Battery balancer?

[Rodger]

My 40 is 24v - 2 12v batteries in series - same as most LCs. For some years the batteries appear, according to the ammeter, to get too much charge and Blown80 and Jon W have both spent time with me addressing the problem. I've replaced voltage regulators (x3), alternator from HD to standard, battery leads replaced and isolator, batteries replaced and so on. I counter the over charge by running with my headlights on all the time but obviously that is not solving the problem.
Now what I understand about electrics can be written on the back of a stamp with space left over but I've just read an article that suggests that a battery balancer/equaliser could solve my problems (well this one at least).
So to my questions but first a little history - the 40 was a winch-race truck and has a secondary fuse board -12v -that currently only powers the cig lighter and the winch switch (I don't currently have a winch) but the take off for this board is from the middle positive post in the series.
The article suggests that such a set up could cause one battery to over charge and the other to under charge. If I fit a balancer/equaliser this would be balanced out and should I fit a 24v-12v converter?
Could this be the cause of my ongoing problem?
Will it work?
And if so, what is a good, reasonably price balancer/equaliser and converter?
Where do I get them from?

Thanks
Regards,

 

[Mblinko]

There are some electrical experts on here who will be along soon, but my first questions would be:

1. By how many volts is it over charging, I assume you mean voltmeter not ammeter.
2. Have you tested the output using different volt meters, I ask as I once though it was over charging but in the end it turned out to be a defective voltmeter.

worth checking these if you haven't done so already.

 

[Rodger]

Hi Mark,

The charge info is from the standard ammeter in the 40 series. We changed to a kms speedo dash set but had the problem before so I don't think it's the ammeter although I am aware that ammeters are not the most reliable source of information. I have recently bought a 24v voltmeter but haven't fitted it yet and that may give me a different picture.

The ammeter shows, with nothing on, plus 30 at around 1200rpm and over 40 at 2000 rpm. We have boiled batteries in the past. With the h/lights on it shows around 10 but we don't boil things.

Regards,

 

[grantw]

Have you had the alternator bench tested and checked all connections - especially the earths to the block and chassis?


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[Rodger]

We were advised that the alternator we had on, which we'd bought new before the problem arose and was a heavy duty one, could be the cause - too much output for a vehicle with very little electrics. We swopped to a standard alternator which we were told had been tested - it was from a reputable dealer.

However I will check the earths. What is the best way of doing that (I do have a multimeter)?

Thanks for your help

Regards,

 

[grantw]

Sounds like the voltage is too high which will be the cause of the batteries boiling. The best way to check is to take them off. Visually inspect and give everything a good clean with a wire brush.

To my knowledge only a faulty alternator or a bad connection will give you the problems you are having. A working heavy duty alternator won't do this.

So check your connections and if you are still having trouble remove the alternator and have it bench tested.


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[Rodger]

Many thanks. I'll give it all a good clean up.

Regards,

 

[grantw]

Good luck ... One more thing I thought of bad batteries can also cause grief ... But that is much less likely.


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[Rodger]

The batteries were replaced about a year ago with a matched pair. The previous pair were of unequal age and the older one , first in the series, was starting to show small bubbles and not showing the same charge. Rather than wait for it to fail we bought two new ones. I also replaced the link cables and isolator switch at the same time. It made no difference to the over charging problem or rate.

Regards,

 

[Towpack]

The impedance of a battery increases with it's state of charge so it will gradually draw less and less current for a given charging voltage as the charge increases. Or to put it another way it becomes harder for the alternator (via the voltage regulator) to 'push' a charge current into the battery. If your ammeter is saying +40 amps with charged batteries, assuming the ammeter is reasonably accurate, the charging voltage must be way too high. You really need to measure the voltage across the batteries when the ammeter is showing +40 at 2000rpm. A heavy duty alternator will not overcharge. It simply has more capacity in reserve to run a bigger load from electrical ancillaries and charge the batteries at the same time. JMO

 

[clivehorridge]

I'm certainly no electrician of any sorts, but I've always been advised that batteries (and other ancillaries) pull amps, the alternator doesn't push.

I would have thought the problem of cooking batteries was too high a voltage (V) as suggested by TP above, which suggests a faulty voltage regulator on the alternator or a regulator elsewhere in the electrical system.

Just my (uneducated) thoughts...

 

[Towpack]

The 'pushing' analogy is just a simpler way of looking at it. Lowering the resistance of a load while keeping the same voltage will increase the current draw or 'pull'. Likewise, keeping the same load resistance but increasing the voltage will amount to the same thing. As far as overcharging the batteries goes, it's the current that does the damage but it needs the voltage (higher) to deliver it.
If you think that It only takes a few milliamps across the human heart to stop it but a high voltage to deliver it. A 12v car battery is capable of delivering several hundred amps but put your hands across the terminals and nothing will happen as there's insufficient voltage to overcome the body's resistance and 'push' the current through.

 

[Mblinko]

I'm not familiar with the 40 but got curious when I re-read the OP.

I assume you have got a 24v alternator and a working 24v to 12v converter. If you haven't got a converter, how are you charging the 12v batteries .... a second alternator ? If not, I'd wager that the 24v system is cooking the batteries.

It sounds like you may have read this article .... http://cruisers.bitwalla.com/articles/24v.html. Some good advice in there.

Pure 24v systems will require a different approach. Certainly I don't have that experience, but someone else here may know more.

 

[uHu]

My 40 is 24v - 2 12v batteries in series - same as most LCs....
....and has a secondary fuse board -12v -that currently only powers the cig lighter and the winch switch (I don't currently have a winch) but the take off for this board is from the middle positive post in the series.
The article suggests that such a set up could cause one battery to over charge and the other to under charge. ...

You have all the info needed to solve your problem here.
If you take any power, however small (e.g. micro-amp), from the middle post (12 v) of a 24 volt set, you will discharge one battery completely. There is no way you can push more power/charge into one battery in the set than into the other, so, over time, you will drain one battery and boil the other one. Period. For a standard standard 24 volt set, that is.
Without going into the solution with an equalizer, you can just disconnect anything you have on the middle post, so that there is only one single cable between the two batteries, and then use a 24 to 12 v converter for your 12 volt supply. Problem solved. Forever.

If the current batteries are still in working order, you can disconnect them from the car and charge them connected i parallell (at 12 volts) so that they start out with the same level of charge before you connect them back into the 24 v setup.
If you want to check the two batteries, then, after charging them fully in parallell and then diconnecting them completely, wait half an hour and measure the voltage over each battery. They should be within 0.1 volt of each other, as a minimum.

 

[Towpack]

You can still charge the batteries separately while still on the car with a 12v charger. Just connect the charger to each one in turn (+ to +, - to -) and charge fully. If you happen to have 2 x 12v chargers lying around you can charge them both simultaneously. Just connect one the charger to each battery as if the batteries were not linked together in series. The fact that they are linked makes no difference. If the tap from the 12v or middle post of the battery feeds only the fag lighter and the redundant winch switch it must be whatever you plug in that's draining one battery.

 

[Firewout]

+1 on the 24 to 12 converter. I use one from victron.
btw, I think there is a 24-12 converter in my bj46. Looks factory but I have to check and the truck is 200 km away now. It's in the engine bay RH side against the bulkhead right under the bonnet.

 

[Rodger]

Many thanks for all the information...
I'll start by disconnecting the 12v supply at the battery and then check the charge condition of both, get them charged and the problem should solved.
I've been emailing with Chris in Oz and, stupidly, I hadn't told him about the 12v take-off!
Before I buy an equaliser I guess I need to decide which winch I want/can afford and establish it's power requirements, and then buy the right one.
The article you mentioned Mark, is the one that set me to wondering if this was the cause of my problem.
Factory equaliser? A part number might help, when you get he chance.
If not factory, what are the aftermarket options...I've been looking at Redarc, but all and any advice is welcome.

Many thanks again for all the input and I shall post how get on.

Cheers

 

[uHu]

You can still charge the batteries separately while still on the car with a 12v charger. Just connect the charger to each one in turn (+ to +, - to -) and charge fully. If you happen to have 2 x 12v chargers lying around you can charge them both simultaneously. Just connect one the charger to each battery as if the batteries were not linked together in series. The fact that they are linked makes no difference. If the tap from the 12v or middle post of the battery feeds only the fag lighter and the redundant winch switch it must be whatever you plug in that's draining one battery.

Yes, its OK to charge like this (at least if the 2 chargers are equal), but you don't get the benefit of equalizing two batteries which have been "mistreated". Also, if you want to check that both the batteries are OK, and following the same charge-level-curve, you have to have them connected in parallell for a bit of time before disconnecting and then measure as the voltage goes down, separately.

 

[Towpack]

Many thanks for all the information...
I'll start by disconnecting the 12v supply at the battery and then check the charge condition of both, get them charged and the problem should solved.
I've been emailing with Chris in Oz and, stupidly, I hadn't told him about the 12v take-off!
Before I buy an equaliser I guess I need to decide which winch I want/can afford and establish it's power requirements, and then buy the right one.
The article you mentioned Mark, is the one that set me to wondering if this was the cause of my problem.
Factory equaliser? A part number might help, when you get he chance.
If not factory, what are the aftermarket options...I've been looking at Redarc, but all and any advice is welcome.

Many thanks again for all the input and I shall post how get on.

Cheers

Why not just forget about a battery balancer and a 12v takeoff and buy a 24v winch or am I missing something?

When you have both batteries fully charged I'd also be inclined to get them both individually drop tested to see if they are still in a similar condition capacity wise.

 

[Rodger]

I had no opportunity to get on the truck today but maybe tomorrow.

The winch question...
It took us two years to get the truck matriculated and registered here in Spain and if I fit a winch then the truck would require a revised fisha technica and also to be re-matriculated which would amount to over 700 euros. Because of its age they would want another engineer's report so I am thinking along the lines of a portable winch but mounted via receiver blocks - front and rear (American style). The receivers would mean the length of the vehicle stays the same (and yes it gets measured when it is being tested). Also they don't like the cable and hook sticking out of the front... so I have a lot of working out to do and that will undoubtedly be the reason for another thread!

But before that I need to get the current problem solved but maybe they do a portable 24V winch.

Cheers and thanks