| Three Batteries and How to Charge Them [message #360877] |
Wed, 16 December 2020 16:23  |
Melbo
Messages: 144
Registered: August 2018
Location: Albuquerque NM
Karma: 0
|
Senior Member |
|
|
We have come to the time with this project that we need to update the battery storage and charging systems. It is a 73 with one battery in the back to start the onan. Two batteries in the front. One to start the 455 and one to power the house systems. The original (I'm Guessing on This) isolator is in place and I get a click when I flip the power boost switch so without a lot of research I am thinking that is normal.
It appears that the two batteries in the front will be charged while driving from the engine alternator. The battery at the Onan is charged by the onan when it is running. Having read about how the Onan will fry the start battery in time I have disabled that feature and when I run the Onan now I connect a battery charger (after all when the Onan is running I have 120 power) as a temporary fix to keep things going. I have removed the buzz box and selected a converter to replace it that has a smart charge feature. When parked the converter should keep the house battery charged and provide the 12 volt system with power.
NOW FOR THE QUESTIONS
If I use the converter to keep the house system battery charged can I also use it to charge the Onan start battery while the Onan is running. I am thinking that I would have it engaged by a relay that is on the fuel pump circuit. When the Onan is on and running there is 12 volts at the fuel pump and have that activate a relay that connects the positive battery post of the onan start battery to the converter charging system using a 10 awg should provide ample charging to maintain it. My question with this is will it interfere with the charging and maintaining of the house 12 volt battery?
Next Question
For those of you who have inverters What size do you use and what all do you run from them. I am thinking that the only thing I would want an inverter to run is the refrigerator and the refrigerator that we will be using draws less than 2 amps. My thinking is that everything else can be left shut down for several hours and have no issues AND maybe this is not necessary to do but keeping the refrigerator running while at a ball game or rodeo and not have the generator running would be preferable. I don't mind running the generator 24/7 when we are around the coach but I prefer it to be shut down when we are not there.
I know everyone uses their coach differently but it is MUCH easier to change things when they are just words on a piece of paper instead of bolted in place. I am getting close to putting things in place and different ideas and opinions are always helpful.
TIA
Melbo
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
|
|
|
|
| Re: Three Batteries and How to Charge Them [message #360880 is a reply to message #360877] |
Wed, 16 December 2020 19:14  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
|
Senior Member |
|
|
Just buy two Yandina combiners. Put one across the isolator under passenger hood and mount and ground to aluminum plate. Put a second one between the Onan batt and house batt and disable the flywheel alternator charge function. Total cost about $140. Or eliminate the Onan garden tractor battery and crank the gen off the house snd save $70.
John Lebetski
Woodstock, IL
77 Eleganza II
|
|
|
|
| Re: Three Batteries and How to Charge Them [message #360881 is a reply to message #360880] |
Wed, 16 December 2020 19:44 |
Melbo
Messages: 144
Registered: August 2018
Location: Albuquerque NM
Karma: 0
|
Senior Member |
|
|
At one time I thought about that BUT I think I would need a number 2 welding cable from the battery in the front to the location by the Onan. That would be a one time cost for a solution and I wouldn't have to mess with it. With that solution the Onan would use the start battery or house battery to operate the fuel pump and would not get a charge so the battery would be drawn down if it was the start battery and would be charged by the converter if it was the house battery. My bus has a diesel generator that has been replaced only once since 2004 so the cost of a battery is kind of irrelevant as long as the system works. BUT I have considered that solution. And I have disabled the battery charge function on the Onan.
Thanks John for the input.
Melbo
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
|
|
|
|
| Re: [GMCnet] Three Batteries and How to Charge Them [message #360885 is a reply to message #360877] |
Wed, 16 December 2020 22:48 |
Dave
Messages: 32
Registered: March 2004
Karma: 3
|
Member |
|
|
Here are some comments on what I did with our 73 GMC.
At 05:23 PM 16/12/2020, you wrote:
> We have come to the time with this project that we need to update
> the battery storage and charging systems. It is a 73 with one
> battery in the back
> to start the onan. Two batteries in the front. One to start the
> 455 and one to power the house systems.
We moved the house batteries to the rear (under the bed). Upgraded
the wiring. Upgraded the batteries to four 6V golf-cart batteries
(2S2P) 260AH each.
> The original (I'm Guessing on This) isolator
> is in place and I get a click when I flip the power boost switch so
> without a lot of research I am thinking that is normal.
That would be normal. The Boost relay ties the start battery to the
house battery to supply extra current to the starter when/if the
start battery is weak.
> It appears that the two batteries in the front will be charged while
> driving from the engine alternator.
True. The output of the alternator goes into a battery isolator that
will supply equal voltage to both the house battery and the start
battery. The voltage sense for the alternator is on the start battery
side of the isolator. Which can be a problem if one of the diodes in
the battery isolator fails.
> The battery at the Onan is charged by the
> onan when it is running. Having read about how the Onan will fry
> the start battery in time I have disabled that feature and when I
> run the Onan now I
> connect a battery charger (after all when the Onan is running I have
> 120 power) as a temporary fix to keep things going.
If the voltage regulator on the Onan is functioning properly, this
should not be a problem. Given the age of these units this is
something that should be checked.
> I have removed the buzz box
> and selected a converter to replace it that has a smart charge
> feature. When parked the converter should keep the house battery
> charged and provide
> the 12 volt system with power.
Good idea. The buzz box is known to be a poor battery charger. Very
slow to recharge and likely to damage batteries if left powered up
for extended periods of time. When we still had the buzz box we used
a lamp timer to power it up for a few hours each week while in
storage but otherwise left it off unless we were running the electric
fridge and other loads. This never equalizes the cells in the
batteries so it is not a good solution if you want really long
battery life. Modern smart-charge converters solve that problem...
> NOW FOR THE QUESTIONS
>
> If I use the converter to keep the house system battery charged can
> I also use it to charge the Onan start battery while the Onan is running. I am
> thinking that I would have it engaged by a relay that is on the fuel
> pump circuit. When the Onan is on and running there is 12 volts at
> the fuel pump
> and have that activate a relay that connects the positive battery
> post of the onan start battery to the converter charging system using a 10 awg
> should provide ample charging to maintain it.
That would work. But I would suggest using a battery combiner. They
have internal controls that will sense the voltage on both sides and
connect or disconnect the relay as needed without the complication of
connecting to the oil pressure switch.
But a simpler solution would to be to check the charger on the Onan
and fix it if it is not working properly. My experience is that the
charger is one of the more reliable components on the Onan. If it is
overcharging the battery you can probably find a used replacement
from someone for a reasonable price.
I added another battery isolator to the Onan compartment. Connected
the center (alternator) terminal to the front isolator center
(alternator) terminal and one of the other terminals to the Onan
start battery. This will charge the Onan battery whenever the front
engine is started. I have never had a problem with the Onan start
battery going dead. Our last couple Onan start batteries lasted 10
years with this setup.
> My question with this is will it interfere with the charging and
> maintaining of the house 12 volt
> battery?
It will not. Just make sure that you take into account the fact that
the Onan will require a few amps of current to run the ignition
system while the engine is running. If you want to use a separate
smart-charger for the Onan, I would suggest something rated at 10+ amps.
> Next Question
>
> For those of you who have inverters What size do you use and what
> all do you run from them. I am thinking that the only thing I would want an
> inverter to run is the refrigerator and the refrigerator that we
> will be using draws less than 2 amps. My thinking is that
> everything else can be
> left shut down for several hours and have no issues AND maybe this
> is not necessary to do but keeping the refrigerator running while at
> a ball game or
> rodeo and not have the generator running would be preferable. I
> don't mind running the generator 24/7 when we are around the coach
> but I prefer it to
> be shut down when we are not there.
This depends a lot on the type of refrigerator that you are using. We
still have the original Norcold electric. It has an internal 12V
inverter that is very low power and very forgiving. It will easily
run for four days with no charging or indefinably if we run the
generator for four hours a day (two in the morning while cooking and
two in the evening while cooking). All of our loads typically use
~100Ah/day. During dry camping the batteries level out between 50-80%
charge per day. Which is Ok for a few weeks at a time..
If you have a propane refrigerato, and want to run it on electric, it
will consume a lot more power. If it is a 3-way, the 12v draw is much
more than the Norcold. If it is a propane/110v unit then it will be
even less efficient (and draw more current through the inverter).
If you have a 110V compressor refrigerator then the problem is not as
much the power consumption as the surge current. Newer refrigerators
are pretty efficient but some have very high start currents and do
not run well on low cost "modified sine wave" inverters. I have an
office fridge that we use as a second refrigerator for special
occasions and I was not able to get it to run reliably using a 750W
modified sine wave inverter. We installed a low cost Chinese 1500W
sine wave inverter and can run the extra fridge, toaster, microwave
or coffee maker. Not all at once but good enough for tailgating or
fixing meals during the campground "quiet times".
> I know everyone uses their coach differently but it is MUCH easier
> to change things when they are just words on a piece of paper
> instead of bolted in
> place. I am getting close to putting things in place and different
> ideas and opinions are always helpful.
Just be aware that the OEM wiring is not up to the task of using
higher power converters, inverters, alternators etc. We upgraded all
of the primary 12V wiring (positive cables and added negative return
cables) using welding wire. Bigger is better (4-6awg) to keep voltage
drops to a minimum. Inverters need short (as in very short) and heavy
gauge cable runs. And dont forget to use appropriate circuit breakers.
We have used the GMC for many things, from extended dry camping in
the heat of summer or the cold of fall to extended full hookup stays
in all seasons. And this setup seems to work really well. We
typically get 10 years out of all of our battery sets. But the key is
to size them properly and be aware of the charge state at all times.
Lead-acid batteries are pretty unforgiving of being overly charged or
discharged but will last a long time if cared for properly...
> TIA
> Melbo
> --
> Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
Dave
Ann Arbor, MI.
73 Sequoia (26'/455/EbH/RwI/ThH/HEI/TBI/160°/3.42/100A/Q55G)
99 Gillig 36' Low Floor Bus (work in progress)
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
| Re: Three Batteries and How to Charge Them [message #360894 is a reply to message #360877] |
Thu, 17 December 2020 09:52 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
Melbo,
By reading the VIN you first posted, the coach is a 26'. But still, as a 73 there are some issues.
First, the regulator on the Onan will do a good job of keeping that battery up. If it fails, replacements can be had on Ebay for a reasonable cost.
Next, if you procure the three battery tray for the right front, you can put in a pair of GC2s and those make a pretty good house bank. Caution down the page. It is most undesirable to have normal lead/acid batteries in the living spaces, but if you upgrade to AGM or Lithium that will not be an issue.
Because it is a 73, there is a single run of #10SAE (not even AWG) from the house bank to the fuse board. This was changed in the most of the later coaches. This means that no matter house big or good the converter that replaces the Tripplite (Buzz Box), you will be limited to about 27~30 for a maximum charge rate. I have a fix if you need it.
You should also arrange to have two big alligator clip jumpers. One of them is to connect the top and bottom most terminals of the isolator to maintain the main engine battery when the coach is not in use. The other requires that you run a lead between the Onan battery and close to the fuse block buss. You put the other jumper there to maintain the APU (generator) battery. Remove both of these when you are doing your pre-departure walk around. (never skip the walk around!)
If the reefer you are referring to a 120V unit, yes, it only draws 2 amps (at 120VAC) running, but it can want 10~12 amps momentarily when starting. If that is the case, I can tell you that a 750/1500 MSW converter from Hazard Fright will do just fine. Induction motors are not very wave form sensitive. In normal operation from shore power, the compressor case is 3~5°F cooler than it is on the inverter and it has been this way for years now. One inverter let the smoke out at a bad time, so I carry a spare than I have not needed for 6 years now. A dorm reefer and two inverters are still about one thousand dollars lass cash out of pocket than a LP/electric replacement. If the coach still have the OE Nocold, keep using it.
To be near the house bank, I put the inverter in the space to the right of the glove compartment. I ran a bundle of #10 wire (3 pos & 3 neg) (3#10 = 1ea #7) because it was easier than finding #6 and getting it in there. There is also a 150 resetable breaker to both protection and a switch. This meant that I only had to pull a single run of 14-3 to the reefer. (Mine is on the other side.)
Here is the caution....
If you upgrade the house bank to a pair of GC2s and you dry camp much at all, the charging current demand of the GC2s can exceed the capacity of the alternator belt. If you have the 60 amp 27SI alternator, it may not matter, but if it is the 80 amp version that can actually crank up close to 100 (96 measured by me) and that is just about the limit of a single belt. They squeal and smoke.
While you are rooting around in there, think about getting a label maker and label every wire you can identify. You or your SO will thank you some day.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
| Re: Three Batteries and How to Charge Them [message #360910 is a reply to message #360877] |
Thu, 17 December 2020 20:12 |
Melbo
Messages: 144
Registered: August 2018
Location: Albuquerque NM
Karma: 0
|
Senior Member |
|
|
John
Thank you for the combiner idea. I was not familiar with those. That would do what I was trying to do and be much more simple.
Now back to rethinking how to proceed.
Matt
Having the inverter near the batteries is really the way to go. I am thinking that I would do a pure sine 2012. I am a little conflicted about having 120 volt wiring in the cockpit area. However a 2000 watt inverter would really only require a single 12/2 because it is less than 20 amps and one circuit should power up everything that I would want to run from an inverter. AC cable would be easy to route about before the walls go in. Also a 120 volt outlet with usb sockets in the dash on the passenger side might be a nice addition.
Dave
Good to see how you solved the three battery problem. My coach is bare to the walls and very easy to add or delete anything. Sounds like you have some serious experience traveling in your GMC. We are new and downsizing to the GMC. Our plans are for only two days maximum dry camping before we need services. We are not sure how it will all work but we like to run the genny 24/7 for AC when we are in the coach driving or parked. Yes it looks like the combiner is a good way to go. Our generator start battery lasted about the same as yours. Like ten years. I am horrible to batteries. I should learn to be better. Start batteries last a long time but house batteries only like six or seven years so I have begun to consider them a simple buffer for what the genny and campground 50 amp plug supply.
Melbo
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
|
|
|
|
| Re: [GMCnet] Three Batteries and How to Charge Them [message #360913 is a reply to message #360910] |
Thu, 17 December 2020 20:43 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
|
Senior Member |
|
|
Melbo,
If I were you, I'd eliminate that Onan-only battery and disconnect its
regulator (they have been known to short out and kill the Onan's
ignition). Use the House battery to support the Onan -- well worth running
the heavier wire (with a circuit breaker at each end) back there.
And, use a Ragusa 3-battery tray at the right front to support two 6VDC
"golf cart" batteries for the House and one 12VDC Chassis battery. Put the
inverter up there near the House battery (mine's in the pedestal under the
passenger's seat). Don't short change yourself for later use of that
inverter: Provide a lot more than 1 outlet! I find that this automatic
120vac source selector is a great addition and have had NO trouble with it
during the 17 years it's been running.
http://www.gmcmhphotos.com/photos/automatic-120-vac-power-source-selection/p8542.html
JWID,
Ken H.
On Thu, Dec 17, 2020 at 9:13 PM melmull--- via Gmclist <
gmclist@list.gmcnet.org> wrote:
> John
>
> Thank you for the combiner idea. I was not familiar with those. That
> would do what I was trying to do and be much more simple.
>
> Now back to rethinking how to proceed.
>
> Matt
>
> Having the inverter near the batteries is really the way to go. I am
> thinking that I would do a pure sine 2012. I am a little conflicted about
> having 120 volt wiring in the cockpit area. However a 2000 watt inverter
> would really only require a single 12/2 because it is less than 20 amps and
> one circuit should power up everything that I would want to run from an
> inverter. AC cable would be easy to route about before the walls go in.
> Also
> a 120 volt outlet with usb sockets in the dash on the passenger side might
> be a nice addition.
>
> Dave
>
> Good to see how you solved the three battery problem. My coach is bare to
> the walls and very easy to add or delete anything. Sounds like you have
> some serious experience traveling in your GMC. We are new and downsizing
> to the GMC. Our plans are for only two days maximum dry camping before we
> need services. We are not sure how it will all work but we like to run
> the genny 24/7 for AC when we are in the coach driving or parked. Yes it
> looks
> like the combiner is a good way to go. Our generator start battery lasted
> about the same as yours. Like ten years. I am horrible to batteries. I
> should learn to be better. Start batteries last a long time but house
> batteries only like six or seven years so I have begun to consider them a
> simple buffer for what the genny and campground 50 amp plug supply.
>
> Melbo
> --
> Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
|
|
|
|
| Re: [GMCnet] Three Batteries and How to Charge Them [message #361531 is a reply to message #360885] |
Wed, 16 December 2020 22:55 |
Dave
Messages: 32
Registered: March 2004
Karma: 3
|
Member |
|
|
Here are some comments on what I did with our 73 GMC.
At 05:23 PM 16/12/2020, you wrote:
> We have come to the time with this project that we need to update
> the battery storage and charging systems. It is a 73 with one
> battery in the back
> to start the onan. Two batteries in the front. One to start the
> 455 and one to power the house systems.
We moved the house batteries to the rear (under the bed). Upgraded
the wiring. Upgraded the batteries to four 6V golf-cart batteries
(2S2P) 260AH each.
> The original (I'm Guessing on This) isolator
> is in place and I get a click when I flip the power boost switch so
> without a lot of research I am thinking that is normal.
That would be normal. The Boost relay ties the start battery to the
house battery to supply extra current to the starter when/if the
start battery is weak.
> It appears that the two batteries in the front will be charged while
> driving from the engine alternator.
True. The output of the alternator goes into a battery isolator that
will supply equal voltage to both the house battery and the start
battery. The voltage sense for the alternator is on the start battery
side of the isolator. Which can be a problem if one of the diodes in
the battery isolator fails.
> The battery at the Onan is charged by the
> onan when it is running. Having read about how the Onan will fry
> the start battery in time I have disabled that feature and when I
> run the Onan now I
> connect a battery charger (after all when the Onan is running I have
> 120 power) as a temporary fix to keep things going.
If the voltage regulator on the Onan is functioning properly, this
should not be a problem. Given the age of these units this is
something that should be checked.
> I have removed the buzz box
> and selected a converter to replace it that has a smart charge
> feature. When parked the converter should keep the house battery
> charged and provide
> the 12 volt system with power.
Good idea. The buzz box is known to be a poor battery charger. Very
slow to recharge and likely to damage batteries if left powered up
for extended periods of time. When we still had the buzz box we used
a lamp timer to power it up for a few hours each week while in
storage but otherwise left it off unless we were running the electric
fridge and other loads. This never equalizes the cells in the
batteries so it is not a good solution if you want really long
battery life. Modern smart-charge converters solve that problem...
> NOW FOR THE QUESTIONS
>
> If I use the converter to keep the house system battery charged can
> I also use it to charge the Onan start battery while the Onan is running. I am
> thinking that I would have it engaged by a relay that is on the fuel
> pump circuit. When the Onan is on and running there is 12 volts at
> the fuel pump
> and have that activate a relay that connects the positive battery
> post of the onan start battery to the converter charging system using a 10 awg
> should provide ample charging to maintain it.
That would work. But I would suggest using a battery combiner. They
have internal controls that will sense the voltage on both sides and
connect or disconnect the relay as needed without the complication of
connecting to the oil pressure switch.
But a simpler solution would to be to check the charger on the Onan
and fix it if it is not working properly. My experience is that the
charger is one of the more reliable components on the Onan. If it is
overcharging the battery you can probably find a used replacement
from someone for a reasonable price.
I added another battery isolator to the Onan compartment. Connected
the center (alternator) terminal to the front isolator center
(alternator) terminal and one of the other terminals to the Onan
start battery. This will charge the Onan battery whenever the front
engine is started. I have never had a problem with the Onan start
battery going dead. Our last couple Onan start batteries lasted 10
years with this setup.
> My question with this is will it interfere with the charging and
> maintaining of the house 12 volt
> battery?
It will not. Just make sure that you take into account the fact that
the Onan will require a few amps of current to run the ignition
system while the engine is running. If you want to use a separate
smart-charger for the Onan, I would suggest something rated at 10+ amps.
> Next Question
>
> For those of you who have inverters What size do you use and what
> all do you run from them. I am thinking that the only thing I would want an
> inverter to run is the refrigerator and the refrigerator that we
> will be using draws less than 2 amps. My thinking is that
> everything else can be
> left shut down for several hours and have no issues AND maybe this
> is not necessary to do but keeping the refrigerator running while at
> a ball game or
> rodeo and not have the generator running would be preferable. I
> don't mind running the generator 24/7 when we are around the coach
> but I prefer it to
> be shut down when we are not there.
This depends a lot on the type of refrigerator that you are using. We
still have the original Norcold electric. It has an internal 12V
inverter that is very low power and very forgiving. It will easily
run for four days with no charging or indefinably if we run the
generator for four hours a day (two in the morning while cooking and
two in the evening while cooking). All of our loads typically use
~100Ah/day. During dry camping the batteries level out between 50-80%
charge per day. Which is Ok for a few weeks at a time..
If you have a propane refrigerato, and want to run it on electric, it
will consume a lot more power. If it is a 3-way, the 12v draw is much
more than the Norcold. If it is a propane/110v unit then it will be
even less efficient (and draw more current through the inverter).
If you have a 110V compressor refrigerator then the problem is not as
much the power consumption as the surge current. Newer refrigerators
are pretty efficient but some have very high start currents and do
not run well on low cost "modified sine wave" inverters. I have an
office fridge that we use as a second refrigerator for special
occasions and I was not able to get it to run reliably using a 750W
modified sine wave inverter. We installed a low cost Chinese 1500W
sine wave inverter and can run the extra fridge, toaster, microwave
or coffee maker. Not all at once but good enough for tailgating or
fixing meals during the campground "quiet times".
> I know everyone uses their coach differently but it is MUCH easier
> to change things when they are just words on a piece of paper
> instead of bolted in
> place. I am getting close to putting things in place and different
> ideas and opinions are always helpful.
Just be aware that the OEM wiring is not up to the task of using
higher power converters, inverters, alternators etc. We upgraded all
of the primary 12V wiring (positive cables and added negative return
cables) using welding wire. Bigger is better (4-6awg) to keep voltage
drops to a minimum. Inverters need short (as in very short) and heavy
gauge cable runs. And dont forget to use appropriate circuit breakers.
We have used the GMC for many things, from extended dry camping in
the heat of summer or the cold of fall to extended full hookup stays
in all seasons. And this setup seems to work really well. We
typically get 10 years out of all of our battery sets. But the key is
to size them properly and be aware of the charge state at all times.
Lead-acid batteries are pretty unforgiving of being overly charged or
discharged but will last a long time if cared for properly...
> TIA
> Melbo
> --
> Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
Dave
Ann Arbor, MI.
73 Sequoia (26'/455/EbH/RwI/ThH/HEI/TBI/160°/3.42/100A/Q55G)
99 Gillig 36' Low Floor Bus (work in progress)
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
