Charging Lithium Batteries

[CPD]

With 3 x 100Ah lithium batteries in parallel, what size DC-DC charger should I be going for, coming from the 12v 115Amp alternator. ? Also, any recommendations for supplier of said charger ?. Many thanks and Merry Christmas to one and all .............

 

[GHA]

With 3 x 100Ah lithium batteries in parallel, what size DC-DC charger should I be going for, coming from the 12v 115Amp alternator. ? Also, any recommendations for supplier of said charger ?. Many thanks and Merry Christmas to one and all .............

Sticking to 50% or less of rated current seems the most common rule of thumb for constant running otherwise it overheats so maybe 50a or less. I got a 25a one off amazon outputting 13.8v for about £30 think it was. Though not checked it for real yet, not been needed.
Merry Xmas

 

[Trident]

50 amp will be ideal - Renogy make a very good 50A DCDC - I have two on my boat .

 

[CPD]

50 amp will be ideal - Renogy make a very good 50A DCDC - I have two on my boat .

Why two Trident ???

 

[Trident]

Why two Trident ???

Twin engines

 

[Neeves]

Twin engines

With 3 x 100Ah lithium batteries in parallel, what size DC-DC charger should I be going for, coming from the 12v 115Amp alternator. ? Also, any recommendations for supplier of said charger ?. Many thanks and Merry Christmas to one and all .............

CPD has a 300 amp house bank - in the absence of a battery charger, solar etc he will need 6 hours of the engine running flat chat to recharge with a 50amp DC-DC charger (assuming he uses his Lithium to the limits).

?

Jonathan

 

[Sea Change]

The Victron Orion series (available in 18A or 30A) is popular, but they get very hot and the output drops. It's essential to mount them in a well ventilated place. Note that the Orion can be either a simple converter, or a charger. You need the charger version, the converter is a power supply only, which doesn't produce a high enough voltage to charge batteries.

The new Victron XS 50A is supposed to run much cooler and with better efficiency, but I've heard that it produces significant interference on ch16. Probably not a problem on a motorhome but not ideal on boats.

 

[noelex]

CPD has a 300 amp house bank - in the absence of a battery charger, solar etc he will need 6 hours of the engine running flat chat to recharge with a 50amp DC-DC charger (assuming he uses his Lithium to the limits).

?

Jonathan

Indeed, assuming the bank was completely discharged.

This charging rate is comparable to the maximum safe current output of a typical 115A alternator, which is approximately 50% of its rated capacity. This is in accordance with the “50% rule” mentioned in post#2.

An alternative approach involves using an external regulator with temperature control directly connected to the house bank, accompanied by a small DC-DC charger to maintain the start battery’s charge. This method provides a more precise delivery of the maximum safe current, but for a standard 115A alternator, the average current is likely to be only slightly higher than 50A.

However, with a high-performance aftermarket alternator or a large-case industrial alternator (my preferred option), significantly higher currents and consequently faster charging of the bank are achievable through the use of an external regulator.

 

[Alex_Blackwood]

CPD has a 300 amp house bank - in the absence of a battery charger, solar etc he will need 6 hours of the engine running flat chat to recharge with a 50amp DC-DC charger (assuming he uses his Lithium to the limits).

?

Jonathan

Hear what you are saying. As is usual in these cases we don't have any information on what other sources he may have. He has asked what he should have for that particular alt. He won't want to be overloading it I would have thought 75 amps would be ideal (Sterling do a 70amp one)

 

[Trident]

CPD has a 300 amp house bank - in the absence of a battery charger, solar etc he will need 6 hours of the engine running flat chat to recharge with a 50amp DC-DC charger (assuming he uses his Lithium to the limits).

?

Jonathan

I'm not sure what you are trying to say other than you can do maths...

No one makes anything reliable bigger than 50 amp so if he lets the batteries run flat then yes he would
Most will of course be using the engines on and off all the time and topping up as they go
He also never mentioned solar or shore power which most will have so its about getting the best possible DCDC charging rate from a reliable charger; hence I recommended Renogy as they make bigger than Victron, and have built in fans for cooling (both and inlet and outlet fan on the 50 amp so it can run for hour after hour without getting too hot and doesn't drop output)

The alternator rated at 115A will only put out 50-60 amps in continuous use so there is little point in using anything larger as the only option that I know if is Sterling which are not great quality and fail quite regularly

 

[Neeves]

I'm not sure what you are trying to say other than you can do maths...

No one makes anything reliable bigger than 50 amp so if he lets the batteries run flat then yes he would
Most will of course be using the engines on and off all the time and topping up as they go
He also never mentioned solar or shore power which most will have so its about getting the best possible DCDC charging rate from a reliable charger; hence I recommended Renogy as they make bigger than Victron, and have built in fans for cooling (both and inlet and outlet fan on the 50 amp so it can run for hour after hour without getting too hot and doesn't drop output)

The alternator rated at 115A will only put out 50-60 amps in continuous use so there is little point in using anything larger as the only option that I know if is Sterling which are not great quality and fail quite regularly

We are all trying to help the OP, in our own small way. Sarcasm is unnecessary.

One of the benefits of Lithium is the ability to use more of the contained amps - the penalty is if you do run this specific battery bank down you then need to run the engines for hours - or add in another source of power to replenish. It is unlikely the OP and crew will welcome the long term use of the engine and he thus needs to consider alternative sources to re-charge his battery. Now would be a good time to consider how he is going to recharge the battery, in addition to using his engine, and the Renogy DC/DC charger as there might be a more cost effective and neater solution if he considers recharging in general - not restricted to a DC/DC charger.

MPPT and DC/DC controllers are not available......?

Jonathan

 

[PaulRainbow]

We are all trying to help the OP, in our own small way. Sarcasm is unnecessary.

One of the benefits of Lithium is the ability to use more of the contained amps - the penalty is if you do run this specific battery bank down you then need to run the engines for hours - or add in another source of power to replenish. It is unlikely the OP and crew will welcome the long term use of the engine and he thus needs to consider alternative sources to re-charge his battery. Now would be a good time to consider how he is going to recharge the battery, in addition to using his engine, and the Renogy DC/DC charger as there might be a more cost effective and neater solution if he considers recharging in general - not restricted to a DC/DC charger.

MPPT and DC/DC controllers are not available......?

Jonathan

The questions is "what size DC-DC charger should I be going for, coming from the 12v 115Amp alternator".

Other charging sources are not relevant to the question. The OP may or may not have a bank of solar panels, but if he runs his engine he needs a way for the alternator to safely charge the batteries.

If it does take 6 hours to charge the batteries that's better than having to run the engine for several shorter periods with lead acid batteries. He'll still need to generate the same amount of power, but with lead acid he'll need to run the engine more often and for longer, due to the additional time it would take to charge LA, plus, they'll never get fully charged.

 

[lustyd]

I have 300Ah lithium on my boat and we have a Victron Orion Xs 50A B2B charger which I downrated in the software to 30A to protect the alternator. It replaced a Victron Orion 30A B2B which was both larger and hotter. I believe my alternator is 70A on the MD2040 so your 115A may allow for 50A charging. The batteries will likely accept anything up to 300A so as Paul says, the alternator is the thing you're measuring against.

 

[Sea Change]

I have 300Ah lithium on my boat and we have a Victron Orion Xs 50A B2B charger which I downrated in the software to 30A to protect the alternator. It replaced a Victron Orion 30A B2B which was both larger and hotter. I believe my alternator is 70A on the MD2040 so your 115A may allow for 50A charging. The batteries will likely accept anything up to 300A so as Paul says, the alternator is the thing you're measuring against.

How do you find the VHF interference?

I'm wondering about the Renogy DC-DC/MPPT myself as it seems very good value.

 

[lustyd]

How do you find the VHF interference?

It's been fine on both units, but the old one interfered with the tachometer which the new one fixed.

 

[Alex_Blackwood]

I'm not sure what you are trying to say other than you can do maths...

No one makes anything reliable bigger than 50 amp so if he lets the batteries run flat then yes he would
Most will of course be using the engines on and off all the time and topping up as they go
He also never mentioned solar or shore power which most will have so its about getting the best possible DCDC charging rate from a reliable charger; hence I recommended Renogy as they make bigger than Victron, and have built in fans for cooling (both and inlet and outlet fan on the 50 amp so it can run for hour after hour without getting too hot and doesn't drop output)

The alternator rated at 115A will only put out 50-60 amps in continuous use so there is little point in using anything larger as the only option that I know if is Sterling which are not great quality and fail quite regularly

Are you suggesting that Sterling are not reliable? ( #9) I don't Know, hence I ask They are a tad pricey though
With ref. to the alt. if it is continuously rated at 115a then it will run at that continuously. It should also run at 120% overload for 20 minutes.
If it is time rated i.e. 115a for 20 minutes Then that is a different story.
Just saying as it can be confusing to just quote, willy nilly, a rating . Sorry if above is all a bit of thread drift.

 

[CPD]

Thanks all, very informtive and helpful, as usual. For info, I have 100W solar and a Rutland 913 wind. Will be looking to add a further 200W solar if I can find somewhere happy to mount it.

 

[CPD]

Confused now .................... where would the VSR go .......... immediately after the alternator I guess ??

 

[CPD]

I should add that the plan is to keep lead acid as starter with the VSR charging that first as usual ..........

 

[lustyd]

where would the VSR go

Deleting, Paul is right there should be no VSR