Help! Is my EHU actually charging my batteries?

[wildebus]

Thanks. V useful suggestions though the thought of upgrading the Sargent unit is a bit daunting. Who could do it up here in East Lothian I wonder.

Meantime, I have access via a neighbour to a free standing smart charger. Is it worth giving the new battery a blast with that to get it fully charged. And would that get me to a point where the Sargent "charger" would do its job?

I'll speak to Alpha and Sargent next week.

It is unfortunate to have to say it, but the sargent charger will never do its job.
The best the sargent charger will do is an initial charge of the battery ready for a 'proper' charger to take over and finish.

What I would say is the best option is not to upgrade the Sargent unit but to simply bypass it as far as the charging aspect goes. It is pretty simple to be honest and from your postings here I would say you would be well able to do it yourself
Basically, you buy yourself a decent standalone smart charger. If you got one of around 15A that would in itself be an upgrade. You then plug the AC input into one of the mains sockets, the DC output you wire direct to the battery terminals and voilá, that is it.
You should have a fuse in line on the DC +ve really (use a midi fuse holder rather than a blade fuse preferably) and turn the Charger switch off on the sargent EC155 and jobs done.
My own preference would be to get a Victron IP22 BlueSmart charger, but there are loads of options.
You then have the Sargent unit as a distribution unit for the 12V, Consumer Unit for the 240V and it will still do the split charge.


Now there has been no mention about the split charge ... depending how you tend to camp might dictate if you should upgrade the split charge. but that is a separate conversation.

 

[Pudsey Bear]

Why 15a David seems high, but you know where I am with this stuff

 

[merl]

I wouldn't have an additional charger on at the same time, I turn the van charger off as it is just a waste of time and use the Ctek on it's own, I also think it could confuse the Ctek if it took the van charger input into it's calculations.

Why 15a David seems high, but you know where I am with this stuff

15A charger on a 110Ah battery seems sensible, ultimately you need to provide enough current to charge the battery from flat/nearly flat in a reasonable amount of time.
Arguably with the Sargeant left in place it would actually keep the battery at 80%+ charge anyway so a smaller (say 5A) cheaper additional charger could be used in parallel with the Sargent and would work fine without any confusion occurring between the two despite Kev's concerns.
I'd avoid a Ctek or any charger with a 'pulse/repair/recondition/desuphate etc etc) mode. I'm not a fan at all unless you go for a really high cost/spec charger that's truly 'intelligent'. I wouldn't trust such a charger to administer over 15V to my battery, I'd rather take control of the topping up routine myself once a week and keep my battery in sulphate free condition so that ultimately a desulpation phase isn't required.
Another very important point that should be noted by anyone else with this Sargent charger is the fact that if the OP had purchased a Lead Carbon battery then there'd be no issue with the undercharge level at all.

 

[trevskoda]

If it were me id rip out all the sargent cr-p and fit a proper sys to the van, numax charger behind the fuse box, 10ah smart unit.

 

[merl]

If it were me id rip out all the sargent cr-p and fit a proper sys to the van, numax charger behind the fuse box, 10ah smart unit.View attachment 118090

Not everyone's as rich as you Trev

 

[wildebus]

I would still not recommend using the Sargent Charger with Lead Carbon. It won't hurt it, but neither will it properly fully charge it.

Why 15a David seems high, but you know where I am with this stuff

A charger that is fitted in a campervan has potentially a different role to a charger that is used to just recharge a battery.
Put a 15A charger on your battery to recharge when van is parked up in storage say, and all it is doing is recharging the battery and all that power is going to the battery.
the same 15A charger used in a campsite when away in the van... as well as recharging the battery, it also has to provide the 12V services.
Say it is a dreich day (a typical summer day up here in Scotland) and you have the TV on (5A), some lights (1A) and got phones plugged in (say 1A again). That is 7A worth of Charger output used up so the 15A charger becomes only a 8A charger as far as battery charging goes. If you went for a 10A charger, you would only have 3A.
If you went for a small 5A charger like some folk do, even though you are plugged into hookup, you would still be discharging your battery! (this is maybe why on Caravans, which are traditionally campsite creatures, TVs are often Mains 240V and not 12V - so they don't draw from the battery at all?).

I said a 15A charger would be an automatic upgrade in itself? this is because the Sargent EC155 charger is a 12A unit - and just like above, whatever 12V loads you have in the camper comes out of the chargers 12A output and is not available for actual battery charging.

 

[Pudsey Bear]

Thanks David, but My Ctek 5amp is there purely to keep the VB charged and topped on the drive, I never use sites so there is no draw at all apart from radio and alarm etc, so I thought it'd be well up to the job, in the past, I have bought chargers from car shops that were only 4 amps and they did eventually bring the battery back to life but not something I'd leave connected, but I suspect the ones in vans are not much better.

So have I bought wrong? it was also based on it being the go-to charger for cars in storage and was also the one I got for my self build.

 

[trevskoda]

Not everyone's as rich as you Trev

10h smart chargers can be got for £14.31 on ebay, I have one in the workshop and its good.

 

[jagmanx]

I have a cheapo voltmeter connected directly to the battery or more accurately the solar mppt unit battery output.
Always viewable
Up to 14.4 in good sunlight.
12.6 at 3am In Autumn
Back up to 13 next morning
Suits me.
The volltage drops but also recovers.

 

[Okta]

As I said the voltage/current comment from the solar is a non issue and incorrect. If you'd like me to elaborate I will but for now ignore the comment.

Please elaborate, it is always helpful to learn something new.

 

[wildebus]

Thanks David, but My Ctek 5amp is there purely to keep the VB charged and topped on the drive, I never use sites so there is no draw at all apart from radio and alarm etc, so I thought it'd be well up to the job, in the past, I have bought chargers from car shops that were only 4 amps and they did eventually bring the battery back to life but not something I'd leave connected, but I suspect the ones in vans are not much better.

So have I bought wrong? it was also based on it being the go-to charger for cars in storage and was also the one I got for my self build.

if it is purely a battery charger (and not a charger + 12V supplier as described above) then you can get away with smaller. Camper Batteries twns to be significantly larger and so can benefit from bigger chargers.
Now something that is not widely known, but can sometimes (but certainly not always) be found on battery manufacturers spec sheets is the details on charging requirements ...
People are familiar with Charge Voltages and Float Voltages. They often know about charge rates e.g. don't charge at more than 10% of the battery rating, or 15% or 25% or whatever may be recommended by the supplier.
But what is often missed is how long a battery should be kept at the absorption voltage level. This is usually between 5-8 hours, after which time charging should stop regardless of how charged the battery is. If the battery charger is too small, it cannot fully charge the battery within the allocated time (it is not a matter of "I just leave the charger on until the battery is charged" if you really want to treat the battery right).
A good quality charger will actually self-limit the absorption duration. The Victron IP22 for example has a settable time for this which can be tuned to your specific battery specs.
a snapshot of some of the IP22 Settings: default Absorption time is 8Hr maximum (the adaptive bit means it will change the time depending on what the voltage was at the start of the charge).

 

[Pudsey Bear]

But what is often missed is how long a battery should be kept at the absorption voltage level. This is usually between 5-8 hours, after which time charging should stop regardless of how charged the battery is. If the battery charger is too small, it cannot fully charge the battery within the allocated time

That then begs the question of whether I am leaving it on long enough at four hours per night?

It's easy enough to make it longer as it's on a timer in the garage, I'm just trying to not have anything on that isn't doing something, the van is on EHU, and the Ctek is simply plugged into a Hab 230v socket, the onboard charger is permanently off as the solar seems happy to keep it topped up although it did struggle when we were away last month with just a few lights and some device charging. so it's up for changing when I get around to it.

 

[merl]

I would still not recommend using the Sargent Charger with Lead Carbon. It won't hurt it, but neither will it properly fully charge it.


A charger that is fitted in a campervan has potentially a different role to a charger that is used to just recharge a battery.
Put a 15A charger on your battery to recharge when van is parked up in storage say, and all it is doing is recharging the battery and all that power is going to the battery.
the same 15A charger used in a campsite when away in the van... as well as recharging the battery, it also has to provide the 12V services.
Say it is a dreich day (a typical summer day up here in Scotland) and you have the TV on (5A), some lights (1A) and got phones plugged in (say 1A again). That is 7A worth of Charger output used up so the 15A charger becomes only a 8A charger as far as battery charging goes. If you went for a 10A charger, you would only have 3A.
If you went for a small 5A charger like some folk do, even though you are plugged into hookup, you would still be discharging your battery! (this is maybe why on Caravans, which are traditionally campsite creatures, TVs are often Mains 240V and not 12V - so they don't draw from the battery at all?).

I said a 15A charger would be an automatic upgrade in itself? this is because the Sargent EC155 charger is a 12A unit - and just like above, whatever 12V loads you have in the camper comes out of the chargers 12A output and is not available for actual battery charging.

I would still not recommend using the Sargent Charger with Lead Carbon. It won't hurt it, but neither will it properly fully charge it.

The important thing is that the big killer of lead acid batteries is leaving them in a partially discharged state which the Sargent is obviously guilty of. Now this wont be an issue with Lead Carbon and the OP wouldn't now be faffing with alternative chargers in order to keep the battery from sulphation.
Agree, it's not perfect because you wont get 100% of battery capacity but the OP or anyone else using this Sargent charger doesn't get 100% battery capacity anyway and that's obviously never been an issue so WRT capacity so they wont know a difference anyway.
Fit a lead carbon is the simplest means to an end and will be an excellent recommendation to many.

 

[merl]

That then begs the question of whether I am leaving it on long enough at four hours per night?

It's easy enough to make it longer as it's on a timer in the garage, I'm just trying to not have anything on that isn't doing something, the van is on EHU, and the Ctek is simply plugged into a Hab 230v socket, the onboard charger is permanently off as the solar seems happy to keep it topped up although it did struggle when we were away last month with just a few lights and some device charging. so it's up for changing when I get around to it.

Kev, essentially charging is complicated, especially if you want perfection. Undercharge and you get sulphation (Bad), overcharging causes cathode plate corrosion (bad) at least.
The ideal charge voltage will depend on temperature and several other factors so if you want perfection it gets very complicated.
Ideally you need to check the specific gravity of the acid but this is not possible on sealed types.
Most folks dont bother and just replace with a new battery every 4-6 years and considering the cost of a charger and the leccy every night it could actually make sense (I'll let you do the maths, I can't be arsed).
One thing I would say again relates to your Ctek which I think has the re-condition/desulphation/repair etc function. There are many ways of employing this function but if your Ctek goes through this cycle for a set period of time every time it's switched on then you could well be doing more harm than good. Out of interest I'd check the battery voltage when on charge and see what the charger actually does during one of it's 4 hour periods.

 

[Pudsey Bear]

I'd need to move the van and then remove the carpet and floor (stupid idea IMHO) What I can do is turn the timer off and see what the display says while charging, but that itself is problematic as it works in different modes, but I think I took a few pictures before we went away of the display when on charge. I'll see if I can find them/it.

 

[merl]

Please elaborate, it is always helpful to learn something new.

Ok, you asked for.it! Snuggle down it'll soon be sleepy time. What's below is simplified but hope it helps.
So, the output voltage from the solar charger may be 14V but that voltage is it's 'open circuit voltage' ie it's voltage when not connected to anything, as soon as it's connected to anything else (for now lets just connect it to a battery that needs charging) it's voltage will be altered depending on :-
A, the potential difference between the 2 batteries.
B, the ratio of the internal resistances of the battery and the solar controller*
This is ohms law and is known as a potential divider.
Think about it this way. We are basically connecting 2 different voltages in parallel right? So when they are connected together they must assume the same voltage as each other. So let's say the solar voltage is 14V and the battery voltage is 12V. WHY, as you suggest, when connected together must the battery now assume 14V (the voltage at the solar output)? Why couldn't the solar voltage assume the same voltage as the battery? (12V)
The truth is that a new common voltage will result and that voltage will lie somewhere in between the 2 original voltages and will depend on the internal resistances* of both the battery and the charger, the lowest resistance will have the greatest priority or effect.
The lead acid battery will have an internal resistance of somewhere around 0.004 ohms (basically as far as internal resistance is concerned it's a dead short)
The solar output will have an internal resistance that's thousands of times higher than the battery.
Consequentially the battery wins hands down and will dominate the equation and drag the solar voltage down massively to a new voltage that's fractionally just above where the battery voltage was before connection.
So going back to connecting 2 mains chargers, a solar charger and a battery all in parallel. Well the mains chargers will be a little lower in internal resistance than a solar controller but not by much. So the 3 charging sources simply 'see' what's happening at the battery and current flows from them all accordingly, nothing get's 'tricked' by anything else because the battery completely and utterly dominates everything WRT the voltage.

 

[merl]

Ok, you asked for.it! Snuggle down it'll soon be sleepy time. What's below is simplified but hope it helps.
So, the output voltage from the solar charger may be 14V but that voltage is it's 'open circuit voltage' ie it's voltage when not connected to anything, as soon as it's connected to anything else (for now lets just connect it to a battery that needs charging) it's voltage will be altered depending on :-
A, the potential difference between the 2 batteries.
B, the ratio of the internal resistances of the 2 batteries*
This is ohms law and is known as a potential divider.
Think about it this way. We are basically connecting 2 different voltages in parallel right? So when they are connected together they must assume the same voltage as each other. So let's say the solar voltage is 14V and the battery voltage is 12V. WHY, as you suggest, when connected together must the battery now assume 14V (the voltage at the solar output)? Why couldn't the solar voltage assume the same voltage as the battery? (12V)
The truth is that a new common voltage will result and that voltage will lie somewhere in between the 2 original voltages and will depend on the internal resistances* of both the battery and the charger, the lowest resistance will have the greatest priority or effect.
The lead acid battery will have an internal resistance of somewhere around 0.004 ohms (basically as far as internal resistance is concerned it's a dead short)
The solar output will have an internal resistance that's thousands of times higher than the battery.
Consequentially the battery wins hands down and will dominate the equation and drag the solar voltage down massively to a new voltage that's fractionally just above where the battery voltage was before connection.
So going back to connecting 2 mains chargers, a solar charger and a battery all in parallel. Well the mains chargers will be a little lower in internal resistance than a solar controller but not by much. So the 3 charging sources 'see' what's happening at the battery and current flows from them all accordingly, nothing get's 'tricked' by anything else because battery completely and utterly dominates everything WRT the voltage.

OK, Ill start you lot off.
Please Sir, Can I go to the toilet?

 

[trevskoda]

Pudsey leave the charger on 24/7 as its they way it works, timmers were for the old constant chargers to stop the battery boiling dry, now go to bed, give you head a break.

 

[RSD7a]

15A charger on a 110Ah battery seems sensible, ultimately you need to provide enough current to charge the battery from flat/nearly flat in a reasonable amount of time.
Arguably with the Sargeant left in place it would actually keep the battery at 80%+ charge anyway so a smaller (say 5A) cheaper additional charger could be used in parallel with the Sargent and would work fine without any confusion occurring between the two despite Kev's concerns.
I'd avoid a Ctek or any charger with a 'pulse/repair/recondition/desuphate etc etc) mode. I'm not a fan at all unless you go for a really high cost/spec charger that's truly 'intelligent'. I wouldn't trust such a charger to administer over 15V to my battery, I'd rather take control of the topping up routine myself once a week and keep my battery in sulphate free condition so that ultimately a desulpation phase isn't required.

Meri, can you recommend a non smart charger. Everything I look at seems to be "smart"

 

[RSD7a]

Thanks all. Plenty of bed time reading here and plenty to chew on.
Bottom line .... I wish I'd bought a lead carbon but was put off by tales of not getting it fully charged. I actually thought I was playing it safe with my purchase. It seems not. Maybe it would be cheaper in the long run to write off my new purchase and start again?