Identification please.

hako · Guru

Identification please.

Tony LEE · Guru

Way too high a voltage for my liking if it is any normal lead acid or lithium chemistry

But what type of battery is it

And what are you using to measure that voltage.

What is the battery voltage with the charger switched off

Voltages to be measured at the battery terminals

-- Edited by Tony LEE on Saturday 31st of October 2020 10:40:41 PM

-- Edited by Tony LEE on Saturday 31st of October 2020 10:42:11 PM

hako · Guru

My thoughts exactly on the voltages Tony, this is not the house battery I'm testing the charger on but a 2 year old lead acid car battery - measuring voltage at the battery with a Fluke mod 77 multimeter. Not sure about residual battery voltage after charger disconnected but will disconnect now and check in morning.

Regards

Whenarewethere · Guru

My Victron charger is 14.4v absorption & 13.8v float, both are adjustable but I have left them at the standard setting.

Recommend 14.2 - 14.6 AGM, 14.1 - 14.4 gel, 14.0 - 14.2 long life gel. 13.5 - 13.8 float.

My Victron DC-DC chargers (2 in parallel) as they are dumb chargers have set them both to 13.89v a bit of a compromise between float & absorption voltage.

Voltage does go higher for desulfation but this in usually a manual process done only if really needed. You don't want to be doing this every week.

The car 12v sockets are pressed sheet & have pretty shocking contacts. I had an arcing issue even with a small load & replaced it with an Anderson plug. The fuse on these circuits will only be 15 - 20 amps so don't overload it.

Whenarewethere · Guru

My car charges at 14.4v & it is very consistent. Kyoritsu 2046R

Mike Harding · Guru

Are there any markings on the semiconductor device? The image is too dark to tell.

It has two of its terminals shorted in the terminal block which makes me wonder if it's a MOSFET wired as a diode?

I am not aware of any lead acid battery which should be charged at 16V8 and would be astonished if there is one. Charging at that level will cause the battery to gas and ruin it. Some constant current chargers will rise to such voltages.

dorian · Guru

Mike Harding wrote:
Are there any markings on the semiconductor device? The image is too dark to tell.
It has two of its terminals shorted in the terminal block which makes me wonder if it's a MOSFET wired as a diode?

It's probably a dual diode. Could it be a boost diode which is intended to trick a smart alternator into charging when it thinks that it shouldn't???

In any case, it seems to me that either the charger is faulty, or it is not sensing the correct battery voltage. Are there any light sense wires running between the charger and the battery, in addition to the heavy current carrying wires?

What is the brand and model of the charger?

-- Edited by dorian on Sunday 1st of November 2020 06:53:51 AM

hako · Guru

Thanks for the replies - last night when I disconnected the charger it was showing 16.28v and charging 6.3amps according to my clamp meter. Battery was getting very warm .
Charger was a Powersaver 15amp smart charger.

Bottom line is the charger clearly is bad so will be turfed along with the voltage cutoff and that strange device in the picture - replace with a simple charger. Battery is only needed to power a TV and the vans LED lights plus on the rare occasion the Purpleline movers.

Hopefully the house battery is OK as was only on the charger once for an hour - I'll connect it to a portable fridge and see how long it takes to run the battery down to 12.0v. The portable fridge draws 5 amps so I should be able to get an idea of the batteries capacity.

Regarding the device in the picture, when the van is connected to the car, the + 12v runs from the car to the 'car' terminal and thru the diode thing and then to the battery. Note the burnt terminal screw where the cable from the car (via anderson plug) connected (cable was black as well). Maybe dorian is right.

Thanks for the comments.

Whenarewethere · Guru

If the charger has the option of a temperature sensor on the batteries, it should drop the standard charge voltage of 14.4v by about 0.15v per every 1°C increase above 25°C.

dorian · Guru

Whenarewethere wrote:
If the charger has the option of a temperature sensor on the batteries, it should drop the standard charge voltage of 14.4v by about 0.15v per every 1°C increase above 25°C.

I see various figures, but this document cites a temperature coefficient of -2mV/C per cell for lead acid chemistries:

https://www.power-sonic.com/wp-content/uploads/2018/12/Technical-Manual.pdf

For 6 cells, that's a tempco of -12mV/C. Other sources cite -3mV/C per cell.

dorian · Guru

hako wrote:
Regarding the device in the picture, when the van is connected to the car, the + 12v runs from the car to the 'car' terminal and thru the diode thing and then to the battery.

It appears that the diode may just be isolating the car's alternator from the smart charger.

-- Edited by dorian on Sunday 1st of November 2020 11:05:54 AM

Warren-Pat_01 · Guru

Hi Denis,
I wouldn't take the battery down lower than 12.3v.
Did the previous owner tell you how long ago the smart charger was fitted, give you the hand book, leaflet on it?

I've had a look at Powersaver chargers on the net. The specs for the BC-012-15AT give 3 voltages (for the 3 different battery types, I assume) with a maximum of 14.8v on absorption, 13.8v on float (calcium, I recall). Are there any switches that have to be set? One other reference shows some switch settings but 16v is higher than anything I've found - it is certain to cook the battery(ies).

I'm carrying a portable 8A 7stage Repco smart charger with me (am stuck in Toowoomba with a haematoma on my leg) - If you'd like to borrow it, please PM me.

dorian · Guru

hako wrote:
the device has MBR6045

That's a dual Schottky diode in a common cathode configuration. Total current rating is 60A (30A per diode).

https://www.onsemi.com/pub/Collateral/MBR6045WT-D.PDF

hako · Guru

Warren-Pat_01 wrote:
Hi Denis,
I wouldn't take the battery down lower than 12.3v.
Did the previous owner tell you how long ago the smart charger was fitted, give you the hand book, leaflet on it?

I've had a look at Powersaver chargers on the net. The specs for the BC-012-15AT give 3 voltages (for the 3 different battery types, I assume) with a maximum of 14.8v on absorption, 13.8v on float (calcium, I recall). Are there any switches that have to be set? One other reference shows some switch settings but 16v is higher than anything I've found - it is certain to cook the battery(ies).

I'm carrying a portable 8A 7stage Repco smart charger with me (am stuck in Toowoomba with a haematoma on my leg) - If you'd like to borrow it, please PM me.

Thanks for that good advice Warren, nothing was passed on to me by the previous owner, an older single lady who would just say 'fix it' and it was just after she replaced the battery that I bought the van. No switches except gel/flooded which makes no difference.

I've removed the diode device and taken another pic of of the BATT wire which as with the car wire has clearly been overloaded. This is strange because it connects the car to the house battery with the device in between. Must have been some serious current passing from the car to house battery!

Mike Harding - the device has MBR6045 WT V P 828Xb 3A 58 on it.

Thanks for the comments

Warren-Pat_01 · Guru

Denis - I've sent you a PM.

Mike Harding · Guru

Toss the charger and diode. Buy a decent charger and simply connect the car to van in the normal manner - you can always fit a DC-DC charger later if necessary but your quoted battery usage suggests you probably won't need it.

I suspect Dorian is correct about the diode being used to fool the alternator - looking at the discolouration on that wire it has carried a *lot* of current more than most chargers could produce.

The battery should be OK if it's just had the one over-charge but a load test is a good idea. I'm not sure why Warren suggests only going to 12V3 I'd take it down to 11V0 to get a better idea.

dorian · Guru

Mike Harding wrote:
I suspect Dorian is correct about the diode being used to fool the alternator - looking at the discolouration on that wire it has carried a *lot* of current more than most chargers could produce.

From the OP's description, it would appear that the current passing through the diode is produced by the car's alternator rather than the charger. The diode would prevent the charger from charging the car battery at the same time as the house battery, if I understand the setup correctly.

This is a better setup:

https://www.outbackmarine.com.au/applications/caravan-and-rv-electrical-systems/basic-caravan-electrical-system/

I suspect that this is the OP's setup:

                                 AC in
                                   |
 .----------.                  .-------.
 |alternator|                  |charger|
 '----------'                  '-------'
      |        .---.               |
      +--------|VSR|----->|--------+
      |        '---'     diode     |
    + |                          + |
     --- car battery              ---  house battery
      -                            -
      |                            |
     ===                          ===
     GND                          GND

VSR = voltage sensitive relay

-- Edited by dorian on Monday 2nd of November 2020 08:55:13 AM

hako · Guru

Update - I took up Warren's kind offer to loan me his charger and also a load so I could drain the battery to judge it's capacity.

The load, which is simply a twin filament headlight bulb drawing 6 amps, took 7 hours to drain the battery down to 12.3v or 50% capacity, so in theory that's 42 amp/hours for what I presume is a 105 amp/hour battery which only has a inbuilt voltage monitor but no name.

Bottom line is that I think that is acceptable - I now have the battery connected to Warrens 7 stage charger and after 6 hours it's still in 'bulk' charge mode which indicates to me that is accepting charge as a 'healthy' battery should. I'm guessing that after fully charged by a decent charger to battery capacity may improve?

Dorian - thanks for that ID on the component - Warren suggested I take it into Jaycar to see exactly what it was supposed to do.

Regards

Warren-Pat_01 · Guru

G'day Mike,
I suggested that Denis should only reduce the voltage to 50% capacity to safe guard its life. As well my charger only puts out 8A so it wouldn't be on charge for ages.

I've seen too many instances where batteries have been abused, at work, friends who didn't know better & in my vehicles. Fortunately I never had a personal battery explosion but I did see one at work (they were sealed AGM batteries) - the results weren't pretty! The only place for an aux battery in Nissan Patrols (GQ, GU) was under the bonnet where temperatures reach much more than the normal desired battery temp of 26degrees. Toyota at least put them up the front but I wasn't willing to shift everything around to do that. Regardless of what manufacturers' agents say, they don't like 70-80 degrees.

dorian, thanks for your input. I wonder how many systems there are of aux battery/car+trailer(caravan) there are around the place?

I rewired my caravan (no, most of you chaps wouldn't agree with it but my battery load is light). I use the solar panel to charge the van battery, the car to run the fridge via the Anderson plug. As we live in a part of Australia that has an abundance of sun & don't often free camp, it works well for us.