Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 04-20-2021, 02:32 PM   #1
Mini-Skoolie
 
Join Date: Apr 2021
Location: Montreal, Canada
Posts: 32
Using same battery for engine and house

Hi, we just bought a bus that was previously converted to a party bus to continue into a full RV and I see that they plugged the internal batteries that charged a fridge, tv's, sound system and 110v outlets all on the same batteries of the engine. Is this recommended? Could I continue to build the RV in this way with at most upgrading to more powerful batteries or should I separate them and use a new set of batteries for the "house"?
CompLexxx is offline   Reply With Quote
Old 04-20-2021, 03:19 PM   #2
Bus Crazy
 
Join Date: May 2014
Location: West Ohio
Posts: 2,308
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
If you're powering something large, or powering something all the time, you'll want separate house/bus batteries. That's so you don't accidentally run the bus batteries down and strand yourself somewhere. If you're using an inverter of any kind, I'd have separate systems as well because an inverter can be accidentally left on, and will draw power even if nothing is using the 120vac being created.

On my bus, the only battery powered items I have is a radio system and some led lights. Neither is a high amp device, and it's obvious if they're on, so I don't worry about forgetting them. So all my stuff is off the 2 bus batteries.
__________________
My build: The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 04-20-2021, 04:21 PM   #3
Bus Crazy
 
kazetsukai's Avatar
 
Join Date: May 2017
Location: Windham NH
Posts: 1,287
Year: 1999
Coachwork: Amtran
Chassis: International RE
Engine: International T444e
Rated Cap: 76
Starter batteries are not built for capacity, they are built for crank. Think short fast sprints, not long , slower, marathons.



The answer really depends on what you intend to power with them, but I lean towards "that's not recommended" for a variety of reasons.
kazetsukai is offline   Reply With Quote
Old 04-20-2021, 05:11 PM   #4
Mini-Skoolie
 
Join Date: Apr 2021
Location: Montreal, Canada
Posts: 32
So if I upgrade the batteries to high power deep cycles or AGM and I run it on Solar with a backup generator that will start charging under 30% is it okay to run them on the same source?

Basically it would save my time space and money. Downside is faster wear I guess?
CompLexxx is offline   Reply With Quote
Old 04-20-2021, 05:16 PM   #5
Bus Nut
 
Join Date: May 2019
Location: Lebanon, Indiana
Posts: 745
Year: 2000
Coachwork: Winnebago
Chassis: Ford F53
Engine: Ford Triton V-10
Rated Cap: currently 2
What battery starts the generator?
Sehnsucht is offline   Reply With Quote
Old 04-20-2021, 05:32 PM   #6
Bus Crazy
 
kazetsukai's Avatar
 
Join Date: May 2017
Location: Windham NH
Posts: 1,287
Year: 1999
Coachwork: Amtran
Chassis: International RE
Engine: International T444e
Rated Cap: 76
Quote:
Originally Posted by CompLexxx View Post
So if I upgrade the batteries to high power deep cycles or AGM and I run it on Solar with a backup generator that will start charging under 30% is it okay to run them on the same source?
You really need to lay out your use case- what do you intend to power. If its anything more than lights and maybe a sound system, I wouldn't recommend it.



Quote:
Originally Posted by CompLexxx View Post
Basically it would save my time space and money. Downside is faster wear I guess?
This is an overly simplistic analysis. An overwhelming majority of rigs use separate systems and for good reasons.


Detail your use case- what you intend to power.
kazetsukai is offline   Reply With Quote
Old 04-20-2021, 05:57 PM   #7
Mini-Skoolie
 
Join Date: Apr 2021
Location: Montreal, Canada
Posts: 32
It would be for full interior, lights, sound system, water pump, AC, laptops, washer dryer etc.

I don't know what the exact reasons for separate them that's why I'm asking
CompLexxx is offline   Reply With Quote
Old 04-20-2021, 06:17 PM   #8
Bus Crazy
 
Join Date: Nov 2016
Posts: 2,182
Really, off grid use requires belt & suspenders redundancy.

A big enough House bank will certainly crank any engine, no need for a dedicated Starter type.

But the only reason to **not** have one is weight and space, not an issue with a bus.
john61ct is offline   Reply With Quote
Old 04-20-2021, 06:28 PM   #9
Mini-Skoolie
 
Join Date: Apr 2021
Location: Montreal, Canada
Posts: 32
Quote:
Originally Posted by john61ct View Post
Really, off grid use requires belt & suspenders redundancy.

A big enough House bank will certainly crank any engine, no need for a dedicated Starter type.

But the only reason to **not** have one is weight and space, not an issue with a bus.
Since we are a family of 4 in it full time any more space is appreciated, there is also the simplicity aspect since all the wiring is already there and I won't have to go in and figure out which connections are which.

But if there is good reason to separate them I will.

One advantage of putting them inside is I could use lithium since I wouldn't use lithium in the outer compartments due to use using the bus in cold Canadian winters, but I think AGM batteries are fine for this.
CompLexxx is offline   Reply With Quote
Old 04-20-2021, 07:21 PM   #10
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 14,742
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
in my DEV bus I have all 4 AGM batteries plus blue tops, 2 for house and 2 for starter.. I use a battery isolater that drops offline when the pack goes down to 12.2 or so.. I can also manually engage it or manually disengage it.. the isolater reconnects the batteries (in auto mode) when either set sees 13 volts (meaning its being charged).. most times I have the isolater set to shut off with the ignition but sometimes I want some extra juice so I leave it connected.. or when im charging on shore power I have all identical batteries so my victron charger charges them all to the same voltage..



seems to work really well for me... .. my alternator can charge them when im driving.. my portable generator can charger them using the victron shore charger if I choose.. or I can connect my portable solar panel
cadillackid is offline   Reply With Quote
Old 04-20-2021, 07:50 PM   #11
Bus Nut
 
Join Date: Apr 2020
Location: Northern California (Sacramento)
Posts: 268
Year: 1999
Chassis: Ford E450
Quote:
Originally Posted by CompLexxx View Post
Since we are a family of 4 in it full time any more space is appreciated, there is also the simplicity aspect since all the wiring is already there and I won't have to go in and figure out which connections are which.

But if there is good reason to separate them I will.
A family of four will quickly drain any and all systems, and lead-acid batteries are unforgiving if drained below 50%.

You can't wing this one. You'll need to learn enough about skoolie electrical systems that you can safely put in at least one deep cycle battery and some lights, and provide some way to keep it charged. It's not that hard, but YOU WILL NEED TO GO IN AND FIGURE IT OUT.

We'll all help with your questions.
Rucker is offline   Reply With Quote
Old 04-20-2021, 08:01 PM   #12
Bus Crazy
 
kazetsukai's Avatar
 
Join Date: May 2017
Location: Windham NH
Posts: 1,287
Year: 1999
Coachwork: Amtran
Chassis: International RE
Engine: International T444e
Rated Cap: 76
Quote:
Originally Posted by CompLexxx View Post
It would be for full interior, lights, sound system, water pump, AC, laptops, washer dryer etc.
Forgive if I misunderstand, I am assuming that we are talking the default battery box the bus uses (I'm imagining generously sized 2'x2'x2' at best), and that you mean to run AC/washer/dryer from solar. If so, there's just no way you are going to be able to physically fit the number of AGM batteries needed to run AC or washer/dryer in the default battery box/compartment.

Quote:
Originally Posted by CompLexxx View Post
One advantage of putting them inside is I could use lithium since I wouldn't use lithium in the outer compartments due to use using the bus in cold Canadian winters, but I think AGM batteries are fine for this.
If you want anything resembling a residential electricity experience while on solar power, you will _need_ the capacity and other capabilities lithium provides. And especially if we are talking running AC or laundry related machines, you will want a system with a higher voltage than 12V to keep costs down and efficiency high.

Quote:
Originally Posted by CompLexxx View Post
Since we are a family of 4 in it full time any more space is appreciated, there is also the simplicity aspect since all the wiring is already there and I won't have to go in and figure out which connections are which.
I understand the idea of simplicity is attractive. When I bring up that this is industry convention, I'm invoking the wisdom of that convention in general. The RV industry does this for a number of reasons, redundancy one of them, practicality another. Almost all house and chassis banks are separated at least by a battery isolator (to allow charge from alternator).

Now many appliances, you may want to run only on shore power. Namely AC and laundry. The amount of power needed to run those is very high. Again, forgive me if I misunderstand what you're saying, but to put things into perspective: I likely have at least four to ten times the energy capacity of any AGM bank that would fit in the space of a stock bus battery compartment (assuming its sized normally) and my batteries would be emptied from full, after a single night of running AC. Which is why I'm in the middle of an upgrade...


Even without AC/laundry on solar you'd need some pretty spartan energy conservation to support the others if you want working 120V outlets while unplugged.



Nothing to say you couldn't _start_ by running a fuse block from the default batteries, but its almost certain not to cut it in the long run.
kazetsukai is offline   Reply With Quote
Old 04-20-2021, 08:14 PM   #13
Mini-Skoolie
 
Join Date: Apr 2021
Location: Montreal, Canada
Posts: 32
Ok perfect, I will go with 400AH Lithium batteries, I already have 2x 320w solar panels and was thinking of getting 2 more.

What would be the optimal setup to have the solar plugged to a backup generator, the engine alternator, and shore capabilities?

I still have the REDARC BMS (https://redarcelectronics.com/products/the-manager30) system from our old Sprinter van and it was an amazingly useful component, but the problem is it caps at 600 something watts of solar, so now upgrading it won't hold anymore. Is there a replacement like the BMS or do I have to go with each component separately?
CompLexxx is offline   Reply With Quote
Old 04-20-2021, 09:33 PM   #14
Bus Crazy
 
kazetsukai's Avatar
 
Join Date: May 2017
Location: Windham NH
Posts: 1,287
Year: 1999
Coachwork: Amtran
Chassis: International RE
Engine: International T444e
Rated Cap: 76
Quote:
Originally Posted by CompLexxx View Post
Ok perfect, I will go with 400AH Lithium batteries.
400AH doesn't tell the whole story- voltage? I personally like using Wh instead of Ah, it conveys capacity in terms of energy (derived) rather than current / time.

Quote:
Originally Posted by CompLexxx View Post
What would be the optimal setup to have the solar plugged to a backup generator, the engine alternator, and shore capabilities?
I think you should start with sizing your system. You gave a basic list of items you wished to power from battery/solar, the best way to nail down the ideal components for your use case is to list in detail all devices/appliances you intend to power, and how much energy those devices use over a 24h period. You can reach decent estimates by examining how much power a device uses on average, combined with how many hours you think you will use that device in a day.

I'm not trying to make things needlessly complex- I want to give you a close approximation of what components would work for what you are asking, including the homework/math of how we got there so you can adjust your plans/expectations accordingly and you can make the best decision for you.

Quote:
Originally Posted by CompLexxx View Post
I still have the REDARC BMS (https://redarcelectronics.com/products/the-manager30) system from our old Sprinter van and it was an amazingly useful component, but the problem is it caps at 600 something watts of solar, so now upgrading it won't hold anymore. Is there a replacement like the BMS or do I have to go with each component separately?
I don't like that they call it a "BMS", as this isn't really what people would consider a BMS. It looks like a multi-source battery charger to me.

When I and many others think "BMS" they are thinking of a device used to manage the health of a (typically) lithium battery bank by providing individual cell monitoring, undervoltage/overvoltage/thermal protection and balancing capabilities.

There are simple, integrated options like Victron Energy's Multiplus and even simpler their EasySolar options- that combine an inverter, transfer switch and battery charger (and in the case of the EasySolar- a solar charge controller and I think even an AC breaker panel).

Kind of a tangent, but most offerings on the market are not limited by wattage per say, but rather voltage and amperage. I have a Victron MPPT solar charge controller rated 150V/100A. If I was asked what maximum solar wattage it could support, I couldn't answer without knowing panel voltage, panel wiring configuration and battery bank voltage. For example, I used to run a 24V battery bank. At this point, 24V * 100A = 2400W, the maximum wattage supported (I would have to wire the panels within the 150V/100A constraints as well). Well, when I upgraded from 700W of solar to 3000W of solar, this wasn't enough anymore... did I spend another $800 on a second or bigger MPPT: No. I instead switched to 48V by rewiring the battery bank. So now I can run 48V * 100A = 4800W of solar on the same solar charge controller.

Smaller solar systems with low demands can and should utilize 12V for simplicity. If you need a highly capable system in my opinion should go higher in voltage to save on costs and efficiency, but this is one of many facets/design decisions which is why sizing is so important:

I think it would benefit you to really hash out the devices you intend to use in detail along with their estimated power requirements, so that we can start asking questions like how many hours/days of standby (little or no solar generation like on cloudy/rainy days) you want your batteries to last, how much generator run time is acceptable, etc. That will help folks here identify the specifics of what your system would need.
kazetsukai is offline   Reply With Quote
Old 04-20-2021, 09:46 PM   #15
Mini-Skoolie
 
Join Date: Apr 2021
Location: Montreal, Canada
Posts: 32
I was planning on having it 12v since most RV equipment is already rigged for 12v so I could plug some components directly through. I did not do the exact calculation yet since we still have to see what we will keep and let go of the current setup but I was planning on setting it all up with 4x 320w solar and see how it goes and if I see the generator kick in too often I would add more panels. But I will do a calculation in the next couple of days when I have a better idea of all the equipment in use. Thanks for all the advice
CompLexxx is offline   Reply With Quote
Old 04-20-2021, 11:20 PM   #16
Bus Nut
 
Rwnielsen's Avatar
 
Join Date: Jun 2020
Location: Long Beach, CA
Posts: 336
Year: 1998
Coachwork: Blue Bird
Chassis: TC1000, 40' MPV
Engine: 5.9 Cummins/B300 trans
Rated Cap: U/K
Quote:
Originally Posted by Sehnsucht View Post
What battery starts the generator?
I have a third battery just for the generator with a solenoid that ties in to the start batteries when driving and an emergency button that ties them together if either gets too low.
Rwnielsen is offline   Reply With Quote
Old 04-21-2021, 12:49 AM   #17
Bus Nut
 
Join Date: May 2018
Location: topeka kansas
Posts: 869
Year: 1954
Coachwork: wayne
Chassis: old f500- new 2005 f-450
Engine: cummins 12 valve
Rated Cap: 20? five rows of 4?
yes, but...

Yup you can use it the way it is.

The risk is that you discharge the batteries so much, you will not be able to start the bus.



william
magnakansas is offline   Reply With Quote
Old 04-21-2021, 06:58 AM   #18
Bus Crazy
 
joeblack5's Avatar
 
Join Date: Dec 2015
Location: pa
Posts: 2,092
Year: 98
Coachwork: 1. Corbeil & 2. Thomas
Chassis: 1 ford e350 2 mercedes
Engine: 7.3 powerstroke & MBE906
We have space and weight constraints and using the same battery. We cook via induction, water pump, refrigerator, freezer, lights,fans, radio ,laptops allen from the same 24 volt and the other bus 12 volt.

We only use the inverter for cooking and a heated shower head.

The 900 watt solar keeps everything charged up.
If you run lead acid you should not go under 50%.
The remaining 50 is plenty to start your bus if the engine is in good shape. The energy to start an engine is very little. The current is high but only for 2 seconds.

If you did discharge your battery more then 50 then you have monitoring or consumption issues. That is not going to be resolved with separated systems.

I like the term " residential experience "
Not for us.
We like the experience to live in "harmony" ( haha) with what the sun provides and be aware of the the consumption and production. If the sun shines and power is plentiful we take a shower, we also like to cook on a wood fire .

It is all what you want and how commuted you are to that.

Good luck
Johan
joeblack5 is offline   Reply With Quote
Old 04-21-2021, 08:35 AM   #19
Bus Crazy
 
Join Date: May 2014
Location: West Ohio
Posts: 2,308
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
Listen to kaz and others.

Most do separate banks for redundancy/failsafe.

If you have large energy needs from a battery bank. It should be separate from the starting bank. Because your starting bank won't have the space/storage capacity needed to provide for it.

Lights and radio? Works just fine off the bus batteries. That's what I have.

Washer, drier, oven, chargers, tv, stereo, AND especially air conditioning? You'll need a dedicated bank, and a huge one at that, if you plan on pulling all of that from batteries.

The stuff in my bus can be inadvertently ran all night, and the batteries will still start my bus in the morning. The key is to have a large enough capacity to give you a buffer like that. With your energy needs/desires, the bus batteries and it's battery compartment won't be large enough to do that.

You need to either build a house bank large enough for your needs, or scale back your needs so that the bus batteries can accommodate them.
__________________
My build: The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 04-21-2021, 09:19 AM   #20
Bus Nut
 
BeNimble's Avatar
 
Join Date: Jul 2020
Location: Sacramento
Posts: 852
Year: 1999
As a RV you might be in a remote area where someone isn't going to be there to give you a jump to start up the vehicle, so its important to have a battery dedicated to getting started. A transit bus doesn't have that issue.
Our friends boat had a failed isolator, and the radio drained the start battery.
Have you heard of the term Dead Calm..
BeNimble is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 04:35 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
×