Charging at home question

[joey2cool]

This is for ridintall:

After a trip I turn off my frig and empty it out. Have to leave the door open over night at least so that the freezer defrosts. Then it gets a wipe down (sanitized and dried) and the doors are closed. I don't have solar and I only hook up shore power when the two house AGMs need to be topped off (about once every two weeks in the summer and sometimes once a week in the winter). My house batteries are completely isolated from all electrical loads through use of a breaker switch.

Just before a trip that I plan to use the frig for I don't need to cool it down. It's usually at 54 degrees just sitting in the carport (pacific northwest). Even so, the last thing I load up is food and beverages from the house frig with a couple freezer blue ice packs (one on top in the freezer and one in the bottom). Then I turn on the dc power and frig just before starting up the van to leave.

While camping with the frig on (at about 3.5), the batteries are good for 24 hours, then they need to be topped off each morning by idling the van for about an hour. I manage use of the frig carefully; don't open the door a lot, don't leave the door open long, and may turn temp down to 3.0 at night depending on how empty the frig is and what's in it (beer keeps real well). Oh, and I monitor the temp with a $10 AcuRite remote display thermometer once or twice a day to see how I'm doing. We normally run from a low of 31 to a high of 44 degrees F over a 24 hour time span. Averages 37. We keep the home frig at 37 degrees normally. Never had a case of food poisoning, although we don't keep a lot of meat, mayo, or real eggs in there long. The health department says keep it at 40 degrees F, and if it's been above that longer than two hours it may not be safe.

P.S. If you've only changed your batteries twice since buyng the van in 2004, I'd say you're doing close to the expected battery lifespan of three years.

[rob_gendreau]

What converter/charger system do you have? I have an intellipower, and they have an add-on smart charger module that does a much more efficient charge of the house batteries than the alternator. You can also select different modes, like a boost mode if you only have limited time to charge. It desulfates as well. I hook to shore power at home and just let it sit.

For the house battery I use a Schumacher trickle charger.

I'd highly recommend you get a smart charger or use one if it's already built in; it will prolong the life of your batteries as well as make sure you get the most juice out of them.

Rob

[ridintall]

Thanks for the responses.

I'm going to check the water level in the starting batteries the next chance I get. It's kind of a pain b/c they're both on the frame rail, but shouldn't be too bad since they're suspended by cables when unbolted. Although now that I think about it, I can't remember if they were the sealed maintenance free kind.

I like the idea of plugging in but turning off the charger, I'll give that a shot since I have solar as well. As far as my charger, I have the 1500W Tripplite inverter/charger. Oh, and about the charger, i was having problems charging last year, the charger would cut off/on continuously when attached to shore power. Thought I needed a new one, but traced it down to a short on the shore power receptacle on the side of the van. Only noticed it b/c the plug was a little burned up on one of the terminals. Replaced it and all was good. Much cheaper than a new inverter!!!

[Scalf77]

I have owned my Sportsmobile t 8 years now. When it is parked in the driveway it is plugged in. I am on my 2nd House battery; the first went bad early on because a battery cable had warn through to bare metal. I am also on my second Van battery; the first one went bad around the 5 1/2 year mark.
I also leave my Refrig on 24/7. Since the van is in my driveway I have to walk by it every day, I have the Tripplite inverter/charger that Sportsmobile was using back in 2004, The Tripplite is a three stage charger that also has temperature feedback, it does have some low and high charge settings but is limited in to actual voltage based on two dip switches your choices are gel and wet cell.
Note: the temperature sensor is taped to the side of the battery and not attached to a battery terminal.
“
• Stage 1 is called Bulk Charge. When a battery is 50% to 90% charged it will take a charge very quickly. A smart charger senses the battery voltage and supplies maximum current at an increasing voltage level to attain a nearly full charge.
• Stage 2 is called Absorption (or Acceptance). At this stage voltage is held at a preset maximum level (typically 14.5 volts) while current slowly tapers off until the battery is 100% charged. High-end chargers may also include a temperature sensor that measures battery temperature. Optimum charge voltage varies based on temperature from as low as 13.8 volts to around 15.5 volts.
• Stage 3 is called Float. After a battery is fully charged it requires a lower voltage to maintain its charge while waiting to be used. This is typically 13.5 volts for regular lead/acid flooded cell batteries, and 13.2 volts for AGM batteries. As with stage 2, the optimum voltage varies with temperature.
• Another 4th stage that some chargers are capable of is known as Equalizing. This involves taking the batteries up to a higher voltage level, about 15.5 volts (or 1 volt higher than Stage 2 if you're using temperature control), for about 2 hours. This ensures all battery cells are equally charged. A more complete discussion of equalizing is included in some of the links at the bottom of the page. Note that AGM batteries should NOT be equalized in normal use. “
Copied from http://www.macandchris.com/BatteryChargers.htm
The TrippLite does have the availability of doing the equalizing stage (manually)
One of the questions on charging a RV system revolves around having a load (refrigerator) and what effect that has on the charger. There are some trains of thought that suggest if you have a load that you should use a two stage charger; some units “Samlex” actually have a switch that will disable the 2’nd stage

The assumption is that a constant or transient load will trick the charger out of the 3rd stage (Float) and back to the 2nd stage(Absorption), thus causing the battery to be overcharged.

See http://www.donrowe.com/battery_charg..._document.html &
http://www.bdchargers.com/2or3stage.php

There does not appear to be any question, that if you do not have a load that the 3 stage charger is better.

So does this mean the TrippLite has a problem, or any other three stage chargers for that mater? I have my van instrumented up and can monitor the voltage and current from the comfort of my house. I have not seen any data that makes me think that this is happening while running my refrigerator. So I am fairly confident that I am not having this issue, while plugged in. You will need to make that decision on your own, and unfortunately my sample of one does not make the case. I believe there are other forum members that have either had this happen or have a concern that it could happen. Most of the data that says the 3 stage with load is a problem is seen with products that have two stage options. I will say that if I need to purchase another inverter/charger I would look more into this and their charging algorithms, but I am not ready to go buy a different model because of it.

-greg

[vlamgat]

Greg - I would say that your performance is "nominal" over 8 years. The AGM house batteries are not generally lasting much over 4 and at best 6 years. And getting 5 years from your Van battery(s) is also normal. In higher or lower ambient conditions people are seeing much less with 3 being the most for the House and 4 for the Van. I have a similar set up to you and used to do the same as you leaving the the van connected. I found that the Tripp Lite was still overcharging the House battery so that my life never exceeded 3 and was often no more than 2+ years with relatively infrequent monthly use. By switching to s smart charger wired directly to each of the House and two Van batteries using extension pig tails I am about to pass year 3 for the first time since 2006 with seemingly full use of my House battery. I also use the Tripp Lite in parallel with my Honda 2000 to run my Danhard A/C which does load the House battery considerably. Especially torturing it if the Honda runs out of gas when the A/C cycles on. So my short life has something to do with those events and the 100+ heat that we see in Texas during the time I most heavily use the van. I am sure that were I in a 70 degree environment I would see what you are exhibiting.

[NRL]

I have a Tripplite Powerinverter. Very happy with it's performance and small size factor.
However, thru the years most of my house batteries didn't last past 2 years (8D AGM Battery), and in the end I found out the the alternator charge line was probably the reason why they got overcharged.

I put a high amperage switch on the alternator charge line that charges the battery when the engine is running. It's convenient when you need it but ever since I put in that switch (keeping it off most of the time since I've got the solar to assist), I'm going on 3 years now and the performance of the two new heavy duty 6 volt AGM's is impressive (larger positive plates)

[vlamgat]

What is a high amperage switch on the alternator charge line? Surely the alternator regulator governs the charge at the level the battery and the van needs? Or am I being naive? In which case there seems to be a market opening for a "smart" vehicle regulator just as these have become the de facto market for wall mounted chargers.

[NRL]

Originally Posted by vlamgat

What is a high amperage switch on the alternator charge line? Surely the alternator regulator governs the charge at the level the battery and the van needs? Or am I being naive? In which case there seems to be a market opening for a "smart" vehicle regulator just as these have become the de facto market for wall mounted chargers.

yes, it's regulated but in my case it shares it with the starting battery via an SMB installed converter so I'm not sure if it was getting overcharged when the starting battery was way low.. There is another spot where you can get another regulated voltage from the fuse box(in the engine compartment) which is where it should be..

I think I used a 120amp or 200amp relay type switch but haven't needed to switch it "on" lately..
Cases when I switch it "on" is when the house battery is "low" and I need some extra help "microwaving" lunch so thats when I'll switch it "on", turn on the engine, to assist with the extra amps needed..to nuke the food.

Back on subject, I did eliminate another type of 12V drained from the back side, after the Tripplite thinks the house battery is fully charged, I had 12Volt devices that stole power from the house battery if the van sat for weeks on house charge.. To fix the ghost draw, I added a separate 12V Power supply with a relay that would click over the 12V circuit when it was docked to shore power.. and click relay back to the house battery when it wasn't connected to shore power.

[daveb]

I do like this idea. If you keep the alternator charge isolated from the house battery system but allow an inverter that has smart charging capabilities to power the inverter/charger, what you get down the road is a smart charge that helps prolong battery life because the only charge is from the smart charger/inverter. Solar backs up the day by day charge. It’s also possible to use an ACR or other high amp switch to connect the alternator if needed from time to time.

An inverter pulling 2000 watts off the starting system might be a problem if needed for long periods though. Fortunately most owners don’t need that kind of heavy load operation and usually run the engine anyway, so a heavy duty alternator should work.

When I did my build back in 05, I looked for something that converted the alternator charge to a smart charge. I think there is something out there by now similar to These. If I could find something like that it would be the ticket. I’d want it to pass the load my high amp alternator puts out.

[Scalf77]

Originally Posted by NRL

I put a high amperage switch on the alternator charge line that charges the battery when the engine is running. It's convenient when you need it but ever since I put in that switch (keeping it off most of the time since I've got the solar to assist), I'm going on 3 years now and the performance of the two new heavy duty 6 volt AGM's is impressive (larger positive plates)

I guess this would be a general question to people with Solar, when you are running and charging off of the alternator, do you still have solar charging battery also?