choke"angle leg part of the existing angle and instead drill and bolt a retainer angle to the uprights?
Now, before you put the new exhaust would make things easier to work on.
Good Idea, However once I removed the stock muffler and installed the resonator, there is plenty of room to remove the batteries. Though a removable retaining lip would make sliding them out and in easier......next time maybe. We go to a Muffler Shop today to have the tail pipe connected to the resonator.
After two days of seeing expected and correct voltage from the trickle charger for the chassis (starter) batteries, I am now seeing a load that is dropping the float voltage down to 12.69 volts at the batteries. The voltage read 12.67 at the trickle charger terminal. If I disconnect the cable to the batteries, the potential at the trickle charger terminal is 13.20 volts, which is the same as at the main output terminal to house batteries.
Something is drawing the trickle charger down. Could it be the original and old isolator? What else could be loading the trickle charger down?
We are on power and have been since we returned from the muffler shop yesterday afternoon. The voltage at the start batteries slowly has dropped overnight to now being stable at 12.69.
Since you are on shore power (inverter/charger charging the house batteries), use the boost switch to jump voltage back up to 13+ VDC on the chassis batteries.
Yes, the batteries could be bad, OR it could just be that the draw exceeds the amp output of your chassis battery charger.
Chassis (start) batteries could be bad, however they are new I just replaced them. I was having similar voltage indications and I assumed that since my start batteries were old and tired they might have been the problem. The new batteries did not change the symptoms I still see. Yes, I can turn the boost on and watch the start battery voltage climb up to the value of the house batteries in a very short time. I agree that it is a distinct possibility that something intermittent is exceeding the amp output of the trickle charger terminal of the Victron Multiplus 3000. Thanks