# Max current per battery chemistry

From the background and responses to my other question I gather that 5 NiMH batteries can provide more than 4 A current, and that Alkaline or Manganese batteries cannot.

So, what about LiPO, LiFePO4, Li-Ion?

Also, how can I find this information? Have googled a bit and looked at several tables of battery data but not seen anything remotely resembling this max current.

Edit: am trying to understand the available choices for powering a bunch of servos in a robot.

• Pick a battery and link to its datasheet and (in your question) we'll have a look at it. Note that chemistry determines the voltage, not the current. The current is determined largely by the surface area of the electrodes. – Transistor Jun 3 '18 at 11:45
• @Transistor: I do not have any specific battery in mind, I want to understand general principles. – Tomas By Jun 3 '18 at 11:49
• @Transistor: so... why cannot Alkalines just have bigger electrode surface area? Is this really the only difference? – Tomas By Jun 3 '18 at 11:50
• They can. AAA, AA, C and D cells for starters. – Transistor Jun 3 '18 at 11:52
• That's not a link to a datasheet. It's a link to a catalog page and there is no datasheet link on it. That's a warning sign for you. Our advice is, "No datasheet? No sale!" Pick another battery with a datasheet and link to the datasheet (not the catalog). – Transistor Jun 3 '18 at 12:10

Figure 1. The maximum discharge current is given in the Electrical Specification section.

In this case the maximum discharge current is limited by the Protection Circuit Module to 600 mA.

... if I want something in the range of 6 V & 4 A (at startup, normally half of that), then LiPO is not possible?

Here's another random datasheet: YT683496EH:

Figure 2. Snother random datasheet YT683496EH.

Main points:

• This one has a capacity of 1500 mAh (line 3). It's 'C' value is 1500 mA.
• Its rapid charge rate is 1C (line 5) or 1500 mA so it will take at least one hour to charge.
• Its dicharge current is quite high at up to 25 C (35 A) continuous or 35 C burst (line 7).

You should be able to find the required information in the datasheets. If there are no datasheets then buyer beware.

• See the update. – Transistor Jun 3 '18 at 12:39

The chemistry does not matter here. It's the surface area of the electrodes.

Each battery type will have a graph like this:

(typical D cell)

The discharge current limits the maximum capacity, for alkalines capacity halves at 500mA.

(typical AA cell)

If you shrink the battery size, the surface area of the electrodes in the battery is smaller. Increasing the internal resistance. Reducing capacity, increasing losses on high currents.
These losses heat the battery, and that causes problems. Often causing the electrolyte to evaporate, causing the battery to expand. But that varies per chemistry.

• Okay... is there, somewhere, a useful comparison of different chemistries in these terms? E.g. what is the crucial difference between NiMH and Alkaline? – Tomas By Jun 3 '18 at 12:05
• @TomasBy The energy density and rechargeable properties. – Jeroen3 Jun 3 '18 at 13:25
• Yes, but I meant more specifically. In the case of 5 AAs, and 4A current, I'd like to see two diagrams where one curve is above and one below, if you see what I mean. – Tomas By Jun 3 '18 at 13:34
• @TomasBy Multiply the X axis with 4? – Jeroen3 Jun 3 '18 at 14:17
• Aren't you comparing same chemistry, different size? I would like to see a comparison of NiMH and Alkaline where the 4A difference appears. – Tomas By Jun 3 '18 at 14:27