Topics

Coach battery hookup


Jerry Knowles
 

Would someone please send me a photo of how their coach batteries are hooked up with Costco 6v Interstates and with solar hooked to the batteries. 

Many thanks,
Jerry Knowles


old_b4_my_time
 

Do you need an actual photo or will this do?


--
Don - 2006 Navion J


old_b4_my_time
 

The solar charge controller wires are run directly to the battery or at least a positive wire is needed to be run to the battery from the positive output of the charge controller which should go through a proper fuse near the battery positive terminal (labeled To +12V) and the negative side of the charge controller can either be attached to the metal chassis frame or run to the battery negative terminal but with this cavaet.   Please note that if you have a battery monitor, it will be typically installed as a shunt in the line between the NEG terminal of the battery and the frame of the vehicle.   If you have a battery monitor and you attach your solar controller negative to the negative terminal of the battery instead of the frame ground of the vehicle (thus bypassing the shunt), your solar charging won't be factored into your SOC state of charge seen on the battery monitor and you really don't want to do this, so hook the negative output of the solar to frame ground.
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Don - 2006 Navion J


old_b4_my_time
 

Here's my box, it's a little messy.   You see I have several connections on the positive terminal including the 4/0 red wire (welding cable) that runs toward the rear to my cabinet where I have mounted the solar charge controller, the inverter and the 14.8VDC bulk charger (rapid generator charger) and this welding cable is fused with a 300A in line fuse right at the battery terminal and my solar controller has its positive wired through a 40A fuse (relative to your converter and solar power) in my "wiring closet" and that solar controller positive is attached to the positive bus bar on the other end of this red welding cable.  Also the tiny red wire goes through a small fuse and powers the shunt that is mounted on the upper left wall.   My negative terminal of the dual series 6V then goes to the shunt and the other side of the shunt (battery monitor shunt) is wired to ground.   My wiring closet gets its ground bus from another black 4/0 chassis ground that is attached to the metal frame work of the coach that is below the wiring closet floor.   So unless you wired your coach the same way as mine, you'd like run your higher AWG red cable directly to the battery and it might be a good idea to place fuses at both end since that wire shorting could both cause damage to the battery or the solar controller as well if there was every a short in your cable run.    Also some people buy expensive switches and while they look good on the wall, for me it would be easier to just pop up the battery drawer and pull the fuse to disconnect the solar controller.   But to each his or her own.


--
Don - 2006 Navion J


old_b4_my_time
 

Another caveat is that since I was once periodically trying to run the microwave off the inverter with this setup, I replaced all the regular cables with 4/0 welding cable to handle the 150A+ load that the inverter pulls from the batteries with the microwave on.    This however is not suggested with a lead acid setup.   By using the microwave (which would only run 5 minutes before the internal resistance of the batteries dropped the voltage below the inverter "low voltage" threshold, I have stopped using the inverter after my lead acids from Costco only lasted a year (wa showing much reduced capacity).   You may also notice that have switches to SAMS club (not my favorite company) and am trying their Duracels out which claim 230aH as opposed to the Costco's which claim 210aH.   True, it's a nit and not likely worth the $25 extra a battery I spend but this next year, we'll see how it goes.   

Now don't forget to check the water at least every couple of months if you leave the coach plugged in or in the sun.   Use safety glasses and distilled water to fill.   One of the new Covid face shields wouldn't be considered overkill either.

I've found these two adequate for daily living but I don't have a CPAP or compressor style refrigerator which I would call a show-stopper for these two keeping a couple happy day to day.   My largest loads are two laptops and the many fans in summer or the furnace heater in winter.   It's also good for a few TV hours per day (note I don't use the inverter for microwave any longer and the TVs and all computer equipment runs off 12V).   Running a leaky inverter (up to 20% power loss from some) would also top these over capacity on daily boondock living.

Lithium is an option but the new equipment to charge them is often as much as the battery.   Also some people fall for the "phycic power" of lithium and while buying them for their ability to charge faster, they often settle for what's called a DC2DC converter that charges at a rate of 30A from the alternator while they complained that 55A one normally sees when these are down to 60% capacity are able to pull.   Still that's not a totally fair comparison since these lead/acids will drop from 55A to 40 in 20 minutes and drop from there over the long charging cycle.

So the short story is in general, don't expect that lithium drop in replacements would be a total bed of roses unless you are willing to go with all the other equipment requires.   And I might also add here to remember that installing a couple of 12V lithium batteries here will require you go back to the same wiring that came stock on the coach, where the two batteries are wired in parallel.

Good luck with the rewiring job!
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Don - 2006 Navion J


Jerry Knowles
 

I don’t what happened to my email but it did not appear as being set. Here’s how I’m hooked up with my 2 Costco Interstate 6v. Negative cable from the left battery connects from negative post to positive post on right battery. Positive cable from right side of fuse connects to left side positive post. Another positive cable from below connects to that positive post. A positive cable from below connects to left side of fuse. 2 negative cables from below connect to negative post on the right battery.
This must be right but I want verification as I’ve gone through 3 sets of batteries in 3 years.
Jerry Knowles
2018J

On Aug 27, 2020, at 9:02 AM, old_b4_my_time <donphillipe@hotmail.com> wrote:


Dunc 18ND W.CO
 

The fuse in the battery compartment is for the inverter. If you are using up batteries at that rate, you should invest in a battery monitor to measure and account for the usage. If you are continually reaching 50% or lower SOC, then the batteries will die prematurely. 

Adjust your usage, else install more battery capacity, else change to a Lithium based battery that will allow full discharge without affecting its life.

On Thu, Aug 27, 2020, 5:24 PM Jerry Knowles <knowlesjv087@...> wrote:




I don’t what happened to my email but it did not appear as being set.  Here’s how I’m hooked up with my 2 Costco Interstate 6v. Negative cable from the left battery connects from negative post to positive post on right battery.  Positive cable from right side of fuse connects to left side positive post. Another positive cable from below connects to that positive post.  A positive cable from below connects to left side of fuse.  2 negative cables from below connect to negative post on the right battery. 
This must be right but I want verification as I’ve gone through 3 sets of batteries in 3 years.
Jerry Knowles
2018J
> On Aug 27, 2020, at 9:02 AM, old_b4_my_time <donphillipe@...> wrote:




--
Dunc, W.CO, 2018 N24D
800W Solar, 10kWh Tesla Coach
Gyrocopter Toad


Frank Hughes
 

Here is how my Victron Solar Charge Controller is connected to the 6volt Trojan batteries.
Frank 2017 24G


Jerry Knowles
 

All of this does not do me any good.  I was hoping for some late model 24s that used the 6v Costco Interstate batteries.


On Aug 27, 2020, at 4:42 PM, Frank Hughes via groups.io <hp_ciscovss@...> wrote:


Here is how my Victron Solar Charge Controller is connected to the 6volt Trojan batteries.
Frank 2017 24G

<batteryconnections copy.jpg>


old_b4_my_time
 

Agreed, I live by my battery monitor.  Also agreed that if running your pair near flat, then a year is about all they will last and if that long.  I have the BMV-702 battery monitor without blue tooth because I personally can jump up and read a wall gauge in about a half a minute and it takes me about 10 minutes or longer to locate my phone and fiddle with all the available apps to locate the right app and hope the phone syncs to the device (greatest example of being "over connected" I've come across).  

Other culprits can be seen in the "battery illness" arena, and I don't think you have this issue but if one attempts to frequently use a microwave of these lead/acid  batteries for 3 minutes or longer, it can really kill a set of GC2s quickly.    I found my Costco set last year was down in capacity a good 15% on at 12 months and down about 30% at 18 months after an abusive time of weekly 3 minute runs of the microwave off the battery bank.  So I replaced with the Duracels to see how they work out but with still the knowledge than I need to abandon running the microwave off the battery.

Do be aware about lithium if that might be what you are considering as a replacement next time.  Remember that while they are extremely advantageous, if you follow popular trends and listen to what a lot of lithium aficionados are now saying, more and more people are saying you also need to keep the lithium above a 50% SOC (state of charge) if you want to see all those seemingly unbelievable long life numbers in the ads.     So if you are going to join the "lithium life protection crowd", aka "the 50% club", realize it's quite possible to invest perhaps $2000 for two 100aH lithium and $3000 or more for all the equipment like dc2dc charger (alternator converter/protector), new solar controllers, and new shore power converters and end up $5000 poorer with the same power profile or one that's not too much better than what you may be giving up with the lead/acid.  

You might even be setting yourself up for for a slower alternator charge profile than what you have now with those two lead/acids if you don't shell out enough cash for the DC2DC charger.   For example even the Costco Lion series of lithium that is advertised as being completely "drop-in swap-able" has this statement in the fine print  (seen in the FAQ at https://lionenergy.com/products/lion-safari-ut-1300#faq regarding charging with the alternator:

Yes, the Safari UT will take too much current so you must limit it with the wire you use to charge it. For example, if you need 10-12 feet of wire, a 10-12 gauge wire will work to limit the current. Double check the actual current with a current meter and size the fuses appropriately. You may need to add fuses and other protective equipment to protect the system. To prevent possible damage to your alternator we recommend using the Redarc (Model #BCDC1225D), which is a DC-DC charger. It will safely charge your batteries while you are driving. .

So they are effectively saying you must minimally run a thinner wire from the alternator that heats like an electric heater element to get the amperage from the alternator down to an acceptable level.   Pretty crazy to see this in print actually, considering the anal nature of most high-dollar RV upgraders and thinking how they might react to that.    Or go the route they suggest as a better idea and you'll find the Redarc BCDC1225D will cost you $381.06 on Amazon and give you only 25a of charge current from your alternator.   If you really want to see the results of what lithium mfgs advertise as where lithium shines with fast charging times, you'll instead want something like a Redarc BCDC1250D at $541.08.   Or why not go even higher?  Still a 50A charging source at a half a grand is kind of laughable considering the capacity of the Sprinter alternator at least on the T1N stock unit is around 150a with a 200a upgrade available.   And with that $541 Redarc you still getting 5A less than the 55A which can be seen with your battery monitor with your current setup anytime you are charging with those lead/acids depleted 40% or more.    

So take the very strong lithium hype found "out and about" with a grain of salt. Just realize you have to pay to play and if you are going to get anywhere you are going to have to invest in all the "baggage" in terms of new devices that go along with the install.   Also realize that buying a couple of Costco 2 for 1 Lion lithiums may not be the answer you are looking for if you are thinking plug 'n play or drop-in and go.  Of course I can't argue lithium is a great alternative to lead/acid (if you can get past the idea they're nothing but a box of sometimes the same batteries that usually go bad in your drill every couple of years) but for some reason these must be better quality than most I've dealt with.    

Otherwise you are just over the threshold of what your lead/acids are capable of it sounds like and agreeing there with @Dunc, adding a battery monitor is going to give you new insight as to what the issues are.    One thing to start with is if you can get off the inverter, do so.   You'll be surprised how many appliances come with a 12V power cord.  Also try never to use the inverter to do something like charge a flashlight, camera battery, phone or tablet.   Always use a 12V to 5V converter or adapter designed for the voltage the device requires.
--
Don - 2006 Navion J


old_b4_my_time
 

@
@Jerry Knowles.  Just saw the comment stating that none of this does you any good.   i would re-read comment from @dunc who states they are hooked up correctly and essentially you must be abusing them in some manner if they are lasting only a year.   Basically you can't have them hooked up wrong and they work at all.  If not lasting long enough, that usually means mishandling.   If you want ones that last longer then begin a program of TLC & watching battery monitor to keep above 50% charge or install two additional in a repurposed storage area or install LiFePo4 technology and expect to pay a good price for the equipment upgrades needed. 

--
Don - 2006 Navion J


Dan Booher
 

Hmmm, I've got two  80 amp hr lithium batteries, with no special charging equipment.  They are  almost 4 years old. I have a $50 hardwired current monitor,   230 w solar. Stock Zamp controller.  I monitor and never dip below 60% capacity. I've been told I can go down to 20%. I have thought about changing the converter to a lithium specific version, but have yet to do so.  ( I hardly ever plug in).  I do almost all boondocking and have never had any issues. 
2016 NJ.

On Thu, Aug 27, 2020, 8:42 PM old_b4_my_time <donphillipe@...> wrote:
@
@Jerry Knowles.  Just saw the comment stating that none of this does you any good.   i would re-read comment from @dunc who states they are hooked up correctly and essentially you must be abusing them in some manner if they are lasting only a year.   Basically you can't have them hooked up wrong and they work at all.  If not lasting long enough, that usually means mishandling.   If you want ones that last longer then begin a program of TLC & watching battery monitor to keep above 50% charge or install two additional in a repurposed storage area or install LiFePo4 technology and expect to pay a good price for the equipment upgrades needed. 

--
Don - 2006 Navion J


old_b4_my_time
 

I've heard that from a couple of other people as well.   I imagine it's all about how much the batteries can demand at their lowest SOC, what's "inside" the BMS and how Mercedes handles a heavy alternator load if and when it gets presented with a significant one nearing the alternator's capacity.   Now I've consulted with some pretty savvy experts over on sprinter-source.com including Midwest Drifter and no one seems to have any clear data on how the Mercedes alternator reacts when it might get slapped in the face with a heavy load (at near its maximum capacity) and assuming a severely depleted lithium bank is thrown across the alternator output to cause that.   Most people I talk to regarding their work on system analysis just walk in somewhere or sign up to the cool-aid group and go buy everything from the most expensive equipment list and settle into that being the norm as the cost of operation.   The died in the wool lithium crowd would likely scoff at what you have @Dan Booher and as to who is right (since you've never discharged them significantly enough to see any smoke rising), therefore I can't know.  I'm guessing that you'd have to run them down a lot more to really test what the alternator is going to do.   Still if you figure a 150a alternator, and with perhaps only the headlights as a load there's a lot of amps available "left over" from that Mercedes alternator and maybe even so many that a 160aH lithium supply greatly depleted would not over tax it.  

There is one fellow I've read an article from who has an interesting way to charge his slightly larger capacity bank (read from sprinter-source) - he uses what I call the "dinky charge option" (one of the 25a DC2DC chargers) while watching an amp meter and when the initial heavy load of the charging cycle passes after about 20 minutes, he says he has a heavy duty switch he throws where the lithium bank is then hooked directly to the alternator.     And if you look on some of the charts I've seen the LiFePo4 cells claim a level of 99% full at 3.5V per cell assuming 4 cells.   Now you divide 14.0 by 4 and what do you get?   So assuming your alternator charges at 14.2V, then you should theoretically be able to get your cells up to 99% charge without any kind of DC2DC converter which touts also raising the voltage to 14.6 or 14.4 or whatever the latest expert is suggesting.   But going the direct alternator connect route (even if at the end of the charging cycle) means you need an alternator that outputs what used to be the US standard of 14.2V.  And it/s weird how standards have turned into open interpretations these days as all my adult life we lived by a required 14.2V seen across a lead acid auto batt as gospel but with European cars I'm never quite sure what it is supposed to be standard now.   I know monitoring my T1N it was 13.8V for years, then it started fluctuating all over the lower value of 13V and finally failed and that was with no abuse or attempt to charge lithium.   Now I tied this failure to when the PO had the battery short out he had reported upon my purchase and I imagine this affected the alternator somewhat.   Anyway I had the alternator repaired and today it's reading 14.2V rock-steady and I know I purchased an after-market Chinese regulator in it as an experiment and it's working as well as any one I've ever seen (I monitor my alternator output with a dash readout).   So short story is however, a direct charging line should keep a bank at least at 99% which one could assuredly "top off" with the solar system if there was any slighting by the alternator charge which would leave only that initial surge to deal with and by being a standing member of that group of "having my cake and eating it too" I'd almost elect to do what the guy in sprinter-source did but approaching it from the perspective of being even more of a miser and leaving out the "dinky 25a charger" all together.   I am sort of thinking about a large wire wound coil out of that 12 gauge wire that Lion lithium FAQ was talking about but instead of stretching it where it might catch something on fire, I'd wind it on a spool like they do the old style golf-cart accelerators, then I'd install a switch like mister sprinter-source and throw it to bridge that resistor after the initial current onslaught to form a direct connect (perhaps after I see the resistor stop glowing - might even toss a nice smoked sausage in the center during the charging process LOL).   To me that would be a lot easier on my miser-dom than throwing down $600 to get a measly 50A out of the alternator through a DC2DC converter, especially when the alternator (depending on model) can output 150-200a).

So my guess is the reason you are still comfortably afloat is first you don't have a massively large bank and you have managed to remain just below the "smoke factor" with your light battery discharges or even your BMS is a little more robust than one's I've seen that can just only switch on and off at various voltages.    So you are lucky from that perspective.

(Side question - Not criticizing or anything but to settle my own curiosity, with the total of 160aH from the two 80aH lithiums, what was the motivation for switching from an option of say a 230aH dual 6V GC2 lead/acid setup over to a lithium bank which I imagine was a little pricey 4 years ago .... was it clean-ness of operation, zero maintenance, lighter weight or all of the above?)
--
Don - 2006 Navion J


Christophe P.
 

Dan,

I have 300ah lithium so about twice as much as you and do the same: Don't use a dc-dc charger nor inverter or whatever. I do override it with a rocker switch though so the alternator doesn't always charge it. I mainly use solar with a 400w system.

Here's the alternator charging chart, you know your sprinter won't get more than 110-130amps at idle. So for a 220amp rated alternator, that's 0.5C which should be safe for your alternator and give lots of amps to your batteries.

Also, just like what Tesla does for their batteries, lithiums shouldn't be charged more than 80% on a regular basis if you want full long life out of them. Once a month or so I do a full charge to balance the cells.
Inline image



Dunc 18ND W.CO
 

Where did you find that 80% charge value?
--
Dunc, W.CO, 2018 N24D
800W Solar, 10kWh Tesla Coach
Gyrocopter Toad


Christophe P.
 

I remember seeing it somewhere but a quick search:
https://evannex.com/pages/tesla-model-3-tips-and-tricks
says 80-90%.
Another one:
https://mashable.com/article/tesla-battery-charge-max/

I guess it's more 90%? My bad. But some other folks on sprinter-source mentioned 80% is a safer value.