mission mike Posted December 3, 2008 Share Posted December 3, 2008 Could anyone answer this question please? When our 89 Winnie is plugged into a shore power source will the motor battery get charged by the coach battery charger, or does the battery isolator prevent this? I've been experiencing low battery starting power when the truck has sat for 4 or 5 days. I left it plugged in to a 110 power source one night this week but still the next morning I could not start the engine. I believe I am bleeding off power from the truck battery somewhere because when I disconnect the ignition wire from the battery I get a spark jump to the wire, this is with everything turned off in the truck and the coach disconnected from the engine battery. Thanks Mike Quote Link to comment Share on other sites More sharing options...
Shoprat Posted December 3, 2008 Share Posted December 3, 2008 Howdy Mike.. I have seen batteries with an internal short go dead, but not very often. Try disconnecting the battery positive post cable and connecting a 12 volt test light between the positive cable end and the batterys' positive post. If you have a draw, the test light will light. If it lights, start pulling fuses until the light goes out. The light going out tells you that circuit has a draw. Hope this helps. John Quote Link to comment Share on other sites More sharing options...
mission mike Posted December 10, 2008 Author Share Posted December 10, 2008 Hi John Thanks for the tip, I bought a 12 volt test light last weekend and did as you suggested, I seem to have a draw down somewhere in the camper section, just a matter of finding it now. Mike Quote Link to comment Share on other sites More sharing options...
WME Posted December 10, 2008 Share Posted December 10, 2008 The shore power does NOT charge the truck battery. You can jumper across the isolater when its storied to let it charge the truck battery. Just remember to remove the jumper when camping season rools around. Quote Link to comment Share on other sites More sharing options...
Shoprat Posted December 10, 2008 Share Posted December 10, 2008 Hey Mikey... Check out all the lights. I helped a friend find a draw on his RV a few years back, and they had left a light on in the closet. Quote Link to comment Share on other sites More sharing options...
mission mike Posted December 10, 2008 Author Share Posted December 10, 2008 Thanks WME and Shoprat, you guys are very helpful, good to know I can charge the truck battery with a jumper across the isolator, next thing on my to-do list is make up a jumper. First thing I checked John was for anything left in the on position in the camper, but a good point all the same. I pulled all of the 12 volt fuses in the camper section, but are still getting a draw down according to the tester, so I am beginning to wonder now if the problem is with the wires underneath the camper along the frame somewhere, so I will wait for a good day when I can crawl around for a look underneath. Mike Quote Link to comment Share on other sites More sharing options...
WME Posted December 11, 2008 Share Posted December 11, 2008 FWIW When I made my jumper I used a 5 amp fuse. It will blow if I try to start the engine with out removing the jumper. Sorta an idiot restant thing and I don't end up with a dead truck battery on the first trip of the year. Quote Link to comment Share on other sites More sharing options...
futar Posted December 11, 2008 Share Posted December 11, 2008 There are some items in some model vehicles that draw electricity when the vehicle is off. One is the engine computer. If you disconnect the battery, it has to reprogram itself. The other are some radios and of course clocks. A GPS will continue to draw if it is not turned off. This is why you see a spark. It's not a matter of some electrical draw but how much draw. First check out the main battery with a load tester. Also check the specific gravity of the battery fluid if it's not a sealed unit. Check your battery isolator, especially if it's an older unit. They can leak. Quote Link to comment Share on other sites More sharing options...
mission mike Posted December 11, 2008 Author Share Posted December 11, 2008 Thanks Futar, Yes I discovered the radio draws power from the memory + lead, even when turned off. The battery was new in July of this year, but I will check the fluid tomorrow, also I will bypass the isolator and retest the wires to the coach, the engine and truck cab seem fine, when I test the positive cable from the battery the 12v tester does not light. The isolator does look like an old one, 3 post, rectangular blue blue box, I can only make out part of the name "Sure ???' Mike Quote Link to comment Share on other sites More sharing options...
bear Posted December 11, 2008 Share Posted December 11, 2008 Thanks Futar, Yes I discovered the radio draws power from the memory + lead, even when turned off. The battery was new in July of this year, but I will check the fluid tomorrow, also I will bypass the isolator and retest the wires to the coach, the engine and truck cab seem fine, when I test the positive cable from the battery the 12v tester does not light. The isolator does look like an old one, 3 post, rectangular blue blue box, I can only make out part of the name "Sure ???' Mike Mike, that's probably a sure power isolator especially if it's rectangular with fins. I take it that you’re running a Toyota chassis, I just picked up an 89 Itasca Spirit and it has the old style 3-post continuos duty solenoid. Found it was bad, in my research I noticed for mine I needed a solid state with 4 posts because of the alternator. Picked up a Sure Power 9523A which is for up to 95 amps. Quote Link to comment Share on other sites More sharing options...
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