Battery charging voltages

[smithy]

I've just bought a new 30A battery charger. I was monitoring the voltage and getting 16.5v on fast charge, still taking 2A and 15.08v on trickle with no current showing. The batteries were pretty well fully charged. These readings seem too high to me, everything else switched off, solar panel disconnected. Readings double checked on battery posts. Am I right to be concerned?

 

[PaulRainbow]

What battery charger ?

 

[smithy]

this one
Röhr Car Battery Charger 12v 24v Turbo Trickle Maintainer Charge Compact DFC-30P 5060569763414 | eBay

 

[Tranona]

Sorry but that is not a suitable charger for your boat. Don't know why it is putting out such a high voltage, but probably a fault. A proper charger is something like this.12voltplanet.co.uk/victron-blue-smart-ip22-battery-charger-12v-30a-1-output-bluetooth-built-in.html

As you can see nearly 4 times the price because it is a multistage charger which ensures it charges the battery using the profile appropriate to your battery bank. What you have is an all or nothing which is worth less than what you paid for it and will ruin your batteries.

 

[Alex_Blackwood]

Sorry but that is not a suitable charger for your boat. Don't know why it is putting out such a high voltage, but probably a fault. A proper charger is something like this.12voltplanet.co.uk/victron-blue-smart-ip22-battery-charger-12v-30a-1-output-bluetooth-built-in.html

As you can see nearly 4 times the price because it is a multistage charger which ensures it charges the battery using the profile appropriate to your battery bank. What you have is an all or nothing which is worth less than what you paid for it and will ruin your batteries.

It is a 12 volt LA battery charger if he has a LA battery on board the charger doesn't know it is on a boat! He doesn't say what his battery is.

 

[PaulRainbow]

It is a 12 volt LA battery charger if he has a LA battery on board the charger doesn't know it is on a boat! He doesn't say what his battery is.

It doesn't matter what his batteries are, the reason it isn't suitable for a boat is that it isn't designed to be permanently charging batteries. It's the sort of thing we used in garages in the 70's to quickly charge your Ford Cortina, no good at all on a boat.

 

[geem]

It is a 12 volt LA battery charger if he has a LA battery on board the charger doesn't know it is on a boat! He doesn't say what his battery is.

You use a car battery charger cos the battery went flat. It's a once in a blue moon application. A boat battery needs charging after every time it's been used using a proper three stage process of bulk, absorption and float. CV then CC until charged then floated.
This charger looks like CC and is not suitable for recharging on a regular basis

 

[Alex_Blackwood]

You use a car battery charger cos the battery went flat. It's a once in a blue moon application. A boat battery needs charging after every time it's been used using a proper three stage process of bulk, absorption and float. CV then CC until charged then floated.
This charger looks like CC and is not suitable for recharging on a regular basis

I agree and also disagree with you and Paul on this one. Yes a boat should have a multi stage charger and yes the regimes are different. Yes I agree that the charger shown is not suitable for permanent boat use but is is after all a battery charger for 12 or 24 volts with fast or trickle charge settings. However a 12 volt lead acid battery charger is a just that. the one in question has a trickle facility. It doesn't know where it is and if the battery is lead acid and within the chargers design parameters (20-240ah) it should trickle charge, but not at 15.08 volts, even the fast charge seems high for what the OP says was a near fully charged battery. The voltages quoted. even if it was on a car, seem odd. You should be able to put a charger on trickle at any time not just in a blue moon! The OP states the following:- 16.5v on fast charge, still taking 2A and 15.08v on trickle with no current. I find it difficult to understand how he can have 15.08 volts and no current on a a 12 volt battery. I would suspect that either the charger is faulty, is on the wrong setting or there is something we do not know.
I have used battery chargers in one form or another for many years and if I saw these sort of voltages on a pretty bog standard charger on a bog standard battery I would want to know why.

 

[smithy]

My boat is on a swinging mooring and a 40w solar panel keeps everything topped up. The charger is only for very occasional use if I'm away cruising and the house batteries get a bit low 2X90ah. I just need to know if these voltages will damage the battery, if so I will send the charger back as faulty.

 

[Alex_Blackwood]

My boat is on a swinging mooring and a 40w solar panel keeps everything topped up. The charger is only for very occasional use if I'm away cruising and the house batteries get a bit low 2X90ah. I just need to know if these voltages will damage the battery, if so I will send the charger back as faulty.

When you say 15.08 volts and no current have you by any chance checked the battery voltage with the charger disconnected? Just seems very strange. I would be inclined to return it if it is putting out that sort of voltage and 16.5 on fast charge into a fully charged battery. There are, I am sure, more suitable small chargers available, that will top up a battery, without going into expensive all singing, all dancing units . I am not up with the market. Perhaps Paul R. will be of more help on that front. Perhaps something along the line of this. from Amazon?
https://aax-eu.amazon.co.uk/x/c/RHh...&pd_rd_r=b1afd387-52bc-44f3-b622-bf9af5d36506

 

[jamie N]

It might also be worthwhile checking that the DVM isn't reading too high.

 

[Alex_Blackwood]

It might also be worthwhile checking that the DVM isn't reading too high.

He doesn't say using a DVM but likely. Perhaps not reading high but maybe on ac setting picking up ripple.? Unlikely but!

 

[Refueler]

The simple answer for OP is to fit a Battery Charge Management unit between that charger and his batterys. No need to start paying out large sums of dosh to solve a simple matter.

Something as simple as this :

XH-M601 Battery Charging Control Module 12V Intelligent Charger Power Control Panel Full Power Off Overcharge Protector Board Charging Discharging Controller

They work ...

The only matter to consider is whether a charger is a smart charger or not. Charge controllers such as these cannot work with Smart Chargers as when the controller cuts off mains voltage - the smart charger will not restart when controller detects low battery voltage and reconnects mains voltage. These controllers are designed to control 'dumb chargers'.

The beauty of these of course is that you can buy a cheaper dumb charger and for peanuts add the controller and have automatic charge control.

I know some are going to say - arrrrr but it has no float charge ........... That is not needed if the controller is maintaining battery to reasonable charge level .... and those levels are adjustable to suit your situation.

 

[PaulRainbow]

Sigh

 

[Refueler]

This is Practical Boat Owner.

Therefore I suggest that a practical solution as I suggested falls into line with that ...

The guy has what appears to be a charger that will plug away at a battery ... liable to cause fluid loss by its constant hammering of charge ... possible shortening of life etc. as Paul and others have mentioned.

The suggestion of discarding the charger and buying a more expensive 'smart charger' is valid - IF the OP is willing to put hand in pocket again.
But the addition of a controller between his existing charger and the battery is a valid solution and does not mean paying out serious money.

The unit I linked to WORKS and works well. Its user adjustable for low and high points. Easy to install.

 

[Refueler]

Sigh

Instead of making such a remark - which helps no-one ... let me ask you.

Have you actually experience of the unit I linked to ? Can you in truth say it will not work ?

Not interested in fancy reply ... just a simple honest reply of whether you have used or experienced such ...

I have used and I can truthfully say - it works.

The units are actually designed to sit between power supplies and batterys to provide 'smart charge' setups. This makes them excellent additions to 'dumb chargers'.

 

[Tranona]

My boat is on a swinging mooring and a 40w solar panel keeps everything topped up. The charger is only for very occasional use if I'm away cruising and the house batteries get a bit low 2X90ah. I just need to know if these voltages will damage the battery, if so I will send the charger back as faulty.

With that size bank you are unlikely ever to need 30A as unless they are flat they won't accept that level of charge. Perhaps better to have a smaller multistage charger - I have one at 8A which I use for charging a 105Ah bow battery when it was not connected to the alternator.. once you get the SOC above 50% or so the acceptance rate of a 180Ah bank will be much less than 10 amps, so a 15A Victron at £135 would be more than adequate. As Paul said earlier those all or nothing 30A chargers have a value for revitalising flat batteries in a short time because charging from flat will absorb those amps for a short time - enough to get an engine going. However from what you say that is not what you want. to use that type of charger to top up you either have to monitor it manually or use one of those cut off devices mentioned above. The risk with leaving this charger on is that it could cook your £250 worth of batteries!

This is the sort of smart charger I use for occasional use as you describe. Much the same price as the one you bought.halfords.com/motoring/battery-maintenance/battery-chargers/halfords-smart-battery-charger-8a-496254.html?cm_mmc=Google+PLA-_-Motoring>Motoring+Products>Battery+Maintenance>Battery+Chargers-_-Motoring>Motoring+Products>Battery+Maintenance>Battery+Chargers-_-496254&_$ja=tsid:|cid:17363835999|agid:|tid:|crid:|nw:x|rnd:10946443999568301870|dvc:c|adp:|mt:|loc:9045525&gclid=EAIaIQobChMIyb3XqZWT_gIVRLDtCh0Otg1vEAQYASABEgIwcvD_BwE

 

[trbt]

It might also be worthwhile checking that the DVM isn't reading too high.

^^^
OP does not say where the readings came from. Some cheap DVMs read high when the DVM battery is low.

 

[smithy]

First thing tomorrow I will check the DVM against another one, if it's correct I'll email the charger suppliers and then take it from there. It looks like its pretty pointless having a larger capacity charger when the batteries won't accept it, just more weight to carry about.

 

[Refueler]

First thing tomorrow I will check the DVM against another one, if it's correct I'll email the charger suppliers and then take it from there. It looks like its pretty pointless having a larger capacity charger when the batteries won't accept it, just more weight to carry about.

True that having a high output charger can be wasted potential. But do not forget that if you want to charge more than one battery at same time via a split charge controller - that extra amp output can prove well founded.

Its a matter of ... you can have too little ampage and always wishing you had more .................

If you have more than needed - you will not be wishing you had more .....