I have a question about the boost switch. It is my understanding it is not meant to be left on all the time. That it boosts the batteries and you can charge the batteries with the house batteries when plugged in. I leave my coach plugged into 110 when parked. Can I leave the boost switch on while parked or is that not a good idea?
Thank you,
Brian
I rarely use my boost switch. I think it's best to leave it off unless it's really needed.
Some do some don't. One big reason not to is that when the house and start are connected by boost they will also drain each other if no 110 is present. So if you somehow popped a breaker you could potentially loose both sets a batteries.
Normally, the only good reason to leave the boost switch on when coach is parked is so the start battery bank gets charged. On a
stock coach, if the boost switch is OFF then the start batteries are
not charged by the onboard charger.
If you have the correct type of boost solenoid, which means
continuous duty rated, then
in theory it should not hurt to leave the boost switch ON for extended periods. There are two down sides to doing so.
1. If you loose shore power to the coach (especially if the inverter is on) then ALL the batteries could be drained to a point that you could not start either the generator or the big engine.
2. A lessor concern: the boost solenoid draws power all the time it is ON, which generates heat in the solenoid and might shorten its service life.
There are several better ways to keep the start batteries charged when coach is parked, like using a stand-alone 110V smart battery charger, or using a "diversion" maintainer (Trik-L-Start), or using a smart battery combiner, or using a solar powered charger. All these methods have been well covered here on the Forum.
"Search" is your friend.
It's not a latching solenoid so if you are charging and lose power, the boost solenoid will flatten both sets of batteries with a good possibility of costing you a lot of $$$ for two new sets of batteries. It's old technology with many better ways of doing things today.
I NEVER use the boost switch to charge batteries. I've used it once to start the coach in freezing high altitude weather and that was about 12 years ago.
Pierce
2. A lessor concern: the boost solenoid draws power all the time it is ON, which generates heat in the solenoid and might shorten its service life.
Strongly disagree. The boost solenoid is EXACTLY the same as your ignition solenoid which is on the entire time you are driving. I leave mine on for extended periods of time with no ill effects, and almost always 24 hours before I start the engine. And.....always use the boost to start the engine.
when i was just starting the huge learning curve of foretravel
ownership, the instructions that came with my 93 U280 said
that the boost switch was to be turned on once a week for a
day to keep start batteries charged. back in the day the books
even included diagrams of how the cabinets were made.
my vote would go for a trik l start.
as far as the learning curve goes, i'm not sure i've even rounded
second base. the collective wisdom on this site is invaluable.
OK, but when driving you don't leave your ignition solenoid
constantly activated for days, or weeks, or months at a time. That would use a LOT of fuel!
And actually, in
my case, the boost solenoid is not exactly the same as the ignition solenoid. I use a Blue Sea 9012 for ignition duties, and a Blue Sea 7701ML as a boost solenoid. The 7701ML draws no current in "ON" or "OFF" state, only draws current when changing state of switch. I COULD (if I so desired) leave it turned on for months at a time with no worries (about heat buildup or current draw).
Solenoid L-Series - 250A 12/24V - Blue Sea Systems (https://www.bluesea.com/products/9012/Solenoid_L-Series_-_250A_12_24V)
ML Solenoid - 12V DC - Blue Sea Systems (https://www.bluesea.com/products/7701/ML_Solenoid_-_12V_DC)
Amazon.com : Blue Sea Systems 7701 12V DC ML Solenoid : Boating Battery... (https://amzn.to/3XKZcTh)
Yes, it does draw power all the time it's on. Yes, it's exactly the same at the ignition solenoid. Both draw power all the time and leaving the solenoid on while on shore power is just asking for trouble.
Why in the world would you turn your boost solenoid on 24 hours before starting the engine? Our 2850 CCA are almost double what we need to start our Detroit. The only reason I can see is someone with a fault(s) in their starting system, cables, old batteries, tired starter, dirty terminals.
Using both to start a coach is just a crutch. When the engine is not starting properly, you will have zero backup and if isolated, you could be up a creek.
Using that logic, why not have an extra battery in the trunk of your car and connect it each time you start your car? Every diesel engine has a CCA requirement needed to start the engine. My 2850 CCA is overkill. Combining with the house batteries would be way over the top.
Pierce
The boost solenoid is a temporary connection to use the house batteries to add a "boost" to the start batteries when required to start the engine.
If you can not start your engine without using the boost switch every time then your starter, starter wiring, or start battery wiring are in disrepair or start batteries are worn out or undersized.
There are many other strategies to keep your start batteries charged without using a boost solenoid. Even through the early 2000s Foretravel provided no alternate way to do this and protect your batteries. Today's technology makes it safe and easy.
You can do whatever you want, it is your coach.
Yep. Boost is for times when the start batteries are weak only or charging the start batteries
Even though we have 2550 CCA for our start batts, which should be 500 or 600 CCA overkill, I would say to hit that boost switch once a month. Or maybe every other. Just to keep your electronic gagetry working. If it just sits there year after year it might not work when / if you need it. JMTC.
And once the main diesel engine is started, the isolator does it's job splitting charging voltage so both sets of batteries are charging while driving. Conventional isolators are being replaced by new technology so investigate possibilities from our archives.
A to Z on isolators: How To Test A Battery Isolator | RV Lifestyle (https://rvlifestyle.com/how-to-test-a-battery-isolator/)
Another reason to bring up the need for twin voltmeters within your range of vision while you are driving. Keeps you ahead of the curve, not surprised by the side of the road.
Latching Solenoids: So, we know that using the boost solenoid will cause it to get hot and run the batteries down if shore power is lost while the batteries are being charged. If you want to keep the same wiring with a small modification, consider the latching solenoid. They are actuated by a momentary push button switch and draw ZERO juice when in either the on or off position, just allowing power to flow in one side and out the other. Here is one latching solenoid that is 100 amps. A larger version or two in parallel will do the trick. Fastronix Solutions--Continuous Duty Solenoids (http://www.fastronixsolutions.com/Relay%20Devices/continuous%20duty%20solenoids.htm)
While a cushion of several hundred CCAs is nice for your start batteries, it can quickly disappear in cold weather starting or as the batteries age. A 850 CCA battery only meets it's specs when new and not 5 or 8 years down the road.
Pierce
Why in the world would you turn your boost solenoid on 24 hours before starting the engine? Our 2850 CCA are almost double what we need to start our Detroit. The only reason I can see is someone with a fault(s) in their starting system, cables, old batteries, tired starter, dirty terminals.
Using both to start a coach is just a crutch. When the engine is not starting properly, you will have zero backup and if isolated, you could be up a creek.
Pierce
Because Foretravel told me to. So I do. More than 20 years now. Everyone else should do what they want.
Please provide the written documentation of Foretravel telling you to do that!
If Foretravel told T to do it 20 years ago I highly doubt he still has the "documentation". That's if it was documented,, possibly just a conversation. And Twig. Do what you do, if its not broke don't fix it.
Agree with Roger on this one,would love to find out what James Trianna would say about leaving it on every start,we attended
the driving school about 5 years ago and the instructor reccommended that procedure and I disagreed with him,our 8.3 engine
starts as fast as a car with the 2 start batteries and everything in good working order,not trying to pull your chain Twig but
maybe something in your start system has been less then 100% for 20 years.If the boost switch was meant to be on for every
start they would not have a boost switch,just one big bank on batteries.
I notice no one has mentioned the C-C-C-COLD. I only use the boost switch when it is below freezing outside and not hooked up so the block heater is not in play and the coach has been sitting for a few days.
I must admit that I have not tried starting in below freezing temps since I added another 980CCA start battery.
Mark, I forget his last name, that was on the tech help desk years ago told me to put the boost switch on everytime when starting. I certainly don't have 2850 cranking amps in a single 8d battery and every thing helps. It certainly doesn't hurt so I'm not sure why anyone would jump on me for doing it. Documentation? I don't need no steenking documentation. My Cummins starts without cranking more than a touch of the key and I like it. The boost on for 24 hours before starting is my idea after it sits for a period of time without a charger on the single 8d.
And it starts fine without the boost on as well. Just not as fast.
Hey Twig,
No one is jumping on you. Absolutely nothing personal as you are a good guy (except for the Cummins). ;) I still remember your advice on finding your brother at Playa Bonita in Puerto Peñasco. ^.^d
I don't believe what 99 % of the shop people tell me. I grew up when "question authority" was on many pumper stickers so just nod and smile when talking to shops but definitely count my fingers after shaking hands with a salesperson.
The boost switch is not unique to Foretravels as it's fitted to many coach brands like ours. While it's great for help starting in some situations, it does draw .5 amp when it's on and combined with other coach parasitic losses, can flatten batteries if there is an extended shore power failure. That's why I brought up the latching solenoid as there is no loss in the solenoid itself but other parasitic losses are still there, especially in the summer months.
I remember many nights at the watering hole in Dortmund where we would drink and then loudly argue with each other until "dawn's early light" only to laugh and be good friends the next day. Don't want an OK Corral the next time we meet. :D
Pierce
On the Monaco Dynasty the boost switch is spring loaded so the switch has too be
held to use. I only used it when it was below freezing. If you are plugged in 24 hours
before you are going to start your coach can be a good idea but not if you are not
plugged in.
Our old technology '89 GV rocker switch has a spring loaded boost to the right, neutral position center, and charge position (not spring loaded) to the left.
I have no problem using my boost switch especially when running generator on a cold morning start. Engine grid heater sucks lots of ampage from my two 11 year old napa group 24 batteries. Why put added stress on everything including starter and alternator.
Actually, as Foretravel built the coaches, there is NO means of charging the chassis batteries.
It would not surprise me for someone at Foretravel to suggest leaving the boost switch on that long when you are on shore power so that the converter or inverter/charger will charge up the chassis batteries.
Are there other means (many better) for charging the chassis batteries? Sure.
Yup Brett. Somebody done did that thing there to our coach. In Charge position while on shore power all three batteries are being charged.
I've used the jumper to keep both the conventional engine batteries charged as well as the AGM coach batteries since 2008. It's plugged in 24/7 while parked at home, only removing before I start the engine. The twin voltmeters are worth their weight in gold as they keep an eye on the alternator, batteries, etc while driving and while parked. They also stay on 24/7. The are fused at the plugs and each end of the cable has a 5 amp fuse so there is no chance of a fire. The Progressive Dynamics converter does an absolutely perfect job of keeping the voltage right around the advertised 13.2 volts. I plug both in at the same time as one end can become electrically hot and could pop a fuse if it touches the ground on the other plug.
No idea where the white specks came from in the photo.
Pierce
Doug the makes perfect sense using your boost switch with the generator running
as depending on you inverter you get a lot of amps while starting and probably the
grid heater won't use any amps from the batteries. I made up my own thing for
charging the chassis battery which I can get up to 80 amps from the house batteries
for starting.
Brett,maybe revise the statement to no way to charge while not running.
Correct. Addressing the topic of use of the boost switch "The night before starting".
As you said, the engine-driven alternator charges both battery banks when the engine is running.
I was having a discussion with a guy on Facebook about leaving the boost on all the time to keep start batteries charged. He produced this from Foretravel.
Said he has kept the boost switch on for years with no issues.
Keith
While the boost switch CAN be used to charge the chassis batteries, it is not what I would call "the preferred method".
If shore power goes down, BOTH battery banks discharge. Now, neither engine nor generator can be started.
I much prefer to see either a "smart thief" like the Xantrex Echo charger OR a good quality small-output smart charged specifically/only for the chassis batteries.
That's exactly what I told him from info learned here.
Keith
Potential problems I see with boost switch on all the time or for long periods,you go out 24 hours before a trip and turn it on,your
2 house batteries are fully charged from the inverter/charger,now your charging the 2 house batteries that are already fully charged.If your start battery is a AGM you should be using a charger that is designed for AGM batteries for optimum life.Plus all the things Brett thought of.
Using a PowerMax and now a Progressive Dynamics converter, our AGMs house batteries are 13 years old with no issues and no special settings. Our jumper keeps the engine batteries up at the same time.
Pierce
Wow, that's impressive. At 5 years our Gels have approx 80% of original AHs. What % of original capacity do you think you have at 13 years?
Wyatt Sabourin. I can hear you laughing. :D
Slight but similar topic, I have been meaning to post this. How would one test their boost switch is working ? I searched and one said to put in a digital volt reader in the cig lighter and see if there is a jump when the switch is on. I tried both cig lighters and the voltage did not change.
I use a 10 amp draw test light take the cables off one side, turn the boost on and
put the test light on the lug that I removed the cable from and if light comes on
the boost works.
My starter turns over faster if I use the boost.
Keith
If it does, you have a fault in the batteries, terminals, cables or starter. I've tried ours on both and there is zero difference. If you have more CCAs than the Cummins CCA recommendation for your engine, something is wrong. Check cranking voltage.
Pierce
Bumping this (can you tell we're collecting spares/zero-ing out the new coach? ;) )
Would this still be the recommendation today?
Not the original poster that shared this but I would recommend these. I had gone through a number of relays in trying to do a battery disconnect on my Tahoe. Finally got he Blue Sea 7701 and it has lasted. The problem I see in using the 7701 for battery boost is existing wiring. In order for this switch to work you need at least 3 wires to the unit. 1 ground, 1 with 12v momentary for on, and 1 momentary for off.
I am getting the Blue Sea 9012 for my HWH power solenoid for the hydraulic pump. I had to replace the HWH ones about 6 years ago with new HWH ones. They are starting to act up again so figured I would get better solenoid this time around.
What were your voltage readings? If plugged in to shore power with the charger on you should be in the 13+ voltage range. With no charger on your chassis batteries you should be in the 12.5-12.7 range. If both are in the 13+ range before starting there is a good possibly that your chassis batteries have a charger on them, or your boost switch is stuck closed (connected)
Yes - I would still recommend this combination. As Turbojack states in Reply #41 (above) the 7701 does require some additional wiring. Nothing that can't be accomplished with a little basic ingenuity. I detailed the installation of my 7701 in the initial post in the thread linked below:
'93 U280 Isolator Panel Upgrade (https://www.foreforums.com/index.php?topic=34743.0)
If putting in the blue sea 7701 you can get rid of the isolator and use the existing cables and both
sets of batteries will charge from either alternator or the inverter charger.
My experience is that any manual way to charge the chassis batteries will finally be forgotten or fail.
Finally went the full route like the new coaches have and put in a blue seas ACR 500 amp magnetic switching relay
Factory boost takes 3amps to keep it connected.
My guru buddy connected the optional starter lug wire from the starter relay to the ACR so that the batteries do not auto connect when starting unless selected to connect. He had a customers coach chassis batteries failing that were being covered up by the auto connect. Did not know they were failing as using both banks covered that up. Pretty smart of Blue-Seas to have that lug on their ACR so you can select to have the starter only use the chassis batteries to start.
The more involved part for me as I have no power in storage was to add a 1100 watt solar system and a PT100 Magnum energy solar controller. Other than corroded battery terminals for sure everything is charged correctly as the Battery Temp system adjusts the solar system charging voltage to the batteries based on their exact temp.
Turns out the pt100 cycles the batteries less in storage than the inverter would have if on shore power as the inverter lets the batteries run down then recharges them. The magnum RC lets them go down 10%? The Magnum ARC I think can be set to let them run down 5% if memory serves me.
Expensive but in my area, in shaky town, a for sure fully charged coach maybe a real necessity. No way out of my area if a disaster occurs. 3 freeway lanes and 30 million people.
the Blue Sea 7701 is automatic and can be done manually.
Sorry, but the Blue Sea 7701 ML is
not automatic - it is a manual control latching solenoid only.
ML Solenoid - 12V DC - Blue Sea Systems (https://www.bluesea.com/products/7701/ML_Solenoid_-_12V_DC)
The Blue Sea 7620 ML-ACR Automatic Charging Relay looks very similar and IS automatic. This may be the ACR to which Bob refers.
ML-ACR Automatic Charging Relay - 12V DC 500A - Blue Sea Systems (https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A)
Thanks Chuck it's the ML-ACR Automatic Charging Relay - 12V DC 500A - Blue Sea Systems that I
have.
As i posted under charge from any source to either battery banks the ML-ACR will remain combined while starting unless you run na sense wire from the starter relay to the dedicated lug on the ML-ARC which then uncombines the battery banks.
Under no charging and with any discharge occurring for a short period of time the combiner auto disconnects the banks so starting would only use the chassis batteries anyway
We elected to not run an additional wire from the ML-ARC to the front selector switch to light up when the batteries are combined.
I my case i have two led battery voltage led readouts installed in the dash battery voltage cigarette plugs. Not as fast indicating connect/disconnect as the switches led indication but running the wire would have been to much time and effort consuming.
This is the ultimate automatic battery combiner relay.
The switch is also lighted, so you know the status at a glance. It has both electric and mechanical forced combined or disconnect functions.
ML-ACR Automatic Charging Relay with Manual Control - 12V DC 500A - Blue Sea... (https://www.bluesea.com/products/7622/ML-ACR_Automatic_Charging_Relay_with_Manual_Control_-_12V_DC_500A)
You will find that most ACR relays with voltage settings based on typical alternator and also float charge settings. As fully charged AGMs and Lithium's will hold the relay closed. In practical use this works out really well for lithium house, AGM engine start combinations. When running with the inverter/charger energized and in float/power supply mode having the AGMs in parallel makes for a good combination to absorb voltage spikes. Unplugged the higher voltage from the Lithium's are ideal for the float maintenance of the AGM. I was planning and still considering going this route. However, the original diode block, Duvac set up is working well to charge the 600 A/H Lithium bank. It provides a level of current limit due to the uncompensated voltage drop across the diodes. I see the current is limited to about 120 amps which is reasonable for my 270-amp alternator.