Victron SmartShunt

[ShedPower]

Batteries in series & paralell.

hi, I currently have 4 12v lead acid batteries in paralell. I have heard and read that 24v is safer and preferable to 12v so I’m thinking of doing two pairs in series and then connect both pairs in paralell. However, would this not mean that I need twice as many batteries to get the same amp hours as I have now in paralell?

[Bala]

If you don't already then it's in your best interest to understand ohms law, cable size calculating, fusing requirements and how to terminate cable properly.

[ShedPower]

It is a fairly cheap inverter, although it is a pure sign wave. Inverter might be the problem. Most of the components are not budget, eg Two Victron chargers, Victron smart shunt, Victron Temperature senser, Automatic transfer switch. The batteries seem fine now I have four of them.

I think next step is to replace the inverter.

[SunEagle]

That makes sense, though not sure what to do about it. The output from the inverter had to come through a plug and a plug has to have a fuse and 13amp is the biggest plug fuse you can get. Any suggestions?

You may need to have a separate system to power your TV. One thing is that a lot of loads that have motors or electronics require a Pure Sine Wave inverter. Some of the cheap Modified Sine wave ones do not work well with those types of loads and end up either hurting the load or having issues. It is possible that the fuse really protected your inverter

[Bala]

So it a 240v 10a lead protected by a13a fuse. Assuming both those items run fine off your mains power through that lead then your stand alone system is the problem.

You said cheap batteries, possibly the cables are to small and insufficiently terminated. Cheap inverter?

What to do about it? Spend more money on bigger better quality components or go back to using grid power.

[ShedPower]

That makes sense, though not sure what to do about it. The output from the inverter had to come through a plug and a plug has to have a fuse and 13amp is the biggest plug fuse you can get. Any suggestions?

[SunEagle]

I have a problem on my system. I have a 1000w inverter which is fine feeding just our freezer, at about 50-70w continuous, often less. I have added our tv which runs at about 100w. However, the 13amp fuse in the plug that comes from the inverter to feed these two appliances, keeps blowing. Its a fairly simple system, and all the connections are good and well made. I haven't yet grounded the system in terms of a rod into the ground. Any ideas as to what might be causing the problem? Many thanks.

Fuses blow for a couple of reasons.

the first is that they get hot due to amps going through them higher then the rating

The second can be due to the high inrush amps that a load can cause when it starts. It is possible that while your loads may have a low running amp rating the freezer may have a high start up amp draw which could be making the fuse blow.

[ShedPower]

Yeah it’s a U.K. 13amp plug, 240v AC from the inverter which is 12v

[Bala]

You are describing a 13A fuse in an ac plug. That is not something I have seen but I'm in Australia.


To help Is the inverter pure or modified sine wave.

What is the voltage in the circuit that the fuse is in.

[ShedPower]

I have a problem on my system. I have a 1000w inverter which is fine feeding just our freezer, at about 50-70w continuous, often less. I have added our tv which runs at about 100w. However, the 13amp fuse in the plug that comes from the inverter to feed these two appliances, keeps blowing. Its a fairly simple system, and all the connections are good and well made. I haven't yet grounded the system in terms of a rod into the ground. Any ideas as to what might be causing the problem? Many thanks.

[ShedPower]

Thanks I will have a look. I do want to always err on the side of caution so I will not mix different size batteries. In terms of parallel batteries, slightly off topic, I have wired mine using two bus bars, one for all the negatives and one for all the positives. And then taken a feed from each bus bar. Measuring the batteries individually, they seem to always be at the same voltage. So I think this works really well for charging and loading evenly. Im not engineer or anything like that, but just found this works well.

[Bala]

Here is a thread from the forum.

https://www.solarpaneltalk.com/forum...es-in-parallel

[SunEagle]

What do you think about this?

https://rvnerds.com/2017/08/07/elect...gescapacities/

I stand by my reasoning. If you choose to have different batteries in the same system then that is your choice. Hopefully they will last as long as you need them to.

[ShedPower]

Ok, thanks. Safety is paramount so I will go with your advice. I have another battery coming so I think I will change it to 24v too.

[Bala]

What do you think about this?

https://rvnerds.com/2017/08/07/elect...gescapacities/

I worked for a truck company for 3 years. Approximately 80 long haul b double units doing 300 000km each every year. Approximately 60 were 12v systems with 4 12 batteries in parallel and 20 with 24v systems batteries in series.

There was never a problem on the units with 24v systems boiling a battery.

It was common for the units with 12 v systems to come in with one battery boiling and it was always the battery in the same position in the pack. The battery packs are designed with the leads to equalise charge and discharge but the batteries are not exactly the same to start with and even with best design of the system they do not discharge and charge equally. Often a second hand battery was put in for the boiled one but before long another would fail.

A boiling battery is a bomb ready to blow. I have had batteries explode that were not boiling, just from load trying to start an engine.

You can always find the info you want to hear online but I think Dave's info is very poor advice. I believe batteries in parallel are not the best option but you will have a better performing and safer system when the batteries are matched as closely as possible.