Battery disconnect...or not?

[Larry-NC]

Originally Posted by vlamgat

So answering my question: ok to disconnect from the bus and leave all the other negative cables connected? I have tried to determine whether the cable leading off the bus is the one that goes to the power distribution board but my multimeter does not have a long enough cable and I need to go buy about 30 feet of 10- or 12-gauge wire to create an extension that will reach to the board.

Isn't this fun and all because I assumed a truck driver used his mirrors.

If you're just extending the multimeter cables to measure voltage, you don't have to use heavy cable for the extension. When set for voltage, the meter has very high resistance (so as not to affect the voltage being measured). The high resistance means very little current will flow. You can use AWG 24 or 26, just like the multimeter cables.

If your bus has connections for the batteries and one or more connections for load, just remove the load connection(s).

[vlamgat]

Originally Posted by Aussieguy

hate to complicate things but what about the chassis battery it needs to be maintained/stored too?
it preferably use a maintenance charger .


.

More easily resolved because on this coach both chassis batteries are easily accessed and their -ve cables detached. Again, no shore power.

[Aussieguy]

Originally Posted by vlamgat

More easily resolved because on this coach both chassis batteries are easily accessed and their -ve cables detached. Again, no shore power.

but it still needs to have a maintenance charge if the repairs are going to take a real long time (months)


take it home too and put it on a trickle?

[vlamgat]

Originally Posted by Aussieguy

but it still needs to have a maintenance charge if the repairs are going to take a real long time (months)


take it home too and put it on a trickle?

Not an option either - the shop may have to move the coach at any time and the def tank has to retain its heating capability. Frequent movements will destroy the motor as in cold starts 3 or 4 times a week without getting to operating temperature. But that's the price we pay for buying complex equipment for which the supply chain is broken. So resigned at best to replacing the chassis batteries and at worst...injectors, fuel pump, def pump/sensors.

Moral of the story with Class A and C's is if you need a body shop, sell it as is or take your chances. I am going to make a 900 mile trip to hopefully pick up some parts next week because neither Fedex nor UPS can do this before Xmas except as an Express shipment costing +$3k for shipping alone. About 2X the cost of the parts.

[Normutah]

Just to jump in on storing SOC for Lithium.

Battleborn specifically states that theirs should be stored at 100%.

[Cold Lake Kid]

I have Class C motor home and in Ontario Canada, we have about 5 to 6 months winter.
I remove my batteries, store them in the basement, on wooden boards, and give them a charge about once a month.
YMMD

[vlamgat]

Update:
The coach has been sitting in the repair yard for 3 weeks. All manual switches are OFF and the positive cable is disconnected from the inverter per the Magnum I/C OM. SoC has declined from 98% to 95% although the house batteries remain connected.

Voltage on the chassis batteries has declined to 12.2/3v so they will need to be recharged. I am working on a way to do that without a cold start and extensive fast idle. I have a Honda 2000 generator with a 12v charge adaptor, but I don't think the amperage is high enough. Although inefficient, I may use a 5-amp battery charger for a few hours.

Message is that you can leave an Explorer I-5 for lengthy periods without having to worry about the LiPo (and probably AGM) batteries depleting to the point they will damage themselves if you can disconnect the I/C. In my case this is much easier than disconnecting the batteries from an accessibility perspective. And I am not sure that doing so would isolate the I/C either.

Chassis is another story. Maybe small solar panels in the windscreen can offset the parasitic draw but still allow the vehicle to be moved and not risk the famous enthusiasm of wrench turners when they tighten battery terminals.

[MGD1961]

I have built a career on lithium and solar systems in the Yacht industry and would like to say just turn your solar panels on, turn off any battery switches you have and let the BMS and Solar controllers do the rest.

Modern solar panels will produce at least a maintenance charge even in the shade or on the cloudiest of days. I don’t know what aH capacity you have but I would bet the panels would have to be totally covered for weeks for the BMS to kick out. I think you are over thinking this in my opinion.

With our travel trailer in Maine with 300 watts of solar, under a winter cover, batteries self maintain at 12.7 all winter as long as I keep the snow off the cover.

We do not have lithium batteries but Mastervolt AGMs due to the below freezing issues and have never had a need for them. That said, if you I/c and controllers are set up right you just shouldn’t have a discharge issue the panels wouldn’t keep up with.

[Aussieguy]

I/C won't act as a battery idolator unless there is a busbar that feeds the I/C and all other loads ... then you can disconnect the battery - busbar - I/C


You have to be positive ,that all the positive cables are positively disconnected


it is so much easier to disconnect the main negative at the battery
usually a lot less wires are connected the battery on the negative than on the positive.


nothing to stop you from disconnecting the positive side of the battery too.

[MGD1961]

My point is let the solar panels do their job. Don’t disconnect anything! If your batteries aren’t being charged your system is not configured correctly

[vlamgat]

Many thanks for the suggestions above. Unfortunately, the conditions of storage and the architecture of this install, largely render them unusable as I explained in earlier posts.

[vlamgat]

Originally Posted by MGD1961

Modern solar panels will produce at least a maintenance charge even in the shade or on the cloudiest of days. I don’t know what aH capacity you have but I would bet the panels would have to be totally covered for weeks for the BMS to kick out. I think you are over thinking this in my opinion.

With our travel trailer in Maine with 300 watts of solar, under a winter cover, batteries self maintain at 12.7 all winter as long as I keep the snow off the cover.

We do not have lithium batteries but Mastervolt AGMs due to the below freezing issues and have never had a need for them. That said, if you I/c and controllers are set up right you just shouldn’t have a discharge issue the panels wouldn’t keep up with.

Your point is taken however, as covered in this string, the residual draws of current by these rigs when the batteries are OFF is enough to deplete them in a week irrespective of 800 watts of solar panels. Shade, poor sun angles, short days, and the adjacent vehicles all add up to significantly less effective wattage for less time while the residual drag is 24/7. And the solar controllers contribute to that drag having their consumption which is net<0 at night.

However, it seems that the OM noticed I/C instruction to pull the +ve off the I/C for long term storage seems to have reduced the drag considerably to the point that I can reasonably expect 2 to 3 months storage without a need to charge the batteries. And to repeat, I cannot remove the batteries until the coach gets into workshop for the repairs for which its being stored.

[Reverse_snowbird]

Originally Posted by vlamgat

Update:
The coach has been sitting in the repair yard for 3 weeks.

Voltage on the chassis batteries has declined to 12.2/3v so they will need to be recharged. I am working on a way to do that without a cold start and extensive fast idle. I have a Honda 2000 generator with a 12v charge adaptor, but I don't think the amperage is high enough. Although inefficient, I may use a 5-amp battery charger for a few hours.

Chassis is another story. Maybe small solar panels in the windscreen can offset the parasitic draw but still allow the vehicle to be moved and not risk the famous enthusiasm of wrench turners when they tighten battery terminals.

Yup. Chassis batteries are a separate issue.

Our rig is on a 2014 RAM Promaster chassis. In the owners manual, they tell you to disconnect the negative cable if you store it for over 2 weeks. As long as the battery is connected, the computer will continue to monitor and control certain things on the rig and slowly draw down the battery.
For safety reasons, it monitors the parking brake for one. We discovered the hard way that when the chassis battery dies completely, it 'captures' the key in the ignition and unlocks the doors.

We have electricity in our storage unit, so we use a battery charger/monitor to keep it charged up.

Thanks for sharing what you've learned. It may help someone else.

[MGD1961]

Not to beat a dead horse but I have to wonder what kind of Controler and inverter/charger you have with that much phantom draw?

[Guido79]

Originally Posted by MGD1961

Not to beat a dead horse but I have to wonder what kind of Controler and inverter/charger you have with that much phantom draw?

The 2021 ISATA5 28ss models shipped with a
2800W 12VDC Pure Sine Inverter/Charger - MS2812
&
Blue Power MPPT 100/30 Charge Controllers

[vlamgat]

Originally Posted by Guido79

The 2021 ISATA5 28ss models shipped with a
2800W 12VDC Pure Sine Inverter/Charger - MS2812
&
Blue Power MPPT 100/30 Charge Controllers

I have the 3012 which is the same. Is draw varies from 15 to 50 watts which over a few weeks let alone months adds up. However it's easily disconnected per the OM, but needs tools. Big surprise to me this week was how much current the jump start coupling feature takes from the house batteries for every start. At least 20%.