I am using the new EB70 to run two devices (50W) in the field. There I want to reload the Bluetti using a 12V lead-acid battery but the input indicator shows poor 30W load and with 50W output this wont work for long. What is the problem? When I use a LiPo (4S) battery the input load is 100W but that one has only a low capacitiy compared to my lead battery. In the documentation I found that on a 12V system the EB70 should be reloaded within 4-5h which means it should input appr. 140W instead of 30W. Any ideas?
Your lead acid battery is dropping its voltage under 30W load. It’s an issue with the lead acid battery, not the EB70. Have you checked what the input voltage is when you have 30W input from that battery?
Hi @percy , We agree with @aaron33 's opinion that the issue is likely due to the lead-acid battery being over-discharged or faulty, which causes the voltage to drop during charging.
Thanks so far, I tried three different batteries one of them quite new, but tomorrow I’ll check the voltage at the battery…
How big is the lead acid battery that you are using? Usually large car lead acid batteries have about a 70Ah capacity, which is 840Wh. However, due to lead acid chemistry, you would only use about 50% of that, going lower means permanent damage/wear to the lead acid battery and the voltage also drops way below to 11.9V if the load is high. So if your lead acid battery is under 50% remaining capacity, then charging the EB70 may be causing it to drop the voltage to way below 11.9V, resulting in the EB70 stopping charging. For car batteries for smaller cars like a Honda, the capacity is even lower at 50Ah. If the 3 lead acid batteries that you have are a similar physical size and age, then you could connect 2 in series to give you a 24V battery. EB70 will work with it as it can accommodate 24V car charging systems as a charging source. So you towards the end of the 24V lead acid battery’s capacity, it will still be at 23.8V, enough to still power the EB70. Make sure you immediately recharge the lead acid battery once it hits 23.8V, as leaving it even for a day or two will cause irreversible damage and you won’t be able to use it to the same capacity again. If you do drain the lead acid battery fully, it will reach 11.59V (23.1V for the 2 batteries in series), and it will have already experienced damage. So don’t let it reach this point.
LiPO batteries are more consistent in their voltage as the capacity is used up. The 4S would be at 16.8V when full, and 14V when empty. That is why the LiPO is working fine for you.
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A typical deep cycle lead acid battery, ie. AGM, GEL or Wet Cell has an at rest voltage of 12.8VDC. A 100Ah, therefore has an approx total of 1280W, which in reality is much less because the voltage will drop off well before it’s flat. Next, discharging (as mentioned above) more than 50% is not good for it. Consequently you would probably get around 600Wh usable from one, which is less than the EB70s 716Wh capacity.
Although you can “top up” the EB70, it will be slower and not cover the entire recharge. You best solution is a LiFePo4 deep cycle as a 100Ah 12V will output over 13V for most of it’s discharge curve = well over 1,000Wh, which will more than double your EB70 capacity and replace what you use faster than you use it.
A vehicle start battery is not deep cycle, it’s meant to give a brief large output to start the engine, not a steady lower discharge. Back to basics, how long will your start battery last if you leave the headlights on, lol.
The battery has an voltage of 12.4V when it has 30W load so it is about 75% full and another one with 12.8V (100% full according to https://www.rebel-cell.com/de/grundlagenwissen/akku-entladung-und-kapazitaet/) only gives 45W (degrading with the batteries voltage), so from my understanding it is a problem with my Bluetti. From the datasheet it should behave different (“can be reloaded by an lead acid battery within 4-5 hours”) I have to contact the ditstributor, for replacemant, didnt I?
I don’t think it is the EB70’s fault because you get the full power input with the 4S LiPO. If both batteries that you are testing now are the same physical size, you can try charging both back up to 100%, and then connecting both batteries in series (positive from one battery connects to the negative of the second battery. Then you connect your clamps to the remaining free positive and negative terminals) before connecting to your EB70 to give 24V. Make sure your EB70’s DC input settings is set to “Other”.
Hello, thanks, could you tell me where I can change the input settings, I didn’t find that in the manual, so didn’t know that there is an option to do so!
I checked the manual and it seems the EB70 doesn’t differentiate between solar and car charging. So just plug it in and as long as the input voltage is less than 28V, it will handle it.
Hi thanks to all, in the latest manual there is no more a direct load to a lead-acid battery but to a car adapter, According to my investigations it only works with the engine turned on which brings up 14.4V from the generator to that plug. My solution now is to connect a 12VDC car load adapter for a laptop (120 W) which outputs 19VDC and input that into the Bluetti. Then it loads with 120W continously until the battery capacity remains 10%. This apapter has an additional loss of 0.6W but in total I get appr. 1000Wh extra. Finally I exchange the lead acid battery every 24h to keep the system in the field running continously.