Battery charging while on Load

[Islam Ghunym]

I have 300 amps 12V Gel deep cycle batteries bluged into suoer 50A smart 4 phase charger and a PC that works on a DC power supply takes around 5-30 A (15 amps most if not all the time).

Now I want to know if this is a good setup because during bulk charge phase the charger will push very high current 50A when the batteries are discharged by 30% and this may damage the batteries? if the PC was turned off. From what I know is that the charging current should not exceed 12.5% of total batteries capacities which is 36 of 300 Amps.

The thing is that I have a smart charger which changes the current and the voltages depending on battery state of charge, but having a load applied on it constantly may make it apply the wrong amount of current and voltages extending the bulk charge period and costant voltage phase and never enter the float charge phase so that does not look good to me, is it?

 

[SCClockDr]

How are you measuring battery current?

 

[nosys70]

charging battery is done related to the capacity (C)
usually you should not exceed .5C , 0.3C usually recommended.
so for a 36A battery, this is 36x0.3=10A.
Since usually the the sun is available for 4-5 hours. you can even do a 0.25 or 0.2C charge.
This means you need to balance Panel power and battery size to be sure to have enough power to recharge battery.
(especially if you have to also provide power to the load at the same time).
Also charger must be able to provide the necessary Amps.
usually if you totally drain you battery ovenight it means either your battery is too small, your load too high , or the battery started the off-sun period not charged enough.
oversizing battery is always interesting because it is good for its health, and give you some slack in case of unnplaned load.
the drawback is the oversizing cacade to all the installation , panels and charger.

 

[Islam Ghunym]

You guys did not read what I wrote properly so pls consider reading correctly first

 

[Islam Ghunym]

How are you measuring battery current?

I don't know what you mean, but if you are asking about the capacity then it has been written in the topic (300A as advertised). if you mean the load then it is also written 5-30 Ah with 15 Ah being pulled from battery terminals most if not all the time.

 

[Islam Ghunym]

usually you should not exceed .5C , 0.3C usually recommended.
so for a 36A battery, this is 36x0.3=10A.
Since usually the the sun is available for 4-5 hours. you can even do a 0.25 or 0.2C charge.

I am not sure from where you got these info but on Gel deep cycle batteries the max charging current is 0.25C and more than that will for sure kill the batteries in pretty short time so 0.25C is "max" not the recommended. However it is well known that the recommended current is 12.5% C or less.
The rest of what you wrote is totally not related to my topic. I understand that you know something that you would like to share it with me thx, but it is not for my topic

 

[nosys70]

yes it is for your topic.
The way you describe your setup it means the charger is connected to the battery as well the PC (or load).
You are never charging a battery while you are discharging at the same time.
either you are charging or either you are discharging.
if you add load during the charge periode, the charging cylcle will slow down and turn into a discharging cycle at worst.
this would be ok for a few seconds (fridge startting up), but any other longer period would be a problem because
either you are not charging the battery anymore so it stay low, or you are discharging just after charging and that is not
good either. The main problem with GEL, is the gaz is not able to move very fast, so you would end up to get a puffed battery.
But in case this is not the situation we got.

For charging, you cannot "push" into battery more current that it will accept (unless you force very high voltage).
so even if your 50A charger release the full 50A, it is only 0.6C of the battery capacity and you stated that the charger
is a smart one that shoudl limit current (there is probably a setting where you set battery capacity or max current).
in that case , if the battery is the only load, that's ok
if there is another load connected on the battery (a PC), the energy of the charger will go to the load and the
current provided will not benefit to the battery, so you will get a slower charge than planned (or even worse , a discharge), even
if the charger is providing the full 50A.
here you stated this load can be anything up to 30A, so a 50A charger will never be overloaded, you would still get 20A left for the battery that is 6% charging at worst. and that would take a long time to charge battery this time.
This is only true if the charger voltage does not drop to low, because in that case, even if you have a few amps left, the difference of voltage between charge and battery will not be high enough to allow these amps to flow from the charger to the battery.
So again , there is no way to damage the battery by overcharging, but it means you have a total power availability problem if your charger is
used to fullfill load instead charging battery.
To avoid that usually the setup use a power manager that merge power from AC, Solar, battery and decide where and how much power goes.
That way , charger is dedicated to battery only.

 

[Islam Ghunym]

yes it is for your topic.
The way you describe your setup it means the charger is connected to the battery as well the PC (or load).
You are never charging a battery while you are discharging at the same time.
either you are charging or either you are discharging.
if you add load during the charge periode, the charging cylcle will slow down and turn into a discharging cycle at worst.
this would be ok for a few seconds (fridge startting up), but any other longer period would be a problem because
either you are not charging the battery anymore so it stay low, or you are discharging just after charging and that is not
good either. The main problem with GEL, is the gaz is not able to move very fast, so you would end up to get a puffed battery.
But in case this is not the situation we got.

For charging, you cannot "push" into battery more current that it will accept (unless you force very high voltage).
so even if your 50A charger release the full 50A, it is only 0.6C of the battery capacity and you stated that the charger
is a smart one that shoudl limit current (there is probably a setting where you set battery capacity or max current).
in that case , if the battery is the only load, that's ok
if there is another load connected on the battery (a PC), the energy of the charger will go to the load and the
current provided will not benefit to the battery, so you will get a slower charge than planned (or even worse , a discharge), even
if the charger is providing the full 50A.
here you stated this load can be anything up to 30A, so a 50A charger will never be overloaded, you would still get 20A left for the battery that is 6% charging at worst. and that would take a long time to charge battery this time.
This is only true if the charger voltage does not drop to low, because in that case, even if you have a few amps left, the difference of voltage between charge and battery will not be high enough to allow these amps to flow from the charger to the battery.
So again , there is no way to damage the battery by overcharging, but it means you have a total power availability problem if your charger is
used to fullfill load instead charging battery.
To avoid that usually the setup use a power manager that merge power from AC, Solar, battery and decide where and how much power goes.
That way , charger is dedicated to battery only.

I was just afraid of losing the 3 phase charging properly as I said 30A is max but 15A is being pulled almost "if not all the time" this means the charger can still do 35A more max which is enough as "max" but if there was no load while charging the current will be as high as 50A and this is a bit harmful. I can set my charger to put more or less current at max, but I won't be doing that everytime I cut or add a load. there is no risk of not being unable to charge but the risk is being unable to put proper charging process. I am just afraid of that load and not sure if that will fool the smart charging process to fully recharge properly. this is all what I asked about. The rest is not for my topic
The last paragraph in my 1st post tells exactly what I want to know

 

[nosys70]

you said it is a smart charger, so it should know how to push the right amount of current in the battery.
50a is the max limit.
In you case yes the fact the charger is smart is not an advantage since it would make the battery look different than it is.
But if the charger is that smart it will return to normal status as soon as the load is cut.

 

[Islam Ghunym]

you said it is a smart charger, so it should know how to push the right amount of current in the battery.
50a is the max limit.
In you case yes the fact the charger is smart is not an advantage since it would make the battery look different than it is.
But if the charger is that smart it will return to normal status as soon as the load is cut.

If I cut the load the charger turns into float charging immediately. However I can set it to 300Ah battery so it gives 36A exactly if it was discharged by let's say 30-40%, but to change the max to 50 I have to set it to bigger about 400-500Ah in order for it to give the full max current, so the charger is fooled thinking that the battery is bigger. will that cause any harmfull effect on the batteries?

 

[nosys70]

you said your PC is asking 20a, so with 36 set, that is still 16 to load battery.
that is not ok ?

 

[SCClockDr]

I don't know what you mean, but if you are asking about the capacity then it has been written in the topic (300A as advertised). if you mean the load then it is also written 5-30 Ah with 15 Ah being pulled from battery terminals most if not all the time.

I'll try again.
What instrument are you using to read

...will push very high current 50A when the batteries are discharged by 30%...

?
Where in your circuit is it located?

...batteries bluged (???) into suoer (???) 50A smart 4 phase charger...

Please read your own OP & correct.

 

[Deleted member 4428]

Try removing the load gradually to see if the charger reacts differently. I wouldn't exceed manufacturers recommended charge rate.

 

[Islam Ghunym]

you said your PC is asking 20a, so with 36 set, that is still 16 to load battery.
that is not ok ?

I think I won't know untill I try myself however less than 30 A is not ok I think. it won't charge in time and I should say that my PC ask for 15 amps so the rest 35 would be fine. Anyway my 4 phase charger itself is floating at 14.4V so if I didn't unplug it after 29 minutes, it would overcharge them. I can notice that from a little water comes out and some noise from the batteries. I will use a regular industrial charger instead of my current 4 phase charger. This regular charger has a big transformer inside weighs 20 k.g then set a proper voltage 10 volts only because this trasformer is pretty powerfull and overkill if it has been set higher. I can confirm it has something inside it to prevent the power from going back from the batteries and it will do 30a at this low voltage as measured then I will set the maximum voltage reading untill the charger stop at 14V. I will add a relay between the charger and the PC 12V adapter so I won't have headaches.