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Topic: Jump starting chassis batteries (Read 1392 times) previous topic - next topic

Re: Jump starting chassis batteries

Reply #25 –
Just a thought, I had the same issue with mine , did a battery test and had a bad cel replaced the battery and bingo . Good luck
Andy & Eileen
MONTROSE COLORADO
1992 U300  40' 6V92 TA
2016 4 Runner
1998 Jeep Grand cherokee

1998 Jeep Grand Cherokee) Build # 4135 Skp# 122921

Re: Jump starting chassis batteries

Reply #26 –
Steve,

AFAIK, the Blue Sea "battery link" and the (replacement?) battery isolator on your coach are not original factory equipment.  Someone has made changes to the OEM charging setup.  It appears odd to me because that Blue Sea device (which is connected to both battery banks at the BOOST solenoid) is normally utilized to serve the same basic purpose as a battery isolator.  Why does your coach have both of them?

BatteryLink™ Automatic Charging Relay - 12V/24V DC 120A - Blue Sea Systems

The fact that your coach is no longer "stock" makes it harder to do remote diagnosis of your problem, because we don't know what was changed.  The changes might constitute an "upgrade", but no way to know.

It sounds like you are not getting sufficient amperage at the starter to crank the engine, OR the starter solenoid is not getting the signal to "crank" from the ignition switch.  This could be caused by:

1.  Bad battery cables, or bad/corroded/broken cable connectors.
2.  A malfunctioning Aux Start Relay.  See B-2126 Wiring Diagram linked in Reply #20 in this thread.
    NOTE:  The Neutral Start Switch must operate correctly to give Aux Start Relay "permission" to close. 
    NOTE:  Even with adequate battery volts/amps at the starter, if Aux Start Relay fails to close, turning ignition key to START will not crank engine.
3.  Loose or broken cables or loose/corroded connections (POS and GROUND) at the starter solenoid.
4.  A malfunctioning starter solenoid (located on the starter).

There is no "easy" way to figure this out.  You need to pursue a logical trouble shooting process.  Start at the batteries, and verify the proper operation of the starting power circuit all the way to the starter motor.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Jump starting chassis batteries

Reply #27 –
Quote from: Chuck & Jeannie –
All I can tell you is it sounds like you are not getting sufficient amperage at the starter to crank the engine. 

Looks like you've got the big Red Cummins ISL 9 450. This engine needs around 1000 amps to start (manual recommends min 1250 CCA).

Jumping to a running car for say 20 minutes should charge good chassis batteries to the point where you maybe can get it started.

Without good chassis batteries that can take a charge, Walmart jumper cables and a car battery alone just won't provide the 1000 amps you need.

If you don't mind spending a few $$ (or have roadside asst) a good heavy tow truck driver with OOO high current cables and charger should be able get you started (he starts big diesels all day long), then you at least can get the coach moved and continue to work on it.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: Jump starting chassis batteries

Reply #28 –
Quote from: prfleming –
Looks like you've got the big Red Cummins ISL 9 450.
As an aside to Peter's comment about the engine...that looks like a terrible place for all those important electrical components to be mounted.  They are crammed up in very close proximity to the HOT engine block, with almost no free air space around them.  A poor engineering decision IMO.

I always thought the placement of the isolator panel on my coach was bad.  Down low, right behind the rear wheels where it gets splashed with water and covered with road grime.  But compared to Steve's coach, the placement in my coach looks a LOT better!  At least my panel gets some cooling air, especially since I replaced the 55 gallon barrel sized OEM muffler with a small resonator.  :thumbsup:
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Jump starting chassis batteries

Reply #29 –
I'm guessing he's got an East, West bed arrangement. Mine looks nothing like that.
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: Jump starting chassis batteries

Reply #30 –
Well, finally had part of a day to resume troubleshooting...and, the coach remains dead-in-place.
Thanks Rudy and Mike for letting me bend their ears.

So many of you have provided a number of insights. It seems logical the process begins with replacing the batteries. With limited time--not enough of it to raise the coach using the reverse method with a portable air compressor--I decided to try something else. Since the current batteries will be replaced I went ahead and purchased 3 new group 31 lead acids. Since I don't have enough room to actually replace the current ones I connected the three new batteries with new cables and then connected them to the chassis batteries with a heavy-duty 2 awg jumper cable. Each battery has 1,000 cranking amps.

It didn't work. Below is a photo of how they were connected.

Interestingly, once connected, the dash voltage gauge did not rise...it was on about 12.2 before connecting, and remained there even after connecting. The connection with the jumper cable was solid on both ends. I even squeezed close enough to the opposite-end chassis battery to connect it after connecting to the other end proved null.

So--
1) was my process of connecting the new batteries flawed?
2) If not, does the voltage not increasing point to a possible problem down the line?
3) Also, I have no idea why the coach has the Blue Sea device along with another aftermarket battery isolator. The Blue Sea device would be easy to remove--should I?

It was too cold today to consider working on it (25F here...I'm a wimp!) and I'll not be able to try anything else until possibly next Sunday.

Thanks for all the input. I'll admit some of it is a bit advanced for me, but I am drilling deeper to understand the devices and terms. Hopefully nobody else ever faces the same situation as me, but, if so, at least I'll be able to help as y'all have.

Thanks!
Steve


Steve & Cindy Rushing
Atlanta, Tx
2003 U320 4020 PBBS
Build #6177
2020 Jeep Wrangler

Re: Jump starting chassis batteries

Reply #31 –
Quote from: SRushing –
1) was my process of connecting the new batteries flawed?
2) does the voltage not increasing point to a possible problem down the line?
3) The Blue Sea device would be easy to remove--should I?
1.  Sounds OK to me, and if everything else on the coach was correct, may have worked (?).
2.  Yes, there is a problem down the line.  Will require further investigation.
3.  No, don't remove it until you understand what it is doing.  Will require further investigation.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Jump starting chassis batteries

Reply #32 –
Steve,
I hate to be a Debbie Downer, but...

With the chassis batteries at 12.2 volts, connecting the new batteries at maybe 12.5 - 12.6 volts will immediately drop the voltage to match because the dead chassis batteries will be drawing a high current trying to recharge.

Even though 2 gauge seems like a heavy jumper, unfortunately this will not give you the 1000 amps needed for cranking. A heavy tow truck uses 000 gauge for jumpers, some with extended cables use 0000 gauge jumpers.

Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B
 

Re: Jump starting chassis batteries

Reply #33 –
Just interesting information for fellow nerds - here is what a heavy tow truck would have mounted. 3000 amps surge, 1000 amps continuous, 3/0 cables, 5 HP gas engine. (19 HP engine with optional air compressor).

Goodall 051538 CAP-START 3000 Vanair Super Capacitor 12V 3000 Amp Jump...
 
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B