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Topic: Replacing Chassis Batteries (Read 625 times) previous topic - next topic

Replacing Chassis Batteries

In other threads, I have discussed and received good advice about replacing my coach batteries and my alternator. Now it is time to determine if my chassis batteries need to be replaced.
 
I now have two yellow tops. Because of the problems I have had with the alternator and coach batteries, I had assumed that the chassis batteries might also need replacing. They have not been properly charged because the chassis charging system has not been functioning. I have "boosted" them with the coach batteries to charge them with the generator running. Because of the degraded coach batteries, I am afraid that may have harmed them further, but do not know.
 
The voltage across the battery pair is about 12.1 volts. I have purchased an HF load tester and attempted to check each of the batteries separate from the other. The method I used was to remove the negative terminal cable from the first battery (black circle) and then remove the positive terminal cable from the second battery (red circle). I do not have real-world experience at isolating two parallel batteries from each other, but, theoretically, this would seem to accomplish that.
 
I then attached the load tester to the first set of battery terminals and held the load test button for about four seconds. I then attached it to the second set of battery terminals and held the load test button for about four seconds. (I was surprised at how hot the load area of the tester got!)

In both cases the meter read 12.1 volts, which was just barely in the green area (good) of the display. When I applied the load, in both cases, the meter went to 10.6 volts which was in the yellow area (weak) of the display.
 
The big question is what do these results mean? Are the yellow tops "good enough" or do they need to be replaced? Keep in mind that I am installing three new Lifeline GPL-8DA batteries, so even if the chassis batteries are not real strong, the boost button will let me start the engine. Until I determine what is wrong with my chassis charging system, I could also charge them with the boost button.
 
If they need to/ should be replaced, could I replace them with another new Lifeline so all four of my batteries would be the same? The CCA specs for the Lifelines seem to be adequate for the task. If that is not advisable, I may try the new Interstate MT7 agm's which come with a 48-month full replacement warranty. Otherwise, I could just buy two new yellow tops, which Sam's Club sells for about $200 each.
 
I appreciate any feedback that y'all are willing to give me.
 
Thanks,
 
Trent
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Replacing Chassis Batteries

Reply #1 –
Trent you need to remove all the battery cables then test each battery separately. Looks like your reading of 12.1v no load indicates a somewhat discharged set of batteries. Also you need to charge the batteries to a full charge some were about 12.50-60v no load the recheck them at 50% of the CCA. As you have already made a substantial investment in batteries, might be worth the piece of mind to replace them with new AGMs for the piece of mind if they are over 3 or 4 years old. Also if one of them is bad you need to replace them both, you battery bank is only as good as the weakest battery.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Replacing Chassis Batteries

Reply #2 –
I too may be ready to replace my starting batteries.  I have a bank of three red top optima batteries.
They have been really good as they appear to be the original in my 02 coach.  Went to storage and had not put on the trickle charger and the coach had been there for about a month.  Turned the key and only a little movement and clicking. Pushed the boost switch and still the same.  Turned on the 24 volts at the door step and the boost started it right up.  Now my trickle charger indicates to ck battery.  It has been said that these Optima batteries are not made the same now so I am looking at other brands.  These batteries are about twice the cost of regular batteries but I just want to install and forget. Maintenance free is a must.  Any brands are best??
Dan & Shirley Stansel
2002 U295 4020 AGDS Build#6054
Towing Buick Enclave & M &  G Braking
Emerald Bay, Lake Palestine, Texas
MC# 16650

Re: Replacing Chassis Batteries

Reply #3 –

Once you get those expensive batteries - permanently install one of these Day one if you are plugged in while stored most of the time -if not go with echo charger or trickle start (I had bad luck with both.....)

Amazon.com: BatteryMINDer Charger/Maintainer/Desulfator System - Model# 1500:

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Replacing Chassis Batteries

Reply #4 –
Trent, those connections with the red and black circles are not the ones going to the coach terminal and ground connections. there is still 12v going to the coach. You only say you removed the ones marked. maybe you meant to say that you repeated this on the other one as well before testing them  UNCONNECTED
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Replacing Chassis Batteries

Reply #5 –
John,

I did not disconnect the battery bank from the RV. What I attempted to do was isolate each of the batteries from the circuit so that I could load test each of them to determine their individual capabilities.
 
I removed the black circled terminal connector (using the handy dandy plastic strap to keep it away from the battery bank) and load tested the first battery by connecting my meter from the (now) empty negative post and attached the other lead to the cluster on the positive terminal of the first battery.
 
I then removed the red circled terminal connector and load tested the second battery by connecting from the (now) empty positive post of the second battery and attached the other lead to the cluster on the negative terminal of the second battery.
 
With my limited electrical system experience, this seemed like the easiest method to isolate each of two batteries. One of the reasons I posted the details was so that those of you who are more experienced than me could let me know if I had accomplished what I set out to do.
 
Afterwards I reconnected the two previously removed connectors to their respective battery terminals. I was then able to drive Ducky out of the gate to mow the lawn before returning Ducky to his temporary home.
 
As always, I appreciate any feedback from others with  more or different experiences with their Foretravels. That is part of what makes this forum such a positive resource for us.

 
Thank you for your feedback,
 
Trent

 
 
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Replacing Chassis Batteries

Reply #6 –
Do you have a battery disconnect (switch) on both systems? 
Do you store without plugging into a SMART charger? 
Before replacing a battery, ensure it has been fully charged (at the proper voltage) for several days. 
A large percentage of the issues with batteries is that they rarely get fully charged.
Older inverters do not put enough voltage to a battery for long enough to bring it to the proper level.
Do you have a TriMetric Battery monitor w/temp sensor?

Handy Bob's blog is a good place to acquire DC knowledge.  pc





S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..

Re: Replacing Chassis Batteries

Reply #7 –
Quote from: pocketchange –
Do you have a battery disconnect (switch) on both systems? 
Do you store without plugging into a SMART charger? 
Do you have a TriMetric Battery monitor w/temp sensor?

Handy Bob's blog is a good place to acquire DC knowledge.  pc

Pocketchange,
 
The answer is no to all three of your questions.
 
I will look for "Handy Bob's" blog.
 
Thanks,
 
Trent
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385
 

Re: Replacing Chassis Batteries

Reply #8 –
HandyBob's Blog « Making off grid RV electrical systems work

Good info make an informed decision ^.^d
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My advice and experiences are Free, you decide if they are worth anything .

John - driving Old Faithful
1994 U280 GV
C8.3, Banks, Pacbrake, 900 watts, Resonator, XLHD tow dolly
Retired Army Warrant Officer

Life is what you make of it - if it is lemons, make lemonade!
Former Coaches:
1988 GV 40' ORED 300HP CAT - 9 years
1990 Winnebago LeSharo - 3 years
2000 Newmar London Aire - 3 years (#18 of 23 produced)