Homemade UPS

UPS Battery Box

Do you need a UPS that can run your computer gear during all day power outages? I put together a homemade double conversion online UPS using off the shelf components, and now when the power goes out, my computer doesn’t skip a beat, even if the power is off for an hour or two… or all day.

The main components of the UPS are:

  1. A pair of 6 volt golf cart batteries wired in series
  2. An automatic battery charger with a DC UPS mode
  3. A 300 watt sine wave inverter

With a double conversion online UPS, your equipment runs off of batteries and an inverter full time. When there is line power, an automatic charger supplies enough current to power the inverter and keep the batteries float charged. When line power is lost everything continues running normally, with the batteries handling the load. When line power is restored, the automatic charger supplies enough current to power the inverter and recharge the batteries.

This also has the side effect of providing really clean, isolated power to your computer equipment, assuming you’re using a sine wave inverter. Power is always converted to DC and back to AC before being used (double conversion).


To get an all day run time, you need some big batteries. Most golf cart batteries are at least 200 AH, and offer a good value at the expense of some convenience. You need to check the water levels in the batteries and add water to them periodically. Also, you should not use them indoors due to outgassing. Lead acid batteries outgas hydrogen as they charge, so they should be used outdoors and need to be well ventilated to prevent explosion.

If you’re willing to spend more money (perhaps twice as much), you could look into using sealed AGM batteries, which don’t normally outgas unless overcharged. These are often used indoors, though I think I’d still prefer keeping them outside if possible.

UPS Battery Box Top View

Here you can see the pair of golf cart batteries I’m using, inside a battery box. I’m using Water Miser Vent Caps on the batteries to help reduce battery watering and to make watering more convenient with flip-tops. They’re optional, though.

I’ve heard Trojan makes great golf cart batteries. I’m using Motolite golf cart batteries, which is what I could find locally, and they work fine. They’ve been in use 3+ years now and still going strong.


UPS Power Pulse Desulfator

I’m also using a Power Pulse desulfator connected to the batteries. This is optional, but I think its really helped. Over time, sulphate will form on the lead plates in the batteries causing reduced capacity. The desulfator helps prevent and even reverse the sulfation. It’s not perfect and the batteries won’t last forever, but it helps.

Before I hooked the desulfator up to the golf cart batteries, I hooked it up to an old 37 AH SLA battery pack that had been in use for about 10 years and was starting to show substantial wear. I kept the Power Pulse desulfator on the battery pack along with a 500 mAH charger for a few weeks, putting it through a few charge/discharge cycles and it really helped improve the condition of the old battery pack. I wish I’d gotten a second Power Pulse desulfator to use on my car battery.

Battery Connections

UPS Battery Box Closeup

The golf cart batteries are 6V so to get 12V for the UPS, a pair of them are wired in series. I’m using a 65A automotive fuse between the negative post of the first battery and the positive post of the second battery. It’s really important for safety to make sure everything is fused properly.

I’m using heavy gauge wire for the battery connections. On the batteries themselves, I’m using some thick yellow automotive wire (labeled with a marker +/-). For the inverter and charger connections, I’m also using heavy gauge (8mm2) wire, but it’s properly color coded (black & red). If I was doing it over again, I’d use the color coded wire for the battery connections, too.

UPS Circuit Breaker

The batteries are wired into an ordinary 50A 240V AC circuit breaker mounted on the outside of the battery box. Ideally, this would be a DC circuit breaker. AC and DC circuit breakers are designed a bit differently, and there are situations where using an AC circuit breaker with a DC load could be problematic. Since the batteries themselves are fused separately, I’m mainly using this as a disconnect switch for convenience. It seems to be working fine for me so far.

UPS Battery Box Side View

From the circuit breaker, connections are made to both the automatic battery charger mounted on the front of the battery box, and the sine wave inverter mounted on the side of the battery box underneath the circuit breaker.

Automatic Battery Charger

UPS Automatic Battery Charger

I’m using a Samlex SEC-1230A 12 Volt 30 Amp Automatic Battery Charger. I have the DIP switch settings set to “Battery with Load” so the charger effectively becomes a DC UPS. There’s a good manual that explains the settings, and it’s available from the Samlex website as a PDF.

The charger comes wired for 120V 60Hz input, but there’s an internal jumper that can be changed to make it 230V 50Hz. If you do that, you need to change the fuse as well. I made the change, and use it with a 220V 60Hz power source and so far I haven’t had any problems.

Sine Wave Inverter

UPS Sine Wave Inverter

For the inverter, I’m using a Samlex PST-30S-12A 300 Watt Pure Sine Wave Inverter (12VDC-120VAC).  I’ve used a modified sine wave inverter with my computer equipment in the past, and it mostly worked fine, but there was some buzzing on my phones. There’s no buzzing with the sine wave inverter.

Some of my gear uses 110V, some uses 220V, and some will use either.  For the stuff that needs 220V, I use a small 100 watt step-up transformer.  I also run my computer (an HP Laptop) off of 12 VDC with an HP KS474AA 90W Auto/Air/AC Adapter.  Other laptops may have similar 12 VDC adapters available.

You’ll need to calculate your load requirements.  If you’re using a desktop system instead of a laptop, you may need a larger inverter. My inverter is supplying power for a 22″ LCD monitor and an assortment of peripherals:  a pair of USB hard drives, speakers, DSL modem, router, switch, USB hub, ATA, and 3 phones.

UPS Power Meter

I’ve got a power meter hooked up to the inverter output, and I’m using less than 100 watts. So for my use, a 300 watt inverter is plenty. The inverter could handle my laptop, too. I already had the 12 VDC laptop adapter, though, so I use it for maximum efficiency.


UPS Battery Box Ventilation

I keep the custom built battery box on an outside covered patio that gets plenty of ventilation and is conveniently located next to my office. There are plastic screens on the top and the sides of the box to let the batteries vent.


UPS Outdoor Connections

I’ve got a set of connectors mounted in the wall in utility boxes to keep things clean. The outdoor connectors (from left to right) are: antenna, ground, line power, UPS power inlet, and 12 VDC input posts.

UPS Indoor Connections

There’s another set of connectors mounted on the other side of the wall in my office. The indoor connectors (from left to right) are: two 12 VDC outlets, two 110 VAC UPS outlets, line power inlet, ground, and antenna. The antenna connector isn’t used for the UPS.


The rough cost for the major components of the system was:

  1. $250 Two 6 volt golf cart batteries
  2. $225 Samlex SEC-1230A Battery Charger
  3. $135 Samlex PST-30S-12A Sine Wave Inverter

I got the golf cart batteries locally, and ordered the charger and inverter from altEstore.

An alternative to all this, is to use a small off the shelf UPS for short power outages, and to simply take a break from the computer during longer power outages. I hear its nice to spend time outdoors. What do you do when the power goes out?

Please note: I’m not an electrician, but I did have an electrician do the wiring for this UPS system for me. There’s no guarantee any of this meets electrical code. Please consult an electrician and check your local electrical code if you want to undertake a project like this.

Update February 2012

I just replaced the golf cart batteries in my UPS with a 100AH 12V AGM battery, that I got from Pure Ener-G (the sponsor of the Solar Panels Philippines Forum).  The golf cart batteries were still working, but they’ve been in use for around 5 years, so I thought it would be good to replace them now rather than have a surprise failure later.

With the old golf cart batteries, I made the mistake of not coating the battery terminals and lugs with some sort of sealant, and they became corroded.

UPS Battery Corrosion

I had a few power outages where the UPS failed.  One of the battery lugs was so corroded that it crumbled apart when I tried to remove it.  So that picture is after removing the old battery lug, with the remnants of the old lug laying on top of the battery.  I know I shouldn’t have let it fall into disrepair, but I was planning on replacing the battery anyway, so I hoped it would keep going a little longer.

Here’s the new 100AH 12V AGM battery. I’ve got some dielectric silicone grease coming that I’ll use on the new battery.

UPS AGM Battery

I was planning on replacing the batteries with a 12V 200AH Motolite Solarmaster battery, but I went with this AGM battery instead.  These are hard to find locally, so thankfully I was able to have it shipped to me from Manila (via Partas).

I replaced the automotive fuse I was using with a Blue Sea 100A DC fuse and fuse block, which you can see sticking out from the positive terminal on the left.

I also replaced the AC circuit breaker with a proper DC circuit breaker, an 80 amp Bussmann MRCB circuit breaker.

UPS DC Breaker and Battery Gauge

And I added a MidNite Solar battery meter, too.

UPS Battery Meter

I should also note that I’m using a Mini-ITX system with a 12VDC power supply with this UPS instead of a laptop now.  The 250 watt M4-ATX DC power supply connects to my battery, bypassing the inverter.  These are also used for Car PC systems.  It runs my i7 2600K system without difficulty (using an Intel DH67CFB3 Mini-ITX motherboard with the integrated graphics from the 2600K).

So those were the UPS modifications I made.  While I have less capacity with the 100AH AGM battery vs. the 200AH system with the golf cart batteries, I’ve also got a diesel generator now, so hopefully the UPS won’t be pushed too hard. And I won’t have to fill the golf cart batteries with water anymore.

  • Hi David, I looked at your excellent setup, but want to power more appliances; at home i want to cover the following items, for a minimum period of 3 hours, using a power inverter and deep cycle batteries.

    80 watts for one 18″ fan
    100 watts for my laptop (my printer has a battery backup)
    30 watts for a couple of energy-efficient lights
    180 watts LCD TV
    200 watts fridge/freezer – peak 400 watts
    TOTAL = 800 watts peak, more like 600 constant.

    Since the run time depends solely on the amount and size (capacity) of my batteries.
    # Total the amps on the batteries and divide by 12. Take that number and set it aside, we’ll get back to it in a moment.
    So that is (say 2 batteries x 100 amps = 200 amps / 12 = 17)

    # Total the amps on the devices you will use on the inverter, add another 1/2 amp for the inverter itself.
    600 watts / 220 = 2.7 + 0.5 = 3.2 amps in total needed

    # Take THAT total and divide into the first number you came up with.
    17 / 3.2 = 5.33 hours runtime.

    Now of course I cannot let the batteries run down below 50% of charge, so actually I should get almost 3 hours of power. In Davao City there are brownouts for 2 hours, 3 times a week, so I guess that’s enough. I can always connect more batteries in parallel if things get worse. Please bear in mind I am a COMPLETE novice at this and am on a steep learning curve.

    So, now the components, borrowing some of your ideas.

    1) Batteries – having spoken to the Motolite rep in Manila, it seems that a pair of these 12V 100AMP solar batteries, connected in parallel, would be suitable. http://www.motolite.com/battery.php?id=16. I would prefer AGM sealed units like http://www.altestore.com/store/Deep-Cycle-Batteries/Batteries-Sealed-Agm/c436/ but the cost would almost certainly be prohibitive.

    2) Inverter – here in Dumaguete there is no choice and only one shop selling a cheap Chinese 1000 watt inverter (with no warranty!). I have bought one of these but have little confidence in its durability. Looking at http://www.altestore.com/store/Inverters/Export-Inverters-230V-50Hz/c1110/ and then the specific $800 model that seems the cheapest that would do the job http://www.altestore.com/store/Inverters/Export-Inverters-230V-50Hz/Xantrex-TR1512-230-50-InverterCharger/p6674/ … it’s a bloody expensive unit! No sign of your Samlex inverters there.

    It’s SO hard to make a judgement about quality and likely durability when just looking on the web. I am tempted by Powerbright inverters though the units are made in China! See http://www.powerbright.com/factory.html. However that may be the case with many electronics components sold in the USA. I am only powering one laptop and it obviously has its own power protection built in, so I think a modified sine wave inverter will be good enough.It looks like the 1500 watt model is more widely available, see http://www.amazon.com/Power-Bright-ERP1500-12-220V-50-Inverter/dp/B001S0FOR0 though I did manage to find the 900 watt one at http://www.invertersrus.com/powerbrighterp900-12.html. Do you think the 900 watt one would be man enough for the job?

    3) Battery charger – I have only found one automatic battery charger here in Dumaguete, seemed to fit the bill even though a bit expensive at 4,200 pesos. However once again there was no warranty and that’s not acceptable. I believe that when we move to Davao on 1st June, we will have much more choice. I am tempted to follow your example and when looking at http://www.altestore.com/store/Charge-Controllers/AC-Charge-Controllers/c473/ I figure that the 15 amp model rather than your 30 amp one would do the job? It appears that batteries should not be charged too quickly or their life will be shortened considerably. A rule of thumb is 10% of the battery’s capacity, or @10amps in my case. I can see from http://www.altestore.com/mmsolar/others/sec1215-1230-2415-switchmanual.pdf that I can charge up to 3 banks of batteries at once and the “Dip Switch set at battery with load” is probably not something one would find on most chargers here in the RP?

    4) Desulfator – this is a new concept for me and I have no idea which of these models would be best? http://www.altestore.com/store/Deep-Cycle-Batteries/Desulfators/c512/ Presumably if I leave the battery charger and batteries connected all the time that would provide the power needed for the desufator? Your thoughts?

    5) Watering caps – something else I would have never have thought about, presumably those are shown at http://www.altestore.com/store/Deep-Cycle-Batteries/Watering-Caps/c718/ Looking at the photo at http://www.motolite.com/battery.php?id=16 it seems there are 6 needed per battery.

    6) You mention a 50A 240V AC circuit breaker … I can’t quite figure out what this is needed for … don’t you just turn the inverter power switch to “off” to get the same result?


  • Hi Adrian. I’m not an Electrician or an expert at this, but with that in mind, here are some things to consider.

    This is how I’d calculate the requirements (I’m not sure I understand your formula).

    Watts = Amps x Volts

    2,400 Watt Hours = 200 AH x 12 Volts

    So you’d have 2,400 Watt Hours to work with. If you drain the batteries down to 40%, you’d have 1,440 usable Watt Hours.

    Factoring in a 15% loss from the inverter would increase the 600 watt load to 690 watts.

    1,440 Watt Hours / 690 Watts = 2 Hours run time

    Another thing that could affect the size requirement for the inverter is the Power Factor. Inverter ratings usually assume a Power Factor of 1, but many devices have power factors more like 0.6 to 0.8. This could increase the size of the inverter you need.

    You also need to look into the surge capacity of the inverter. When the compressor in your refrigerator starts, it will require a large starting current. It wouldn’t surprise me if your 200 watt refrigerator surges to 1,000 watts or higher briefly when the compressor kicks in. I think it will be your biggest problem of the devices you mention.

    If you’re in the Philippines, you’d ideally want a 220V 60 Hz inverter, but these are not easy to find. If you use a 220V 50Hz inverter instead, it could cause some problems (50Hz vs. 60Hz).

    A 900 watt inverter may be enough, but I just don’t know. The wildcard is your refrigerator. Ideally, you’d probably want a 1,000+ watt 220V 60Hz sine wave inverter with a large surge capacity.

    A modified sine wave inverter may work fine for your computer, but I suspect your refrigerator and fan (devices with motors) could have problems with it. A sine wave inverter would really be recommended if you’re dealing with motors.

    You could get a 120V inverter and use a step-up transformer for 220V. That’s what I do for the devices I use that require 220V. I would have preferred a 220V inverter, but using the 120V Samlex model made more sense, since 220V 60Hz sine wave inverters are hard to find (let me know if you find one), and the price was right on the 120V model. Of course there’s some additional loss in efficiency from the step-up transformer, then.

    You could check the Samlex PST-100S-12A 1,000 watt 120V sine wave inverter (altEstore).

    Or the Samlex PST-150S-12A 1,500 watt 120V sine wave inverter (altEstore).

    I’m using the Samlex PST-30S-12A 300 watt 120V sine wave inverter (altEstore).

    Regarding the batteries, it’s generally not a good idea to add more batteries to a battery bank after its been in use for awhile. The wear on all of the batteries in the battery bank should be even, otherwise there can be issues charging them together. So you’d want to make sure you calculate the battery capacity you want up front.

    Regarding the charger, if you’ll be using the setup like I do, as a UPS, the charger does double duty providing power to your devices as well as charging the batteries, so you need to take that into account.

    For example, in my case 30 amps x 12 volts provides about 360 watts of power. My computer equipment load is about 150 watts (12.5 amps), so that leaves about 210 watts (17.5 amps) for charging.

    If your devices will only be connected during power outages, and the charger is strictly used for charging the batteries, a 15 amp charger would probably be enough. That would mean switching things around and plugging/unplugging during power outages. Otherwise, you may need a larger charger.

    If you’re using two 100 AH 12 Volt batteries in parallel, you’ll have one 200 AH battery bank, so the C/10 charging rate would be 20 amps.

    The DC UPS feature on the Samlex charger is key for this system to work as a UPS. Many automatic chargers use 3 stage charging: Bulk, Absorption, and Float. If you’re powering devices while the system is charging batteries, you can run into problems during the Absorption stage. The DC UPS “battery with load” feature basically disables the Absorption stage from what I understand.

    Regarding desulfators, some types are only meant to be used for a limited time to recondition a battery. The one I’m using can be hooked up all the time. I ordered the one I’m using here. The batteries/charger provide the power for it, and it uses very little power.

    Regarding the watering caps, since I’m using two 200 AH 6 volt golf cart batteries wired in series, there are only 6 cells total. If you were to wire two 100 AH 12 volt batteries in parallel instead, you’d be correct that you’d have 12 cells. These are the Water Miser Vent Caps that I’m using.

    The main purpose of the circuit breaker in my system is for use as a disconnect switch to cut-off the batteries from the inverter and the charger. You could turn off or unplug the inverter and charger and it would have a similar effect, but I like to have the separate disconnect switch. It also provides some additional protection if something were to get shorted.

    If it were me, and I wanted to power things like a refrigerator, I’d probably start considering a generator. It might end up being less expensive. Though really, I don’t find 2-3 hour power outages to be an issue for the food in the refrigerator.

    We experience those now and then, and as long as you don’t open the door too often, the food stays cold enough. For longer 12 hour power outages I transfer perishables from the refrigerator to the freezer. There have been a few 24+ hour power outages since I’ve been here, and then we’ve got to throw out the food. A generator would have been especially nice to have, then.

    You might also consider a 12 VDC fan to bypass the inverter. I ordered one from Camping World more than 10 years ago and use it with a separate 37 AH portable battery pack that I can move around and it comes in really handy.

  • Get a lot of brownouts where I’m at the Philippines, and this looks like a good solution to keeping the computer running. But I sure would need my electrician to do the wiring. I would probably electrocute myself!

  • Good plan Dave! I had my electrician do the wiring for this, too. Our power was out from around 6:00 AM to 4:30 PM this past Saturday, and the system worked fine the whole day.

  • Well Dave, I sure prefer your method of assessing likely power requirements over mine! I can see exactly how your approach works!

    Here are yet more musings!

    You are using two 6V golf cart batteries and you say these combined give you 30 amps to play with? Did you ever consider a pair of 100 amp solar batteries?

    I would indeed only use the inverter when power was off. I have a laptop and therefore don’t really need a UPS.

    Looking at page 2 of the Samlex battery charger brochure at http://www.altestore.com/mmsolar/others/sam_batterycharger_brochure.pdf it seems that the 15 amp unit can charge up to 3 ‘banks’ of batteries. So I figured that it could charge two 100 amp batteries simultaneously at 15 amps each from the one 15 amp charger. Or is my interpretation wrong?

    At the end of your last message you mention the 12V fan which you power with \a separate 37 AH portable battery pack that I can move around\ … is this a standard 12V car battery? The lack of a fan during a brownout is the very first thing that drives me out of the home!


  • Hi Dave, here’s another US power inverter supplier http://www.dcacpowerinverters.com. However, going the 1000 watt 220V 60Hz PURE sinewave route, plus a step up transformer and surge protector comes to a massive $489 + $234 shipping to the Philippines! This is getting to be an expensive idea!


  • Hi Adrian. The charger gives me 30 amps @ 12V to power my devices and charge the batteries.

    The two 200 AH 6V golf cart batteries wired in series give me 200 AH @ 12V, the same as you’d have with two 100 AH 12V solar batteries wired in parallel.

    When you wire batteries in series you add the voltage together and the AH capacity remains the same (6V + 6V = 12V, still 200 AH). When you wire batteries in parallel you add the AH capacity together and the voltage remains the same (100 AH + 100 AH = 200 AH, still 12V).

    Generally it’s better to have a battery bank wired in series if possible. You’re less likely to have uneven battery wear. It’s not a big deal to wire them in parallel, though. It should be just fine.

    I’m pretty sure the 15 amp charger can only output 15 amps total regardless of the number of battery banks. In your case you’d have one battery bank comprised of the two batteries wired in parallel. The inverter can only run off of one battery bank.

    The battery pack I’m using for the 12V fan uses a Sealed Lead Acid battery (SLA). I’ll take a picture and post it so you can see what I’m talking about.

    The inverter you’re referencing here is actually a 220V 50Hz inverter for Europe. The Philippines uses 220V 60Hz, so you may have problems with it (like burning up your refrigerator).

    Most 220V inverters available are 50Hz for Europe. Not as many countries use 220V 60Hz like the Philippines, so maybe that’s why it’s so hard to find inverters.

  • Hi Dave,

    My conclusion is that this approach is simply not cost effective for running an entire household. If going for a 1000 watt system with a modified sine wave inverter, you are looking at 48,000 pesos. With a pure one it’s 58,000 pesos … and all you get for that is just under 2 hours of runtime with 1200 watt hours available, assuming the 50% rule! It’s been a fascinating exercise, but has proved to be far too expensive.

    My solution is this – my real issue is lack of fans when the power goes off. I can work for a couple of hours (the average brownout time in Davao, 3 times a week) with my laptop battery and there is no need to drive a fridge or anything else really, given the short duration. I have bought two rechargeable 12V fans for 2,000 pesos in total … that will work! One of them has an input socket so I could connect a car battery if needed, but between them they supposedly provide 10 hours of power, driving fans only.

    Thanks for helping me put some ‘science’ behind my idea and preventing me from making an expensive mistake


  • Hi Adrian. You’re welcome. I’m glad you were able to come up with a solution that will work for your situation.

  • Hey David,ur article is nice.this helped me in my projectwork…thaks buddy……….

  • Hi shilpa, glad it helped.

  • Hey Dave great article I’m still working my way through a lot of the more complicated work and the end work may not look as good but I appreciate the time it took to document this for people like me! Just want to say thanks and keep up the good work. Also I found a new supplier thats has really worked well for me

  • You’ve got great insights about home made energy, keep up the good work!

  • Hi. I have a 900AH battery bank consisting of 8x250AH batteries on a 24v system. I intend to run a printer with a 1230watts rating for 10hrs as backup. this system will be connected to utility 220 v power.what is the best charger size to use on this batt bank.

  • Hi Allan. I think I’m missing some details, because I’m having trouble reconciling 900AH with 8x250AH @ 24V. What voltage are the individual batteries at?

    Assuming you’ve got eight 6V 250AH batteries, that’s about 12kWh capacity (6kWh @ 50% DOD). Maybe that would run your 1230 watt load for about 4-5 hours.

    Anyway, you’d want to check to see what charge rate the battery manufacturer recommends. If they’re lead acid batteries, I think C/10 is usually a reasonable rate.

    First figure out your battery capacity (Watts = Amps * Volts), then divide by the charge rate. For example, if you’ve got a 12kWh battery bank, a C/10 charge rate would be 1.2kW. That would be 50 amps at 24V.

    It might be worth checking the actual printer load with a watt hour meter, too. If there are times the printer is idle, the overall consumption may be lower.

  • Love the portability of this set up.

  • I am not positive the place you’re getting your information, but good topic. I must spend a while finding out much more or understanding more. Thank you for excellent info I was looking for this information for my mission.

  • Great web site. Plenty of helpful information here. I am sending it to a few pals ans additionally sharing in delicious. And obviously, thank you for your sweat!

  • Please see the end of the post for UPS modifications that I made (February 2012).

  • David, I like your digital power meter, where did yu bought this from? can it monitor amperage coming-in and out of the battery? Also, the motolite golf cart batteries did you you ordered directly from motolite? please advise, thanks a lot.

  • Oscar, I got the power meter a really long time ago in the US. I can’t remember if I got it directly from them (http://www.brandelectronics.com/) or from a store. It’s 110V only, though. It measures the load going to the inverter.

    I think I got it before less expensive power meters like the Kill-A-Watt and their clones became available. I recently got an Omni power meter locally for 220V that works fine, too.

    I don’t have an amp meter measuring the output from the battery, but there is an amp meter on the battery charger. When it’s just float charging that’s pretty close to measuring the total load for the battery.

    I got the Motolite golf cart batteries in Manila, but I’m sorry I don’t remember where, anymore.

  • David, thanks for the reply; from your UPS article, you have used the motolite golfcart batteries for 5 years fitted with the special cap “the fliptops”.. :).How was the deep cycle capability of this battery for 5 years? How is it compared with the inochi AGM in terms of discharge rate cycling capabity? I wonder which will give more numbers of deep cycle. Advise form your experience will highly be appreciated… 🙂 thanks.

  • Oscar, the Motolite batteries performed well. I discharged them a lot. I haven’t discharged the new AGM battery much, yet, though. It’s mostly getting float charged, and occasionally runs for 30 seconds or so during power outages.

    I expect the new AGM battery to perform about the same as the Motolite batteries, with the main difference being that the AGM battery is maintenance free, and the Motolite batteries required watering on a regular basis.

    If I could have found somebody willing to ship me a new Motolite Solarmaster battery, I would have gotten that instead. It’s cheaper. But I don’t regret going with the AGM, since it’s nice not having to worry about watering the battery.

    Having used both now I prefer the AGM and think it’s worth the extra money.

  • I did a 30 minute load test on the new AGM battery yesterday. No problems and the battery meter was at 90%.

  • Where did you get your fuses, and the type?

  • R. Brown, the fuse I have on there now is a “Blue Sea Systems” I got from Amazon. “Blue Sea Systems 5183 100A Fuse Terminal” and “Blue Sea Systems 5191 Fuse Block Terminal 30-300 AMP.”

    Before I got that, I just used an automotive fuse I got locally from some small store.

  • If I connect the battery charger to the battery, and connect the battery to the load, with charger set to “batery with a load”, I can operate a 12VDC LED light circuit?

  • Roger, yes, that should work fine.

  • Thanks, I am in the Philippines, and need back up for night, and security lighting, have worn out 3 battery’s (car type), and now have a 40 kilo 200AH solar battery,I got the battery local, but no one here has a clue about automatic charger like in the artical. Even the shop I got the battery from had no idea about chargers. My daughter is bringing the charger from US this Saturday.

  • Good luck with your project. When you get the charger, remember to check the manual for instructions on changing the input voltage to 230V and setting the charging mode.

  • I got the water miser caps, but they do not fit the Philippine battery Motolite solar battery I bought.
    Company said they had never seen a battery cap like the ones here.Charger is here, and battery is topped off.

  • Sounds like you’re all set. Strange about the battery caps, though.

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