Charging 18V Makita batteries

Hi qldcamper,
I do lots of corrugation and trackless (no roads) country driving. I've been using Supercharge Allrounders for years; currently, one is 2.5 years old and another I replaced after 2 years 7 months. Note I only use Allrounders.

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Phil, "2 years 7 months" is a rather short life for a lead-acid battery. But I notice that Supercharge only offer 12 months warranty on their 'All-Rounder' battery.
Generally, I would be expecting 4 years life on any reputable lead-acid battery operated under manufacturer's recommendations, but maybe less if subjected to the heat and vibration hardships of 4WD operation.
Of course, there are those among us who claim 8+ year life achievement of their batteries but they must be leading a more virtuous life than I.

I used good quality wet cell cranks in the OKA initially.
I got 2 years from the first and 3 years from the second.
The third was a 120Ah Fullriver HGL AGM. I changed it after 9 years for a "cheap" 125Ah AGM that is now 4 years old.
Corrugations kill wet cell batteries. They fall apart internally.
Cheers,
Peter
OKA196 motorhome

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Peter, why did you move from Fullriver to "cheap" AGM's?...... Cost effectiveness?

Yes, I got much better AGM life when I moved them from the engine bay (above the front axle) to inside the cab about midway between the axles.

Hi Allan B (Sunshine Coast),

My batteries get a hard life because of the type of travel I do; I'm pleased with what I get out of them. I use a Redarc 40amp charger system between the two.
I also have a 100 a/h Lithium in the back with its own Redarc 40amp charger system.

My tyres also get a hard life. I'm not going to mention the brand I use because everyone has their favourite.

kindest
Phil

PS I hope you're growing webbing between your toes resulting from the heavy rains over that way.

I believe Fullriver are over priced.
I am now using an NPP.https://www.batteryvalue.com.au/
I can also crank from the house batteries, charge the house from the alternator directly or charge the crank from the solar, simply by linking them via a solenoid. No DC-DC required.
Cheers,
Peter
OKA196 motorhome

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Yes Phil, there is no doubt that physical shock stresses a battery. Some construction (Fullriver) manages that better but at a premium price. Lithium are maybe yet to demonstrate their vibration durability.

Rain has not been excessive at 'Camelot' (Sunshine Coast) lol. However we were down in S.A. and heading home via the Murray when we decided to opt out and run for home. We missed a bullet!
I must say that I have never seen the S.A. Fleurieu Peninsula look so green. Just like the British Isles.
We had a great time amongst the vineyards!

Still running a 2013 optima in the ute running the fridge 24/7- the cheapest batteries are never the cheapest to buy. From my experience with fleets, 2.5 yrs is a decent run out of the allrounders. Someone makes money out of them but it isn't the end user.

I second this. I have a 12 volt cigarette lighter input Makita Charger for charging 18 v Makita batteries and can confirm it works very well.

Macca.

I charge 18v Makita batteries on a fast charger DC18RC using a Victron Phoenix 350w inverter. I found that the circuit breaker I had fitted would constantly trip, so fitted a higher amp one & all has been well since. If I remember correctly I had a 30amp CB, & the DC18RC would at times pull 32 or 33 amps for brief periods. I now have a 50amp CB in that circuit. I had fitted oversize cabling during the initial fit out so no qualms there.

I run this from a bank of 3 x 120Ah Ritar AGMs with no problem. First 3 lasted about 10 years.
I never run the engine to charge the Makitas, but wait until the AGM's have reached flot or are close to it & that the sun is shining.

EDIT: In case anyone is puzzled by the figures I have quoted above, you are not alone - so am I.
A 350w in inverter should at a nominal 12v be good for a max of a bit under 30Amps, at a more likely
13v a max of around 27amps and yet my previous battery monitor(NASA BM1) & it's replacement
(Victron 702) both showed a peak of 32-33 amps when charging the Makitas on the DC18RC
charger. And it tripped a quality Blueseas 30amp circuit breaker.

I put this down to the Victron Phoenix being underrated, not just capable of higher peak currents for
brief periods - but able to sustain higher than rated for long periods.
I have 'tested' it , running combined loads of 500w for an hour.

But that's not the puzzling part, I think it just shows that these toroidal inverters are high quality &
rated very conservatively.

What does puzzle me is that the DC18RC Makita fast charger is rated at 240w .(I assume this is max
wattage) which at a nominal 12v is only 20amps, (and at 13v a tad under 18.5 amps)
Drawing 32 amps (416w @ 13v) from an appliance rated at just 240w is quite a discrepancy

Am I missing something?

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Hi Cuppa, Yes, you may be "missing something"..........
The product ratings you quote are just that........ nominal manufacturer product ratings. Nominal, don't expect them to be exactly what you see in actual use.
And the readings you see on your meters may not be "accurate". Now this gets a bit complicated to express in a few words, but due to the nature of inverters and chargers, the current flow is not exactly smooth DC but can be in short fast pulses (for want of a better description) and the current meters get fooled and will indicate an approximation which may not be what you expect.
That may explain your apparent discrepancies, or it may not! There are many mysteries in electronics!

However, if it works, then it works. Be happy. lol

High Nick,

To answer your question regarding a cigarette lighter charger, Makita make a dedicated 12 volt input charger, the DC18SE, as in the attached photo. It takes around between 45 mins to an hour to charge a 5 AmpHr battery.



Macca.

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Yes, and it's only 150 bucks!

Allan B, I can understand both battery monitors possibly reading less than 'accurately;, but does the same explanation hold for why the 30 amp circuit breaker would consistently trip

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Cuppa, the 30A rating of the circuit breaker is "nominal" and, due to manufacturing deviation, the breaker may have tripped at a lower current. Or maybe the RMS current was other than what your meter was showing. Or maybe something else. Conjecture is unreliable and I would not wish to make rash diagnosis unless I performed hands-on investigation myself. In general, a circuit breaker or fuse should not be operated at, or close to, its rating. A 20% overrating is reasonable. But the real point is that the breaker was tripping, and your replacing it with one of higher rating solved the problem. Does that not seem in accord with what I am saying?

In case you are wondering, the reference to "RMS current" above is an electrical engineering term which refers to the current waveform and is the energy or heating effect of the particular current. Often meters, in particular digital types, actually read the current based on 'average' or 'peak ' measurement which show a different value and can confuse. Digital meters operate by 'sampling' the measured value in a series of quick bites. An inverter, being a PWM device, has an input current which is not steady but is a series of pulses. A digital ammeter may see differing instantaneous values at each sample which can cause errors in the displayed reading. Some more expensive meters classed as 'True RMS' type overcome this problem.

Allan, Thanks & yes, you are correct - I don't have a problem any more ..... just curiosity.

I understand the issue of obtaining 'averaged' readings when PWM is used as a means of current control but imagine that the limits of variation wouldn't be great?

The fly in the ointment as it were, in my situation wasn't, I think, primarily a meter reading 'inaccuracy' , but an appliance rated at 20 amps drawing circa 50% more than that. Sounds like Nick B Boab probably experienced the same, with the same model charger.

I note your point about 'nominal' manufacturer product ratings, but I had always been of the understanding that wattage ratings on appliances were the maximum the appliance might use. I just googled that & https://www.energy.gov confirms that the rating should be for maximum not 'nominal'.



I imagine most folk, like myself, would use the stated appliance wattage to be a useful guide to circuit breaker size, going up a size if the rating were close to the breakers rating for the reason you describe. Mostly in all the electrical installs I have done this has guided me well. In this instance however the issue seems to be a case of Makita providing a misleading wattage rating. Possibly 'nominal' as you suggest

I have found this interchange useful as it has led me to this understanding, but changes nothing of course, as I had already acted to resolve the problem I'd experienced. Just niggles me a bit that Makita, through their wattage rating clearly not being the maximum for that model charger, cost me a replacement breaker & the work involved in fitting it, following a 4 month trip where what should have worked just fine ....didn't.

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"Nominal" in my usage meant what the circuit breaker manufacturer nominates as the maximum current carrying capacity. Consumer grade thermally actuated circuit breakers are notoriously unreliable in their operating rating. It is the nature of the beast. It is a piece of bi-metal heated by a current passing through it or through an adjacent resistance wire. Damned difficult to achieve repeatability in a simple manufacturing process. Don't expect too much from them. More often, manufacturers err on their safe side and allow a generous margin of reliability and accordingly they usually trip at a significant margin over the rating. But don't count on it. The ones marketed for the 12v consumer market are simple things after all.

The reference you posted from energy.gov relates to 240v consumer appliances load rating which is much easier to manufacture to spec. The reference to "maximum power" allows for appliances which may draw variable power for irregular reasons.... e.g. Low-Medium-High or different loads.

I have no explanation to offer for the apparent discrepancy of the Makita power rating. I could postulate a number of reasons but none would have value. Only physical testing with appropriate instruments may lead to an explanation. You will probably have to live with your frustration and be satisfied that you did achieve an acceptable result.

Sorry Wooly that your post has been hijacked! Hope it had some interest.

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Cuppa, perhaps I should have asked this earlier..... what instrument are you using to measure your currents?

Allan, It was in one of my earlier posts.

At the time when I first began using the Makita charger I had a NASA BM1 Battery monitor


Now I have a Victron BMV 702 Battery monitor


Both showed the same current being used

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Cuppa, Certainly the Victron BMV702 is a well respected product but I know nothing about the NASA BM1 other than Derek Bester of ABR offers it so it's probably reliable.

The fact that they both read the same current is significant although it is just possible that they could both be fooled in the same manner. Not saying that it is likely.... just possible. Anyway, at least you weren't using a cheapie DVM clamp meter from Super Cheap. Alas, I have no explanation to offer.

Actually I'm surprised the NASA BM1 is still being sold. I have little doubt that the Victron product is superior, better cabling, & a higher rated shunt too. When I bought the NASA unit I organised a group buy, & brought in around a dozen units from the UK, I can't recall if they were just cheaper, or whether they weren't available in the Australia at the time. Compared to the few alternatives on the market back then they were far more affordable. I recall some costing $600+ back then!

However after a number of years bouncing around the outback the BM1 started to become unreliable & I didn't always trust what it was telling me any more, so around 2 years ago I replaced it with the Victron (Whose pricing was, I suspect, responsible for bring the market prices of battery monitors generally down to more affordable levels).

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Since moving to the Sprinter, I have been haunting the American based Sprinter Forum and also grazing across the USA Sprinter build-up offerings. From them you might expect that there is no other available than Victron. These Yanks do not appear very adventurous! lol

Hi Allan,

I think $150 is a lot cheaper than most 300 Watt Inverters.

Macca.

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Yes Macca, but Nick wanted to use his existing installed inverter.
The suitable DC18SD charger sells for $50.

Hi Macca, yep it is cheaper (especially if you add the cost of a 240v charger to the cost of the inverter).

However it really depends upon what you want. An inverter will run a Rapid Charger which will re-charge the Makita battery much quicker. Makita say that that their DC18SE 12v charger will charge a 3Ah 18v battery in 60 minutes. The Rapid charger will do the same in 1/3rd of that time.

An inverter also has other uses (I always like to have multiple uses for things I carry when travelling, at least as much as I can) . As well as powering the Makita battery charger my 350w Victron inverter gets regular use charging my laptop, my phone & my wife's iPad, plus camera batteries & stick mixer/blender thingo. Probably other things too occasionally. I know that some of these things can be powered from 12v, but having both 12v & 240v available does offer greater flexibility.

Both ways of charging Makita batteries will work, & both solutions offer different things.

'Ya pays ya money & takes ya choice' according to what fits best for you.

Heat can also cause the circuit breaker to trip while being used if it's mounted under the bonnet or in an alloy canopy that's not insulated.

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Yes Batt's, ambient temperature is one of the influencers of thermal-type circuit breakers. It applies to fuses also. Which is why some allowance is incorporated in the rating of these devices. I would avoid under-bonnet applications of thermal-type circuit breakers.
Consumer grade circuit breakers are generally less reliable devices than fuses, but do have the convenience of serving as manual isolators as well as current limitation.
In industrial applications where accurate current limitation is required, more sophisticated devices are employed.

Allan, your reply to Batts led me to reminding myself as to what type of circuit breakers I fitted to protect the circuits in the aluminium canopy on our car (It was a number of years ago I set it up & couldn't be certain - only that they were made by Blueseas). They are Magnetic Hydraulic breakers which I believe are more accurate/reliable than thermal types? I use them as switches, only turning on circuits when needed.

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Hi Cuppa,

Yes, magnetic-type circuit breakers are not as affected by ambient temperature are thermal type. The "hydraulic" refers to a damping mechanism to avoid nuisance tripping due to brief overcurrents. Blue Seas are good products. Thermal breakers achieve damping inherently.

Both circuit breakers and fuses achieve current limitation in cases of dramatic short-circuit. However circuit breakers are more appropriately employed where overloads, typically caused by excessive electrical or mechanical burdens, may need to be interrupted yet conveniently reset to continue operation. Fuses do not offer this convenience.
And of course breakers can also function as combination overcurrent and switching devices. However, using them as primarily switches is expensive. Suitable switches are available at lower cost.

Yes, expensive if just for switching, but if they have the switching ability & all the breakers are in the same place it makes for easy use. I do have a couple of light switches for individual lights in different places, but leave the most used one switched on & just turn the circuit on/off most of the time, occasionally flicking another switch if more light is needed.

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Sorry Cuppa, I didn't mean to be critical of your using CB's as switches. In fact I have done the same for reason of uniformity on the panel. I did however use a rotary/cam type 200A isolator switch for my main 12v switch which has a removable knob. I don't want the inquisitive apprentice fiddling with my system when the vehicle goes for service. Not LOL!

Allan, the written word can be a funny thing, I didn't for a moment perceive you as having been critical, so no apology needed. I like the thinking about the removeable knob. Wish I'd thought of that when I was building ours.

18 years ago, I used 240VAC circuit breakers to protect the 12VDC wiring in the OKA.
If you read the fine print, 240VAC CBs are rated to 48V DC, they have top quality silver contacts (so arcing is unlikely to be an issue) and they cost under $10 up to about 60A. They are also available from the local hardware store.
They do take longer (x root 2) to break at overload compared with AC.
At the time, it was difficult to assess the quality of DC CBs (still is),, but there are pretty good standards applying to the high volume AC stuff.
I use them as occasional switches on stuff like pumps for isolation purposes, but do try to avoid switching under load.
Cheers,
Peter
OKA196 motorhome

"With the car running during this testing holding 14.2V" is the alternator voltage and tells you nothing about the battery.
Cheers,
Peter
OKA196 motorhome

Nick, the fault lights on the Makita Battery Chargers can be caused by a number of different conditions. One is that the battery is too hot, another is that the battery charger is too hot, and another is low input voltage. Not saying that this is the issue in the case you have described, just that these are some of the reasons for the fault lights.

Macca.

Macca : it was my guess that the voltage was to low from a bad anderson connection & the other possibility weren't in play imo . Cheers

Peter : not sure what you mean ?