I have just registered on the forum because this is where I seem to always end up finding good info. I am currently planning a hybrid boat conversion project that will rely on Victron gear.
I will be installing a new 48v battery bank and solar array for propulsion. 12v House loads will be from a 48/12 converter
I want to charge my 12v bow thruster/ windlass/ starter AGM battery from the 48v bank with a DCDC charger. Maximum charge current for my preferred 12v battery is 10A.
The Orion-Tr 48/12—30A charger is too big. Victron dont seem to have a 10A option.
For a battery required to produce several hundred Amps for a bow thruster or Windlass, 10A max charge current seems very small. Do check your discharge current rating for this battery, compared with the motor needs of the Bow thruster, Starter and windlass.
Also, it should be possible to program a lower max current for the 48/12 converter should the need arise.
What you say about battery is what I expected to be the case.
One usually needs a largish AGM battery to get the CCA needed for thruster. I was surprised to find the Optima D34M has ample CCA of 750A with capacity of only 55Ah. They quote 10A Max charge. They do say that there is no current limit if temperature is monitored. I don’t think any of these chargers have temperature monitoring.
When I checked the manual for the Orion-Tr 48/12-30, I did not see any settings for current. If it can be adjusted then that’s a good option.
Anther option might be to use an Orion-Tr 48/12-9 as a trickle charger, with it’s output set to float voltage.
ok, these spiral wound batteries do have high CCA to Ah ratios. Yes, you can charge at higher currents, but need to watch the temperature rise as advised. you could still use the 30A model, and with the voltage set to float (you would need to do this in any case as it is not a 3 stage charger) the current would tail off fairly quickly. There is no VE-direct input, so programming current does not seem to be an option.
This was a bit confusing. I Was talking about Orion Charger here, when I said I could not finding current settings. Then I seamlessly jumped to talking about 48/12-9A Converter.
Can anyone confirm if the Charger has adjustable current? I suppose I could set it to a shorter Bulk charge time, and lower Absorption voltage to manage current.
You might be able to use an Orion-Tr 48/24-5 120 W or an Orion-Tr 48/48-2.5 120 W into a 75/10, 75/15 or a 100/20 MPPT. This will be super cheap, and the 48V will be isolated from the 12V system, and you also get current adjustment using the MPPT. The only problem is that there is no smart, and it will be on all the time. You will need to use a VSR or the remote switch.
I do sometimes use a trolling motor DC-DC converter to charge from battery to battery. I boost it from 12V to 24V into the MPPT for charging a 12V battery. This is very useful for different chemistry. It is undocumented and probably not recommended, but the MPPTs in the small size are so cheap, and they have an external fuse.
I do use the Tr models. They are definitely not current adjusted, and they put out as much current as they can. You can fry an egg on them. I did have to charge a small battery once with a 30A charger. I put really long leads on the output, and that increased the voltage on the output, and it throttled the current. Reducing the voltage did get the desired charge profile, but this was only temporary in a pinch.
I was planning to use an MPPT as my DCDC charger, then I read this thread: MPPT as Battery to Battery Charger? - VictronEnergy(Victron%20Energy,mentions%2C%20this%20is%20not%20recommended.&text=It%20will%20work%20fine%2C%20as,not%20intended%20for%20this%20application.
That is why you need the isolator first, then the MPPT. If you just go from the battery, it will backfeed. You also have the risk of the MPPT failing internally, and you will have the 48V on the 12V system. At the moment, it’s $88 AUD for the Orion-Tr 48/48-2.5 and $65 for a 75/10. That is really cheap. The other option is to get a small inverter like a 500W Phoenix and use an AC charger like a 5-10 amp.