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Updated : 2/02/2018.   

                            

 

"I would like to thank you once again for the excellent and prompt service you gave to me when I travelled to North Wales. The repairs to the Schaudt Elektroblock EBL 271 unit certainly saved my holiday to Spain, the Ferry had already been booked for that weekend.
I just wish that all companies were as friendly and efficient as yours.
Vernon"
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            Which are the cheapest Motorhome Habitation Batteries?


                      WE DO NOT SELL ANY BATTERIES, THIS IS INDEPENDENT ADVICE



15 years ago, when Lucas was a quality brand, most Leisure Wet Acid batteries were pretty much the same technology. 

These days the best manufacturers have adopted advanced technology, the Budget Battery manufacturers just don't have the the same R & D budget. 

Technology has changed so much in the last few years, that the very best Leisure Wet Acid batteries have exceptional qualities that could not be dreamt of 5 years ago.

Budget batteries are generally poor quality versions of outdated 1980's technology.  

Those batteries that have adopted new technology can last twice as long as a conventional battery, yet cost cost less.



There is a Habitation Area battery that stands above all others yet is only slightly more than the budgets, £95 (November 2017). 

The reason it is like no other is because the advanced technology is Patented, no one can copy it's very special technology which is called 'Powerframe'.

Johnson Controls build two identical batterry ranges on the same production line, one labelled as Varta LFD and the other built for Bosch : the Bosch L series. 

The Bosch  L version often has a better guarantee and different marketing, but it's specification is identical to the Varta LFD.


They are Wet Lead Acid batteries, so operate with ALL existing chargers and Alternators. They have some special details inside the battery that makes them more appropriate to Motorhome and Caravan use than any other battery in the up to £150 price range. The production process uses 20% less energy than a conventional battery so it costs little more than the usual poor quality 'Leisure' batteries.


Although the Bosch and Varta batteries are identical, Bosch take a different marketing angle so label theirs Deep Cycle L5 Leisure batteries. Varta describe theirs as Dual Purpose LFD Starter/Leisure batteries. Despite the different marketing approach, they are physically identical and both able to Deep Cycle and start a Truck engine. Both use the Patented Powerframe Technology.


They have unique technology inside that results in higher performance than almost all other Lead Acid batteries : longer life, greater real power, more efficient with faster charging times. They can harge up to twice as fast as conventional batteries and they don't self discharge or vent ANY Gas or fluid. 

These are safer inside the habitation area than a Gel or AGM battery.




So why is a Varta LFD90 and the Bosch L5 so special?



A conventional battery starts to corrode internally from the moment it is used, as in the photo on the left above. Corrosion, some times called Grid Growth, acts as a barrier to current flow. Plate Corrosion also causes 'Paste shedding' which can result in a battery Self Discharging faster than normal.

Where corrosion has usually taken place, so has Fluid loss. The two go hand in hand in most wet batteries, rapid fluid loss equals rapid corrosion.

 

You can see from the photo on the Right that Powerframe technology reduces this Corrosion to zero levels, which also means zero fluid loss. It endows the battery with higher efficiency than anything in it's class, Bosch/Varta claim upto 70% better electrical flow as the batteries age. 

Bosch claims very high charge acceptance. It is one of the fastest charging batteries around on conventional Alternators and mains chargers. 

In the average Motorhome, it charges even faster than an AGM, yet the Varta/Bosch Powerframe doesn't suffer the AGM's charger intolerance, temperature issues and resultant short life.


The lack of Corrosion/Grid Growth also means that the normal loss of adhesion by the Lead Paste is reduced, so there is also less 'Paste shedding'. Therefore the battery AH Capacity does not deteriorate to the extent other batteries do, performing closer to maximum Ah capacity for longer, right up to end of life. 


The advanced, Patented Powerframe Technology means fluid loss will not even occur at the higher temperatures and voltages that would have an AGM/Gel battery gasping out dangerous Hydrogen and Oxygen.  

When extreme temperatures/voltages/currents are reached, and AGM/Gel batteries are expelling Gas, a Powerframe batteries construction is such that even under these conditions the Hydrogen and Oxygen is contained and returns to the cells as Water. 

Even under adverse conditions, a Powerframe Battery doesn't Gas or lose fluid, unlike Gel or AGM. 

 

The Powerframe high Silver content further adds to battery efficiency at both High and Low temperatures. The Bosch L5 Deep Cycle battery will start a big truck engine in freezing conditions and last longer and perform better than most batteries in hot Desert temperatures.      

This technology also has very, very low self discharge rates. 

Put a perfect one in the Shed in October and it will still be near full charge in March. Although an interim 3 month charge is strongly recommended.



So How Does It Manage To Be So Good?

The special Silver Alloy Grid is manufactured using a 'Rolling' process, not Stamped or Pressed, which changes the molecular structure of the metal resulting in it becoming highly corrosion resistant. 

This combination of the Silver Alloy (Silver is a very efficient electrical conductor with exceptional anti-corrosion properties) and the Rolling process makes a huge difference to the way it behaves. There are several other clever manufacturing touches, but the Powerframe Silver Alloy Grid is the key. 


This resistance to corrosion not only improves battery efficiency, but when corrosion is the primary cause of Wet Acid battery failure, battery life is also dramatically improved over a conventional battery. 

See the chart below from a battery Lifetime study of thousands of batteries showing that 86% of Wet Acid batteries go 'End of Life' from Grid Corrosion as the primary cause of failure.

If you take Corrosion damage out of the equation, you have the potential for one very long life battery where the actual cycle life of the battery will determine it's replacement, not some other side issue :


Two other things you might note about the above chart -

1. That AGM and Gel (VRLA) suffer slightly less from Corrosion, but it still destroyed nearly 60% of all AGM/Gel batteries in the survey 


2. That 30% of AGM and Gel batteries died from 'drying out'. Remember hearing the myth that Gel and AGM's never Gas or lose fluid? 

Together 'Dry Out' and Corrosion accounted for the destruction of 92% of all AGM/Gel batteries. 


So not only does Powerframe technology address the primary forms of battery failure, like Corrosion, Fluid Loss, etc but endows it with efficiency streets ahead of anything else. Efficiency that lasts right to EOL. 


You don't believe a Powerframe battery will never Gas or lose fluid?


The graphic below from the Bosch website shows the 'Special Lid Structure' that prevents fluid loss outside the battery making it 100% gas tight. 

We quote from the Bosch page : 

"...Labyrinth construction ensures that evaporated liquid remains in the battery. This makes the battery 100% maintenance free, as well as leak-proof and tilt-proof. The Central ventilation opening (as in linking the cells, not as in 'to the atmosphere' ) means it is suitable for installation inside the passenger compartment".


Note how they are so confident they say, "it is suitable for installation inside the passenger compartment". 


Full extract here :





The above Bosch web page twice states "100% Maintenance Free" and  "evaporated liquid remains in the battery". 

Despite all the above some people still compare Powerframe batteries it to a conventional Wet battery when it really, really isn't. Even battery retailer sales teams rarely have a clue how special this battery technology is.


This battery is safer to use inside the habitation area of a Motorhome/Caravan than even a Gel battery. 

 

The Bosch PDF, available further down the page, states : 

PowerFrame® technology

▶ PowerFrame®: flow optimized grid design for optimum current flow, reduced corrosion and a long service life

▶ Maximum safety through double backfire protection

▶ No leakage of the acid thanks to the sealed design of the battery lid

▶ Absolutely maintenance free

In the notes of the same document it states :

Labyrinth lid : returns condensed water to the battery.




More evidence to back up Powerframe capability :

Extracted from the Varta website : 

Greater efficiency, up to 70% improved current flow, longer life, more power, faster charging, extreme temperature operation, etc.

     



Primary benefits of a Varta LFD90 and Bosch L5 over other batteries in the up to £150 price range are : 

Low self discharge : Stays highly charged up for 6 months +. Varta claim a 12 month shel life, but regard that with caution?


High efficiency : Up to 70% better current flow over a similar age older battery. 


Very Low internal corrosion : This makes it more efficient than the opposition, especially after 2 years +. 


Long life and strong performance right to End Of Life


Maintenance free : Zero fluid loss (so as safe inside the MH as Gel/AGM battery, see evidence below), actually safer, as the LFD is less likely to explode than either Gel or AGM.


Low cost : It's production uses 20% less energy, so it costs less than it's technology would normal merit., 


Faster charge up : Upto twice that of a budget 110Ah battery. See more below on "110Ah Budget batteries". 


Lightest load on a charger of any battery technology : Significant from our point of view, they place a lighter load on the battery charging systems, both Mains 230v and the Alternator.


Exceptional high/low temperature operation rangeTo support this claim of high temperature tolerance, we publish this image below showing a Varta Silver/Bosch Silver Powerframe lasting more than twice as many miles as ordinary batteries in Desert conditions :


 


We can't verify the above tests validity in Desert conditions, but 95,000 miles versus 41,000 miles is a ratio greater than 2 to 1. In other words, at an annual mileage of 10k, a Varta Powerframe starter battery lasts 9.5 years versus just 4 years for a conventional battery in exceptionally punishing conditions.

We think, strong evidence that the Varta LFD90/Bosch L5 will not only out last a conventional wet habitation battery by a big margin, but do so when used in the Desert like conditions of Morroco

Some budget Leisure's struggle with a Summers day in Brighton. 



The LFD90 is the same physical size as the Leisure Exide G80 so fits most locations on most Motorhomes and Caravans. 

It is also the same size as that fitted as the Starter Battery of most Fiats, Mercs and Renaults from 2000 to 2017.



Because the LFD90 is also designed to start an Engine, it copes with a short duration high current draw. It is better suited for powering a Motor Mover on a Caravan (some of which can draw over 140amps from the battery) more than almost any other battery. 

However, even an LFD90, AND the Mover Electric Motors, should be rested for 1 minute for every three minutes of use of a powerful Motor Mover setup.



Where to buy a Varta LFD 90/Bosch L5?


This company below sells the LFD90 at around £95, it is a small business with limited stock space so you can be sure the battery has not lost half it's life from sitting on the shelf for months. They can deliver to your door and because the Varta LFD 90 is so well sealed it travels better than most wet batteries. 

However be warned the 'Sales Team' appear to have a brief to sell batteries with the highest profit margin, not those that are the best. They push quite hard their own label batteries, saying they are as good when they are not half the battery the Varta is :


Tayna batteries - https://www.tayna.co.uk/  -  01745 823399


Battery Mega store is another good source with a high turnover of Varta Batteries so they should also be 'fresh'. Again watch out for the Sales team pushing higher profit margin, poorer quality batteries. 

Which is better for a battery Sales Team : To sell you a battery that lasts a long time so you won't be back for more than 5 years, or a poor battery for similar cost that brings you back inside 2 years?




How can the Varta LFD90/Bosch L5 wet batteries be safer inside the Motorhome than a Gel battery?

                  Because :

                        1. it does not Bubble, but should that occur, the fluid condenses back to Water, remaining inside the battery.

                        2. Gel and AGM batteries operate under pressure, the safety valve can, and does, fail causing explosion.   

                        3. See the section near the bottom of the page on Battery Explosions and Thermal Runaway.

                         

AGM batteries used in the Motorhome environment where an AGM optimised charger is rarely available, have a higher premature failure rate and a higher risk of explosion. See top of the "Long Term EHU" webpage for the email from Sarah if you think that is rare.


Note that Gel, like all VRLA batteries, can have a higher 'resting', or 'start' voltage which affects the 'guide' discharge voltage. If you look at the chart below from Yuasa Batteries, a VRLA/Gel battery is 50% discharged at 12.5v, whereas a conventional battery is 50% discharged at 12.1v. 


We suggest you use the Sealed VRLA graphic above as a guide to the discharge level for a Varta LFD/Bosch L5 battery as they have a resting voltage nearer to that of Sealed/VRLA and their characteristics are more on par with a VRLA than a 'conventional' battery.  

You will find many different charts around, but most seem to be based on redundant technology Antimony based batteries, which fell out of favour in the eighties. 

A battery 'State of Charge' chart that doesn't recognise that different technology batteries have different voltages, is clearly out of date. 

A Customer who brought his own LFD90's for us to fit had charged them at home for 24 hours the week before.

When they arrived with us they were showing 12.88v, and once charged/discharged a few times (most batteries only reach their peak after 20 - 30 charge/discharges)  typically reach 12.95v, very close to that of Gel and AGM VRLA batteries.



The chart shows just how different this battery is in REAL use :

If you look at the chart above, you will note that the VRLA/Powerframe column has a voltage range of fully charged to discharged of 13.0v to12.0v. A full 1volt range. The chart shows a Yuasa Conventional batteriry has only a 0.8v range from 12.6v down to 11.8v. Remember this is a Yuasa chart of Yuasa quality batteries, don't expect a Numax Battery to perform as well as a Yuasa Conventional battery.


Not only does this suggest a Powerframe LFD 90 is a more usable battery, but when 50% discharged they have almost the same voltage as a fully charged conventional Lead Antimony battery!!  

A HALF discharged Varta Powerframe LFD 90 is 12.5v and a FULLY charged QUALITY conventional battery is 12.6v.

That is useful higher 'voltage' when it comes to Diesel heating, which can  draw so much start-up current it can cause significant voltage drop. Likewise some TV's that require a minimum voltage, will run better on a Varta/Bosch Powerframe.


If nothing else, this demonstrates that the LFD90/L5 is no ordinary 'wet' battery, it's efficient technology translates to real World, visable voltage improvements. 




That is all very well, but a 90Ah battery is too small for me, I like 110Ah batteries?               

          

Why you should think twice about 110Ah batteries?

When a battery is constructed there are choices that have to be made on Capacity versus Durability. For Deep Discharge strength the plates have to be stronger, this takes up more space effectively reducing the Plate 'capacity'. 

Generally (very broad brush generalisation for Lead batteries) the greater the durability that is required, the lower the battery Ah capacity.  


For example the very durable long life Exide G80/ES900 is an 80Ah battery at the physical size of L-353mm, W-175mm, H-190mm of most Motorhome battery boxes

The Deep Cycle Bosh L5/Varta LFD90 is 90Ah, again in the same physical size as a G80. 

The Banner Energy Bull is 100Ah in the same physical package 

The similar physical sized budget Lion leisure is a 110Ah battery. 


So if you are looking for a tough Cycling battery, be cautious about batteries claiming 110Ah in this size, unless it uses some very special technology. We don't mean it says on the label it is 'Super Heavy Duty', take the advertising with a big pinch of Salt. Especially avoid the 'Calcium' batteries being advertised as some kind 'of new technology', they are Shallow Cycle batteries unsuited to Habitation Area use. 


Ask yourself why Bosch, Exide, Varta, Yuasa, Banner, etc. don't make a 110Ah battery in the above size of  L-353mm, W-175mm, H-190mm

Yet all the 'budget' battery manufacturers 'favour' this capacity in this size.


When we were cutting open batteries in 2012/2013, the budget 110Ah batteries all showed poor quality construction and significant signs of failure. They might start off at 110Ah (although there has been much discussion that the batteries are 'overcharged' to artificially boost their capacity prior to testing) but we would suggest their 'real' capacity drops below 110Ah very quickly once it is used. 


The evaluations of batteries we dissected in 2012/2013 led us to conclude, they are so poor, that if a Battery Retailer offers you a 110Ah, it is because of the profit margin he makes, not because he thinks they are any good. 


If you find a battery retailer, from the biggest whoilesalers, to the smallest Motorhome or Caravan Dealer, selling, Varta/Bosch batteries then we would suggest their attitude is biased towards the customer, not just pure profit.

 

We don't sell any batteries, this is as independent as it gets. And no I don't have any links with Varta!!. 

If the new Exide Carbon Boost Battery technology developments advance as we suspect, we may be switching our advice to that technology. 

We will always publicise what we think is the best habitation battery, we have no allegence to anyone. 

  





Lead Crystal Batteries?


We would advise caution in regard to buying Lead Crystal batteries as the very technology inhibits the heat transfer that develops whenever any battery is used. Therefore it's use may be severly limited by this restriction to an even greater degree than the poor performing Gel or AGM.

The marketing blurb states : 

"A unique micro-porous high absorbent mat (AGM), pure lead plates, safe SiO2 electrolyte solution that solidifies into

a white crystalline powder when charged/discharged"


They also require special battery chargers/Alternators, see this below from the Blurb, which took me some time to find on the Betta website as it's not covered at all on the usual marketing pages :  

"Our patented Lead Crystal® Batteries have different charge characteristics compared to conventional lead based batteries and therefore need suitable chargers to function optimally. The Lead Crystal chargers are embedded with optimized micro-processor controlled charging algorithms that ensure correct charging of all Lead Crystal® Batteries".


Note that failure to use of one of their special chargers will almost certainly invalidate the Warranty and definitely cause the battery to underperform.

How you would integrate one of these chargers with something like a Sargent EC325, EC328, etc. and still have the charging information displayed on the LCD unit above the door would be a complex puzzle for someone. As it would be for most Power Controllers where the charger is integrated into the entire Power control/Distribution unit. 



Note that despite a claimed 8 - 10  year life, the warranty is just 3 years, less than some poor quality budget batteries.

In any case the warranty is pretty much useless as the battery has to have failed to the point were it is absolutely devastated beyond scrap before you can even think of making a claim, see this extract :

"Betta Batteries will replace a battery if, when used within its parameters, the available capacity falls to a level lower than 40% in 10 hours under no load within 18 months, or if the capacity falls lower than 30% in 10h under no load within 19 to 36 months.

The guarantee will be null and void in the event the battery is installed incorrectly, misused, used or (dis)charged outside specifications, damaged by external influences".


In other words the battery has got to be so bad that when standing idle the warranty will only be valid if the battery leaks 60% of it's capacity in just 10 hours!!

I would guess that to get to the position of making a claim, you would need to continue using the battery long after it was past it's best to the point it will have already damaged the Alternator and mains charger.

Can you imagine still even thinking of using a battery that self discharges to flat in 10 hours when not even being connected to the vehicle, let alone being used!! 

To me that is a warranty designed so noone can make a claim. Add in the very short warranty period and that doesn''t suggest to me that the manufacturer thinks it will have a long trouble free life, does it? 


So anyone trying out this new technology who thinks the Warranty provides a 'cushion' if things go wrong, might be a bit disappointed. 

 

Not a confidence boosting start when considering such an expensive battery,  £272 for a very small 35Ah battery and around £450 for a 100Ah battery?. 


Expect very short life, and under capacity, if you use it without the special charger.


We would suggest that you let others test drive this technology and wait a few years to see just how it lives up to the claims of both usage and warranty. 





BATTERY EXPLOSION + TOPPING UP BATTERIES

Battery explosion is not common, but does happen, see the email we got from Sarah at the top of the "Long term EHU" webpage.


Precautions When Checking/Topping up lost fluid and Battery Explosions 

 According to PREVENT BLINDNESS AMERICA, nearly 6,000 motorists suffered serious eye injuries annually from working around car batteries. We know in the UK what horrific injuries 'Battery Acid on the face' can cause.


While rarely fatal, each year battery explosions cause tens of thousands of eye and burn injuries from battery acid globally.

We can't find any similarly good advice from a UK source so we publish this US based guidance :


PREVENT BLINDNESS AMERICA write :

"Be especially careful when topping up the fluid in a battery,. Hydrogen and Oxygen may be released the minute you unscrew the top. Hydrogen is explosive in just a 4% mixture with Air.

Before topping up a battery, turn off the 12v power and EHU, ensure the battery is not being charged. 

Ideally top up the battery after it has been standing unused for a week when the explosive Gas has had time to disperse. 

Take great care not to make Sparks, by undoing/re-attaching a battery clamp during/after the Top Up process. Ventilate the area well before starting the Check/Top-Up procedure.


Ensure the battery is a wet battery, some AGM batteries have seemingly removable caps which should never be removed.

If it is a Wet Acid battery meant to have maintenance, undo the Battery Caps. If the battery does not have battery caps then it is probably not meant to be topped up so seek advice.

Shine a torch down into the Battery and check the electrolyte is at least covering the Plates. Some batteries have min/max marks which should be used, if available.

If the Plates are visible it is likely the battery has suffered damage.

Add distilled water, or at least de-ionised water. Tap water can shorten the batteries life by years.

Note exactly how much water you need to add as this will be a guide to how often you need to check the battery, but also a guide to the likely damage if the Plates were visable. 

If you need to add significant water to cover the Plates, we would suggest you consider battery replacement. At the very least, monitor the battery carefully and check it more regularly. Also monitor the charging voltages of all the charging systems, Alternator, Mains, Solar, etc to ensure they are all within specification.  


A less common form of battery explosion occurs when the battery is subjected to high temperatures while charging causing thermal runway in AGM or Gel batteries.

Should a battery explosion occur and battery electrolyte (battery acid) gets in the eyes, flush with any drinkable liquid immediately because SECONDS count, continue flushing with water for at least 15 minutes, and seek immediate medical attention. 


In addition, neutralize residual battery acid in the area around the incident, by thoroughly washing the area with a solution of one-pound baking soda (bicarbonate of soda) to one gallon of warm water and rinse thoroughly with water".



Better still, only use a 100%, Absolutely Maintenance free battery that does not lose fluid so does need topping up.



 




Example battery types and sizes:


The Varta LFD90 is L - 353mm W-175mm H-190mm, Capacity 90ah, MCA 1,000A, CCA/800A, Cost about £95  


The smaller Varta LFD75 is 278mm long, 175mm wide, 175mm high. 12V, capacity 75Ah, cold test current 650A (sometimes called cranking amps).  

Note that the Exide ES900 and the older G80 Gel batteries  are 353 x 175 x 190 (incl. terminals) so a match for a 90Ah Varta LFD90  (information courtesy of David Chambers).

Note 2 : The Varta LFD 90 and Bosch L5 make a better Starter battery than almost any other battery when used in a Motorhome. Motorohome Starter batteries tend to discharge lower when idle for weeks at a time than most Starter batteries are designed for. A load the Varta LFD 90 is designed for and surprisingly they are more powerful than many dedicated Starter batteries, especially during the freezing conditions on mid Winter.

The size matches most Fiat, Renaults, Mercs made after 1999, direct swap for the OEM Starter battery.


The LFD 75 Silver is a perfect replacement for Ford Transit Silver starter batteries, more powerful than the originals at half the cost of a Ford OEM battery. 



bosch brochure 2014.pdf bosch brochure 2014.pdf
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A cautionary warning about industry 'Battery tests' 

A cautionary warning about "Industry 'Battery tests" as they can be quite misleading in relation to a Motorhomes true battery condition.

Bear in mind that while we probably know more about batteries than many, battery test units are not our speciality as we don't think there is a better battery test than carrying out your own, see bottom of page for details.

However we will try and give a run down on what we know of the battery testing tools, their strengths and weaknesses, in laymans terms. Perfectly happy to be corrected by those specialists in this area.


There are three common test units. The first is the old fashioned 'Drop Tester' which places a huge load on the battery to see how it handles that load. 


These are becoming less common as they can stress the battery, sometimes resulting in a damaged battery that was previously good, especially a leisure battery. 

The second type of tester is a small electronic device that attempts to 'guess' the batteries state by checking it's resistance and voltage then making an assessment based on what it finds. The technology is more complex than this simplified explanation. 

 
The third, and more expensive type, places a set load on the battery (not as stressful as the old Drop Tester) and monitors what power the battery actually delivers plus other parameters. They usually also use this data in association with a battery resistance/voltage check. These are very expensive so less common.


The problem with the old fashion car battery Drop tester is the stress it places the battery under. They were designed for Starter batteries so assumes the battery is from a Car/truck and so designed to deliver the big currents drawn by a Starter Motor for Starting an Engine. 
Clearly a Motorhome Leisure/Habitation area battery isn't designed to do that, they deliver small current over long periods of time so a demand for a large current won't do a habitation battery any good. 
It may pass the test but have suffered internal damage that will show up later.. 

Suggest you never let anyone 'Drop Test' a pure leisure battery, especially if it is less than 90AH and Gel based.


The second type of tester measures battery voltage and resistance.
The resistance varies with the state of charge, not just internal degradation, which can skew the results. While they sometimes use the voltage to asceratin a batteries state of charge, few are able to cater for the different voltage ranges of the different battery technologies. 
The resistance may also vary with different forms of degradation, such as Internal corrosion, plates partially shorting, etc. So while the resistance may indicate an issue, the device can only guess at what that issue might be.
Further to that, one issue may reduce the resistance, like Antimony poisoning, while Internal Corrosion may increase it balancing each other out and showing a 'healthy' battery when it isn't.

Batteries degrade for a number of reasons and it is possible to fully charge a battery that then delivers enough power to start a Fiat 3.0, but will slowly lose charge over days/weeks.

So while the Starter battery might get a 'Pass' of 550 out of 650 'cranking amps' when tested straight after a recharge, it may be down to half that after just a week.
Such a battery is no use to many motorhomes that stand isle for long periods, but be perfectly adequate for a Car/Van.
Conversely a battery could be down to 60% of it's power delivery yet hold it's charge for months.


The third type of battery tester that adds a 'small 'load' just prior to the resistance check, can be more accurate, but is still flawed.


All the test units check primarily for the 'instant' power a car/Van/truck Starter battery can deliver, as this is the most important factor for the vast majority of vehicles that are used every day.

But a Motorhome Starter battery can be used very differently, standing idle for many weeks and where it's ability to hold capacity, is a more important factor.
Just as it is for most Habitation batteries.

Hence why conventional car battery testers are flawed for Motorhome owners. 



Testing your own Starter and Habitation batteries:

In my opinion, you can't beat your own test of fully charging a battery, leaving it for 2 weeks (to test it's ability to hold a charge), then placing a known small load to see what it's capacity is (to test it's how many Ah it can deliver).

However, it is VERY important not to discharge the battery in the test below 50% Depth Of Discharge (DOD) and the voltage you need as guidance will vary according to the batteries Technology.

A conventional battery will be 50% discharged at about 12.1v, a Gel battery at 12.5v and a Lead Acid Powerframe battery, like the Bosch L5/Varta LFD90, very close to the Gel voltage range.
See chart below :



You can see from the chart that taking a quality technology battery down to a conventional batteries 12.1v will discharge it more than ideal, likely to seriously shorten it's life by up to a third. 
Taking a Gel or Powerframe battery down to 12v, or below, can result in up to half the life being lost. 

While the range of Automotive/Habitation batteries we use are regarded as '12v', the majority of quality batteries are now 13v, and why an old fashioned 13.8v charger is far less effective than it was in the 1970's when even the best batteries were nearer 12.5v. 
If you 'upgrade' from a conventional battery, check your charger is up to the job.