Fluctuaring DC charge to a 12V battery

Product Discussion BLUETTI AC Series
1

I have an AC180 and a cable connecting the cigarette DC port of the Bluetti to a 12V battery to charge it. I used it like that for weeks with an AGM battery outputting 120W. It seemed normal.

Then I got a lithium EcoWorthy 100Ah battery with Bluetooth. Same exact setup and cable. At times I get no DC output from Bluetti to this battery, at times 15W, at times 40W maximum. I noticed if the EcoWorthy is very low, like say 15% Bluetti can output some 40W, but when EcoWorthy is like 40% it stops charging it…

I do not understand. Where can the issue be? Any help please? Thanks!

2

@Tio

  1. ECOWORTHY lithium batteries are mainly lithium iron phosphate batteries, and the following is an analysis of lithium iron phosphate batteries:
  2. the standard output voltage of AC180 cigarette lighter is 13.5V when unloaded, in fact, the charging voltage of 12V lithium iron phosphate battery ranges from 12.8V to 14.6V. charging is flowing from high voltage to low voltage, if the voltage is not high enough, there is no way to charge. It is generally recommended to use a special charger with 14.4V to 14.6V and make sure the charging current is enough.
3

Thank you for the reply. It confirms my suspicions… I am buying a special charger for these batteries.

But it would be ok you think, to still charge from Bluetti DC as long as it works? Meaning if the voltage is higher for Bluetti and it is working to charge the EcoWorthy battery. Would that damage Bluetti or the EcoWorthy battery?

Thank you again for the help! Much appreciated!

4

@Tio
It can be charged without damaging either battery, but to fully charge it, a suitable charger is necessary.

1 Like
5

Thank you very much!