Mixing Batteries?

larrygee

New member
So, I am about to change out my chassis battery and the shop recommended an AGM. Ok.

So I start reading other posts in the forum and I start seeing things that get me wondering so I have a few questions to make sure I understand what I am reading.

1) is there any reason why having an AGM chassis battery AND a wet cell lead acid HOUSE battery is a bad idea?

2) do AGM batteries require any SPECIAL type of trickle charger, designed for AGM only? I know some trickle charger are BETTER than others but I am asking if agm's require any unique type of charger.

Even though the house battery is connected to the chassis battery, I have trickle chargers on BOTH batteries.

3) Is this overkill? If I trickle the chassis battery, will it (since it's connected in..parallel?.)...charge the house battery?

Thank you in advance.
 
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georgelesley

New member
Larry, I don't see why the two types should be a problem. They are isolated from each other to prevent coach useage from draining the chassis battery and I have for years used two trickle chargers, one on each. Yes my understanding is that a lead acid battery needs a trickle charger that "floats" at 13.5. The one I have has that float voltage and has worked for years. Using this type of charger I have kept my boat deep cycle battery fresh over winter and never have had to add water. The same is true of lead acid batteries I have had on previous RV's.

AGM batteries from what I have read and found out from personal experience, yes I cooked one once, need a separate charger that "floats" at 13.2 volts. This past winter I used just such a charger on our two coach batteries with no ill effect.

I have checked the float voltage of both and verified the readings. Buy good chargers. I bought a cheapo once from harbor freight I think and it cooked the battery. Never again.
 

david_42

Active member
You will have to buy a trickle charger designed for AGM batteries and you'll need an isolation switch between the batteries. The advantages of using an AGM battery for the chassis are minor; I'd stick with a standard battery.
 

awaywego

2008 NCV3 2500
The AGM is maintenance free whereas in the std. batt. the levels will need to be maintained...it is a pain in the neck to open the compartment under the driver's feet to do that.
Furthermore, fumes from a std. battery could potentially be an issue because it is in the cabin as opposed to under the hood.
 

georgelesley

New member
The lead acid battery in our sprinter by the drivers seat is the sealed type, so fumes are very minimal, and water is never added. Trickle charging it is easy using the factory jump starting posts in the engine compartment. Before I spent big bucks on an AGM for the chassis battery I would price out sealed lead acid unless the new ones have an AGM original equipment. Our 2013 has sealed lead acid.
 

Old Crows

Calypso 2014 View Profile
I would replace it with a sealed lead acid battery. Exactly like the OEM. The Sprinter electric system is fussy enough without adding an unknown quantity at the heart of the system.
 

ChiefNic

New member
LarryGee asked,
"Even though the house battery is connected to the chassis battery, I have trickle chargers on BOTH batteries.
3) Is this overkill? If I trickle the chassis battery, will it (since it's connected in..parallel?.)...charge the house battery?"

I'm a new Spinter owner, 2008 Gulf Stream Vista Cruiser on 2007 Dodge/Freightliner chassis. Is the house battery the one under the hood, and the chassis battery under the driver's floor? I was told the one under the floor is the 'starter' battery. Is there a way trickle charge both at the same time? I have solar panels charging a bank of 4-golf cart batteries. I thought these were my 'house' batteries. How can I use that charging source to charge my 'starter' and 'chassis' batteries at the same time?
Thanks for you help and patience.
 

larrygee

New member
LarryGee asked,
"Even though the house battery is connected to the chassis battery, I have trickle chargers on BOTH batteries.
3) Is this overkill? If I trickle the chassis battery, will it (since it's connected in..parallel?.)...charge the house battery?"

I was told the one under the floor is the 'starter' battery. Is there a way trickle charge both at the same time? I have solar panels charging a bank of 4-golf cart batteries. I thought these were my 'house' batteries. How can I use that charging source to charge my 'starter' and 'chassis' batteries at the same time?
Thanks for you help and patience.
My batteries are under the drivers side floor mat and under the seating bench in the rear of the vehicle. I have a 2008 chassis with a 2010 build date.

I think what I learned from reading various posts is that due to something called an isolator, which apparently segregates the house and chassis battery, you can't charge both batteries with one charger. Where I get confused is by some posts that suggest that if you leave the 12v switch on yr panel to the ON position, then perhaps it removes the isolator from the equation and you can charge both batteries with one charger. :idunno:

I just decided to put a multi stage charger on each battery. I have each charger plugged into a power strip and from there to a long extension cord. I put ring connectors on both batteries with an SAE plug on the ends to make quick disconnect easy..

Good luck...
 

aljimenez

'13 LTV Serenity on '12 3
Please read my previous post and its links for a much much cheaper solution that works. Your proposal will work but unnecessarily very costly and with much weight added to your vehicle.
 

Old Crows

Calypso 2014 View Profile
LarryGee asked,
"Even though the house battery is connected to the chassis battery, I have trickle chargers on BOTH batteries.
3) Is this overkill? If I trickle the chassis battery, will it (since it's connected in..parallel?.)...charge the house battery?"

I'm a new Spinter owner, 2008 Gulf Stream Vista Cruiser on 2007 Dodge/Freightliner chassis. Is the house battery the one under the hood, and the chassis battery under the driver's floor? I was told the one under the floor is the 'starter' battery. Is there a way trickle charge both at the same time? I have solar panels charging a bank of 4-golf cart batteries. I thought these were my 'house' batteries. How can I use that charging source to charge my 'starter' and 'chassis' batteries at the same time?
Thanks for you help and patience.
Chief,

I think you are overthinking the issue.

OEM...The starter/chassis battery is under floor next to driver's seat. The house battery is under the hood.

The 4 battery bank / solar charger is an add on? If you have a solar charger for the battery bank, why do you need a trickle charger? The solar panel/regulator should keep those puppies in a full state of charge .....

The starter battery is charged off the alternator. It is a "storage" battery and should be good without trickle charging for 30-45 days if it's in good shape. The alternator should also charge the the house batteries if they are not drained badly.

Unless your RV is going to sit for 4-6 months at a time I'm not seeing the need for the needless complication of redundant charging systems. Seems like a bunch more failure points to me.....

Is this your RV? http://www.gulfstreamcoach.com/towablelanding/brochures/2007/2007 Vista Cruiser Mini.pdf
Even less so, if your RV has a generator set. You can top off the batteries just by running the generator every 4-6 weeks.
 
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ChiefNic

New member
Yes that's my RV, the Model 4230. When we bought it last year, we upgraded the RV battery capacity and added two 160 watt solar panels. It seems to me to be a waste of capability if the solar panels don't also trickle charge the chassis and/or house battery while also keeping our bank of 6v batteries charged. Am I correct that when I'm on a shore line or running the generator neither the chassis or house batteries are being charged? We want to get AC power from the battery bank through an inverter to power a portion of our AC circuit, and I would like to learn how to do it myself.
Thank you for your thorough response.
 

ChiefNic

New member
Back to "Mixing Batteries", I discovered that my 'starter battery' in the floor under the driver's feet is an AGM battery and the house battery under the hood is a regular lead/acid battery. They look to be identical dimensions and the power ratings are similar. Is this going to cause me problems? Is there any benefit to this arrangement?
 

larrygee

New member
Not sure what you mean by the similar power ratings but what I've gathered from this rather well educated group is that there is no problem having an AGM battery start battery and a lead acid for the house. There was one poster who suggested that an AGM start battery was not "standard issue" and could affect your Canbus system but I didn't read anything supporting that argument.

What is important is that your house battery be a deep cycle battery, to support the constant draw demands.

Hope that helps...
 

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