Votronic VCC 1212-90 battery to battery charger starting & stopping every 5 seconds??

[nigelivy]

Hi Folks

I've just recently put a new LiFePO4 battery into my motorhome and am charging it with a combination of three chargers:
1) Votronics VCC 1212-90 battery to battery charger
2) Votronics Pb 1215 SMT 2B 240v charger
3) Epever XTRA4210N MPPT solar charge controller

The 240v charger that I've connected to my EHU plug on the outside of the MH works perfectly. It charges the battery up to the maximum output capacity of the charger (15a) and works flawlessly.

The battery to battery charger is getting current from the alternator and it starts up (fan spinning, etc..), starts outputting current to the leisure battery and then after about 5 seconds it turns off for a few seconds and then starts the process again. It keeps doing this indefinitely and never charges consistently. It also will not charge the battery to a full state of charge.
Does anyone know why this battery to battery charger would be doing this?

 

[Pausim]

I think the first thing to do is check the wiring and settings of the B2B. Has it been set up to be triggered by a D+ connection or voltage sensing?

I am only guessing but if it is voltage sensing perhaps it is tripping itself up. Being a hefty 90A beast I wonder if it might possibly be putting such a heavy load on the alternator and engine battery that as soon as it cuts in, the voltage drops back below the threshold so it turns itself off again. At this point the voltage will go back up so it turns itself back on and the cycle repeats.

D+ is in my opinion much the better way to operate a B2B. What make and size of LiFePO4 have you fitted?

 

[nigelivy]

I think the first thing to do is check the wiring and settings of the B2B. Has it been set up to be triggered by a D+ connection or voltage sensing?

I am only guessing but if it is voltage sensing perhaps it is tripping itself up. Being a hefty 90A beast I wonder if it might possibly be putting such a heavy load on the alternator and engine battery that as soon as it cuts in, the voltage drops back below the threshold so it turns itself off again. At this point the voltage will go back up so it turns itself back on and the cycle repeats.

D+ is in my opinion much the better way to operate a B2B. What make and size of LiFePO4 have you fitted?

I have the voltage sensor cables & D+ connected to the B2B, but I've programmed the B2B to use the D+ to activate charging. I believe you can have both connected and choose which activates the charging (according to the manual) but I wonder if having both is causing a conflict.

My alternator in the MH is 120amp, so I assumed it would cope with the load, but it might not be up to the task?

The battery I've fitted is a set of 200ah DIY LiFePO4 Winston cells with the 123 Smart BMS.

 

[Wissel]

What voltage is the Votronic set at, and is it tripping the BMS Vmax?

Have you tried putting a multimeter across the van battery terminals and seeing if the voltage drops when the charger kicks in?

 

[SandraL]

Can you program the b2b to reduce its output?
If this works it might indicate base vehicle cannot support such a high charge rate.

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[nigelivy]

Have you tried turning the charger down to a lower current?
What voltage is the Votronic set at, and is it tripping the BMS Vmax?

I have not, but I will try and see if I can adjust the current. I don't think you can set the current at a particular amperage on these Votronic units - I think it's more of a case of setting it to high or low, but I'll try that!

I've looked through the 123 Smart BMS manual and don't see anything in there that would indicate that the BMS is stopping the charge. I have 123 Electric's Smart Relay installed as well, so I would have thought that I would hear the relay opening and closing if the BMS was stopping charge, which I did not hear?

 

[Wissel]

I have not, but I will try and see if I can adjust the current. I don't think you can set the current at a particular amperage on these Votronic units - I think it's more of a case of setting it to high or low, but I'll try that!

I've looked through the 123 Smart BMS manual and don't see anything in there that would indicate that the BMS is stopping the charge. I have 123 Electric's Smart Relay installed as well, so I would have thought that I would hear the relay opening and closing if the BMS was stopping charge, which I did not hear?

Did you see my edit? My best guess would be voltage drop

 

[Pausim]

You can limit the input and the output amperage.

 

[Wissel]

You can limit the input and the output amperage.

It's on p14 of the manual:

The multimeter on SB would be a quicker way of seeing if this was the issue though. If the alternator wasn't up to the output, the SB voltage should drop quite drastically

 

[nigelivy]

It's on p14 of the manual:
View attachment 449669
The multimeter on SB would be a quicker way of seeing if this was the issue though. If the alternator wasn't up to the output, the SB voltage should drop quite drastically

Thanks, will try this and see if that's the case. Will also adjust the B2B draw settings to see if that helps.

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[Pausim]

I understand what you say about connecting both D+ and Vb-/Vb+, it should be ok but I would be inclined to try the D+ independently just to rule out the possibility that there is a voltage drop involved. If you have fully disabled the voltage sensing with both dip switches to the left then the V wires ought to be redundant anyway. I admit I do not fully understand the D+ and High setting, it seems to be a hybrid control but probably still subject to voltage drop issues.

Another possible area to look for is whether an existing battery linking relay is creating an electrical loop when the engine is running. I got this wrong when I first installed my VCC 1212-45 in my previous motorhome. It caused some erratic behaviour, though it wasn’t quite the malfunction you describe.

 

[nigelivy]

I understand what you say about connecting both D+ and Vb-/Vb+, it should be ok but I would be inclined to try the D+ independently just to rule out the possibility that there is a voltage drop involved. If you have fully disabled the voltage sensing with both dip switches to the left then the V wires ought to be redundant anyway. I admit I do not fully understand the D+ and High setting, it seems to be a hybrid control but probably still subject to voltage drop issues.

Another possible area to look for is whether an existing battery linking relay is creating an electrical loop when the engine is running. I got this wrong when I first installed my VCC 1212-45 in my previous motorhome. It caused some erratic behaviour, though it wasn’t quite the malfunction you describe.

Thank-you! I’ll try disabling Vb-/Vb+ and see what that does. Appreciate the help!

 

[Lenny HB]

120 amp alternator is quite small for a Motorhome, 160/180 more normal so it could be the alternator shutting down if the B2B is set for max output.

 

[nigelivy]

I've just tested the suggestions by adjusting the settings on the battery to battery charger to the minimum input & output and it has helped, but not solved the problem. Previously the charger would stop/start regardless of whether I revved the engine or not, but since adjusting to the minimum input & output, the charger only turns off when the engine is idling and it is not consistent. It's pretty random. So by this, I'm guessing that the suggestions that the charger is drawing too much for the alternator are correct.

 

[Pausim]

So by this, I'm guessing that the suggestions that the charger is drawing too much for the alternator are correct.

It does look that way.

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[nigelivy]

It does look that way.

That leaves me with the option of either reducing the capacity of my B2B charger or increasing the capacity of my alternator.

I plan on changing my cam belt next spring, so would make sense to change the alternator at the same time, if I decide to go that route. I guess one thing to consider is: what damage (if any) could be caused to either the B2B charger or battery by waiting until then?

 

[Wissel]

Will you be using your van much before the Spring? If not you could disconnect it?

It's a great charger that will deliver the full 90a into your battery with a bigger alternator (I have same charger and similar setup)

 

[nigelivy]

Will you be using your van much before the Spring? If not you could disconnect it?

It's a great charger that will deliver the full 90a into your battery with a bigger alternator (I have same charger and similar setup)

Yes, am planning to use the van a far amount between now and spring. I guess leaving this one behaving like it is until spring is not a good option.

It seems to charge fine at high revs now that I’ve adjusted it to min input/output, but turns of and on when idling.

 

[Wissel]

I'd guess it more likely to damage your alternator than the charger, but I don't think I'd risk it personally.

Can you use EHU for a few months?

 

[SandraL]

Will you be using your van much before the Spring? If not you could disconnect it?

It's a great charger that will deliver the full 90a into your battery with a bigger alternator (I have same charger and similar setup)

Wissel
Does yours stop charging when engine is idling?
I would expect it to if lithiums were getting charged at 90 amps as most of that at idling speed would be coming from starter battery instead of alternator, even with a larger output alternator.
Otherwise if sat in traffic idling for long periods it would result in flat starter battery.
Once the lithiums are nearly charged the b2b output will be lower and this issue will not be there.
Perhaps an email to Votronics might throw some light?

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[Wissel]

Wissel
Does yours stop charging when engine is idling?
I would expect it to if lithiums were getting charged at 90 amps as most of that at idling speed would be coming from starter battery instead of alternator, even with a larger output alternator.
Otherwise if sat in traffic idling for long periods it would result in flat starter battery.
Once the lithiums are nearly charged the b2b output will be lower and this issue will not be there.
Perhaps an email to Votronics might throw some light?

Mines fine, but I think I have a higher output alternator. I had mine replaced in 2019 and requested the highest output Bosch (but no idea which model was fitted, or the output)

I did do a lot of testing when I fitted my 90a changer, checking the voltage across the SB. I get a small amount of voltage drop when idling (still way higher than resting), and no drop at 1500rpm. It works perfectly regarding charging.

Where I found it not as good was maintaining the SB. I guessed this was due to the different LiFePO4 voltage so disabled this feature and fitted a VanBitz battery master. All good now.

 

[SandraL]

Having had a read of the manual it seems if you use the voltage sensing of starter battery to turn the b2b on it can be set to react at different voltages.
This suggests it will turn itself off if starter battery voltage drops below a set figure, say 13.0v.
I think that at idle with 90 amps being drawn by b2b plus normal engine loads then this could well occur, giving result of cycling on and off the b2b until revs, and alternator output, rise.
Have pasted a bit of table 4 below. Appreciate you may/are useing d+ signal but surely the votronic design will protect starter battery by shutting down on low volts?
If so you are experiencing normal use , ie not a fault
Have you put voltmeter on starter battery while this is happening? If so what results?

Table 4:
Selector
Switch
IN Input Side of the Charging Converter:
Set the operating range and the behaviour of the charging converter up to the starter
circuit. Also refer to
"Function of the Power Control at Starter Battery and Generator", page 17.
1. Pure voltage control of the charging converter, leave terminal "D+" blank:
Because of the high voltage thresholds, only to be used with "Vs- and Vs+" start sensor cables,
sufficiently dimensioned cable cross-sections and powerful generator.
The starter battery will not be discharged under any circumstances.
Increase of the charging capacity: > 13.50 V
Reduction of the charging capacity: < 13.20 V
Switching off threshold: < 13.00 V 30 sec.
2. Pure voltage control of the charging converter, leave terminal "D+" blank:
Like 1. However, lower switching thresholds, negligible load of the starter battery.
Increase of the charging capacity: > 13.30 V
Reduction of the charging capacity: < 13.00 V
Switching off threshold: < 12.80 V 30 sec.

 

[footscray188c]

Fit the voltronic D+ module to provide the signal to the trigger D+ connection on the B2B unit .My unit would not work properly using the Voltage sensing .

 

[nigelivy]

Thought I'd update you on what I landed up up doing for this issue that I was facing. I had wanted to change my alternator at some point, so decided that I would just go ahead and do that.

I bought a 160A alternator and fitted that on my van and has pretty much solved the issue. The charger now runs constantly and doesn't stop/start when the vehicle is idling. I spent quite a bit of time interacting with the owner of Link Removed (who I bought the charger from) and he has assured me that the charger will not damage the alternator and it stopping/starting was to ensure that it did not draw too much for the alternator to handle and also that that is designed behaviour for the charger, so it would not have problems either.
Nevertheless, I changed the alternator anyway because I felt that my previous 120A alternator wasn't powerful enough for what I needed anyway and it has solved the issue. I have cycled my LiFePO4 battery a number of times now and charged it from low SOC and not had problems.

Thanks again for all your input!