January 17, 20179 yr 11 hours ago, dax021 said: Chris, so what batteries would you recommend? My needs are very similar to this and I already have an Axpert 3Kva Plus 48V and 4 x 295W panels. At the moment my Trojans (T1275) are poked and I need to buy something soon. Thanks I have found the OmniPowers to work quite well with Axpert inverters. Sacred Sun and Vision batteries also work quite well.
January 17, 20179 yr 1 hour ago, plonkster said: You cannot do an equalisation charge on Trojans with an Axpert. That's the low-down. They cannot push the voltage that high on their own, and if you do it with an external charger with the Axpert in circuit you will either pop a capacitor or two or at least severely shorten their life. That means that for this once in a lifetime event (or two, or three) you need extra equipment and you're without power while you're doing it. I think it's an acceptable trade-off to those who know what they are doing, but unacceptable for an end-user system. Humble opinion of course :-) @plonkster this makes me wonder: How difficult would it be to build a buck booster / limiter that could work with 100A / 54V? i.e. if you could put a buck booster in between the batteries and the Axpert, then you could use a Victron (or other favorite) MPPT charger and always ensure charging is to speck?
January 17, 20179 yr 2 minutes ago, SilverNodashi said: I have found the OmniPowers to work quite well with Axpert inverters. OmniPower is a good quality VRLA battery.
January 17, 20179 yr Just now, SilverNodashi said: How difficult would it be I think it would be way more effort than it is worth. Buy different batteries and be done with it :-) You should check out the EEVBlog on youtube, that guy had a complete field day with a product called the "Batteriser", essentially a little sleeve insert that boosts AA or AAA batteries to an exact 1.5V so they "last longer"... :-)
January 17, 20179 yr 50 minutes ago, plonkster said: I think that is why the Axpert cannot run with a <200Ah battery, or at least it is not advised. You need some bulk to absorb the overshoots :-) I would love to see that thing on something small, like a 50Ah battery perhaps. That should be fun. that can be arranged. Will you sponsor the goods?
January 17, 20179 yr Just now, SilverNodashi said: that can be arranged. Will you sponsor the goods? Oh man, that made my day :-)
January 17, 20179 yr 1 minute ago, plonkster said: I think it would be way more effort than it is worth. Buy different batteries and be done with it :-) Ok, but how much more effort would it be, for it not to be worth-while?
January 17, 20179 yr 59 minutes ago, plonkster said: Capacitors. Although the FETs do come into it. I meant capacitors .....silly arse
January 17, 20179 yr 12 minutes ago, SilverNodashi said: Ok, but how much more effort would it be, for it not to be worth-while? Well, this thing would have to be bi-directional, init? It has to look like a battery to the inverter, accept charge from it and put it into the batteries, and at the same time supply charge to the inverter, doing a voltage level conversion both ways. I think it would be so much trouble you'd be better off buying a proper inverter :-)
January 17, 20179 yr 2 hours ago, plonkster said: Well, this thing would have to be bi-directional, init? It has to look like a battery to the inverter, accept charge from it and put it into the batteries, and at the same time supply charge to the inverter, doing a voltage level conversion both ways. I think it would be so much trouble you'd be better off buying a proper inverter :-) True, but if it cost say R2K, or even R5K to build, a "proper inverter" would be way out of budget still. Especially since your "proper inverter" (aka Victron) still needs it's own MPPT charger. But at R5K it would mean that I have it and can add Trojan batteries, or even other batteries in future, at no additional cost. But this is all just curiousity more than anything else. Does something like this even exist? On this scale, I mean? Or is it possible to build such a circuit? a 60V level shifter is fairly easy to build, but to handle 100A as well, that's a whole different story. That's a LOT of power / energy to dissipate. So I guess it's cheaper to upgrade the DC components inside to 80V capable components?
January 17, 20179 yr Lol. Yes I was being a little cheeky there :-) I'm not qualified enough to tell you what it would take to build such a thing. I'm just a hobbyist with a middle-of-the-road understanding of buck and boost converters. I'd say 5k is optimistic, it would take more. It would cost at least as much as two MPPTs of the same sort of power level, because that's what it would be, two cooperating converters. It also adds another +-10% drop into the chain, a chain which is only about 91% efficient as it stands. The right answer is to buy another inverter, or to upgrade the components in the one you have. I believe some Ausies have done it. The idea of such a converter did briefly cross my mind when we discussed super-capacitors. You may recall, the issue with those is they discharge linearly and to get all the energy out you have to go as low as possible.
January 17, 20179 yr 1 hour ago, plonkster said: . I believe some Ausies have done it. The Aussies have been busy http://forums.aeva.asn.au/forums/pip4048ms-inverter_topic4332_post63745.html#63745 What's that you say? You think I might be voiding my warranty?
January 18, 20179 yr Author On 1/16/2017 at 6:47 PM, DeepBass9 said: Got some info about the existing system. A Steca Pr2020 charge controller, 2x 100Ah Stride batteries. And an Omnipower 300W 12V inverter. So all in all, hopelessly inadequate for the loads required. Looks like she is in for about R20-25k for a big enough system, i.e about 1000W of panels, 4 x +-200Ah batteries, 2-3kW inverter and MPPT.
January 18, 20179 yr 12 minutes ago, HeinTheTerrible said: Axpert 3kva with no MPPT + Microcare 20A LED http://www.solarsolved.co.za/index.php/products/inverters/off-grid-inverters/axpert-off-grid-inverter-charger/axpert-1kva-800w-12v-off-grid-inverter-charger-detail How about this one? 12V 800W with a separate 20A Controller.
January 18, 20179 yr Just now, Johann1982 said: http://www.solarsolved.co.za/index.php/products/inverters/off-grid-inverters/axpert-off-grid-inverter-charger/axpert-1kva-800w-12v-off-grid-inverter-charger-detail How about this one? 12V 800W with a separate 20A Controller. PWM charge controller. Not ideal
January 18, 20179 yr Author 3 minutes ago, Johann1982 said: http://www.solarsolved.co.za/index.php/products/inverters/off-grid-inverters/axpert-off-grid-inverter-charger/axpert-1kva-800w-12v-off-grid-inverter-charger-detail How about this one? 12V 800W with a separate 20A Controller. Im not sure it will pull a fridge starting up. Id rather also go for a 24v system.
January 18, 20179 yr Just now, Johann1982 said: @HeinTheTerrible You can use a separate MPPT controller. You're better off getting the Axpert with no charge controller then. Save a little bit of cash.
January 18, 20179 yr 4 minutes ago, Johann1982 said: How about this one? Be careful for too small an inverter that will stop working if the Fridge comes on when rest is powered. Been there, done that.
January 18, 20179 yr 3KVA MKS Plus then. 24V with enough power and built in MPPT and not too expensive.
January 18, 20179 yr http://www.bonanzatech.co.za/index.php?id_product=7845&controller=product http://www.thepowerstore.co.za/pMKS6130-24-PLUS/3KVA-Axpert-60A-MPPT-24Vdc-Sinewave-Inverter.aspx
January 18, 20179 yr 1 hour ago, HeinTheTerrible said: Axpert 3kva with no MPPT + Microcare 20A LED The LED-model MPPTs have a very low Voc...
January 18, 20179 yr Author According to Microcare, having your panel voltage <4 times your battery voltage is better as that is where the buck converters are most efficient. Another think I just realised is that lots of LED lights work on 10-30V, so on a 24V system you can easily run LEDS directly for lighting (ant they will still run no matter how pap your batteries get!). Like these for example (the first that google came up with) : https://www.superbrightleds.com/cat/recessed-led-light-fixtures-10-30v/ I think that will help with the efficiency of the system quite a lot, and your won't need so much 220V wiring (there is no existing wiring in the house AFAIK) Is anyone familiar with the Steca Pr2020 charge controller that she has? It is supposed to be 12/24V and 20A. That should still be usable? It looks like a good piece of kit. Not an MPPT, but you could pay for an extra solar panel with the amount you would lose by selling it and buying another charge controller. : http://www.steca.com/index.php?Steca-PR-2020-IP-en
January 18, 20179 yr On 2017/01/17 at 5:21 AM, DeepBass9 said: How long did your T1275s last? I have 8 of them that are getting towards 2 years old now, with no problems as yet. Just wrote you a long reply but lost it somehow. Short version, they were finished when I got them. Only running 12V LED's at night and a 350W cheapy inverter when the sun shines
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