The EB200 can do this but the manual says: Supported but not recommended in order to protect the lifespan of the battery.
How bad is this, i.e. how much is battery life affected? Are there certain scenarios that are ok and others that are not?
Hi @Joules22 , thanks for your question.
Below is the explanation by support staff.
This issue is the same as the principle of charging our mobile phones, which can support charging and discharging at the same time, regardless of the device used, but this must have a loss.
The exact amount of loss depends on the power of the device and the length and frequency of use, which cannot be calculated precisely.
Just like our mobile phones, those that are charged and discharged separately are more durable than those that are charged and discharged at the same time.
This is not really helpful. If a precise calculation is not possible, can a general guideline be given, e.g. simultaneous charging/discharging may reduce battery life by 50% if done frequently…?
All you’ve done here is to acknowledge that simultaneous charge/discharge is harmful without providing any useful information as to the extent of that harm.
Further,
Will the more powerful units have a greater loss or less?
Please advise.
BUMP to provide notice of edit (previous post).
i seem to recall reading a previous post where the problem with simultaneous charge/discharge is the individual cells end up unbalanced. thus some cells can be more heavily used (imagine writing to a single sector in an ssd over and over can use up that sector’s life span).
the solution is to periodically drain and recharge without load so the cells can be rebalanced. the more often you do this the less permanent effect you have. hard to estimate though.
I found a couple of plausible posts on Reddit. The second one echos what you said:
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As we all know, temperature is main factor for battery life. The temperature of a battery can sometimes rise very quickly if it is charged and discharged simultaneously. EB3A supports pass-through charging. But it’s better for battery life to minimize the use of pass-through charging.
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The bms cannot equalize the batteries if they are at constant charge while used. Thus some batteries will have more or less charge than the rest, with a potential short or over charge of said cells. You can use it as you say for a while but it’s a good practice to drain and charge fully every so often to allow the BMS to level off the individual cells.
item 1 is the fault of bluetti. they should be monitoring the battery temperature. maybe better handle pass-through charging so it happens less often and is more of a trickle charge. this is a common complaint on the eb3a. it usually bypasses the battery but it occasionally goes down to 99% and the charger goes nuts (charges at full power and full fan) until its back to 100%.
item 2 is what i was referring to and is probably not something they can automate without a lot more circuitry. so you have to manually initiate occasionally.