Location of battery // not "directly" above Multiplus 2 ?

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marcobs asked May 14, '23

Location of battery // not "directly" above Multiplus 2 ?

Hi,

the Multiplus 2 manual states "Never position the appliance directly above the batteries.", however that is exactly what can be seen in many installation pictures, including the ones Victron is showing in their advertisements / videos.

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* What is the reason why batteries shall not be placed below the Multiplus 2?

* What is the definition of "directly"?

* Would, e.g., having a bank of 4 Pylontechs in a steel cabinet placed in a distance of 10..15cm from the front of a Multiplus (which means the Multiplus would be 15cm behind and 10cm above the battery cabinet) be an issue?

Thanks for any feedback!

Multiplus-II battery design

victron.png (21.3 KiB)

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Kevin Windrem answered · May 14, 2023 at 09:00 PM

The other issue for vented lead-acid batteries is they will can expel sulfuric acid (the electrolyte). This can corrode the metal in the Multi.

Sealed batteries usually don't produce anything of concern so can probably be located below the Mult. This is certainly the case for LFP batteries.

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Answer 1 · 2023-05-14T18:46:26Z

hominidae answered · May 14, 2023 at 06:46 PM

...IMHO, this rule applies to batteries, that normally can produce/exhaust hydrogen gas because of their internal chemistry reaction (like with lead acid batteries) and need to vent this gas.

When the inverter is positioned directly above, the gas can enter into the unit, either by normal convection/flow or by active intake from the inverter fans and a spark i..e from a relay/switch could ignite the whole thing.

When LifePo4 batteries produce gas, they are already burning, which renders this problem useless ;-)

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hominidae commented · May 14, 2023 at 09:37 PM

OK; maybe I needed to be more specific for LFP batteries...sorry for that, as english ist not my mother tongue (and I am not a chemist either).

This is what I know so far: LFP batteries do not generally catch fire. In case of abuse or mishandling, LiFePO4 batteries will not burn, and they are also not an easy target to thermal runaway. They should remain stable in cases of mishandling during charge or discharge as well as a short-circuit. However, when exposed to a lot of heat and suffering from mechanical damage, they can decompose and vent gas, which will eventually ignite. But again, LFP will not be the first cause of the problem here.

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Answer 2 · 2023-05-14T20:30:26Z

banne answered · May 14, 2023 at 08:30 PM

LFP does not burn so that solves the case :-)

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Answer 3 · 2023-05-15T22:01:28Z

marcobs answered · May 15, 2023 at 10:01 PM

Thanks for sharing your points of view and thoughts, appreciate it!
It confirmed what I have roughly assumed, thus your comments and explanations made it clear to me.

It would be great if Victron's documentation would be more precise / specific within this detail - unfortunately it isn't in many areas. It goes to a certain level, but misses to get to the point when going into a deep dive.

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