Engine Batteries acting like they are weak

[encantotom]

Hi all,

this will be a long post. i am also willing to admit i am not as good as i thought i was on this. so you will find at the end i found out what was wrong, but think you might learn something from my blunders along the way.

the last few times i used the coach, it acted like the engine batteries were real weak. it would just click. when merge switch was on, it would turn over faster and may start or not. i would charge everything for days and same results.

so i started on my qwest to figure out why. i checked the voltage across each battery and they were all 13.6 volts. my engine batteries were interstate workhorse and were 4.5 years old. here in arizona, batteries just dont last that long, so i took them out and at SAM's club had them checked. i was sure they would have a bad cell or two, but they load checked good. since they were so old and soon to fail, i went ahead and bought two new 8D batteries at sams club. their house brand is Powerfast and they are made by interstate. they actually have a higher CCA than the interstate workaholic. 125 bucks each, good deal. i put them in and as i climbed into the cockpit with confidence, no go. same thing.

i had never changed the merge solenoid, so i was getting some funky readings on it so i changed it. walla, no difference. i would get voltage across both terminals.

my merge switch was acting funny and i spent hours tracing out the merge wiring. it would only merge off of the house batteries and not the engine batteries.

i cleaned all the battery cables i could get at and checked for corrision and they appeared just fine.

so, i put a clampon amp meter on the starter positive cable right at the starter. it would peak at 1300 amps and float at 600 and under. so when i told the starter place that rebuilt my alternator last year that he said that was probably too much.

so i took the starter out. easier said than done. use the air to lift the coach as much as i can, use 2 20 ton bottle jacks to hold it up and off i go.

first take the screen off that covers the entire bottom of the engine. then disconnect all the batteries and use the dissconnect switch. take the cables off the starter. then i attached a strap around the starter, had my 17 year old daughter hold it up top as much as she could and i took the bolts off. they were really in there an i had to use a rubber mallet on an box end wrench (no socket can get in there) to get them loose. then an makeshift ratchet box end wrench with a piece of pipe on it to get the top bolt off.

btw, the starter weighs about 80 pounds or a little more. it is huge. she held the strap and i jockeyed the starter around some oil lines. she then slowly lowered the starte as i held it overhead while on a creeper. it weighs almost as much as she does...

i set it on my chest to catch my breath and that didnt work very well. it really took my breath away as it sat there. i quickly got it to the ground.

i quickly put it in my car and drove looking like a dirty bigfoot to the shop that was 25 miles away in far west phoenix. i got to this great little shop and they stayed open for me as i got there after 5pm. they bench checked it with no load and it was ok. he said that it likely was worn and would fail under load. so he made me a great deal on a rebuilt starter with a one year warranty and figured i would just get it and put it in. if nothing else another thing not to fail. it was the original starter. 250 bucks for the starter.

while i was up there that far i popped over to suprise arizona and saw my grandkids...

the next day i installed the starter. put it on a floor jack, tied two straps to it and had a burley buddy up top and me down below. i am doubly burley at 6'2" and 300 pounds...i got it installed in about 15 minutes..but it is really heavy and you could easily crush yourself without help.

now i am really confident...i go to start it and nothing. exactly the same. i got it started on merge, but not on engine batteries only.

so, i tear the back stainless panel that covers the disconnect switches etc out and trace all battery cables around and take them off and clean them. i started ohming each one out to make sure it would get down to as close to zero ohms as possible. they were ok. but, i had an open between the ground cable for the engine batteries where it mounts to the frame and the negative of the last engine battery.

now here is where i feel dumb. the big brass looking round 600amp fuse that is bolted on the battery on the ground of the first battery was blown. no indications other than it was totally open. the reason i didnt catch this is i checked the voltage on each battery a number of times by just checking across the positive and negative of each battery and of course they said good. i never went from positive to coach ground....then i would have know there was no ground.

here is another strategic mistake i made. i would turn the engine batteries off and stil measure voltage at places it should have been the engine batts. what i had neglected to do was turn the coach charger off that was plugged into the house. it must send juice all over the place. so i was getting bogus readings.

so, for the last few months i was only starting it from the house batteries and i suspect they really are getting weak as they are standard workaholic batteries that have been charged and discharged a bunch of times. i took the fuse off of that one and put it on the starting batteries and it started right up easily....duh......

so i ordered off of ebay a couple of those fuses. they sell for 90 bucks at grainger and i got 2 of them for that price on ebay.

so, i have batteries that are new that i would have done soon anyway, a new starter that shouldnt fail for the life of me and the coach, and now the merge works the way it should....

so, i dont know what caused the fuse to blow. i am assumming that perhaps when i changed the alternator i must have done something...or when the regulator on the old alternator shorted out.

so, lesson learned until the next time i blunder around. maybe you guys can learn from it as well.

at least my labor is cheap......and i understand alot more about how things are wired...

later

tom