Lippert/Shaudt WA 121545 'booster' DC-DC Charger. Technical support - easy questions

[animology]

Hi there. Looking for someone who has some experience with the Lippert/Shaudt WA 121545 'Booster' or similar model.

Can't get any advice from Lippert/Shaudt as they point blank refuse to talk directly to the customer and can't find a distributor that has any technical knowledge either. Shockingly bad support really for a pretty premium product.

Very simple questions but very specific to this charger or 'booster' as they describe it.

There is no voltage drop between the starter battery and booster.

1. Is the voltage boosted to constant 14.4 when charger set to 'Lithium' and using the starter battery sensor? Say just after start up when starter battery might be a bit low - say 13.8v for sake of argument. Looking for real world info - not from instructions.

2. I’m measuring the current draw with a clamp meter and when charger is set for 45 amp limiting it’s getting to 50 amps. Is this normal?

Neither is that critical really just trying to understand what's going on. The battery will charge at anything around 14v and can handle as many amps as the alternator can put out. Batteries BMS will sort out most issues.

This is what I get for 'upgrading' to a DC-DC charger...

Thanks for the help.
Paolo

 

[Lenny HB]

Ditched my Schaudt 25 amp one didn't like the lithium setting and fitted a Victron Orion XS, I have Rewired the Schaudt with a switch inline with the D+ so I can use it when I need a bit more charge.

 

[LostInSpace]

Not so sure that I can answer your specific points, but I can make the following comments.

The motohome came new fitted with smart alternator and a 121545 and a 95Ah AGM battery. Everything worked fine.

I swapped the AGM for 180Ah of Sterling Power LiFePO4 lithium and changed the 121545 DIP switch to 'lithium'.
Again everything just works fine - still giving upto 45 amp charge when needed whilst driving. Never seen 50 amp

Yes, I know it does not have a float setting - but, that is what the battery BMS is for - to manage the battery.

 

[animology]

I'll try it at different charge limit settings and see it changes. In theory it can charge at 70amps but not sure my puny 90amp alternator would like that long term!

It's more the 'boost' function I was wondering about - the unit is called a booster after all. It's kind of irrelevant as there's no real voltage drop between starter and leisure battery I'd just like to know it's working as it should.

The whold DC-DC thing seems kind of irrelevant considering the battery has it's own BMS with overcurrent - under/over voltage etc built in...

 

[animology]

Ditched my Schaudt 25 amp one didn't like the lithium setting and fitted a Victron Orion XS, I have Rewired the Schaudt with a switch inline with the D+ so I can use it when I need a bit more charge.

The lithium setting is fine if the battery has it's own BMS - it doesn't need to go to float voltage or aything like that. The charger should give a steady 14.4v all the time when using the starter battery sensor. That is what I'm not seeing though - I only see whatever voltage the starter battery is getting.

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[Hoovie]

The lithium setting is fine if the battery has it's own BMS - it doesn't need to go to float voltage or aything like that. The charger should give a steady 14.4v all the time when using the starter battery sensor. That is what I'm not seeing though - I only see whatever voltage the starter battery is getting.

Are you sure you are seeing specifically the same voltage on the output (leisure) as the input (starter)? TBH I would be surprised UNLESS you actually have another charge system in place such as a relay that is in parallel with the Booster. You could confirm this by pulling the D+ wire from the Booster and see what the voltages are.
It is possible that if this Booster was added, whoever did it may not have disabled the existing charger device.

You are measuring the current and seeing ~50A? where are you measuring this? is it on the Booster in, the Booster out, or on the +ve cable coming onto the Leisure Battery?

I can't recall if the 45A value is meant to be the output max current or the input max current. If it is say the output current and the input voltage is lower than the output voltage, the input current will be more than 45A (bit of ohms law .... P=IV or Power = Current x Voltage. ignoring losses within the charger, if the power out = power in, when the voltage is lower in than out, the current must be flipped for the maths to work. dunno if that makes sense or not to you?)
Should the charger put out more than the rating? not unusual for a lot of chargers actually. The Ablemail B2Bs I have installed in my MH will output upto 15% more than the quoted rating depending on the level of charge in the battery. The Victron chargers tend to output >100% also.

It is important to note that the voltage setting - 14.4V - is not neccessarily what you see when the Booster/B2B (it is called a "booster" but it is a B2B) is charging the battery. That is the maximum voltage and it will only get to that when the Lithium Battery is just about full. When it is say at 90% SOC, the voltage is probably going to be around 13.8-13.9V I would guess.
Not seeing 14.4V is not a problem in itself.

 

[autorouter]

There is no voltage drop between the starter battery and booster.

there's no real voltage drop between starter and leisure battery

It is possible that if this Booster was added, whoever did it may not have disabled the existing charger device.

You could try a test to see if this is what is happening. Disconnect one of the wires - for example the booster input - and use your clamp meter at the leisure battery terminals to see if you get any amps flowing into the leisure battery when the engine is running. If the Booster is wired correctly, the amps will be practically zero. If the split charge relay has not been disabled, you should get a noticeable amps value, probably 20A at least.

 

[Lenny HB]

Yes, I know it does not have a float setting - but, that is what the battery BMS is for - to manage the battery.

The lithium setting is fine if the battery has it's own BMS

No it's not the BMS should be treated as a last resort to protect the battery.

I don't like the Schaudt units 14.4v is a bit high for lithium and and not turning off or going to float when the battery is charged is not good.

I replaced mine with an Orion XS a far better unit.
I have reconnected my Schaudt unit in parallel with a switch in line with the D+ for emergency use when I need more charge.

 

[G1969]

No it's not the BMS should be treated as a last resort to protect the battery.

I don't like the Schaudt units 14.4v is a bit high for lithium and and not turning off or going to float when the battery is charged is not good.

I replaced mine with an Orion XS a far better unit.
I have reconnected my Schaudt unit in parallel with a switch in line with the D+ for emergency use when I need more charge.

Mine was left in, with no switch ( as far as I am aware) presumably most of it's output powers the fridge, the xs will switch off automatically. What are the consequences, is it just potentially reduced battery life or worse?

 

[Lenny HB]

Mine was left in, with no switch ( as far as I am aware) presumably most of it's output powers the fridge, the xs will switch off automatically. What are the consequences, is it just potentially reduced battery life or worse?

Possibly reduce battery & BMS life, if you are going to spend all that money on lithium why treat them like sh*t.

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[LostInSpace]

No it's not the BMS should be treated as a last resort to protect the battery.

Perhaps, they should be called a BPS (Battery Protection System).

 

[G1969]

Possibly reduce battery & BMS life, if you are going to spend all that money on lithium why treat them like sh*t.

Okay, good point

 

[animology]

It's taken weeks to get an answer from anyone that deals with Lippert - tried all of UK and Europe! Got a reply from TOOSOLAR.COM in Greece today - they contacted Lippert on my behalf.

"the Booster will charge with 14,4 V until the set current limit (eg. 45A) is reached.
The the voltage drops until the voltage is barely enough to charge the battery.
As the voltage of the battery rises, the voltage oft he booster rises also.
So measuring on an empty battery will not be 14,4V."

Trying to remember CC/CV charging from past LiPo RC days now...

Either way - the 'booster' is fitted now and it's charging so guess I just trust it's doing it's thing. I just like to know how things work rather than just blindly fitting something and hope it works correctly.

I'd avoid Lippert/Schaudt for anything in the future - can't think I've ever dealt with any company that's just flatly refused to engage with a customer this way. I used to be scared to phone Sterling Power in case I got Charles Sterling in the phone but at least you got an answer to your question. "Ben" is dealing with technical questions now who is super helpful

 

[animology]

I don't like the Schaudt units 14.4v is a bit high for lithium and and not turning off or going to float when the battery is charged is not good.

So was yours sitting at 14.4v all the time? That's basically what my alternator would do with no charger in place.

 

[AdrianChen]

It's taken weeks to get an answer from anyone that deals with Lippert - tried all of UK and Europe! Got a reply from TOOSOLAR.COM in Greece today - they contacted Lippert on my behalf.

"the Booster will charge with 14,4 V until the set current limit (eg. 45A) is reached.
The the voltage drops until the voltage is barely enough to charge the battery.
As the voltage of the battery rises, the voltage oft he booster rises also.
So measuring on an empty battery will not be 14,4V."

Trying to remember CC/CV charging from past LiPo RC days now...

Either way - the 'booster' is fitted now and it's charging so guess I just trust it's doing it's thing. I just like to know how things work rather than just blindly fitting something and hope it works correctly.

I'd avoid Lippert/Schaudt for anything in the future - can't think I've ever dealt with any company that's just flatly refused to engage with a customer this way. I used to be scared to phone Sterling Power in case I got Charles Sterling in the phone but at least you got an answer to your question. "Ben" is dealing with technical questions now who is super helpful

Yes Charles was a little brusque at times....

I also think that explanation may have lost a bit in translation......

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[LostInSpace]

So was yours sitting at 14.4v all the time? That's basically what my alternator would do with no charger in place.

Exactly. The difference is that the 121545 will limit the charging current to 45 amps. The alternator wuld not.

 

[autorouter]

It's taken weeks to get an answer from anyone that deals with Lippert - tried all of UK and Europe! Got a reply from TOOSOLAR.COM in Greece today - they contacted Lippert on my behalf.

"the Booster will charge with 14,4 V until the set current limit (eg. 45A) is reached.
The the voltage drops until the voltage is barely enough to charge the battery.
As the voltage of the battery rises, the voltage oft he booster rises also.
So measuring on an empty battery will not be 14,4V."

Trying to remember CC/CV charging from past LiPo RC days now...

As you say, it is a CC/CV system. That reply shows they simply do not understand the first thing about it.

The first stage of charging is Constant Current (CC), and is called the Bulk stage. In detail, what this means is that the charger applies a fixed current, equal to its maximum output amps. That's 45A in this case. This amps flow is pushed into the battery that needs charging. The resulting voltage is whatever it is. The charger measures this voltage continuously.

If the voltage is less than the set 'absorption voltage' of 14.4V, then it continues to push out the maximum of 45A, while continuously monitoring the voltage as it slowly rises. This is how Constant Current mode works. There is no fixed voltage, it is varying all the time, it's the current (amps) that is fixed. If you measure the battery terminal voltage during the Constant Current Bulk stage, it will be less than the 14.4V absorption voltage, until right at the end of the Bulk stage.

Eventually as the the voltage gradually rises, it will reach the Absorption Voltage of 14.4V. That's when the charger switches from Constant Current (CC) mode into Constant Voltage (CV) mode. This second charging stage is called the Absorption stage. At this point, if it's a lead-acid-based battery (flooded, gel, AGM etc) then it's about 80% full. If it's a lithium it's over 95% full.

In Constant Voltage mode, a fixed voltage is applied, while continuously monitoring the amps. The amps value will start at the maximum output at the CC/CV mode switchover. The amps will gradually fall as the battery becomes fully charged. When it reaches a minimum limit, about 1/10 of the maximum amps, called the Tail Current, the charger decides the battery is fully 100% charged, so it has finished the Absorption stage, so it switches to the Float stage.

The Float stage is also Constant Voltage mode, but the voltage is reduced until there is almost zero amps going into the battery. Just enough to make up for the internal self-discharge of the battery.

Some types of lead-acid battery (Gel, AGM) require a timed extended absorption stage. This is for 'recombination', where the small amount of oxygen/hydrogen gases that might be produced during charging are recombined back into water into the electrolyte liquid/gel. This might take several hours for a very discharged battery. If this stage is missed, the battery gradually loses electrolyte liquid/gel and so loses capacity.

In contrast, an alternator outputs a constant voltage, say 14.4V. The current (amps) is whatever it is. For a lead-acid-based battery the voltage will have been chosen so that the amps is a reasonable value, so as not to overload the alternator. If you go connecting a lithium battery to the same alternator, and apply a fixed 14.4V to a flat lithium battery, then the resulting amps demand may be much more than the alternator can supply without overheating. That's when you get overheating problems, especially if you're stuck in traffic on a hot day.

That's why a Booster (B2B charger) is needed for a lithium battery. It ensures that the amps from the alternator can never be more than the B2B decides to draw.

 

[G1969]

As you say, it is a CC/CV system. That reply shows they simply do not understand the first thing about it.

The first stage of charging is Constant Current (CC), and is called the Bulk stage. In detail, what this means is that the charger applies a fixed current, equal to its maximum output amps. That's 45A in this case. This amps flow is pushed into the battery that needs charging. The resulting voltage is whatever it is. The charger measures this voltage continuously.

If the voltage is less than the set 'absorption voltage' of 14.4V, then it continues to push out the maximum of 45A, while continuously monitoring the voltage as it slowly rises. This is how Constant Current mode works. There is no fixed voltage, it is varying all the time, it's the current (amps) that is fixed. If you measure the battery terminal voltage during the Constant Current Bulk stage, it will be less than the 14.4V absorption voltage, until right at the end of the Bulk stage.

Eventually as the the voltage gradually rises, it will reach the Absorption Voltage of 14.4V. That's when the charger switches from Constant Current (CC) mode into Constant Voltage (CV) mode. This second charging stage is called the Absorption stage. At this point, if it's a lead-acid-based battery (flooded, gel, AGM etc) then it's about 80% full. If it's a lithium it's over 95% full.

In Constant Voltage mode, a fixed voltage is applied, while continuously monitoring the amps. The amps value will start at the maximum output at the CC/CV mode switchover. The amps will gradually fall as the battery becomes fully charged. When it reaches a minimum limit, about 1/10 of the maximum amps, called the Tail Current, the charger decides the battery is fully 100% charged, so it has finished the Absorption stage, so it switches to the Float stage.

The Float stage is also Constant Voltage mode, but the voltage is reduced until there is almost zero amps going into the battery. Just enough to make up for the internal self-discharge of the battery.

Some types of lead-acid battery (Gel, AGM) require a timed extended absorption stage. This is for 'recombination', where the small amount of oxygen/hydrogen gases that might be produced during charging are recombined back into water into the electrolyte liquid/gel. This might take several hours for a very discharged battery. If this stage is missed, the battery gradually loses electrolyte liquid/gel and so loses capacity.

In contrast, an alternator outputs a constant voltage, say 14.4V. The current (amps) is whatever it is. For a lead-acid-based battery the voltage will have been chosen so that the amps is a reasonable value, so as not to overload the alternator. If you go connecting a lithium battery to the same alternator, and apply a fixed 14.4V to a flat lithium battery, then the resulting amps demand may be much more than the alternator can supply without overheating. That's when you get overheating problems, especially if you're stuck in traffic on a hot day.

That's why a Booster (B2B charger) is needed for a lithium battery. It ensures that the amps from the alternator can never be more that the B2B decides to draw.

Thanks for this very detailed explanation, so in layman’s terms , it does switch off/ down if the batteries are full then?

 

[autorouter]

it does switch off/ down if the batteries are full then?

Yes. For a lead-acid-based battery, the third stage (Float) is a voltage just a bit higher than the internal battery voltage, usually about 13.5V, but it depends on the battery type. That is just enough to keep the battery topped up to 100%, but won't overcharge it. It stops the buildup of sulfation that can happen if left for weeks without any charging.

A lithium battery doesn't need a Float stage, it doesn't deteriorate in storage due to sulfation or anything else. It's OK to store a lithium battery for months at say 50%. However if the charger float voltage is less than the lithium battery internal voltage, then no amps will flow in or out of the battery. There is a tendency for the amps to flow from the battery into the charger because the battery voltage is higher than the charger voltage. However there is a diode in the charger output, which stops any amps flowing back into the charger.

A fully charged lithium battery has a voltage of about 13.6, so if the float voltage is set to less than that, it will be OK. 13.2V is recommended, I think.

 

[AdrianChen]

Thanks for this very detailed explanation, so in layman’s terms , it does switch off/ down if the batteries are full then?

The instruction manual seems to confirm Lenny's findings, that when set to lithium the unit outputs a steady 14.2v, so in lithium mode it appears not to be acting as a 3 stage smart charger, but like the old fashioned constant voltage type.

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[treblid]

when set to lithium the unit outputs a steady 14.2v

It's actually 14.4V constant once in CV mode with lithium selected.

 

[Ian_H]

It's actually 14.4V constant once in CV mode with lithium selected.

Or you can set it to gel mode so it drops down to 13.8V for absorption phase....

 

[LostInSpace]

When the battery type is set to Lithium, is just outputs a constant voltage of 14.4 volts whenever the D+ signal is 12v.

Ideal for charging LiFePO4 batteries or powering a fridge whilst driving.

 

[treblid]

When the battery type is set to Lithium, is just outputs a constant voltage of 14.4 volts whenever the D+ signal is 12v.

Ideal for charging LiFePO4 batteries or powering a fridge whilst driving.

It is not a constant 14.4V if the battery is not near full. The charger will be in CC mode at 25A with a voltage that provides that current.

 

[AdrianChen]

Thanks for clarifying - what will the voltage be when the battery is full, and I have 6 hours driving left?

It is not a constant 14.4V if the battery is not near full. The charger will be in CC mode at 25A with a voltage that provides that current.

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[treblid]

Thanks for clarifying - what will the voltage be when the battery is full, and I have 6 hours driving left?

It will stay at 14.4V constant once in CV mode with lithium selected.

 

[autorouter]

Thanks for this very detailed explanation, so in layman’s terms , it does switch off/ down if the batteries are full then?

Yes. For a lead-acid-based battery,

However for a lithium battery

It will stay at 14.4V constant once in CV mode with lithium selected.

The manual says its charging characteristic for Lead-acid-based batteries is 'IUoU', which is:
I = Constant Current (amps), voltage varies.
Uo = Constant Voltage, the 'o' means it's a higher voltage that shouldn't be sustained indefinitely.
U = Constant Voltage, which is suitable to be sustained indefinitely.

However for lithium it says the charging characteristic is 'CCCV', which is:
CC = Constant current (amps), voltage varies, just like the I in IUoU.
CV = Constant Voltage, amps varies, voltage 14.4V constant, does not reduce to a lower voltage as the IUoU characteristic does.

I think for lithium batteries this is not a good idea. For most usage it won't matter - two or three hours of driving starting with a low battery for example. However starting with a full battery and driving for six hours or so could overcharge it. Lithiums should not be overcharged.

 

[LithiumConvert]

I don't like the Schaudt units. 14.4v is a bit high for lithium

The documentation for my Sterling Power batteries says that the recommended charging voltage is 14.4v.

It is not a constant 14.4V if the battery is not near full. The charger will be in CC mode at 25A with a voltage that provides that current.

The Schaudt documentation for the WA121545 says that when set to Lithium, the voltage is constant at 14.4v.
The 121545 is never in Constant Current (CC) mode when set to Lithium
(and has a default charging current limit of 45A, not 25A)

 

[autorouter]

The Schaudt documentation for the WA121545 says that in lithium mode the voltage is constant at 14.4v.
The 121545 is never in Constant Current (CC) mode when set to Lithium
(and has a default charging current limit of 45A, not 25A)

The documentation sometimes omits a reference to the Constant Current mode, especially when discussing voltages. However it is clear from the documentation that the first part of the charging characteristic is a Constant Current stage. For example here, it definitely says the lithium profile is CCCV. The voltage stage is constant, ie it does not drop when current falls below the switchover current or when a time elapses.

 

[treblid]

The 121545 is never in Constant Current (CC) mode when set to Lithium

As autorouter has clearly explained above. It would also self destruct if it had no current limiting!

(and has a default charging current limit of 45A, not 25A)

My error. I was thinking of the 121525. Principal is the same.

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