My BJ75 is destroying low side batteries (1 Viewer)

[Reinhardtius]

Please starting reading from post # 5.

Hi Folks

My BJ75 was not turning over two weeks ago, having just resolved an issue with my 14V superglow starting system. It's winter here and I start the truck every week so that it warms up (obsessive and probably unnecessary, I know). Two weeks ago, I started it in -7°F temperatures and it started without any smoke or any issue. Two days later, I went back out again to start it, and the starter would not turn over.

Now, I bought a 24V charger/maintainer and yesterday, I charged the batteries. I then tried to start again, and it started immediately. Brilliant! The 14v superglow starting system is working beautifully.

However, taking my multimeter to the battery, I observe a voltage drop .01 volts about every second. That, to me, is a precipitous drop, and indicates that something is drawing power.

Questions:
1. What are the classic sources of parasitic draws on a 24V 70 series? The truck, I believe, is 100% factory. It has no aftermarket stereo, accessories, lights...etc. I did see a blue 12 volt hella relay on the passenger side, next to the voltage regulator. No idea what on earth that is, but it looks hooked up to a s***load of wires. (see photo)

2. What is the most efficient way to test and resolve draw issues? I hear the Power Probe is great, but do I need that if I have a good multimeter?

3. For now the truck is on the charger. Is that OK, or should I disconnect the batteries to turn "off" whatever is still drawing power?

 

[Freewheel]

Best way to narrow down draw issues is to pull fuses one at a time and see whether the draw stops.

What was the issue with the Glow system? Whenever I "resolve" an electrical issue, and new electrical issues pop up immediately, I get a bit suspicious... You may want to do some Glow system testing to see if there's any stray weirdness there..(like disconnect the whole system at the fusible link, since there's not a useful dash fuse to pull if theres a problem in the glow system- the "glow" fuse is just on the lamp, not the whole system)

 

[roscoFJ73]

No idea what on earth that is, but it looks hooked up to a s***load of wires.

Does it have spotlights? Thats usually what Hella relays are for. If they are not there, they may have been removed because they were wired wrong and causing problems.
You have a battery switch, why not turn the batteries off until you find the problem

 

[Reinhardtius]

Does it have spotlights? Thats usually what Hella relays are for. If they are not there, they may have been removed because they were wired wrong and causing problems.
You have a battery switch, why not turn the batteries off until you find the problem

The truck does not have spotlights installed. I suppose that I could consider removing that relay, and see what happens.

For now, given that I have not yet identified the origin of the current draw, the batteries are turned off via the KILL switch.

I watched a few videos on how to identify parasitic draw. I think I will be following them.

 

[Reinhardtius]

UPDATE:

7 months ago, my truck became slow to start. I noticed that the passenger side (low side) battery would not hold a charge. I thought the issue was due to old batteries. I replaced both batteries with brand new units. The truck was then a total delight to start.

Fast forward seven months. The truck became slow to start again (as mentioned in post #1). Now, it does not turn over. I bought a load tester and new battery charger. I charged both batteries up. With the load tester, I noticed that the driver side battery (high side) is very good, but the passenger side (low side) battery performance under load is very poor.

My friend who used to work for Bosch suggested that I check the resistance of the battery cables and circuts, for they could indicate that there is resistance somewhere, which is causing battery imbalance, resulting in eventual battery failure.

I then disconnected both batteries and checked the resistance of the battery cables.
Test 1: Connecting the low side + battery cable with the high side - battery cable, I get a reading of 0.00 ohms.
Test 2: Connecting the low side - battery cable with the high side + battery cable, my multimeter reads O.L. (over limit).

What do you make of these results, and what could be destroying my low side batteries?

A photo attached to remind you what the batteries arrangement is.

 

[BreckenridgeCruiser]

FYI: since many rigs here in the 24v/diesel forum may be RHD, it is better to describe the system using low side (12v) and high side (24v).

The first thing to do is check that you have NOTHING trapped off of the low side positive terminal. There should be nothing attached to that terminal or the high side negative terminal (yet another tricky way to tap 12v off of the system).

If you find nothing trapped, then you could check your alternator voltage regulator to make sure it is not overcharging the system as a whole...

The issue with checking resistance with a multimeter like you have done is that at a minimal voltage, you may not get an accurate reading versus when a lot of voltage is flowing across the cables, like when starting the truck. If your cables even look a little crusty, it might be a good time to build a new set with good terminals and quality thick gauge cable.

 

[Reinhardtius]

FYI: since many rigs here in the 24v/diesel forum may be RHD, it is better to describe the system using low side (12v) and high side (24v).

Okay, adjusted the language. Mea culpa; I did not know about high and low side.

The first thing to do is check that you have NOTHING trapped off of the low side positive terminal. There should be nothing attached to that terminal or the high side negative terminal (yet another tricky way to tap 12v off of the system).

If you find nothing trapped, then you could check your alternator voltage regulator to make sure it is not overcharging the system as a whole...

Nothing appears to be attached to the low side positive terminal, nor is there anything attached to the high side negative terminal. HOWEVER, as you can see in the photo, there is a kill switch attached to passenger side frame, which can sever the connection between the low side negative, and the engine block.

How can I check the alternator voltage regulator?

The issue with checking resistance with a multimeter like you have done is that at a minimal voltage, you may not get an accurate reading versus when a lot of voltage is flowing across the cables, like when starting the truck. If your cables even look a little crusty, it might be a good time to build a new set with good terminals and quality thick gauge cable.

I will definitely build new cables in either case. The low side battery is toast. I just tried to recharge it and it performed poorly again on the load test.

 

[BreckenridgeCruiser]

Two things to think about... The kill switch may be limiting current to the ground side of the low battery. That may create resistance and act like a bad ground in system which can load the hell out of the low side battery specifically. I melted a post of my low side battery due to bad grounding so this is not speculation. Secondly, you may want to move the kill switch to the edic circuit which will let the car crank but never catch and frustrate a thief more than a completely dead system.

Once you do replace the batteries, it will be a good idea to swap them left to right regularly to make sure that one does not get over/under charged consistently due to position in the circuit.

 

[BreckenridgeCruiser]

Oh and no worries on the language. I just had to look at the picture for your brake booster to know which side was which!

 

[tornio]

hi, like BreckenridgeCruiser said the "kill switch" can cause some problem....
i usually see them wired on the positive side (+24)
remove it and make sure that the "ground" side (0V) has a good contact !

but before you have to charge the batteries one at time (12V) (check if both are good)
the batteries must have the same level of charge at the starting point

and if not in use remove the hella relay and his harness

 

[Reinhardtius]

Two things to think about... The kill switch may be limiting current to the ground side of the low battery. That may create resistance and act like a bad ground in system which can load the hell out of the low side battery specifically. I melted a post of my low side battery due to bad grounding so this is not speculation. Secondly, you may want to move the kill switch to the edic circuit which will let the car crank but never catch and frustrate a thief more than a completely dead system.

The kill switch will be removed and new cables built. If someone wanted to steal the car, they could just read this thread and see how I have it set up. But more importantly, it may, as you say, be limiting current to the ground side.

I also noticed that the high side negative cable was partly melted. Not sure if that indicates anything.

Once you do replace the batteries, it will be a good idea to swap them left to right regularly to make sure that one does not get over/under charged consistently due to position in the circuit.

Yes, and I would be able to do this more easily with newly built cables with marine terminals, which are much easier to take on and off with a 12mm nut that stretching out and clamping those lead connectors every time.

@BreckenridgeCruiser, any tips on testing the voltage regulator as you mentioned previously?

hi, like BreckenridgeCruiser said the "kill switch" can cause some problem....
i usually see them wired on the positive side (+24)
remove it and make sure that the "ground" side (0V) has a good contact !

but before you have to charge the batteries one at time (12V) (check if both are good)
the batteries must have the same level of charge at the starting point

@tornio, if the high side battery is seven months old, and I put in a new battery on the low side, do you think that they will be a persistent problem? Must I install two new batteries?

 

[tornio]

OH YES ,the best is both batteries new .... but one is only 6 month old so you can try ...

Let me say that when you have two batteries wired at 24v you would install not only new batteries but batteries from the same batch
some good company-factory labeled the batteries with these number and inform :

WHEN WIRED IN SERIES INSTALL ONLY BATTERIES WITH THE SAME BATCH NUMBER

every battery (like every generator) has his own internal resistance (elettric resistance) and this resistance is influenced bj the amount of oxide presents on the battery plates . this oxide will grow during the life (even more if un-used) so also the resistance.
when you put two batteries in series is the optimal to have the same resistance to avoid charghing imbalance.
i hope to explain myself...

 

[Reinhardtius]

OH YES ,the best is both batteries new .... but one is only 6 month old so you can try ...

Let me say that when you have two batteries wired at 24v you would install not only new batteries but batteries from the same batch
some good company-factory labeled the batteries with these number and inform :

WHEN WIRED IN SERIES INSTALL ONLY BATTERIES WITH THE SAME BATCH NUMBER

every battery (like every generator) has his own internal resistance (elettric resistance) and this resistance is influenced bj the amount of oxide presents on the battery plates . this oxide will grow during the life (even more if un-used) so also the resistance.
when you put two batteries in series is the optimal to have the same resistance to avoid charghing imbalance.
i hope to explain myself...

Thank you. Interstate Battery found that one of the batteries had a bad cell. They replaced them with two new batteries from the same batch.

I was at the Toyota Dealer picking up a key for my Tacoma. I asked the service manager, "could a parasitic draw destroy a cell in a battery?" He said, yes, especially in our cold climate. What happens, he says, is that a draw will deplete a battery, causing the fluid inside to freeze, which allows the plates to touch each other, causing the destruction of one of the cells.

I reinstalled the new Interstate Batteries as well as new, custom cables, and new marine terminal posts. The truck starts like a rocket, per spec. I have disconnected the batteries for now, and I will have someone identify if I have a draw somewhere, and if so, from where. This is pathetic, but I don't know how to test for a parasitic draw on a 24v system like the ones we have.

 

[tornio]

happy to ear they changed both batteries !

parasitic draw : in our old toy (your toy isn't old but i bet it share the same electric wiring / layout like j4 maybe with some features more) when the key is off there must be no current circulating so is pretty simple :
with a multimeter , a probe to a good chassis "gound" and the other to low side - ( or a probe to high side + and the other to fusibile link ) there must be no reading or " 0 "
if you find some current flowing start disconneting " loads " untill you find the culprit

modern vehicles have a lot of electronics things = a lot of condenser / capacitors that when old usually go to ground, bastards
but our toys don't have

example if you see that disconetting 1 fusibile link there is no more flow ( with the wiring diagram on your hands ) you have discovered the section where there is dispersion
many times is simplier to take off the fuses to see where is dispersion
good luck

but pay attention before cutting all the wiring : if there is parisitic draw the voltage of you batteries bank will go down fast under 25,7 25,6 in few hours

 

[Reinhardtius]

First photo is with the green connector fusible link connecting the battery to the truck electrical system, and the second is with it disconnected. Note the parasitic draw.

Now I have to figure out where it comes from...

 

[Reinhardtius]

First photo is with the green connector fusible link connecting the battery to the truck electrical system, and the second is with it disconnected. Note the parasitic draw.

Now I have to figure out where it comes from...

View attachment 1948330

View attachment 1948332

An update on this parasitic draw. I have traced a draw to a 7.5 amp fuse, which is for the dome light. I removed the fuse, and the draw goes away. I adjusted the position on the rocker switch of the dome light and the draw remains (18mA, which is not much). I removed the dome light bulb, and the draw remains (18mA).

Questions!
Is 18mA enough to deplete a battery in three days in freezing cold temperatures?

Why would it destroy my low side battery first?

Does anyone know what else is on this 7.5 amp fuse? I also noticed that the quartz clock does not keep memory with this fuse out. Perhaps that is the 18mA draw?

My hypothesis is that this draw is what drained one of my batteries this last winter. You may remember from my first post that it drained it, and with the voltage low, one of the cells must have frozen, killing the battery. It was only two months old. Of course, the battery could have simply been bad. Bear in mind, however, when I bought the truck, six months after purchase, the low side battery failed. So, I've had two low side batteries fail to date.

Since the two-month old batteries died, they were replaced with brand new matching units. With the 7.5A fuse out, the truck has not had experienced and weird battery behavior.

 

[Freewheel]

I spent some time tracing a "parasitic draw" in my truck, and found that the clock drew what I considered to be a shocking amount of power for such a minor item. I think it was drawing about an 1 amp. When I'm not daily driving the truck, I always have it on a dual battery charger, to keep this from being a problem.

Not sure if all the clocks draw this much power, or whether they can have an age failure that makes them draw more, while still working fine, but that was my discovery a couple years ago...

 

[Reinhardtius]

I spent some time tracing a "parasitic draw" in my truck, and found that the clock drew what I considered to be a shocking amount of power for such a minor item. I think it was drawing about an 1 amp. When I'm not daily driving the truck, I always have it on a dual battery charger, to keep this from being a problem.

Not sure if all the clocks draw this much power, or whether they can have an age failure that makes them draw more, while still working fine, but that was my discovery a couple years ago...

I think 18mA is .018 amps, so that is quite a difference between your situation and mine... hmmm, if only this forum was cross-listed with electrical engineering forums...

 

[Gengis]

Are you testing your dome lights by holding the door open or using the on switch?? Sounds like a dumb question but the dash "door open" lamp draws quite a bit of current itself. Same goes for any of the dash lamps but they are usually off when the key is out.
18mA is cool if you can get there. At that rate you could leave it for almost half a year.

 

[Reinhardtius]

An update on this parasitic draw. I have traced a draw to a 7.5 amp fuse, which is for the dome light. I removed the fuse, and the draw goes away. I adjusted the position on the rocker switch of the dome light and the draw remains (18mA, which is not much). I removed the dome light bulb, and the draw remains (18mA).

Questions!
Is 18mA enough to deplete a battery in three days in freezing cold temperatures?

No, it is not. The reason your batteries were depleted is because they were overcharged and one of the cells was damaged in the battery. The reason they were overcharged is because there was a piggypack wiring harness between the voltage regulator and the alternator. It looked like this:

Why would it destroy my low side battery first?

It did not cause the destruction of the battery, the overcharging did.

Does anyone know what else is on this 7.5 amp fuse? I also noticed that the quartz clock does not keep memory with this fuse out. Perhaps that is the 18mA draw?

My hypothesis is that this draw is what drained one of my batteries this last winter. You may remember from my first post that it drained it, and with the voltage low, one of the cells must have frozen, killing the battery. It was only two months old. Of course, the battery could have simply been bad. Bear in mind, however, when I bought the truck, six months after purchase, the low side battery failed. So, I've had two low side batteries fail to date.

These batteries failed from overcharging.

Since the two-month old batteries died, they were replaced with brand new matching units. With the 7.5A fuse out, the truck has not had experienced and weird battery behavior.

This 7.5A fuse out is a coincidence and not the solution to the batteries. Correcting the overcharging corrected the battery issues.