Charging Lithium Batteries

[PaulRainbow]

Confused now .................... where would the VSR go .......... immediately after the alternator I guess ??
View attachment 187140

This is incorrect, you are not going to use it to run loads, but to charge the Lithiums, surely ?

The DC-DC charger replaces the VSR. This allows the alternator to safely charge the Lithiums without overheating the alternator.

Solar and wind connect straight to the Lithiums.

Mains can go to both if it's a multi output charger, or to the engine battery if single output.

 

[Sea Change]

Solar and wind connect straight to the Lithiums.

Slight thread drift, I've found myself in possession of a Silentwind and as far as I can tell I can't connect it directly to lithium using the supplied charge controller... What's the best way round this? I may just use it to top up the starter/windlass circuit and if it's producing enough power, the DC-DC should kick in and send some power to the lithium. This is assuming that I don't wire the DC-DC to come on with the ignition, but instead set it to start charging above a certain voltage.
(And I don't expect it to work very well since the Silentwind is unlikely to keep up with the 18A DC-DC)

 

[Neeves]

Slight thread drift, I've found myself in possession of a Silentwind and as far as I can tell I can't connect it directly to lithium using the supplied charge controller... What's the best way round this? I may just use it to top up the starter/windlass circuit and if it's producing enough power, the DC-DC should kick in and send some power to the lithium. This is assuming that I don't wire the DC-DC to come on with the ignition, but instead set it to start charging above a certain voltage.
(And I don't expect it to work very well since the Silentwind is unlikely to keep up with the 18A DC-DC)

Surely one option is to ask Silent Wind.

Its in their interests to have a simple answer or they immediately deny their own access to a huge segment of their potential market. Most owners of a Silent Wind unit will also have solar and many will have Lithium batteries. Its difficult to believe you are the first to have an issue.

Jonathan

 

[Trident]

How do you find the VHF interference?

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

Personally I always fit DCDC and MPPT separately and I think I've only ever supplied the combined unit once.

It does save a little money if you buy the Renogy dual unit but its a single point of failure for all your charging then which seems like a bad idea on a boat.

 

[Trident]

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.

I have seen and heard more issues with Sterling stuff than any other. I had two failures on a customer's boat with their DCDC - both bought by him - the second being a replacement for the first that dies about 6 weeks out of warranty . (It was a 24v model) also the set up and display via a million christmas tree lights D) is not great. If I had to have a larger DCDC I would use two Victron or Renogy rather than one Sterling . Having said that, for balance they have lots of satisfied customers and some people on here swear by them so perhaps my experiences with them have been unusual.

 

[Neeves]

Personally I always fit DCDC and MPPT separately and I think I've only ever supplied the combined unit once.

It does save a little money if you buy the Renogy dual unit but its a single point of failure for all your charging then which seems like a bad idea on a boat.

In previous posts others (and you?) have extolled Renogy - have you any background to Renogy failures, the DCDC units, the MPPT units and the combined units? (accepting you have only fitted one of the latter (but you might talk to others and get some background.

I suspect not - or you would have quoted them

What is the price difference and how big is the combined unit vs 2 separate units.

Edirt. Here the DCDC unit is 50 amp (with the MPPT controller) and list price is stg250 but its on special from a number of outlets at stg200. (10% sales tax)

Jonathan.

 

[Neeves]

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.

I suspect you might need a new and/or another solar controller - a combined DCDC and MPPT controller seems an interesting option.

Options for solar panels seems to include guard rails, stanchions, cantilevered out.

 

[Neeves]

I note Epever offer a DCDC charger 65amp combined with a MPPT controller and inverter.

Jonathan

 

[Sea Change]

Personally I always fit DCDC and MPPT separately and I think I've only ever supplied the combined unit once.

It does save a little money if you buy the Renogy dual unit but its a single point of failure for all your charging then which seems like a bad idea on a boat.

I'm thinking of fitting one alongside two other MPPTs so I would have some backup. I don't generally use my alternator to charge, I rely almost entirely on solar.
I'll probably just go Victron though... because it's available locally and I like them...

 

[Trident]

In previous posts others (and you?) have extolled Renogy - have you any background to Renogy failures, the DCDC units, the MPPT units and the combined units? (accepting you have only fitted one of the latter (but you might talk to others and get some background.

I suspect not - or you would have quoted them

What is the price difference and how big is the combined unit vs 2 separate units.

Edirt. Here the DCDC unit is 50 amp (with the MPPT controller) and list price is stg250 but its on special from a number of outlets at stg200. (10% sales tax)

Jonathan.

My apologies - the Renogy DCDC is 60 amp not 50 - the MPPTDCDC is 50 amp

The MPPT version is £210 whilst the 60 amp DCDC is £149 UK
Obviously it depends how big an MPPT you need to make up the difference - A Victron 100/30 is around £60

I've not seen any failures so for with the Renogy MPPT stand alone units - and I've fitted well over a hundred over 5 years. Equally I can say the same with Victron which I've also fitted dozens or hundreds of.
No failures on DCDC from either but the Victron get hot and output suffers due to the lack of cooling.
The one guy who had a DCDC MPPT was on here and noted a lot of issues with getting to work in all modes properly but I think sorted it out in the end .

With my boat I am away from the dock for months or years at a time and so redundancy is key . I just wouldn't want to risk one unit doing everything. Of course if you have plenty of MPPT already and want a DCDC then the combined unit may be a good choice.

 

[lustyd]

but the Victron get hot and output suffers due to the lack of cooling

Not the case with the new one.

 

[Trident]

Not the case with the new one.

True but at huge cost

 

[Neeves]

Its not only cost but space - the combined units seem to be smaller than separate units which on a yacht, multihulls excluded, space can be a premium.

From memory I think the Epever unit I quoted is also an inverter, as well as a DCDC charger and MPPT controller.

It does save a little money if you buy the Renogy dual unit but its a single point of failure for all your charging then which seems like a bad idea on a boat.

Looking at the costs - your idea of a little money is different to mine - the Epever combined unit (which as I say may include an inverter) costs almost half the cost of the prices you quote. Whilst redundancy is a good thing rejecting a combined unit on fears of failure seems perverse when historically most of these units seem extremely reliable.

If you fear failure you could buy 2 Epever units, DCDC/MPPT/Inverter which will cost similarly to buying the seperate units - and keep one Epever in its box - just in case . You can then sell the unused unit in 10 years time


The reality is that you might lose your combined unit but you would still have your alternator and could live, at a pinch (big pinch) by rewiring the LA battery to use for essentials. The 'real' world is never very far away.

Jonathan

 

[Trident]

Its not only cost but space - the combined units seem to be smaller than separate units which on a yacht, multihulls excluded, space can be a premium.

From memory I think the Epever unit I quoted is also an inverter, as well as a DCDC charger and MPPT controller.



Looking at the costs - your idea of a little money is different to mine - the Epever combined unit (which as I say may include an inverter) costs almost half the cost of the prices you quote. Whilst redundancy is a good thing rejecting a combined unit on fears of failure seems perverse when historically most of these units seem extremely reliable.

If you fear failure you could buy 2 Epever units, DCDC/MPPT/Inverter which will cost similarly to buying the seperate units - and keep one Epever in its box - just in case . You can then sell the unused unit in 10 years time


The reality is that you might lose your combined unit but you would still have your alternator and could live, at a pinch (big pinch) by rewiring the LA battery to use for essentials. The 'real' world is never very far away.

Jonathan

Can you show me this Epever product - I just searched their website and can't find one at all that is DCDC and MPPT and certainly nothing with an inverter. Are you confusing their dual battery MPPT perhaps?

Plus just for the record I would never put Epever on my or my customers boats.

And rather than spend £40 more you would choose in an emergency to dump your lithium, rewire your boat on the fly to put essential systems on a starter battery and run the engine most of the time to charge it? Ok, well you do that - I shall continue to recommend sensible options for cruising boats at reasonable cost. Everyone makes choices ...

 

[Neeves]

Plus just for the record I would never put Epever on my or my customers boats.

Any specific reason....?

Jonathan

 

[Sea Change]

Plus just for the record I would never put Epever on my or my customers boats.

Interesting. I've had four Epever products over the years.
3kw inverter which died after a year during a BMS over current shut down. Is that the inverter's fault? Can't say I was desperately happy.
Three 40A MPPTs, one of which died when I inadvertently disconnected the battery whilst the PV was on.

I chalked up the inverter as bad luck. It certainly seemed robustly built. The MPPTs have nice chunky cable entries and hefty heatsinks, and have worked well. You need to program them using a fiddly control panel, but that's a one off inconvenience. At the time (2021), they were half the price of the equivalent Victron, but I think the gap has shrunk since then.

 

[Trident]

Interesting. I've had four Epever products over the years.
3kw inverter which died after a year during a BMS over current shut down. Is that the inverter's fault? Can't say I was desperately happy.
Three 40A MPPTs, one of which died when I inadvertently disconnected the battery whilst the PV was on.

I chalked up the inverter as bad luck. It certainly seemed robustly built. The MPPTs have nice chunky cable entries and hefty heatsinks, and have worked well. You need to program them using a fiddly control panel, but that's a one off inconvenience. At the time (2021), they were half the price of the equivalent Victron, but I think the gap has shrunk since then.

Lower prices mean two things generally - lower quality parts which don't stand up to marine life as well and fewer protections when , as we all do sometimes , we make silly mistakes that wouldn't damage a unit with additional protections built in.

I mostly work on converting boats for longer term cruising - adding solar and lithium etc and so I try to ensure everything is bullet proof, user proof and that there are redundancies . I also don't want to have to waste time, usually unpaid with replacing parts on warranty and so far in the last few years I have had zero failures of parts I supplied because I'm fussy about suppliers.

I'm sure Epever have lots of happy customers but they are far from the best as your experience shows

 

[noelex]

One potential disadvantage of a unit that functions as both a DC-DC charger and a MPPT regulator is the lack of a readily available replacement component in the event of its failure.

I was unaware that any manufacturer offered such a combination. I cannot find a listing from any manufacturer for such a unit. If Epever does indeed produce such a device, its replacement will likely be challenging. A more conventional and, in my opinion, superior solution is the use of a separate DC-DC charger and MPPT controller, which is available from multiple manufacturers. This combination is unlikely to require any rewiring, even if the brand or model is changed.

 

[Sea Change]

.

 

[Sea Change]

One potential disadvantage of a unit that functions as both a DC-DC charger and a MPPT regulator is the lack of a readily available replacement component in the event of its failure.

I was unaware that any manufacturer offered such a combination. I cannot find a listing from any manufacturer for such a unit. If Epever does indeed produce such a device, its replacement will likely be challenging. A more conventional and, in my opinion, superior solution is the use of a separate DC-DC charger and MPPT controller, which is available from multiple manufacturers. This combination is unlikely to require any rewiring, even if the brand or model is changed.

12V 50A DC to DC Battery Charger with MPPT for LiFePO4, Lead-Acid, SLA, Gel, AGM Batteries

It's an interesting concept. I haven't looked in it on detail yet but for a new installation it might mean less work. At the end if the day both an MPPT and a DC-DC are doing similar jobs- they're DC transformers- so maybe it does make sense to have one big lump of copper rather than two?
I agree that it's a single point of failure, but it's also only one unit to install and find space for.

Edit to add: it's not that different to an inverter charger, in a way. Using a single device to do two distinct jobs.