I have a friend with a renix era XJ. He has a 40-50" LED light bar, four 2x2" LED cubes, and a strobe module. He is running the stock alternator and complaining of his battery running down.

He had his lights installed at a shop professionally (he's not too happy with the result).

Since he said his battery is running down even when the lights aren't being used, and he has a manual battery cutoff switch, is the problem likely that the stock alternator is just not able to keep up?

Or does that NOT apply since the switches are OFF on the lights and they wouldn't drain any power?

I want to help him figure this out.

 

upgraded bat cables is where I would start first. As for the LED light bar taking that much power from the bat is kinda a long shot, unless his bat is in poor shape. For the bat running down even when the lights off, hmmm bad alt or lose belt? Do you mean even when the jeep is running or when it sits over night the bat loses juice?

 

O.K., just got more details. Not a large LED bar. He has rigid industries LED cubes, 5ea on roof, 5ea on back, 2ea (total) on side, and 2 amber cubes on the winch bumper (Yup, a lot of lights). He also has a CB, Warn Winch, large power inverter. Factory alternator, the XJ is a 1990.

Optima yellow top few months old.

He said he loses juice when it sits for a while (two weeks or so without being driven) and then it doesn't do longer or why speed trips but 1-2 times a month.

It has a pressure pad switch box, to control the accessories, with LED indicator lights.

 

I found this at Optima

What are storage recommendations for OPTIMA® batteries?

The most important consideration when storing any battery is to make sure the voltage never drops below 12.4 volts. We recommend using a type of "battery maintainer" – a device that will monitor your battery and keep it at full state of charge during storage.

There are two types of maintenance chargers:

1. Preferred – Fully automatic multistage or multistep chargers, which monitor the battery and charge it as necessary. Multistage maintainers will charge at varying voltages and varying amperage (rarely exceeding 2-amps). Some of these multistep chargers are also capable of being regular battery chargers (seven amps or more).
2. OK but not preferred – Traditional float chargers provide constant voltage with tapering amperage to the battery even when it is fully charged. For float charging, we recommend 1 amp max, 13.2-13.8 volts.

If it is not possible to use a maintenance charger, disconnect the battery from the vehicle during storage to prevent small electrical drains from discharging the battery. Always provide a full charge with a battery charger prior to storage, and then check the battery voltage every three to six months. Charge the battery if it falls below 12.4 volts.

Also, when possible, store your battery in a cool, dry location.


Why is my battery dead? (troubleshooting battery/electrical issues)

Fully charged, engine not running, starting batteries (all REDTOP® or BLUETOP® 34M) should measure about 12.6 volts to 12.8 volts. Deep-cycle batteries (all YELLOWTOP® and dual-purpose BLUETOP) should measure approximately 12.8 volts and 13.0 volts. Voltage measurements of the battery when the engine is running are the output of your alternator. This measurement should be about 13.3-15.0 volts, which may differ due to temperature. At average operating temperatures of 50° to 80°F, your alternator output voltage should be about 14 volts to 14.8 volts.

If you don’t have a multimeter, you can test the output of your alternator by starting the car and turning on the headlights. If they are dim, it indicates the lights are running off the battery and that little or no power is being produced by the alternator. If the lights get brighter as you rev the engine, it means the alternator is producing some current, but may not be producing enough at idle to keep the battery properly charged. If the lights have normal brightness and don't change intensity as the engine is revved, your charging system is probably functioning normally.

If this checks out, you should determine whether or not the battery is holding a charge, or if something on the vehicle is discharging the battery.

There are three likely scenarios to explain the problems you're having:

1. A high parasitic draw (key-off load).This can quickly discharge a battery and decrease its service life. This may be caused by a trunk light, cigarette lighter, clock/radio, alarm system or any other electrical device. Current drain on the battery can be checked with an ammeter. With the ignition off, disconnect one of the battery cables. Connect one ammeter lead to the battery and the other to the cable. The normal current drain on most vehicles should be about 25 milliamps or less. If the key-off drain exceeds 100 milliamps, there's an electrical problem that requires further diagnosis. If you don’t want to take your car to a mechanic, the easiest way to isolate the problem is to pull one fuse at a time from the fuse panel until the ammeter reading drops.
2. A problem with your battery is causing it to not hold a charge. To check this, remove the battery from the vehicle, charge it to the full voltage, wait 12 to 24 hours then measure its voltage. Another faster, but less preferable way to do this is to turn on the high-beam headlights for 15 seconds, turn them off, wait 5 to 10 minutes, then check the voltage. If you measure the voltage of the battery the next day, week or even a month later, the voltage should be close to the max voltages listed above. If the voltage holds when not installed in your vehicle but drops when it is in your vehicle, see #1 above.
3. The battery was somehow discharged, and your maintenance charger is not able to properly charge your deeply discharged battery. Please see the directions for charging a deeply discharged battery.

_____________________________


I still would upgrade the cables if I was him it will help.

 

Dumajones-Great information man! Thank you so much. My friend is dropping his Jeep off to me tonight to look at it this weekend. I am creating a trouble shooting checklist now so I'll have good things to check when it's here.

I need to find out what amp rating the stock 90' XJ has, and add up all the amp requirements of all the accessories. He may have two different issues (a power leak somewhere) and an alternator that can't keep up with his power demand when he uses accessories on occasion.

 

If he has a manual battery cut-off switch, and he's actually turning it off, and he's still suffering form gradual drain, I'd say its the battery.

You did peak my interest at "large power inverter". If he's got a big inverter wired straight to the battery, and this bypasses the cutoff switch, you'll get a lot of parasitic drain. Disconnect the inverter and see if you still get a dead battery.

That amount of LED cubes (12-14) by themselves will pull about the same amount of power as 4-5 standard halogen headlights if you have them all running at once. The Dually units are rated at 20 watts, so it only takes 5 of them running to equal a pair of halogen headlights. The question is... How long are they running?

 

A larger alt. is needed when winching for very long to keep the battery charged and the winch pulling up to speed even with a large battery.

I have a lot of lights 5 sets of Hella "Black Magic"'s that draw quite a bit of juice along with radio gear one being an amateur radio that has 200w of output and 2 others with 50w output. My outboard air compressor has a large amp draw also but airs up the tires quickly after air down while on the trail.

As posted earlier you do need to upgrade your wiring battery/alt/grounds/etc. as well, I use a set from 5-90 kellyswipe on here great kit BTW.

 

After talking to him, he doesn't run the LED's too often, only late evening.

That's a good point on the inverter. I says 1000 on it (1000 watt)? I'll have to see if it is wired straight to the batter.

I measured a 0.06 mA current loss off the pos. terminal after about one hour after shut off. Is this "normal", or will that kind of mA kill a battery if it isn't being used often?

He drives this thing as a ranch vehicle, 2-3 times a month with almost 2 weeks in-between start-up on average.

 

Have you tried a parasitic draw test?

Everything on the Jeep needs to be off - radio, fans, heater, AC, int./ext. lighting, doors closed, accessories, auxiliary equipment, etc.

Using a DMM set to current (amps) red probe inserted 10A or 20A (AMPS) plug-in and black probe inserted into the COM. (Don't connect the DMM to read mA (milliamp) current measurements the parasitic draw can be too high and blow a fuse)

Remove the Neg- battery cable and connect the Red probe to the battery Neg- cable and the Black probe to the Neg- battery post.

Amp readings should be around 50 milliamps (.05 amps) If the reading is 100+ milliamps (.1+ amps) start to remove fuses and disconnect aux. equipment until the current is under 100 milliamps closer to 50 milliamps.

The test should help determine the sort of parasitic drain while the vehicle is sitting and what devices might be causing an excessive drain.

____


A 88-90 parts catalog shows oe alternators for 4.0L 88 - 90 CHEROKEE, WAGONEER, COMANCHE

60, 85 and 100 amps

JR77 5127 1 60 Ampere Tagged 110 1168 Remanufactured
1 60 Ampere Tagged 110 1168 Export (Use 100 AMP)
JR77 5126 1 85 Ampere Tagged 110 1170 Remanufactured
5300 2898 1 85 Ampere Tagged 110 1170 Export
JR77 5125 1 100 Ampere Tagged 110 1167 Remanufactured
5300 2897 1 100 Ampere Tagged 110 1167 Export

 

Muddz-yes, great suggestion. I already did that though and it is drawing 0.06amps.

Brought it to a dedicated starter/alternaot shop here yesterday where they check your starter and charging system/battery.

They said the alternator is fine (not running the all accessories, this was just a normal driving test), battery good, starter good.

The guy thinks it might be low fuel pressure. He heard it turn over (It takes 2.5-3 seconds to chug over).

I'm going back there today to have the FP checked. Will keep you all posted. Thank you.

 

I looked one up for my 98 at O'Reilly's and they are no longer stocking a 119 amp. They are all being rewound for 136 amp it seems. Not exactly answering your need but letting you know there's a bolt in option.

 

Need to test the alternator when hot and all accessories on while idling.... High beams all lights a.c. everything then measure both dc and a.c. voltage

 

That's a good point, since it's at the alternator shop, might as well have them check the output with everything on (the winch will be hard to do

This way he'll know if he needs to upgrade. Not a good time to find out you need one when you need one.

 

If thinking about upgrading ... in 1991 XJ's started using a Denso 90 amp with different mounting.

Stock alternators through 1990 are a Delco CS series alternator. CS-121, CS-130 ...

The CS-130 can be upgraded to around ~140 amps. There is also a CS-144, which I don't think was ever used as stock alt in the XJ, because of the switch to Denso.

http://catalog.remyinc.com/Product/R...r L6 - 242 CID

There are also many HO options, better for winching, high wattage lighting, etc.