Invertor/charger not charging at rated A

[Rocksteadee]

I have a Vivtron Invertor/charger Multiplus Compact 12/1600/70-16/230. 300Ah of batteries.
The manual states 70A charge which is limited to 75% (52A)
Overnight at anchor the drain is approx 100Ah
This requires the genny run for about 5 hours a day. Max charge current is 45A, for 1 3/4 hours bulk charge. The genny gets turned off after charge is down to about 35A and into absorption .
Why is current limited to 75%?
Why is charge only 45A ? If it was 70A would require genny running for 2 hours less per day.

 

[PaulRainbow]

Charge acceptance rates are limited by internal battery resistance, the higher the battery SOC the higher the resistance, the lower the charge acceptance rate. You'd never get 70a into the batteries for long, unless they were very flat.

You would benefit from Lithium batteries. which would give you more usable ah and have a much, much higher charge acceptance.

 

[GEM43]

Charging to 100% SOC by generator isn’t practical because charge acceptance beyond 80% SOC (see Paul’s earlier response) is minimal, the generator is simply burning diesel producing hardly any energy via the charger - madness. Nigel Calder promulgates the 80% rule - don’t try to charge beyond 80% SOC other than via shorepower or solar. One shouldn’t regularly deplete VRLA batteries below 50% SOC, thus your 300ah house bank gives you a useable (away from shorepower) capacity of 90ah (300 x (80%-50%)). When charging from 50% SOC to 80% SOC your charger will be in bulk then absorption phases, the most productive part of the charge cycle, and assuming an average of 40A charging rate it should take no more than a couple of hours (ish) to get back to 80% SOC. Then shut the genny down.

 

[Hurricane]

Yep - the previous two posts have the cause.
Essentially, batteries will take the most charge when they are most depleted.
And it takes ages to completely charge them back to 100% - not practical unless plugged into shore power.
This is a problem with most motor boats.
Staying on anchor away from shore power and just recharging (with generator) for a few hours each day, eventually takes the batteries down to a level in which they will be damaged.
My experience is that the %age charge falls a bit further each day - after 3 days or so, they then need a full charge.
My solution was solar panels.
You don't need to cover the whole charge cycle with solar - just enough to "finish" the charging cycle after the generator has done most of the work.
After the generator has don the bulk charge, the batteries won't take many amps anyway so the solar panels can finish the job.
This process made a huge improvement to our battery charging regime.
As said above monitor your batteries with a proper battery monitor using %age charge - don't rely entirely on voltage.

 

[vas]

+100 on what the previous three posters say

further, 100Ah overnight for a 300Ah (assume LA of some sort) bank is a lot to ask for on a daily basis unless it's a one off and then you're on shore power...
As Paul points, LifePO4 would be suitable for you - unless you can optimise and lower your overnight consumptions.
On a 43ft mobo (with one crappy fridge working almost 90% and a second working normally I get 60Ah overnight and have 600W solar to recoup that next day in the Med, works fine, batteries are never fully charged (they shouldn't!), everyone is happy. Geny is run only for the watermaker unless underway that I run it through the Victron Multiplus II 24/3000

V.

 

[GEM43]

I very much agree with Vas that a lot is being asked of a 300ah battery bank. Also with Hurricane that solar is a critical part of the solution. It is important to tackle the problem from both ends - reducing consumption where possible and optimising supply. On my boat I’ve fitted a 750ah bank, a 120A charger inverter, a 100A Balmar alternator and 500w of solar via an MPPT. We also have a 4kw genny. We’re never short of power, we’re mostly anchored (in Scotland) all summer and we rarely use the genny. A balanced system can easily provide a sustainable solution.

 

[Forty_Two]

I have a Vivtron Invertor/charger Multiplus Compact 12/1600/70-16/230. 300Ah of batteries.
The manual states 70A charge which is limited to 75% (52A)
Overnight at anchor the drain is approx 100Ah
This requires the genny run for about 5 hours a day. Max charge current is 45A, for 1 3/4 hours bulk charge. The genny gets turned off after charge is down to about 35A and into absorption .
Why is current limited to 75%?
Why is charge only 45A ? If it was 70A would require genny running for 2 hours less per day.

The 75% default is adjustable in the settings in my Phoenix Multiplus 12/3000/120. Your installation manual should show how to adjust.

Some good advice above, i went the @Hurricane route & installed 450w solar. Reduced geny time to 2 hours in the morning. I use 150Ah overnight & have 800Ah of AGM's

 

[Rocksteadee]

Only at anchor for a few days, then on shore power.
Have LA batteries.
BM is a victron 712.

The peak current at 45A is a function of charger, not batteries. As they were down to 12.2v at 50% so internal resistance would have allowed for higher A, verified by charging individual batteries and in combination, peak was still 45A.

Having 300Ah gives a useable 90Ah (80%-50% so turning off gen not long after reaching absorption to maintain efficiency. 30% x 300)
90Ah at 45A gives 2 hours in bulk charge.
But at 60A would reduce bulk charge to 1.5 hours

The 60A given by 300Ah x 20%
So within max charge A. of 0.2 - 0.3 Capacity

Unfortunately I do not have the PC interface which is required for the MP compact.

Solar of any size not an option on 40’ fly as only deck space has Astro turf for the dogs and no coach roof.
Thought about Lithium but to get any usable size is horrendously expensive, plus dc to dc charge for when running on alternators.
Space is also an issue but I could possibly squeeze another battery.
Have minimised usage with all LEDs, can do so further by only using tender crane when gen or engines running, using gas for kettle rather than electric off Invertor.
Also intending fitting a VSR to start battery instead of the 4A aux output from charger. Had disconnected this in the hope that the total current output from charge may increase, it didn’t

Thanks for all the replies and I think I have answered everyone

 

[vas]

@Rocksteadee

thanks for the extra info.

TBH I'd skip the VSR and buy the victron PC interface (probably about the same cost )
a starter bank is only used for that, so 10mins (max) and they are again at float, so not much to affect the charging regime hence you didn't see and difference when removed.
configure the Multiplus carefully and you'll probably get what you want without messing with LifePO4 and B2B for the alternator

 

[Portofino]

Only at anchor for a few days, then on shore power.
Have LA batteries.
BM is a victron 712.

The peak current at 45A is a function of charger, not batteries. As they were down to 12.2v at 50% so internal resistance would have allowed for higher A, verified by charging individual batteries and in combination, peak was still 45A.

Having 300Ah gives a useable 90Ah (80%-50% so turning off gen not long after reaching absorption to maintain efficiency. 30% x 300)
90Ah at 45A gives 2 hours in bulk charge.
But at 60A would reduce bulk charge to 1.5 hours

The 60A given by 300Ah x 20%
So within max charge A. of 0.2 - 0.3 Capacity

Unfortunately I do not have the PC interface which is required for the MP compact.

Solar of any size not an option on 40’ fly as only deck space has Astro turf for the dogs and no coach roof.
Thought about Lithium but to get any usable size is horrendously expensive, plus dc to dc charge for when running on alternators.
Space is also an issue but I could possibly squeeze another battery.
Have minimised usage with all LEDs, can do so further by only using tender crane when gen or engines running, using gas for kettle rather than electric off Invertor.
Also intending fitting a VSR to start battery instead of the 4A aux output from charger. Had disconnected this in the hope that the total current output from charge may increase, it didn’t

Thanks for all the replies and I think I have answered everyone

Just fit a bigger charger . = the elephant in the room !

We do the same as you geny up for an hr or two usually at anchor as the boats ( hob ) all electric .
By way of real example.
Two X 180 batt banks .
Let’s disregard the starter bank , so that leave s 360 ah .
Back in 2001 it was factory fitted with a 35 a charger .That packed in shorty after I got it 2014 .
I got a boat sparky round and he fitted a modern 100 ah charger ,he lent me a 80 as temporary measure ( keeps spares on the van ) until the new one arrived .He did the calcs + spec ing .

We have a gauge that shows ah going in when the chargers on for both banks.
So after a night at anchor I geny up to boil a kettle and recharge .Sometimes I see up to 80 ah immediately being stuffed in .Not for long thought….about 1/2 hr later it’s about 1/2 the rate as initially. Within hr it’s down below 10 , near 5 .
This is the house side ^
The charger has three independent outlets so on the starter side it something like 3 .
As others have said it never drops to zero ie stops charging but pretty dam close .

Then we up anchor and motor off ( geny and main charger off ) relying on the engine alternators to cope which they do .

If I weren’t to geny up in the morning , instead motor to a port for the shore power ….connect up then i see lower amount getting initially stuffed in say 40:ah instead of the 80 asa three hour run with the alternators had helped a bit .

Imho you don’t need any solar , lithium or fancy auto anything .

Just a correctly specced modern all singing and dancing charger ( I think they all are now even £20 car trickle chargers ) .


Another thing as well add more sound insulation to the geny case ….any auto car components store .
You should not be inhibited running the geny with noise .

 

[Rocksteadee]

Just fit a bigger charger . = the elephant in the room !

We do the same as you geny up for an hr or two usually at anchor as the boats ( hob ) all electric .
By way of real example.
Two X 180 batt banks .
Let’s disregard the starter bank , so that leave s 360 ah .
Back in 2001 it was factory fitted with a 35 a charger .That packed in shorty after I got it 2014 .
I got a boat sparky round and he fitted a modern 100 ah charger ,he lent me a 80 as temporary measure ( keeps spares on the van ) until the new one arrived .He did the calcs + spec ing .

We have a gauge that shows ah going in when the chargers on for both banks.
So after a night at anchor I geny up to boil a kettle and recharge .Sometimes I see up to 80 ah immediately being stuffed in .Not for long thought….about 1/2 hr later it’s about 1/2 the rate as initially. Within hr it’s down below 10 , near 5 .
This is the house side ^
The charger has three independent outlets so on the starter side it something like 3 .
As others have said it never drops to zero ie stops charging but pretty dam close .

Then we up anchor and motor off ( geny and main charger off ) relying on the engine alternators to cope which they do .

If I weren’t to geny up in the morning , instead motor to a port for the shore power ….connect up then i see lower amount getting initially stuffed in say 40:ah instead of the 80 asa three hour run with the alternators had helped a bit .

Imho you don’t need any solar , lithium or fancy auto anything .

Just a correctly specced modern all singing and dancing charger ( I think they all are now even £20 car trickle chargers ) .


Another thing as well add more sound insulation to the geny case ….any auto car components store .
You should not be inhibited running the geny with noise .

That was the reason for fitting a 70A charger which was in the middle of max charge current for 300 Ah (300 x 0.2 to 0.3 C)
Yet it only charges at 45A so adds the the charging time on gen.

 

[Baggywrinkle]

You want to fit a charger that doesn't exceed the max charge current specified by the battery manufacturer (which you have almost certainly done) ... but on LA chemistry you will rarely see this current as hopefully, you never discharge deeply enough - regular deep discharge with LA chemistry is a sure way to shortened battery life. As already mentioned in this thread, on deeply discharged batteries, the initial current is high but it tails off quickly as the SOC rises. Most of the charging time is spent at much lower currents.

Lithium is a different story, a heavily discharged LI battery will accept huge charging currents up to around 80% soc, which requires (apart from the recommendation to get a proper 3-stage charger) the use of DC-DC Chargers which are usually fitted between the alternators and large lithium banks - this limits the charge current to a sensible level and prevents your alternators from overheating, it also provides a level of protection for your alternators should the LI BMS decide to switch off, causing a voltage surge which will also fry the alternator. It does depend heavily on alternator spec and battery bank capacity .... big alternators and small battery capacity can work ... I have used a boat where the owner did this but the alternator regularly cut off due to overheating and could be seen regularly delivering 120A to the LI bank - if only for a short period.

Solar is excellent for completing the charge cycle as @Hurricane said, if you want to avoid marinas, generators and shore power, then solar is a great solution.

My new electrical system which will hopefully go in this winter uses a very high output alternator to put an initial high charge into the lithium bank (when raising anchor and motoring out of the anchorage) ... 30 mins of 190A @ 48V ... so 9kW ... and after that, the sails go up and a 1kW solar array will take over ... more than enough for my daily usage. The lithium bank will be around 10 kWh and it will be feeding the currently fitted 520Ah Lead System running all the 12V systems.

 

[Alicatt]

Reading this with interest, I have a Victron 24/2000/50 Multiplus Compact with two semi traction 230Ah 12V batteries in series for the 24V domestic, the lower 12V battery is at a lower state of charge compared with the other 12V battery, just now and for most of today I have been charging the lower battery to get it to a point where I can connect the battery balancer I got this week.