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hunkaman

Coach battery charging

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I have a couple of questions regarding the charging process on the coach battery. I assume the coach battery is being charged as you are driving (?) but is the coach battery also being charged when plugged into shore power?  If the coach battery IS  being charged while on shore power, is the truck (starting) battery also being charged?  If and when you need to replace a coach battery, do the newer "gel" type batteries have an advantage over the conventional "acid/water" filled batteries? Furthermore is a deep cycle battery preferred for a coach battery over a non deep cycle? Are deep cycle "gel " type batteries available? I am sure some of my questions have been answered before, thank you for your time.  joe from dover

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Charging from converter yes, charging from running truck yes, charging truck battery with converter no, gel battery is fine (cost is greater than flooded battery by a factor of 2),  deep cycle yes.  A sealed battery AGM etc. usually lasts longer but to me it would have to last a lot longer to make up for the price a standard flooded battery they are good for about 5 years under normal use.

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47 minutes ago, Maineah said:

... charging truck battery with converter no,

Unless the standard issue 'battery isolator' wiring is modified so that the truck battery is no longer isolated.

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10 hours ago, Derek up North said:

Unless the standard issue 'battery isolator' wiring is modified so that the truck battery is no longer isolated.

IF you modify it, sooner or later you will forget to "unmodify' it for and a long drycamp and be stuck in middle of nowhere with a dead truck battery.

 

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maineah, when you say, "charging from" and "charging with" converter, i assume you are referring to an on board factory installed converter.  sorry for my ignorance. i am trying to become more educated in the ways of the motorhome, and no better place than here thanks to all of you. joe from dover

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13 hours ago, WME said:

IF you modify it, sooner or later you will forget to "unmodify' it for and a long drycamp and be stuck in middle of nowhere with a dead truck battery.

 

And a coach battery too!

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39 minutes ago, hunkaman said:

maineah, when you say, "charging from" and "charging with" converter, i assume you are referring to an on board factory installed converter.  sorry for my ignorance. i am trying to become more educated in the ways of the motorhome, and no better place than here thanks to all of you. joe from dover

Yes the onboard charger, it doesn't charge the truck battery because when the engine is off the truck battery is disconnected from the coach battery by the isolator this keeps your truck battery from being discharged when you are stopped by the electrical stuff in the coach it better to have no lights than a truck that won't start in the morning. When the truck is running the isolator is "on" so at that point both batteries are being charged by the truck when you stop the engine the isolator is "off" so the batteries are not longer connect to each other.

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I have the same camper.  Your house battery should be charging while driving.  Use a multi meter to check.  Or turn on cabin lights, start engine - they should get noticeably brighter with engine running.  Wiring between engine battery and cabin battery is fairly straight forward.   I can tell you that it would take a lot of driving to keep a cabin battery charged.   The standard wiring has the engine battery positive terminal  wired to the positive terminal on the cabin battery.   Modern charging circuits have the alternator measuring voltage at both batteries.  On our toys, when the engine battery is full charged, the alternator is reducing output even though the cabin battery may be quite low.  Essentially the cabin battery is being trickle charged.

 

While on shore power, the standard power converter powers a rectifier that provides 12v dc to operate all dc cabin items.  It also isolates the cabin battery and charges it.    Again when the 120v ac is turned on the cabin lights should get noticeably brighter.

 

A word about about deep cycle batteries - they will last longer if kept fully charged and not run all the way down.

 

I would take a basic multimeter and  check the engine to house battery circuit.  You should have about a 1/2 volt drop in measure voltage from the engine battery to the choud battery.  The drop is at 2 circuit breakers and at the isolater solenoid.  Note that even though that solenoid looks like an old ford starter solenoid it is significantly. The ford starter version is high draw/ shot duration while the rv version is low draw/long duration.

Edited by DanAatTheCape

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Yes it is a long process to charge a coach battery and the alt does relay on the truck battery for regulation but the batteries will charge one another as long as they are joined to the point of equalizing but that too is a long process it's not going to happen going to the store and back.

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I have the same motorhome. I remove the isolator and the 10 gage wire between the truck battery to couch battery.I have replace with the cteck d250s dcbattery charger and the 2 gage welding cable. Like dan say's the alternator is reducing output .but the ctek raise the voltage to 14.4 volt until the couch battery is 80-85% charge.It work very well for me, it's 20 amp max but i see 22 on my clamp meter.

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As others have mentioned before the older stock converters that came standard are piss poor battery chargers.

They will boil a battery if left on too long; i look at them as more of a topper or float charger. Mine also is weird; only puts between 13.5-13.8 volts on the coach battery, which is low and not optimal for a full charge.

The other day i had a bad alternator experience in my dodge ram 2500, went through all the hassle of replacing the alternator only to find they had a "fusible link" posted 160 am fuse inline; waste of a day and busted knuckles.. but the one good thing? i grabbed a new battery charger from autozone (which i despise but i had a coupon) and its unlike any other charger I have tried.

ive recently had schumacher and battery minders go bad (probably from my trying to bring dead lawn tractor batteries back being a cheapo) and tried this one:

http://www.autozone.com/test-scan-and-specialty-tools/battery-charger/duralast-battery-charger-with-engine-start/58755_0_0/?checkfit=true

I love it. and I absolutely hate admitting that i love anything with a "duralast" label but this thing rocks.

what attracted me to it was its charge amp abilities, capacity monitor, alternator tester and sever other features. It does progressive charging all the way to 20 amp and will back it down based on the batteries resistance or manually by type setting so you dont fry your smaller tractor batteries. My ram has 2 huge "maintenance free" batteries and on my max setting of 10 amp of the old schumacher would take days to charge, now on this one only hours. It doesnt have a desulphator but I am a big believer in the wiz bang ones anyway so it was perfect.

 

I love that it will display the battery in volts or as a percentage of capacity of charge. When it shows 100% you are good to go. I noticed the batteries i charged with it all seem to really have good stamina now too..excellent unit. no reviews on it yet either so it was a long shot. I'll continue to beat on it and see what it can do.

 

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