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AGM battery charging intensity?

published: 17/11/23, 09:46
Hello everybody

I have 3 Victron 22Ah AGM batteries connected in parallel. From what I have read, the maximum admissible charging current is 25%, or 5.5A for a battery.

Given that I made a parallel connection, should I add up the total capacity (22Ah * 3 = 66Ah) and consider that I can charge them with a maximum intensity of 16.5A?

Goods.

Re: AGM battery charging intensity?

published: 17/11/23, 10:09
yes if the 3 batteries are in parallel, each absorbing around 5A, the total current drawn will be 15A.

Be careful, if you put them in series, the charger should deliver 5A at approximately 40 V (3x12 + charging voltage).

Re: AGM battery charging intensity?

published: 17/11/23, 11:42
For one battery, but 3 in // will not always be balanced. There is no BMS, I would limit to 0.2 C

Why not take a 66 Ah?

Re: AGM battery charging intensity?

published: 17/11/23, 12:16
izentrop wrote: 3 in // will not always be balanced

Well if they are necessarily on the voltage at their terminals since in //!!

We don't balance the internal elements of a lead-acid battery...well not to my knowledge!

Re: AGM battery charging intensity?

published: 17/11/23, 12:26
Zizi just wanted to be an expert, he has the same expertise on batteries as on covid.

There is one parameter that could slightly change the current entering each battery, it is their internal resistance, but in principle on 3 identical batteries from the same manufacturing batch, the difference is tiny.

Re: AGM battery charging intensity?

published: 17/11/23, 13:13
Christophe wrote:
izentrop wrote: 3 in // will not always be balanced

Well if they are necessarily on the voltage at their terminals since in //!!
A defective element is common, especially at the end of its life...
the current no longer passes through the battery and is distributed among the other two... 8 A for a 22 Ah, 0.38 c, she may not like it very much

Re: AGM battery charging intensity?

published: 17/11/23, 13:49
An AGM battery does not charge at the same voltage as a conventional car battery. an old generation car battery charger will slam your AGM batteries

Re: AGM battery charging intensity?

published: 17/11/23, 13:59
An old charger without sufficient current and voltage limitation will kill you just as easily with an acid battery.

Re: AGM battery charging intensity?

published: 21/11/23, 20:29
Hello
No, parallel connection does not increase the maximum admissible load current. Even if the total power is 66 Ah (22 Ah * 3), the high charging current per battery is 5.5 A. Furthermore, you will be required to charge all the storage systems in parallel with a maximum current of 5.5 A so as not to damage your equipment.

Re: AGM battery charging intensity?

published: 21/11/23, 21:05
Hello,
Martine24 wrote:Hello
No, parallel connection does not increase the maximum admissible load current. Even though the total power is 66 Ah (22 Ah * 3), the high charging current per battery is 5.5 A.
Can you prove your statement? Because the charging current in each battery depends mainly on their internal resistance.