BCM Community
Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Mike in GA on November 02, 2014, 04:12:46 PM
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My literature from Lifeline says the charge rate for the new batteries should be on bulk between 28.4 and 28.8 volts. On float they stipulate between 26.4 and 26.8
The voltage put out by the bus alternator today after a one hour run was 27.8 volts so I guess the screw on the voltage regulator needs adjusting.
Question - do I choose to raise the alternator output to the required bulk rate, or lower it to the float rate?
I usually only hit the batteries going down the road for a couple hours max, so my guess is the higher rate.
Will either change affect the flooded wet cell coach/start batts?
Thanks in advance for the shared wisdom.
Mike in GA
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Mike, I haven't looked at this closely but my first instinct is to add a separate alternator for the "house batteries" and set that for AGM. You'd have redundancy and a source of charge that you can set to the exact needed voltage.
But that may be over-thinking.
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Hi Mike,
You could easily install a switch on the dash along with a volt meter for the house bank and simply
flip the switch off when you think the bank is where you need it. This will allow the start batteries
to continue to charge normally from the engine.
Another option would be to install AGM's for your start bank and set the alternator accordingly.
Good Luck
Nick-
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Check out the Balmar systems i seem to remember they had a system for that problem
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I set my alternator to suit the start batteries and I set the inverter to suit the house batteries. That high charge rate for the AGM's will damage the start batteries long term. The lower voltage for the start batteries won't damage the AGM's, so that's where I go.
Brian
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We don't have the full picture of your system. Is the engine alternator the sole charging source for your house batteries or do you have a decent solar system to top them off.
Realistically it is rarely possible to fully-charge house batteries from the engine using a simple connection because the alternator characteristics are set so as to not overcharge the start batteries during continuous running (which is what passenger buses are built for)
Also - there are two parameters involved in battery charging. There is charge rate in Amps, and end of bulk charge voltage (and of course float voltage as well) and you don't have much if any control of either of these with a simple alternator system. If you have a shunt and ammeter and voltmeter installed in your house battery circuit you would be able to know exactly what you are achieving. Voltage by itself isn't much help.
On my MCI, after a few days camping without decent solar input, the alternator puts about 160 amps into the 520Ah battery and this tapers off over the first 90 minutes to about 50 amps at which point the battery is still only less than 50% charged so the current has never been high enough to cause problems with the AGM battery. I generally isolate the alternator charging not long after that and let the 600W of solar finish the job.
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Tony not many have solar systems on their buses, very few I think. My engine charging system keeps my house batteries full when on road, thought most did.
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So last week, I was messing with my fan vent in the bathroom and if you recall, I was having air line issues to my front airbags. So I had my gen running to get power to the fan and I was doing this while on lunch break. So I turn off gen and go back to work. I forgot to turn off my house battery power and inverter. It wasn't until a few days later that I remembered and drove back and sure enough my AGM 2 batteries were near dead. I just bought those last year so I was looking at a $700 stupid mistake.
Once I got the air line fixed, I got it back to my house so I could put my battery charger on them. It took a good 4 days for my charger to get one of the batteries to 100%. I'm currently charging the 2nd one now.
From what I read, AGM recharging is a slow charge rate but I'm just glad they are taking a charge.
I know most in here are vets in the bus world but please tell me I'm not the only one that has been a dummy and left something on before? I've basically drained every battery except for the gen battery and I'm including the TOAD.
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I left the vanner connected and it discharged my batteries to 1.5 volts. They came back, though. Rolls battery suggests that a 12V AGM should be charged at around 14.8 volts and 0.2 - 0.3 times the 20hr AH rating in amps. So a 200 AH battery would be charged at 14.8 volts and 40 - 60 amps. http://support.rollsbattery.com/support/solutions/articles/4345-agm-charging
Slower is fine. AGM's are designed for deep discharge (to 20% SOC) and have a reputation for recovering from bad things. If their gas relief valves have popped, the battery is usually considered done for.
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please tell me I'm not the only one that has been a dummy and left something on before? I've basically drained every battery except for the gen battery and I'm including the TOAD.
You are definitely not the only one, but after you ruin a few, the memory gets better. My main problem has been trickle chargers that start draining the battery if the power goes off (and you have to remember to disconnect them when there is a power outage). ???
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Leaving things turned on, is like leaving the house without your pants on...
You had to be taught modesty, it took a lot of effort by our parents...
You have to teach yourself that there is ALWAYS a shut down process that MUST be followed, EVERY TIME.
Not a hobby for those lacking in self discipline?
Or, spend a lot of bu$ buck$ repeating purchases that you already made...
Happy coaching!
Buswarrior
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I think it's safe to say that this mistake should scare me straight and to take my time when shutting down. The ironic thing is the past month, I've been trying to make sure everything is right for my first dry camp at Talladega races.
The one good thing about this is if it didn't happen, I would have had that air issue as I was getting ready to leave for the races which would have given me little time to fix. That being said, I don't want to get in the habit of draining these batteries b/c I'm told that they are great batteries but don't like to be drained all the way down.
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There are cutoff devices that will disconnect when voltage drops below X. Plus, you should be able to nurse the batteries back to life since the duration of total discharge is not long, not like being discharged for months or years.
BW - "Not a hobby for those lacking in self discipline?"
Was that supposed to be a statement rather than a question?
In a perfect world, a the novice bus conversion nuts would have sufficient extra time/energy to devote to practicing bus operator skills. The reality is many do not have even enough time to just take a journey much less extra time to practice such that there is "self discipline" imprinted in the rote memory cells in our brains.
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You've read enough forums and social media sites.
The same people murdering batteries over and over, spending a lot of money unnecessarily, and if enough of them keep typing, it appears to be normal for the new busnut?
Will not those lacking in self discipline be spending a lot of money that could be spent on other things?
Happy coaching!
Buswarrior
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I spent 23 years in the army buswarrior so blanketly stating I lack self discipline is bullsh*t. If you think that anyone that makes a mistake or overlooked something falls into that category then I would like to know how it feels to be so perfect in life. Sitting pretty high on your horse judging like that.
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Settle down.
No insult was intended.
The last thread should have started with, "windtrader, you've read..."
The discussion is about all of us, existing and intending busnuts.
It ain't easy being a busnut.
Happy coaching!
Buswarrior
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Fair enough...
I'm just having a heck of a day dealing with metrics and corporate today. Ironically, it's taking a lot of self discipline to not tell corporate to shove it!
;D
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As the proud new owner of an AGM bank this topic interested me. I eventually found some spec sheets saying same for charging voltages 14.4-14.8v 13.6 float.
As far as keeping things charged, solar , I'd think even 300-400 watts would do fine. Right now I've got my 2000 watts keeping my electric water heater on as well as the fridge and other stuff while the bus sits in the driveway. I was down to 80% soc over night, should be up to
Here is the bank if anyone is interested.
https://www.youtube.com/watch?v=PZCPSNnoDns
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Used to be that the military used a lot of checklists, I doubt that has changed. We'd have a checklist for going to the john, I swear. OK so that's overdoing it but the point is valid, for those more important things (like making sure the batteries don't get drained unnecessarily) a checklist is still useful. If you make up a medium sized card, laminate it, put it on a string or chain so it can't wander, and then put it in a prominent place then you only have to make a habit of looking at it every once in awhile and soon you will know it by heart. Better still you can add those things that you keep asking, "Now which way did it go?" and remove the doubt.
Jim
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Used to be that the military used a lot of checklists, I doubt that has changed. We'd have a checklist for going to the john, I swear. OK so that's overdoing it but the point is valid, for those more important things (like making sure the batteries don't get drained unnecessarily) a checklist is still useful. If you make up a medium sized card, laminate it, put it on a string or chain so it can't wander, and then put it in a prominent place then you only have to make a habit of looking at it every once in awhile and soon you will know it by heart. Better still you can add those things that you keep asking, "Now which way did it go?" and remove the doubt. Jim
Since I'm entering my 54th year of being a licensed pilot, I have checklists for many things on my bus. But since I'm old enough to have been a pilot for 54 years, I have trouble remembering to use them.
(PS Mfr. of my AGM bank says charge at 14.4, float at 13.6 +.2/-0.)
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Then I guess all hope is lost. Remind me not to fly with you! :P
Jim
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Mike, I haven't looked at this closely but my first instinct is to add a separate alternator for the "house batteries" and set that for AGM. You'd have redundancy and a source of charge that you can set to the exact needed voltage.
But that may be over-thinking.
And that is why my starts are my house(well one reason).
I have 2 8ds now but have had 4. Depends on my plans/needs.
DEKA Marine AGM
Going on 8 years. This set. 16 years of combined.
probably looking for new soon.
PS Mfr. of my AGM bank says charge at 14.4, float at 13.6 +.2/-0.)
PS. My charge rates are the same...my inverter/charger and alternator are set to (pretty close) those parameters.
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I'm still at the beginning of my bus project and i have been thinking for a while about this battery bank vs alternator charging.
Since AGM batteries need a special charging algorithm, an alternator alone won't do!
What i'm thinking about for the house batteries is to have separate charger for each battery fed by an inverter or two or shore power.
Maybe four 8d (AGM). While under way, the alternator (let's say 450-500 amps 24v) would fed the inverters to supply 110-120 VAC to fridge, water heater and battery chargers. For sure it would require a lot of high amps relay to isolate each battery in the bank while in charge mode.
What do you think ?
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Personally, I'd never run a battery charger from an inverter. You're just layering loss on top of loss.
If you want to have something between the 24v chassis batteries and the AGM house batteries, then get something like this:
https://www.sterling-power-usa.com/SterlingPower24volt-to-12volt-dc-to-dc-batterytobatterycharger.aspx
We're using one to charge our 780 Ah 12v battery bank from the chassis alternator while underway. Allows us to push up to 70 amps to the battery bank, which for ours is just the right size charge. (Trojan recommends about a 10% charge for flooded cell).
The Sterling battery-to-battery charger can be setup to charge AGM batteries, it's a smart multi-stage charger, and it makes the whole thing really simple. Ours is connected in a way so that I've got to flip a switch to start the charging, but out of the box it will automatically charge when ever the chassis alternator is putting out a charging voltage.
The 120v battery chargers should be used only when on shore power or on generator power, not from another battery. Not sure why you need a separate charger for each battery either - just get one large enough to handle the whole battery bank and wire them all in parallel to each other.
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I'm still at the beginning of my bus project and i have been thinking for a while about this battery bank vs alternator charging.
Since AGM batteries need a special charging algorithm, an alternator alone won't do!
What i'm thinking about for the house batteries is to have separate charger for each battery fed by an inverter or two or shore power.
Maybe four 8d (AGM). While under way, the alternator (let's say 450-500 amps 24v) would fed the inverters to supply 110-120 VAC to fridge, water heater and battery chargers. For sure it would require a lot of high amps relay to isolate each battery in the bank while in charge mode.
What do you think ?
I'm by no means an expert if you have ever read any of my posts but I'm confused with your statement. As long as I'm either connected to shore power or running the generator, my inverter charges my 2 house AGM batteries. My assumption is that's the norm when having an inverter but maybe I'm wrong about it.
My alternator charges my start batteries btw.
I don't understand why you think you need a separate charger for your house batteries.
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I'm by no means an expert if you have ever read any of my posts but I'm confused with your statement. As long as I'm either connected to shore power or running the generator, my inverter charges my 2 house AGM batteries. My assumption is that's the norm when having an inverter but maybe I'm wrong about it.
My alternator charges my start batteries btw.
I don't understand why you think you need a separate charger for your house batteries.
Sounds like you have an inverter/charger. When you are plugged in, it acts like a charger for your house batteries. When you're not plugged in, it draws from your batteries and puts out 120vac. To contrast what you've got, our system uses a stand-alone charger that will charge the house batteries when we're plugged in, and a stand-alone inverter to make 120vac from the batteries when we're not.
Seemed like to me that he was going to use the chassis 24v system to power a couple of stand-alone 24v-to-120v inverters, and then use those inverters to power a couple of stand-alone 120v-to-12v battery chargers. That's why I recommended he skip the middleman (inverter) and just use a 24v-to-12v charger.
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I was just being too paranoid about batteries imbalance. You know, separating each battery for them to be charge by an intelligent charger.
I guess trying to achieve perfection is overkill...
Yes, will look at the Sterling products. Thanks !
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...Yes, will look at the Sterling products. Thanks !
If you have questions about the Sterling products, don't hesitate to call the number on their website. The guy that does their US sales seems to know his stuff and he was quite helpful when I was setting mine up. Their chargers give LOTS of options for how to set up.
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Sounds like you have an inverter/charger. When you are plugged in, it acts like a charger for your house batteries. When you're not plugged in, it draws from your batteries and puts out 120vac. ...
Yes, Brad, you have an inverter/charger, as Richard describes. That's the "default" for most installations (bus conversions, service vehicles, specialty vehicles like mobile classrooms or bloodmobiles, etc.). But some people prefer to have a separate charger for specific control of the charging; other people prefer to use models of inverters (brands like some models of AIMS, or Power Jack, for instance) that don't have chargers as part of their design.
You and I - and probably most other people that we'd meet at a bus rally - have inverter/chargers but; when we're talking about specifics of systems, it's probably good to remember that system types vary and a few people have systems that don't involve an inverter/charger, so when we're talking about those, their charging setup will be different.
I have a 2kW "Outback" inverter/charger that has very good control of house battery charging; there is a separate control module that allows a flexible range of settings. That part is really good, some of the other design characteristics and features of the inverter, I'm not so crazy about.
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I have an old Trace 2512 modified sine wave inverter with 3 stage charging. I have 2-8D Lifeline AGM. I have the charge set at 14.1v max, and 13.2 float. First set lasted 7 years (with 5yr warranty). Now on second set.
Now starting to look at Lithium Iron batts. About 1/3 the weight, but about 5 times the cost of AGM. Good Luck, TomC
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Yes, Brad, you have an inverter/charger, as Richard describes. That's the "default" for most installations (bus conversions, service vehicles, specialty vehicles like mobile classrooms or bloodmobiles, etc.). But some people prefer to have a separate charger for specific control of the charging; other people prefer to use models of inverters (brands like some models of AIMS, or Power Jack, for instance) that don't have chargers as part of their design.
You and I - and probably most other people that we'd meet at a bus rally - have inverter/chargers but; when we're talking about specifics of systems, it's probably good to remember that system types vary and a few people have systems that don't involve an inverter/charger, so when we're talking about those, their charging setup will be different.
I have a 2kW "Outback" inverter/charger that has very good control of house battery charging; there is a separate control module that allows a flexible range of settings. That part is really good, some of the other design characteristics and features of the inverter, I'm not so crazy about.
Thanks to Richard and you. I assumed that all inverters were also chargers.